JP2019026189A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire capable of securing uneven wear resistance and chain hooking property, and reducing noise.SOLUTION: A pneumatic tire comprises on a tread face 3: plural circumferential main grooves 20; plural lug grooves 40; and plural land parts 10. Out of the plural circumferential main grooves 20, the circumferential main groove 20 arranged on an outermost side on a tire width direction is a shoulder circumferential main groove 20, and out of the plural lug grooves 40, the lug groove 40 which is arranged on outside in the tire width direction of the shoulder circumferential main groove 22 and opened to the shoulder circumferential main groove 22 from outside of the tire width direction is a shoulder lug groove 42, and at the time, the shoulder lug groove 42 has first lug grooves 70 and second lug grooves 80 whose groove depth is different, and the groove depth of the first lug groove 70 is deeper than that of the second lug groove 80, and the first lug grooves 70 and second lug grooves 80 are alternately arranged in the tire circumferential direction.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire.

  In pneumatic tires, a plurality of grooves are formed on the tread surface for the purpose of draining water between the tread surface and the road surface when traveling on a wet road surface. It becomes the cause of. For this reason, in many pneumatic tires, a plurality of pitch lengths, which are intervals between adjacent grooves in the tire circumferential direction, are set, and a plurality of types of pitches are appropriately combined on the tire circumference to be generated during vehicle travel. Reducing noise.

  However, when a plurality of pitch lengths are set, a plurality of types of sizes of blocks divided by grooves are set. If the block size is different, the rigidity of the block will also be different, so the level of ground contact characteristics during tire rolling will also be different, leading to a decrease in steering stability and uneven wear resistance. For this reason, some conventional pneumatic tires are designed to suppress a decrease in steering stability and uneven wear resistance when a plurality of pitch lengths are set and the rigidity of the block differs according to the pitch length. is there. For example, in the pneumatic tire described in Patent Document 1, the small pitch portion and the large pitch portion are formed by making the groove depth of at least a part of the lateral groove of the small pitch portion shallower than the groove depth of the lateral groove of the large pitch portion. The rigidity difference of the block is reduced, and the level fluctuation of the ground contact characteristic during tire rolling is suppressed.

Japanese Patent Laid-Open No. 11-78425

  Here, the vehicle may travel on a snowy road surface in addition to a dry road surface or a wet road surface, but when traveling on a snowy road surface, a tire chain is attached to a pneumatic tire to ensure traction performance. You may travel with the The tire chain is mounted so as to cover the tread surface of the pneumatic tire, and a part of the chain is caught in the groove, thereby suppressing a relative shift in the tire circumferential direction between the pneumatic tire and the tire chain, It is possible to transmit driving force and braking force between the two. However, if the groove depth of the lateral groove is reduced in order to reduce the rigidity difference of the block, the chain hooking property, which is easy to hook the chain into the groove, is reduced, and the pneumatic tire and the tire chain are not easily Therefore, there is a possibility that the shift is likely to occur and it is difficult to transmit the driving force and the braking force.

  On the other hand, when the depth of the groove is increased in consideration of the chain hooking property, the rigidity of the land portion tends to decrease, and therefore, there is a possibility that uneven wear is likely to occur. For example, when the depth of a so-called lug groove, which is a groove extending in the tire width direction, is increased, heel and toe wear may easily occur. Further, in recent years, there is a demand for reduction of passing sound emitted from the ground contact area of the pneumatic tire when the vehicle is traveling. Passing sound tends to increase when the tread surface comes into contact with the ground when the tread surface passes through the lug groove extending in the tire width direction to the outside in the tire width direction. There is a risk that this passing sound will increase. As described above, it has been extremely difficult to achieve both chain hooking properties and uneven wear resistance and to further reduce noise.

  The present invention has been made in view of the above, and an object of the present invention is to provide a pneumatic tire capable of reducing noise while ensuring uneven wear resistance and chain hooking property.

  In order to solve the above-described problems and achieve the object, a pneumatic tire according to the present invention is formed on a tread surface, and is formed on the tread surface with a plurality of circumferential main grooves extending in the tire circumferential direction. A plurality of lug grooves extending in the width direction, and a plurality of land portions defined by at least one end in the tire width direction by the circumferential main groove, and the tire width direction of the plurality of circumferential main grooves The circumferential main groove located on the outermost side is a shoulder circumferential main groove, and among the plurality of lug grooves, the shoulder circumferential main groove is located on the outer side in the tire width direction with respect to the shoulder circumferential main groove. When the lug groove that opens from the outer side in the tire width direction is a shoulder lug groove, the shoulder circumferential direction main groove and the shoulder are on the outer side in the tire width direction of the shoulder circumferential direction main groove. A shoulder block row in which shoulder blocks, which are the land portions defined by the lug grooves, are arranged in the tire circumferential direction is disposed, and the shoulder lug grooves have a first lug groove and a second lug groove having different groove depths. And the groove depth of the first lug groove is deeper than the groove depth of the second lug groove, and the first lug groove and the second lug groove are in the tire circumferential direction. It is characterized by being arranged alternately.

  In the pneumatic tire, of the plurality of land portions, one end of the land portion adjacent to the shoulder circumferential main groove from the inner side in the tire width direction is open to the shoulder circumferential main groove, and the other end. However, it is preferable that a third lug groove, which is the lug groove that terminates in the land portion and has a groove depth shallower than the groove depth of the first lug groove, is provided.

  In the pneumatic tire, the first lug groove, the second lug groove, and the third lug groove may be configured such that the second lug groove is from a position at which the first lug groove opens in the shoulder circumferential main groove. The distance in the tire circumferential direction to the position where the shoulder circumferential main groove opens is L12, and the first lug groove is the shoulder circumferential main from the position where the third lug groove opens in the shoulder circumferential main groove. When the distance in the tire circumferential direction to the position where the groove opens is L13, the relationship between the distance L12 and the distance L13 is preferably in the range of 0.2 ≦ (L13 / L12) ≦ 0.8. .

  In the pneumatic tire, the land portion where the third lug groove is provided has one end opened in the circumferential main groove defining the inside of the land portion in the tire width direction, and the other end in the land portion. A fourth lug groove that is the lug groove that terminates is provided, and the third lug groove and the fourth lug groove are alternately arranged in the tire circumferential direction. By being provided, it is preferably arranged in a staggered arrangement.

  In the pneumatic tire described above, the distance in the tire circumferential direction of the opening position of the third lug grooves adjacent to each other in the tire circumferential direction to the shoulder circumferential main groove is L33, and the third lug grooves adjacent to each other in the tire circumferential direction. And the fourth lug groove, the distance in the tire circumferential direction between the opening position of the third lug groove to the shoulder circumferential main groove and the opening position of the fourth lug groove to the circumferential main groove. In the case of L34, the relationship between the distance L33 and the distance L34 is preferably in the range of 0.3 ≦ (L34 / L33) ≦ 0.5.

  In the pneumatic tire, the second lug groove is a bend at which the groove width changes within a range of 40% to 60% of the width of the shoulder block in the tire width direction from the end in the tire width direction. And the groove width is constant from the bent part to the inner side in the tire width direction, and the groove width increases from the bent part to the outer side in the tire width direction toward the outer side in the tire width direction. The groove depth of the second lug groove in the region from the position of the bent portion in the second lug groove to the end on the outer side in the tire width direction is D21, and the groove depth of the third lug groove is D31, When the groove depth of the fourth lug groove is D41, the third lug groove and the fourth lug groove are groove depths D31, D41 with respect to the groove depth D21 of the second lug groove. Respectively 0.8 ≦ (D31 / D21 ≦ 1.2,0.8 ≦ preferably in the range of (D41 / D21) ≦ 1.2.

  In the pneumatic tire described above, the first lug groove has a smallest groove width at a portion located within a range of 40% to 60% of a width of the shoulder block in the tire width direction from an end portion in the tire width direction. When the groove width W11 is set, the relationship between the groove width W12 at the outer end in the tire width direction and the minimum groove width W11 is within a range of 1.3 ≦ (W12 / W11) ≦ 1.7. preferable.

  In the pneumatic tire, the second lug groove has the smallest groove width in a portion located within a range of 40% to 60% of the width of the shoulder block in the tire width direction from the end in the tire width direction. When the groove width W21 is set, the relationship between the groove width W22 at the outer end in the tire width direction and the minimum groove width W21 is in a range of 1.1 ≦ (W22 / W21) ≦ 1.5. preferable.

  In the pneumatic tire, the first lug groove and the second lug groove are groove widths within a range of 40% to 60% of a width of the shoulder block in the tire width direction from an end in the tire width direction. Each of which has a bent portion, and the groove width is constant from the bent portion to the inner side in the tire width direction, and the outer side in the tire width direction from the bent portion toward the outer side in the tire width direction. The groove width of the first lug groove in the region from the position of the bent portion in the first lug groove to the outer end in the tire width direction is defined as D11, and the second lug groove When the groove depth of the second lug groove in the region from the position of the bent portion to the outer end in the tire width direction is D21, the groove depth D11 of the first lug groove and the second lug groove With groove depth D21 Engagement is preferably in the range of 0.2 ≦ (D21 / D11) ≦ 0.5.

  In the pneumatic tire, the first lug groove and the second lug groove have a relationship between a maximum groove depth D15 of the first lug groove and a maximum groove depth D25 of the second lug groove of 0. 0. It is preferable to be within the range of 1 ≦ (D25 / D15) ≦ 0.5.

  In the pneumatic tire, the first lug groove and the second lug groove are grooves at a position of 20% of the width in the tire width direction of the shoulder block from the inner end in the tire width direction to the outer side in the tire width direction. The depth is within a range of 1 mm or more and 5 mm or less, and the first lug groove is a groove at a position of 20% of the width of the shoulder block in the tire width direction from the end on the tire width direction outer side to the tire width direction inner side. The depth is within a range of 6 mm to 15 mm, and the second lug groove is a groove at a position of 20% of the width of the shoulder block in the tire width direction from the outer end in the tire width direction to the inner side in the tire width direction. The depth is preferably in the range of 1 mm to 5 mm.

  In the pneumatic tire, the first lug groove and the shoulder circumferential main groove include a groove depth D12 in a region 10 mm inward in the tire width direction from an end of the first lug groove in the tire width direction, The relationship between the shoulder circumferential main groove and the groove depth DC is preferably in the range of 0.6 ≦ (D12 / DC) ≦ 1.0.

  In the pneumatic tire, the first lug groove and the second lug groove are a groove width W12 at an end portion on the outer side in the tire width direction of the first lug groove, and an outer side in the tire width direction of the second lug groove. The relationship with the groove width W22 at the end is preferably in the range of 1.1 ≦ (W12 / W22) ≦ 1.3.

  In the pneumatic tire, the first lug groove and the second lug groove are within a range of 40% of the width of the shoulder block in the tire width direction from the inner end in the tire width direction to the outer side in the tire width direction. It is preferable to have a portion where the groove depth at the same position in the width direction is the same.

  In the pneumatic tire, three of the circumferential main grooves are provided side by side in the tire width direction, and the land portion is provided by arranging four rows in the tire width direction, and among the plurality of land portions, The land portions other than the shoulder block rows are not formed with grooves and sipes that open to both of the two circumferential main grooves that define both sides of the land portion in the tire width direction. One end of each of the land portions adjacent to each other in the tire width direction across the center circumferential main groove, which is the central circumferential main groove among the circumferential main grooves, is open to the center circumferential main groove. The lug grooves each having the other end terminating in the land portion are provided, and the opening positions to the center circumferential main grooves are shifted by 10 mm or more in the tire circumferential direction between the lug grooves of the two land portions. It is preferable.

  The pneumatic tire according to the present invention has an effect that noise reduction can be achieved while ensuring uneven wear resistance and chain hooking property.

FIG. 1 is a meridional cross-sectional view showing a main part of a pneumatic tire according to an embodiment. FIG. 2 is an AA arrow view of FIG. FIG. 3 is a detailed view of part B of FIG. FIG. 4 is a detailed view of part C of FIG. FIG. 5 is a detailed view of part D in FIG. 6 is a cross-sectional view taken along line EE in FIG. 7 is a cross-sectional view taken along line FF in FIG. 8 is a cross-sectional view taken along the line GG in FIG. 9 is a cross-sectional view taken along the line HH in FIG. FIG. 10 is an explanatory diagram of the outer regions of the first lug groove and the second lug groove. FIG. 11 is a detailed view of a portion J in FIG. FIG. 12 is a detailed view of a portion K in FIG. 13 is a cross-sectional view taken along line MM in FIG. 14 is a cross-sectional view taken along line NN in FIG. FIG. 15 is an explanatory diagram relating to the positions of the first lug groove, the second lug groove, and the third lug groove. FIG. 16 is an explanatory diagram of a positional relationship between the third lug groove and the fourth lug groove. FIG. 17 is an explanatory diagram of the positional relationship between the fourth lug grooves provided on different center ribs. FIG. 18 is a modified example of the pneumatic tire according to the embodiment, and is an explanatory view when a sipe is formed on a tread surface. FIG. 19A is a chart showing the results of a performance test of a pneumatic tire. FIG. 19B is a chart showing the results of a performance test of a pneumatic tire. FIG. 19C is a chart showing the results of a performance test of a pneumatic tire. FIG. 19D is a chart showing the results of a performance test of a pneumatic tire.

  Hereinafter, an embodiment of a pneumatic tire according to the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be replaced by those skilled in the art and can be easily conceived, or those that are substantially the same.

  In the following description, the tire width direction refers to a direction parallel to the rotational axis of the pneumatic tire, the inner side in the tire width direction refers to the direction toward the tire equator in the tire width direction, and the outer side in the tire width direction refers to the tire width. The direction opposite to the direction toward the tire equatorial plane. Further, the tire radial direction means a direction orthogonal to the tire rotation axis, the tire radial direction inner side means the direction toward the tire rotation axis in the tire radial direction, and the tire radial direction outer side means from the tire rotation axis in the tire radial direction. The direction to leave. Further, the tire circumferential direction refers to a direction rotating around the tire rotation axis.

Embodiment
FIG. 1 is a meridional cross-sectional view showing a main part of a pneumatic tire 1 according to an embodiment. The pneumatic tire 1 shown in FIG. 1 is provided with a tread portion 2 at the outermost portion in the tire radial direction when viewed in a meridional section that is a section passing through the tire rotation axis in a direction parallel to the tire rotation axis. The surface of the tread portion 2, that is, the portion that comes into contact with the road surface when the vehicle (not shown) on which the pneumatic tire 1 is mounted is formed as a tread surface 3. A plurality of circumferential main grooves 20 extending in the tire circumferential direction and lug grooves 40 (see FIG. 2) extending in the tire width direction are formed on the tread surface 3. On the tread surface 3, a plurality of land portions 10 are defined by the plurality of circumferential main grooves 20 and lug grooves 40, and the plurality of land portions 10 have at least one end in the tire width direction. It is demarcated by the circumferential main groove 20.

  Both ends of the tread portion 2 in the tire width direction are formed as shoulder portions 4, and sidewall portions 5 are disposed from the shoulder portion 4 to a predetermined position inside the tire radial direction. That is, the sidewall portions 5 are disposed at two places on both sides of the pneumatic tire 1 in the tire width direction.

  Further, bead portions 30 are located on the inner side in the tire radial direction of the respective sidewall portions 5, and the bead portions 30 are disposed at two locations on both sides of the tire equatorial plane CL, similarly to the sidewall portions 5. ing. That is, a pair of bead portions 30 are disposed on both sides of the tire equatorial plane CL in the tire width direction. Each of the pair of bead portions 30 is provided with a bead core 31, and a bead filler 35 is disposed on the outer side of each bead core 31 in the tire radial direction. The bead core 31 is formed by winding a bead wire, which is a steel wire, in a ring shape. The bead filler 35 is a rubber material disposed in a space formed by folding an end portion in the tire width direction of the carcass 6 to be described later outward in the tire width direction at the position of the bead core 31.

  A belt layer 7 is provided on the inner side in the tire radial direction of the tread portion 2. The belt layer 7 has, for example, a multilayer structure in which a pair of cross belts 7a and 7b and a belt cover 7c are laminated, and a plurality of belt cords made of steel or organic fiber materials such as polyester, rayon, and nylon are covered with a coat rubber. And is formed by rolling. Among these, at least a pair of cross belts 7a and 7b have different belt angles defined as inclination angles in the tire width direction of the belt cords with respect to the tire circumferential direction, and are laminated by crossing the inclination directions of the belt cords. It is comprised as what is called a cross-ply structure.

  A carcass 6 including a radial ply cord is continuously provided on the inner side in the tire radial direction of the belt layer 7 and on the tire equatorial plane CL side of the sidewall portion 5. The carcass 6 has a single-layer structure composed of one carcass ply or a multilayer structure formed by laminating a plurality of carcass plies, and is bridged in a toroidal manner between bead cores 31 disposed on both sides in the tire width direction. It constitutes the tire skeleton. Specifically, the carcass 6 is disposed from one bead portion 30 to the other bead portion 30 of the pair of bead portions 30 located on both sides in the tire width direction so as to wrap the bead core 31 and the bead filler 35. The bead portion 30 is wound back along the bead core 31 from the inner side to the outer side in the tire width direction. The carcass ply of the carcass 6 arranged in this way is a steel cord, which is a carcass cord made of a steel material, and is formed by rolling a plurality of steel cords with a coat rubber. That is, the carcass 6 is configured using a steel carcass material.

  An inner liner 8 is formed along the carcass 6 on the inner side of the carcass 6 or on the inner side of the carcass 6 in the pneumatic tire 1.

  FIG. 2 is an AA arrow view of FIG. Three circumferential main grooves 20 are provided side by side in the tire width direction, and four rows of land portions 10 defined by the circumferential main grooves 20 are provided side by side in the tire width direction. Of the three circumferential main grooves 20, the circumferential main groove 20 located at the center in the tire width direction is provided as a center circumferential main groove 21, and the two circumferential main grooves 20 located on the outermost side in the tire width direction. The groove 20 is provided as a shoulder circumferential main groove 22. That is, the two shoulder circumferential main grooves 22 are disposed on both sides of the tire equatorial plane CL in the tire width direction, and the center circumferential main grooves 21 are two shoulder circumferential main grooves in the tire width direction. 22 and is disposed on the tire equatorial plane CL. These circumferential main grooves 20 are all formed to extend linearly in the tire circumferential direction.

  The circumferential main grooves 20 are all formed to extend linearly in the tire circumferential direction, and have a groove width in the range of 4 mm to 8 mm and a groove depth in the range of 10 mm to 20 mm. The circumferential main groove 20 may be formed in a shape other than a linear shape, for example, may be formed in a wavy shape or a zigzag shape that repeatedly extends in the tire width direction while extending in the tire circumferential direction. Good.

  As the lug groove 40, the center lug groove 41 disposed between the adjacent center circumferential main groove 21 and the shoulder circumferential main groove 22 and the outer side of the shoulder circumferential main groove 22 in the tire width direction are disposed. Shoulder lug grooves 42 are provided. Among these, the shoulder lug groove 42 is located on the outer side in the tire width direction of the shoulder circumferential main groove 22 and penetrates the land portion 10 located on the outer side in the tire width direction of the shoulder circumferential main groove 22 in the tire width direction. doing. That is, the shoulder lug groove 42 has an inner end in the tire width direction that is open from the outer side in the tire width direction with respect to the shoulder circumferential main groove 22, and an outer end in the tire width direction is the shoulder portion 4. And is open toward the outside in the tire width direction.

  Since the shoulder lug groove 42 penetrates the land portion 10 located on the outer side in the tire width direction of the shoulder circumferential main groove 22 in the tire width direction in this way, the land on the outer side in the tire width direction of the shoulder circumferential main groove 22 is The portion 10 is partitioned as a shoulder block 12 by a shoulder circumferential main groove 22 and a shoulder lug groove 42. That is, as for the shoulder block 12, the inner side in the tire width direction is partitioned by the shoulder circumferential main groove 22, and both sides in the tire circumferential direction are partitioned by the shoulder lug grooves 42. A plurality of the shoulder blocks 12 formed in this manner are arranged in the tire circumferential direction. For this reason, the shoulder blocks 12 are arranged on the outer side in the tire width direction of the shoulder circumferential main grooves 22 in the tire circumferential direction. A shoulder block row 13 is arranged in a row. The shoulder block row 13 is disposed at two locations outside the two shoulder circumferential main grooves 22 in the tire width direction.

  Further, the shoulder lug groove 42 has a first lug groove 70 and a second lug groove 80 having different groove depths. The groove depth of the first lug groove 70 is deeper than the groove depth of the second lug groove 80, and the first lug grooves 70 and the second lug grooves 80 are alternately arranged in the tire circumferential direction. . In this case, the comparison between the groove depths of the first lug groove 70 and the second lug groove 80 is an average depth obtained by weighting the groove depth by the groove area, so-called weighted average groove depths are compared with each other. It has become. That is, the first lug groove 70 has a weighted average groove depth deeper than the weighted average groove depth of the second lug groove 80.

  The center lug groove 41 has one end in the tire width direction that opens into the center circumferential main groove 21 or the shoulder circumferential main groove 22, and the other end between the center circumferential main groove 21 and the shoulder circumferential main groove 22. It is provided as a one-sided opening lug groove that terminates in the land portion 10 located in between. Since the center lug groove 41 which is a one-side opening lug groove does not penetrate the adjacent circumferential main grooves 20, the land portion located between the adjacent center circumferential main grooves 21 and the shoulder circumferential main grooves 22. 10 is formed as a center rib 11 which is a rib-like land portion 10 extending in the tire circumferential direction without being divided in the tire circumferential direction. That is, in the pneumatic tire 1 according to the present embodiment, out of the plurality of land portions 10, the land portions 10 other than the shoulder block row 13 have two circumferences that define both sides in the tire width direction of the land portions 10. Grooves and sipes that open to both of the direction main grooves 20 are not formed.

  The center rib 11 is disposed at two locations on both sides in the tire width direction of the center circumferential main groove 21, and the inside in the tire width direction is partitioned by the center circumferential main groove 21, and the outside in the tire width direction is the shoulder. It is partitioned by the circumferential main groove 22. For this reason, the center rib 11 is adjacent to the shoulder circumferential main groove 22 from the inner side in the tire width direction, and is adjacent to the shoulder block row 13 via the shoulder circumferential main groove 22.

  The center lug groove 41 is provided in the center rib 11 formed as described above, and the third lug groove 50 and the fourth lug groove 60 are provided as the center lug groove 41. Among these, the third lug groove 50 has one end opening in the shoulder circumferential main groove 22 and the other end terminating in the center rib 11. The fourth lug groove 60 has one end opened in the center circumferential main groove 21 and the other end terminated in the center rib 11. Further, both the third lug groove 50 and the fourth lug groove 60 have a groove depth shallower than the groove depth of the first lug groove 70.

  The third lug grooves 50 and the fourth lug grooves 60 are arranged in a staggered arrangement by alternately providing the third lug grooves 50 and the fourth lug grooves 60 in the tire circumferential direction. ing. In other words, the center lug groove 41 is opened in the shoulder circumferential main groove 22 by alternately arranging the third lug grooves 50 and the fourth lug grooves 60 in a predetermined direction in the tire circumferential direction. The center lug grooves 41 and the center lug grooves 41 opened in the center circumferential main groove 21 are alternately arranged.

  Further, the center rib 11 is provided with a plurality of notches 90 that are located on the extension line of the end portion of the center lug groove 41 that terminates in the center rib 11 and that open to the circumferential main groove 20. Specifically, the notch 90 includes a first notch 91 that is a notch 90 that opens in the center circumferential main groove 21 and a second notch 95 that is a notch 90 that opens in the shoulder circumferential main groove 22. A plurality of them are provided. Among these, the 1st notch 91 is located on the extension line | wire of the edge part 54 by the side which terminates in the center rib 11 in the 3rd lug groove 50, and the 2nd notch 95 is in the 4th lug groove 60. It is located on the extension line of the end portion 64 on the side terminating in the center rib 11.

  The notch 90 referred to here is a recess formed by recessing from the tread surface 3 and having a width in the tire width direction of less than 5 mm. The center lug groove 41, that is, the lug groove 40 is the tire width. A width in the direction is 5 mm or more. Further, the notch 90 does not have to be located on the extended line of the end portions 54 and 64 on the side terminating in the center rib 11 of the center lug groove 41 in the entire notch 90. The notch 90 is formed in a circumferential main groove 20 that is different from the circumferential main groove 20 in which the center lug groove 41 is opened, out of the two circumferential main grooves 20 that define the center rib 11 in which the center lug groove 41 is provided. When the center lug groove 41 is extended toward the center lug groove 41, at least a part of the notch 90 only needs to be positioned within the range of the groove width of the center lug groove 41.

  The center lug grooves 41 and the notches 90 that open to the same circumferential main groove 20 are alternately arranged in the tire circumferential direction. In other words, the third lug grooves 50 and the second notches 95 opened in the same shoulder circumferential main groove 22 are alternately arranged in the tire circumferential direction, and the fourth lugs 50 opened in the same center circumferential main groove 21. The lug grooves 60 and the first notches 91 are alternately arranged in the tire circumferential direction.

  In addition, as the third lug grooves 50 and the fourth lug grooves 60 are alternately provided in the tire circumferential direction, both the first notches 91 and the second notches 95 alternately in the tire circumferential direction. Is provided. That is, the first notch 91 and the second notch 95 are formed by the first notch 91 and the second notch 95 in the tire circumferential direction, similarly to the third lug groove 50 and the fourth lug groove 60. By providing them alternately, they are arranged in a staggered arrangement. Furthermore, the center lug grooves 41 and the notches 90, which are provided in plural, are arranged in a staggered manner, so that the center lug grooves 41 and the notches 90 are also arranged in a staggered manner. .

  FIG. 3 is a detailed view of part B of FIG. The first lug groove 70 has a constant width portion 71 formed with a constant groove width and a widened portion 72 where the groove width changes by bending the groove wall near the center in the length direction of the first lug groove 70. And have. Similarly, in the second lug groove 80, the groove wall is bent in the vicinity of the center in the length direction of the second lug groove 80, so that the constant width portion 81 formed with a constant groove width and the widening in which the groove width changes. Part 82. In both the first lug groove 70 and the second lug groove 80, the constant width portions 71, 81 are located inside the wide width portions 72, 82 in the tire width direction, and the wide width portions 72, 82 are the constant width portions 71, 81 is located outside in the tire width direction. That is, in the first lug groove 70 and the second lug groove 80, the constant width portions 71 and 81 open to the shoulder circumferential main groove 22, and the widened portions 72 and 82 face the outer side in the tire width direction at the shoulder portion 4. Open.

  FIG. 4 is a detailed view of part C of FIG. The constant width portion 71 of the first lug groove 70 is in the tire width direction from the inner opening 74 that is the opening portion of the first lug groove 70 to the shoulder circumferential main groove 22 to the vicinity of the center of the shoulder block 12 in the tire width direction. It extends toward the outside. In the present embodiment, the constant width portion 71 of the first lug groove 70 is inclined in the tire circumferential direction while extending in the tire width direction, and the inner opening 74 is chamfered.

  The widened portion 72 of the first lug groove 70 extends from the outer end in the tire width direction of the constant width portion 71 toward the outer side in the tire width direction. That is, the groove wall of the first lug groove 70 has the bent portion 73 near the center of the shoulder block 12 in the tire width direction, and the widened portion 72 is formed to extend outward from the bent portion 73 in the tire width direction. ing. The widened portion 72 has a groove width that is the same as the groove width of the constant width portion 71 at the position of the bent portion 73 that is a boundary position with the constant width portion 71, and extends from the inside to the outside in the tire width direction. The groove width increases as you go. That is, the bent portion 73 is at a position where the groove width of the first lug groove 70 changes, and the first lug groove 70 is formed with a constant groove width on the inner side in the tire width direction from the bent portion 73. From 73, the groove width becomes wider from the outer side in the tire width direction toward the outer side in the tire width direction. In addition, the bending part 73 may be formed in both the groove walls which the 1st lug groove 70 opposes, and may be formed only in one groove wall of the groove wall which opposes.

  Since the first lug groove 70 has the constant width portion 71 and the widened portion 72 in this way, the outer end in the tire width direction is larger than the groove width at the position near the center of the first lug groove 70 in the tire width direction. The groove width at the position of the portion is larger. Specifically, the narrowest portion of the first lug groove 70 located in the measurement region AM that is in the range of 40% to 60% of the width WB of the shoulder block 12 in the tire width direction from one end portion in the tire width direction. The groove width is defined as the minimum groove width W11, and the groove width at the outer end in the tire width direction of the first lug groove 70 is defined as the groove width W12. In this case, in the first lug groove 70, the relationship between the minimum groove width W11 and the groove width W12 is in the range of 1.3 ≦ (W12 / W11) ≦ 1.7.

  That is, in the first lug groove 70, the bent portion 73, which is the boundary position between the constant width portion 71 and the widened portion 72, is located in the measurement region AM, and the minimum groove width W11 is located in the measurement region AM. The groove width of the constant width portion 71 is obtained. In addition, the groove width W12 at the outer end in the tire width direction of the first lug groove 70 is a groove in the outer opening 75 that is a portion of the widened portion 72 that opens toward the outer side in the tire width direction at the shoulder 4. It is wide. In the first lug groove 70, the ratio of the groove width W12 of the outer opening 75 to the minimum groove width W11 is in the range of 1.3 to 1.7.

  In addition, it is preferable that the minimum groove width W11 of the 1st lug groove 70 exists in the range of 4 mm or more and 8 mm or less, and the groove width W12 in the edge part of the tire width direction outer side of the 1st lug groove 70 is 6 mm or more and 12 mm or less. It is preferable to be within the range.

  FIG. 5 is a detailed view of part D in FIG. Similarly to the first lug groove 70, the constant width portion 81 of the second lug groove 80 also extends from the inner opening 84 that is the opening portion of the second lug groove 80 to the shoulder circumferential main groove 22. The tire blocks extend toward the outer side in the tire width direction while being inclined in the tire circumferential direction to the vicinity of the center of the shoulder block 12 in the tire width direction. The second lug groove 80 also has a bent portion 83 in the vicinity of the center of the shoulder block 12 in the tire width direction of the groove wall, and the widened portion 82 is formed to extend outward from the bent portion 83 in the tire width direction. ing. The widened portion 82 has a groove width that is the same as the groove width of the constant width portion 81 at the position of the bent portion 83 that is a boundary position with the constant width portion 81, and extends from the inside to the outside in the tire width direction. The groove width increases as you go. That is, the bent portion 83 is at a position where the groove width of the second lug groove 80 changes. The second lug groove 80 is formed with a constant groove width on the inner side in the tire width direction from the bent portion 83. From 83, the width in the tire width direction outer side becomes wider toward the outer side in the tire width direction. Similarly to the bent portion 73 of the first lug groove 70, the bent portion 83 of the second lug groove 80 may be formed on both of the opposing groove walls of the second lug groove 80. It may be formed only on one groove wall.

  Similar to the first lug groove 70, the second lug groove 80 also has a constant width portion 81 and an enlarged width portion 82, so that the groove width at a position near the center of the second lug groove 80 in the tire width direction is The groove width at the outer end portion in the tire width direction is larger. Specifically, the narrowest portion of the second lug groove 80 located in the measurement area AM that is in the range of 40% to 60% of the width WB of the shoulder block 12 in the tire width direction from one end portion in the tire width direction. The groove width is defined as the minimum groove width W21, and the groove width at the outer end in the tire width direction of the second lug groove 80 is defined as the groove width W22. In this case, in the second lug groove 80, the relationship between the minimum groove width W21 and the groove width W22 is in the range of 1.1 ≦ (W22 / W21) ≦ 1.5.

  That is, in the second lug groove 80, the bent portion 83 that is the boundary position between the constant width portion 81 and the widened portion 82 is located in the measurement region AM, and the minimum groove width W21 is located in the measurement region AM. The groove width of the constant width portion 81 is set. Further, the groove width W22 at the outer end in the tire width direction of the second lug groove 80 is a groove of the outer opening 85 which is a portion of the widened portion 82 that is open toward the outer side in the tire width direction at the shoulder portion 4. It is wide. In the second lug groove 80, the ratio of the groove width W22 of the outer opening 85 to the minimum groove width W21 is in the range of 1.1 to 1.5.

  In addition, it is preferable that the minimum groove width W21 of the 2nd lug groove 80 exists in the range of 4 mm or more and 8 mm or less, and the groove width W22 in the edge part of the tire width direction outer side of the 2nd lug groove 80 is 5 mm or more and 10 mm or less. It is preferable to be within the range.

  Furthermore, the first lug groove 70 and the second lug groove 80 have a groove width W12 at the outer opening 75 of the first lug groove 70 that is greater than the groove width W22 at the outer opening 85 of the second lug groove 80. It is getting bigger. Specifically, the first lug groove 70 and the second lug groove 80 are the relationship between the groove width W12 in the outer opening 75 of the first lug groove 70 and the groove width W22 in the outer opening 85 of the second lug groove 80. However, it is in the range of 1.1 ≦ (W12 / W22) ≦ 1.3.

  6 is a cross-sectional view taken along line EE in FIG. 7 is a cross-sectional view taken along line FF in FIG. 8 is a cross-sectional view taken along the line GG in FIG. 9 is a cross-sectional view taken along the line HH in FIG. The first lug groove 70 and the second lug groove 80 have different weighted average groove depths, and the weighted average groove of the first lug groove 70 is larger than the load average groove depth of the second lug groove 80. The depth is deeper. That is, the first lug groove 70 and the second lug groove 80 are different from each other in the form of the groove bottom 76 of the first lug groove 70 and the form of the groove bottom 86 of the second lug groove 80. The average groove depth is different from each other.

  Specifically, the second lug groove 80 has a substantially constant groove depth from the inner opening 84 side to the outer opening 85 side, whereas the first lug groove 70 has an inner opening. The groove depth is deeper on the outer opening 75 side than on the 74 side. More specifically, the first lug groove 70 has a substantially constant groove depth from the position of the inner opening 74 to a predetermined position on the outer side in the tire width direction, and from the predetermined position to the tire width direction. Groove depth increases toward the outside.

  Specifically, the first lug groove 70 is located at a position Pin that is 20% of the width WB in the tire width direction of the shoulder block 12 from the end on the tire width direction inner side of the first lug groove 70 toward the outer side in the tire width direction. The groove depth D13 is in the range of 1 mm to 5 mm. Similarly, the second lug groove 80 also has a groove depth at a position Pin that is 20% of the width WB in the tire width direction of the shoulder block 12 from the inner end in the tire width direction of the second lug groove 80 toward the outer side in the tire width direction. The depth D23 is in the range of 1 mm to 5 mm.

  Further, the second lug groove 80 has a groove depth at a position Pout of 20% of the width WB in the tire width direction of the shoulder block 12 from the end of the second lug groove 80 on the outer side in the tire width direction toward the inner side in the tire width direction. The length D24 is in the range of 1 mm to 5 mm. On the other hand, the first lug groove 70 is located at a position Pout of 20% of the width WB in the tire width direction of the shoulder block 12 from the end of the first lug groove 70 on the outer side in the tire width direction toward the inner side in the tire width direction. The groove depth D14 is in the range of 6 mm to 15 mm.

  In this case, the ends of the first lug groove 70 and the second lug groove 80 on the outer side in the tire width direction are the positions of the shoulder portions 4 of the tread surface 3 in the tire width direction.

  The first lug groove 70 and the second lug groove 80 are the tire width direction of the shoulder block 12 from the inner end in the tire width direction of the first lug groove 70 or the second lug groove 80 toward the outer side in the tire width direction. In the range AH which is 40% of the width WB, the groove depth at the same position in the tire width direction is the same. In this case, having a portion where the groove depth is the same means that the portion where the difference in groove depth at the same position in the tire width direction is 0.3 mm or less is 2 mm or more continuously in the tire width direction. It is formed. In addition, as for the part where the groove depth of the 1st lug groove 70 and the 2nd lug groove 80 is the same, it is more preferable that the width | variety in a tire width direction is 5 mm or more.

  Further, in the first lug groove 70 and the second lug groove 80, the relationship between the maximum groove depth D15 of the first lug groove 70 and the maximum groove depth D25 of the second lug groove 80 is 0.1 ≦ (D25 /D15)≦0.5. In this case, the maximum groove depth D15 of the first lug groove 70 is, for example, the groove depth in the vicinity of the outer opening 75 of the first lug groove 70, or the first lug groove 70 in the position in the vicinity of the shoulder portion 4. Groove depth. Similarly, the maximum groove depth D25 of the second lug groove 80 is, for example, the groove depth in the vicinity of the outer opening 85 of the second lug groove 80 or the groove of the second lug groove 80 in the vicinity of the shoulder portion 4. It is deep.

  Further, the first lug groove 70 includes a groove depth D12 in a defined region A12 that is a region 10 mm inward in the tire width direction from an end on the tire width direction outer side of the first lug groove 70, and the shoulder circumferential direction main groove 22. The relationship with the groove depth DC is in the range of 0.6 ≦ (D12 / DC) ≦ 1.0. In this case, the groove depth D12 of the first lug groove 70 in the defined area A12 is a groove depth obtained by weighted averaging the groove depths of the first lug groove 70 in the defined area A12. The first lug groove 70 has a groove depth D12 obtained by weighted averaging the groove depths in the defined region A12 with respect to the groove depth DC of the shoulder circumferential main groove 22 in which the first lug groove 70 opens. It is formed in a shape with a ratio of 1.0 or less.

  FIG. 10 is an explanatory diagram of the outer regions of the first lug groove 70 and the second lug groove 80. The first lug groove 70 has a groove depth closer to the outer opening 75 than the groove depth closer to the inner opening 74, whereas the second lug groove 80 Regardless of the position in the tire width direction, the groove depth is substantially constant. For this reason, the first lug groove 70 and the second lug groove 80 are greatly different in depth particularly at a position closer to the outer side in the tire width direction. Specifically, when the groove depth of the outer region A11 of the first lug groove 70 is D11 and the groove depth of the outer region A21 of the second lug groove 80 is D21, the groove depth of the first lug groove 70 is set. The relationship between the length D11 and the groove depth D21 of the second lug groove 80 is in the range of 0.2 ≦ (D21 / D11) ≦ 0.5.

  The outer region A11 of the first lug groove 70 in this case is a region from the position of the bent portion 73 in the first lug groove 70 to the outer end in the tire width direction of the first lug groove 70, that is, the outer opening 75. is there. Similarly, the outer region A21 of the second lug groove 80 is a region from the position of the bent portion 83 in the second lug groove 80 to the outer end in the tire width direction of the second lug groove 80, that is, the outer opening 85. . The groove depth D11 of the first lug groove 70 in the outer region A11 of the first lug groove 70 is a groove depth obtained by weighted averaging the groove depths of the first lug groove 70 in the outer region A11. Similarly, the groove depth D21 of the second lug groove 80 in the outer region A21 of the second lug groove 80 is a groove depth obtained by weighted averaging the groove depth of the second lug groove 80 in the outer region A21.

  As described above, the groove depth of the second lug groove 80 is substantially constant, whereas the groove depth of the first lug groove 70 differs depending on the position in the tire width direction, and the shoulder portion 4 The groove depth is deeper than the groove depth of the second lug groove 80 at the close position.

  FIG. 11 is a detailed view of a portion J in FIG. FIG. 12 is a detailed view of a portion K in FIG. The third lug groove 50 formed in the center rib 11 and opened to the shoulder circumferential main groove 22 has a constant width portion 51 formed with a constant groove width and a widened portion 52 where the groove width changes, The widened portion 52 opens in the shoulder circumferential main groove 22. Among these, the constant width portion 51 is an end portion 54 on the side that terminates in the center rib 11 in the third lug groove 50 from the portion of the widened portion 52 that is opposite to the side that opens in the shoulder circumferential main groove 22. It extends to. Further, the widened portion 52 has a groove width substantially equal to the groove width of the constant width portion 51 at the position where the constant width portion 51 is connected, and the shoulder circumferential main groove from the constant width portion 51 side. The width of the groove increases toward the side opening at 22. A portion of the widened portion 52 formed as described above that opens to the shoulder circumferential main groove 22 is an opening 53 of the third lug groove 50 with respect to the shoulder circumferential main groove 22.

  Similar to the third lug groove 50, the fourth lug groove 60 formed in the center rib 11 and opened to the center circumferential main groove 21 has a constant width portion 61 formed with a constant groove width, and the groove width changes. And the widened portion 62 is open to the center circumferential main groove 21. Among these, the constant width portion 61 is an end portion 64 on the side that terminates in the center rib 11 in the fourth lug groove 60 from the portion of the widened portion 62 on the side opposite to the side that opens to the center circumferential main groove 21. It extends to. Further, the widened portion 62 has a groove width that is substantially the same as the groove width of the constant width portion 61 at the position where the constant width portion 61 is connected, and the center circumferential direction main groove from the constant width portion 61 side. The width of the groove becomes larger toward the side opening at 21. A portion of the widened portion 62 formed as described above that opens to the center circumferential main groove 21 is an opening 63 of the fourth lug groove 60 with respect to the center circumferential main groove 21.

  In addition, it is preferable that the 3rd lug groove 50 is formed in the range whose groove width of the fixed width part 51 is 3 mm or more and 8 mm or less, and the groove depth of the fixed width part 51 is 1 mm or more and 5 mm or less. The fourth lug groove 60 is also preferably formed so that the groove width of the constant width portion 61 is in the range of 3 mm to 8 mm and the groove depth of the constant width portion 61 is in the range of 1 mm to 5 mm.

  Further, the notch 90 formed in the center rib 11 has a width in the tire circumferential direction as it approaches the circumferential main groove 20 from a position away from the circumferential main groove 20 in which the notch 90 opens in the tire width direction. It is formed in a trapezoidal shape that becomes larger. That is, the first notch 91 that opens in the center circumferential main groove 21 has a width in the tire circumferential direction as it approaches the center circumferential main groove 21 from a position away from the center circumferential main groove 21 in the tire width direction. Is getting bigger. Similarly, the second notch 95 that opens in the shoulder circumferential main groove 22 increases in the tire circumferential direction as it approaches the shoulder circumferential main groove 22 from a position away from the shoulder circumferential main groove 22 in the tire width direction. The width has increased.

  The cutout 90 formed in this way is formed in substantially the same shape as the widened portion 52 of the third lug groove 50 and the widened portion 62 of the fourth lug groove 60. That is, the notch 90 and the widened portions 52 and 62 have the same width in the tire circumferential direction and the width in the tire width direction, and the depth in the tire radial direction is also the same depth. ing.

  13 is a cross-sectional view taken along line MM in FIG. The third lug groove 50 is formed so that the groove width is greatly different between the constant width portion 51 and the wide width portion 52, and the groove depth of the wide width portion 52 is deeper than the groove depth of the constant width portion 51. Yes. Specifically, in the third lug groove 50, the minimum groove depth D31 of the constant width portion 51 is 0.2 ≦ (D31 / D32) ≦ 0.5 with respect to the maximum groove depth D32 of the widened portion 52. It is within the range.

  Further, the widened portion 52 of the third lug groove 50 has a groove depth that is approximately the same as the depth of the shoulder circumferential main groove 22, and the maximum groove depth D32 of the widened portion 52 is the widened portion. 52 is within a range of 0.8 ≦ (D32 / DC) ≦ 1.0 with respect to the groove depth DC of the shoulder circumferential main groove 22 in which 52 is opened.

  14 is a cross-sectional view taken along line NN in FIG. The fourth lug groove 60 is also formed such that the groove width is greatly different between the constant width portion 61 and the widened portion 62, and the groove depth of the widened portion 62 is deeper than the groove depth of the constant width portion 61. Yes. Specifically, in the fourth lug groove 60, the minimum groove depth D41 of the constant width portion 61 is 0.2 ≦ (D41 / D42) ≦ 0.5 with respect to the maximum groove depth D42 of the widened portion 62. It is within the range.

  Further, the widening portion 62 of the fourth lug groove 60 has a groove depth that is approximately the same as the groove depth of the center circumferential main groove 21, and the maximum groove depth D42 of the widening portion 62 is the widening portion. With respect to the groove depth DC of the center circumferential main groove 21 in which 62 is opened, the distance is in the range of 0.8 ≦ (D42 / DC) ≦ 1.0.

  Further, in the third lug groove 50, the minimum groove depth D31 of the constant width portion 51 is 0.8 ≦ (D31) with respect to the groove depth D21 of the outer region A21 (see FIG. 10) of the second lug groove 80. /D21)≦1.2. Similarly, in the fourth lug groove 60, the minimum groove depth D41 of the constant width portion 61 is 0.8 ≦ (D41 / D21) ≦ 1 with respect to the groove depth D21 of the outer region A21 of the second lug groove 80. Within the range of .2. That is, in the third lug groove 50 and the fourth lug groove 60, the groove depths of the constant width portions 51 and 61 are approximately the same as the groove depth of the second lug groove 80.

  FIG. 15 is an explanatory diagram regarding the relationship between the positions of the first lug groove 70, the second lug groove 80, and the third lug groove 50. Similar to the first lug groove 70 and the second lug groove 80, the third lug groove 50 that opens in the shoulder circumferential main groove 22 has a position in the tire circumferential direction adjacent to the first lug groove 70 in the tire circumferential direction. Between the two lug grooves 80, the shoulder circumferential direction main groove 22 is opened. Specifically, the distance in the tire circumferential direction from the position where the first lug groove 70 opens to the shoulder circumferential main groove 22 to the position where the second lug groove 80 opens to the shoulder circumferential main groove 22 is L12, When the distance in the tire circumferential direction from the position where the third lug groove 50 opens to the shoulder circumferential main groove 22 to the position where the first lug groove 70 opens to the shoulder circumferential main groove 22 is L13, the distance L12 And the distance L13 are in the range of 0.2 ≦ (L13 / L12) ≦ 0.8.

  In this case, the distance L12 and the distance L13 are distances in the tire circumferential direction at the intersections between the center line of each lug groove 40 in the tire width direction and the shoulder circumferential main groove 22. Further, when chamfering is performed at a position where the lug groove 40 is opened with respect to the shoulder circumferential main groove 22, the center line of the groove width of the lug groove 40 not considering chamfering, the shoulder circumferential main groove 22, and It is the distance in the tire circumferential direction of the intersection of. That is, the distance L12 is such that the center line of the constant width portion 71 of the first lug groove 70 intersects the shoulder circumferential main groove 22 and the center line of the constant width portion 81 of the second lug groove 80 is the shoulder circumferential main direction. This is the distance in the tire circumferential direction from the position intersecting the groove 22. Further, the distance L13 is such that the center line of the constant width portion 71 of the first lug groove 70 intersects the shoulder circumferential main groove 22 and the center line of the constant width portion 51 of the third lug groove 50 is the shoulder circumferential direction main. This is the distance in the tire circumferential direction from the position intersecting the groove 22.

  FIG. 16 is an explanatory diagram of the positional relationship between the third lug groove 50 and the fourth lug groove 60. Since the third lug groove 50 and the fourth lug groove 60 are arranged in a staggered manner in the center rib 11, the third lug groove 50 and the fourth lug groove 60 are mutually positioned in the tire circumferential direction. They are arranged at different positions. Specifically, the distance in the tire circumferential direction of the opening position to the shoulder circumferential main groove 22 between the third lug grooves 50 adjacent in the tire circumferential direction is L33, and the third lug groove 50 adjacent in the tire circumferential direction is The distance in the tire circumferential direction between the opening position of the third lug groove 50 to the shoulder circumferential main groove 22 and the opening position of the fourth lug groove 60 to the center circumferential main groove 21 in the fourth lug groove 60. In the case of L34, the relationship between the distance L33 and the distance L34 is in the range of 0.3 ≦ (L34 / L33) ≦ 0.5.

  In this case, the distance L33 and the distance L34 are also the distance in the tire circumferential direction of the intersection of the center line of the groove width of the lug groove 40 and the circumferential main groove 20 not considering chamfering, like the distance L12 and the distance L13. Yes. That is, the distance L33 is a distance in the tire circumferential direction between positions where the center lines of the constant width portions 51 of the third lug grooves 50 adjacent in the tire circumferential direction intersect the shoulder circumferential main groove 22. Further, the distance L34 is such that the center line of the constant width portion 51 of the third lug groove 50 intersects the shoulder circumferential main groove 22 and the center line of the constant width portion 61 of the fourth lug groove 60 is the center circumferential direction main. It is the distance in the tire circumferential direction from the position intersecting the groove 21.

  The distance L34 is a position where the fourth lug groove 60 is open to the shoulder circumferential main groove 22 out of the two third lug grooves 50 on both sides in the tire circumferential direction of the fourth lug groove 60. The opening position of the third lug groove 50 closer to the circumferential main groove 21 with respect to the shoulder circumferential main groove 22 and the opening position of the fourth lug groove 60 with respect to the center circumferential main groove 21 This is the distance in the tire circumferential direction. For this reason, (L34 / L33) is 0.5 at the maximum.

  FIG. 17 is an explanatory diagram of the positional relationship between the fourth lug grooves 60 provided in different center ribs 11. The fourth lug grooves 60 provided in each of the two rows of center ribs 11 adjacent to each other in the tire width direction with the center circumferential main groove 21 interposed therebetween are the fourth lug grooves 60 of the two rows of center ribs 11. The position of the opening to the direction main groove 21 is shifted by 10 mm or more in the tire circumferential direction. That is, the distance L4 in the tire circumferential direction of the opening position to the center circumferential main groove 21 of the fourth lug groove 60 provided in each of the two rows of center ribs 11 adjacent to each other across the center circumferential main groove 21 is: The size is at least 10 mm.

  The distance L4 in this case is also the distance in the tire circumferential direction at the intersection of the center line of the groove width of the fourth lug groove 60 and the center circumferential main groove 21 without considering chamfering. That is, the distance L4 is a distance in the tire circumferential direction between positions where the center line of the constant width portion 61 of the fourth lug groove 60 intersects the center circumferential main groove 21.

  The pneumatic tire 1 according to the present embodiment configured as described above is used for a heavy-duty pneumatic tire. When the pneumatic tire 1 is mounted on the vehicle, the pneumatic tire 1 is mounted on the vehicle in a rim-assembled and inflated state. The pneumatic tire 1 in a state where the rim is assembled to the rim wheel is used by being mounted on a large vehicle as compared with a passenger car such as a truck or a bus.

  When the vehicle equipped with the pneumatic tire 1 travels, the pneumatic tire 1 rotates while the tread surface 3 positioned below the tread surface 3 is in contact with the road surface. When driving on a dry road surface with a vehicle equipped with pneumatic tires 1, the driving force or braking force is transmitted to the road surface or the turning force is generated mainly by the frictional force between the tread surface 3 and the road surface. To drive. Further, when traveling on a wet road surface, water between the tread surface 3 and the road surface enters the circumferential main groove 20 and the lug groove 40, and water between the tread surface 3 and the road surface is discharged by these grooves. Drive while discharging. As a result, the tread surface 3 is easily grounded to the road surface, and the vehicle can travel by the frictional force between the tread surface 3 and the road surface.

  In addition, the shoulder lug grooves 42 that define the shoulder block 12 have first lug grooves 70 having a relatively large groove depth and second lug grooves 80 having a relatively small groove depth alternately in the tire circumferential direction. Since it is arrange | positioned, it can suppress that the rigidity of the shoulder block 12 becomes low too much, and the rigidity of the shoulder block 12 can be ensured. Thereby, for example, uneven wear of the shoulder block 12 such as heel & toe wear can be suppressed.

  Further, when the pneumatic tire 1 rotates, a hitting sound is generated when the land portion 10 comes in contact with the road surface, and this hitting sound spreads through the shoulder lug groove 42 to the noise. It will contribute. In contrast, in the pneumatic tire 1 according to the present embodiment, the second lug groove 80 having a shallow groove depth is used for the shoulder lug groove 42. For this reason, the sound generated in the inner region in the tire width direction of the shoulder circumferential main groove 22 is less likely to flow into the second lug groove 80 of the shoulder lug groove 42 and passes through the shoulder lug groove 42 to the outer side in the tire width direction. The amount of sound that flows is reduced. As a result, the amount of sound flowing from the ground contact area of the pneumatic tire 1 to the outside of the ground contact area is reduced, and the passing sound can be reduced, so that noise reduction during vehicle travel can be achieved.

  Further, when traveling on a snowy road surface, in order to ensure traction performance, the pneumatic tire 1 may be traveled with a tire chain attached thereto. However, the tire chain is provided on the tread surface 3 of the pneumatic tire 1. By mounting so as to cover, and a part of the chain is caught in the groove formed in the tread surface 3, it is possible to suppress a relative shift in the tire circumferential direction between the pneumatic tire 1 and the tire chain. In the pneumatic tire 1 according to the present embodiment, since the first lug groove 70 having a deep groove depth is used for the shoulder lug groove 42, when the tire chain is attached to the pneumatic tire 1, The chain can be easily hooked into the first lug groove 70. That is, since the first lug groove 70 has a deep groove depth, the chain can be prevented from coming off when the chain enters the first lug groove 70, and the chain is caught in the first lug groove 70. Can be maintained. Thereby, generation | occurrence | production of the shift | offset | difference between the pneumatic tire 1 and a tire chain can be suppressed. As a result, it is possible to reduce noise while ensuring uneven wear resistance and chain hookability.

  In addition, the third lug groove 50 provided in the center rib 11 has one end opened to the shoulder circumferential main groove 22 and the other end terminated in the center rib 11, so that the rigidity of the center rib 11 can be ensured. . Thereby, uneven wear can be more reliably suppressed. Moreover, since the 3rd lug groove 50 terminates in the center rib 11, it can suppress that the sound generated at the time of the earthing | grounding of the land part 10 flows from the center circumferential direction main groove 21 side to the shoulder circumferential direction main groove 22 side. The amount of sound flowing from the ground contact area of the pneumatic tire 1 to the outside of the ground contact area can be reduced more reliably. Thereby, the passing sound at the time of driving | running | working of a vehicle can be reduced more reliably. As a result, noise can be reduced more reliably while ensuring uneven wear resistance.

  The relationship between the distance L12 in the tire circumferential direction between the first lug groove 70 and the second lug groove 80 and the distance L13 in the tire circumferential direction between the third lug groove 50 and the first lug groove 70 is 0.2. Since it is within the range of ≦ (L13 / L12) ≦ 0.8, it is possible to more surely suppress uneven wear and reduce passing sound. That is, when the relationship between the distance L12 and the distance L13 is (L13 / L12) <0.2 or (L13 / L12)> 0.8, the third lug groove 50 and the first Since the distance to the lug groove 70 or the second lug groove 80 becomes too close, the rigidity of the surrounding land portion 10 may be too low. In this case, it may be difficult to effectively suppress uneven wear. Further, since the distance between the third lug groove 50 and the first lug groove 70 or the second lug groove 80 becomes too close, the sound that flows from the third lug groove 50 to the shoulder circumferential main groove 22 is first. Since it becomes easy to flow into the lug groove 70 or the second lug groove 80, there is a possibility that it is difficult to reduce the passing sound when the vehicle travels.

  On the other hand, when the relationship between the distance L12 and the distance L13 is within the range of 0.2 ≦ (L13 / L12) ≦ 0.8, the third lug groove 50, the first lug groove 70, and the second lug groove 70 Since it can suppress that the distance with the lug groove 80 becomes too close, the rigidity of the land part 10 around the 3rd lug groove 50 can be ensured more reliably, and it suppresses uneven wear more reliably. be able to. Moreover, since it can suppress that the distance of the 3rd lug groove 50, the 1st lug groove 70, and the 2nd lug groove 80 becomes too close, from the inside of the 3rd lug groove 50 to the shoulder circumferential direction main groove 22 It can suppress that the sound which flowed flows into the 1st lug groove 70 or the 2nd lug groove 80, and can reduce the passage sound at the time of driving | running | working of a vehicle more reliably. As a result, noise can be reduced more reliably while ensuring uneven wear resistance.

  In addition to the third lug groove 50, the center rib 11 is provided with a fourth lug groove 60 that opens to the center circumferential main groove 21 and terminates in the center rib 11. The center circumferential direction main groove 21 side and the shoulder circumferential direction main groove 22 side can have the same degree. Thereby, the partial wear which originates in the rigidity difference of the inner side in the tire width direction of the center rib 11 and an outer side can be suppressed. Further, since the third lug groove 50 and the fourth lug groove 60 are arranged in a staggered arrangement, the difference in distance between the third lug groove 50 and the fourth lug groove 60 adjacent in the tire circumferential direction is Can be approached evenly. Thereby, the difference in rigidity of the center rib 11 generated due to a large difference in the distance between the third lug groove 50 and the fourth lug groove 60 adjacent in the tire circumferential direction can be reduced. It is possible to suppress uneven wear caused by the above. Moreover, since the 4th lug groove 60 terminates in the center rib 11, it can suppress that the sound generated at the time of the earthing | grounding of the land part 10 flows from the center circumferential direction main groove 21 side to the shoulder circumferential direction main groove 22 side. Further, it is possible to more reliably reduce the passing sound when the vehicle is traveling. As a result, noise can be reduced more reliably while ensuring uneven wear resistance.

  Further, a distance L33 in the tire circumferential direction between the third lug grooves 50 adjacent in the tire circumferential direction and a distance L34 in the tire circumferential direction between the third lug groove 50 and the fourth lug groove 60 adjacent in the tire circumferential direction. Since the relationship is within the range of 0.3 ≦ (L34 / L33) ≦ 0.5, uneven wear can be more reliably suppressed. That is, when the relationship between the distance L33 and the distance L34 is (L34 / L33) <0.3, the distance between the third lug groove 50 and the fourth lug groove 60 becomes too close, so that the surrounding center There is a possibility that the rigidity of the rib 11 becomes too low. In this case, it may be difficult to effectively suppress uneven wear. On the other hand, when the relationship between the distance L33 and the distance L34 is within the range of 0.3 ≦ (L34 / L33) ≦ 0.5, the distance between the third lug groove 50 and the fourth lug groove 60 is Since it can suppress becoming close too much, the rigidity of the center rib 11 around the 3rd lug groove 50 and the 4th lug groove 60 can be ensured more certainly, and uneven wear is controlled more certainly. Can do. As a result, uneven wear resistance can be ensured more reliably.

  Further, the third lug groove 50 and the fourth lug groove 60 are the groove depth D21 of the second lug groove 80 in the outer region A21 of the second lug groove 80, the groove depth D31 of the third lug groove 50, and the Since the relationship with the groove depth D41 of the four lug grooves 60 is in the range of 0.8 ≦ (D31 / D21) ≦ 1.2 and 0.8 ≦ (D41 / D21) ≦ 1.2, it is more reliable. Furthermore, it is possible to suppress uneven wear and to reduce the passing sound. That is, when (D31 / D21) <0.8 or (D41 / D21) <0.8, the groove depth D31 of the third lug groove 50 or the groove depth of the fourth lug groove 60 is satisfied. Since the length D41 is too shallow, it is difficult to appropriately reduce the rigidity of the center rib 11, and it may be difficult to reduce the difference in rigidity between the rigidity of the center rib 11 and the rigidity of the shoulder block row 13. In this case, it may be difficult to effectively suppress uneven wear due to the difference in rigidity of the land portion 10. When (D31 / D21)> 1.2 or (D41 / D21)> 1.2, the groove depth D31 of the third lug groove 50 or the groove depth of the fourth lug groove 60 is satisfied. Since the depth D41 is too deep, it may be difficult to reduce the sound generated in the ground contact region of the pneumatic tire 1 from flowing through the third lug groove 50 and the fourth lug groove 60. In this case, it may be difficult to effectively suppress the sound generated in the inner region in the tire width direction of the shoulder circumferential main groove 22 from flowing to the outer side in the tire width direction of the shoulder circumferential main groove 22. .

  In contrast, the relationship between the groove depth D21 of the second lug groove 80, the groove depth D31 of the third lug groove 50, and the groove depth D41 of the fourth lug groove 60 is 0.8 ≦ (D31 / In the case of D21) ≦ 1.2 and 0.8 ≦ (D41 / D21) ≦ 1.2, by reducing the rigidity difference between the rigidity of the center rib 11 and the rigidity of the shoulder block row 13, Uneven wear due to the difference in rigidity of the land portion 10 can be more reliably suppressed. In addition, by reducing the ease of sound flow in the third lug groove 50 and the fourth lug groove 60, the sound generated when the land portion 10 touches the outer side in the tire width direction of the shoulder circumferential main groove 22. Can be suppressed, and the passing sound during traveling of the vehicle can be more reliably reduced. As a result, noise can be reduced more reliably while ensuring uneven wear resistance.

  In the first lug groove 70, the relationship between the minimum groove width W11 in the measurement region AM and the groove width W12 at the outer end in the tire width direction is in a range of 1.3 ≦ (W12 / W11) ≦ 1.7. Therefore, uneven wear can be suppressed while securing the chain hooking property more reliably. That is, when the relationship between the minimum groove width W11 and the groove width W12 is (W12 / W11) <1.3, the groove width W12 at the outer end in the tire width direction of the first lug groove 70 is too small. When a tire chain is attached to the pneumatic tire 1, the chain may not be easily caught in the first lug groove 70. In this case, there is a possibility that it is difficult to secure the chain hanging property when the tire chain is mounted. In addition, when the relationship between the minimum groove width W11 and the groove width W12 is (W12 / W11)> 1.7, the groove width W12 at the outer end in the tire width direction of the first lug groove 70 is too large. There is a possibility that the rigidity in the vicinity of the outer end in the tire width direction of the first lug groove 70 in the shoulder block 12 becomes too low, or stress concentration is likely to occur when the shoulder block 12 contacts the ground. In this case, it may be difficult to effectively suppress uneven wear of the shoulder block 12.

  On the other hand, when the relationship between the minimum groove width W11 and the groove width W12 is within the range of 1.3 ≦ (W12 / W11) ≦ 1.7, the first time when the tire chain is attached to the pneumatic tire 1 While securing the chain to the 1 lug groove 70, the rigidity of the shoulder block 12 can be ensured to an appropriate size, and uneven wear can be suppressed. As a result, uneven wear resistance and chain hooking properties can be ensured more reliably.

  Further, in the second lug groove 80, the relationship between the minimum groove width W21 in the measurement region AM and the groove width W22 at the outer end in the tire width direction is in a range of 1.1 ≦ (W22 / W21) ≦ 1.5. Therefore, uneven wear can be suppressed while securing the chain hooking property more reliably. That is, when the tire chain is attached to the pneumatic tire 1, the chain is caught not only in the first lug groove 70 but also in the second lug groove 80, so that the chain can be secured. 2 When the relationship between the minimum groove width W21 and the groove width W22 of the lug groove 80 is (W22 / W21) <1.1, the groove width W22 at the outer end in the tire width direction of the second lug groove 80 is small. Therefore, there is a risk that it is difficult to secure the chain hooking property to the second lug groove 80. In this case, there is a possibility that it is difficult to secure the chain hanging property when the tire chain is mounted. Further, when the relationship between the minimum groove width W21 and the groove width W22 is (W22 / W21)> 1.5, the groove width W22 at the end of the second lug groove 80 on the outer side in the tire width direction is too large. There is a possibility that the rigidity of the shoulder block 12 near the end of the second lug groove 80 on the outer side in the tire width direction becomes too low, or stress concentration is likely to occur when the shoulder block 12 contacts the ground. In this case, it may be difficult to effectively suppress uneven wear of the shoulder block 12.

  On the other hand, when the relationship between the minimum groove width W21 and the groove width W22 is within a range of 1.1 ≦ (W22 / W21) ≦ 1.5, the first groove chain is attached to the pneumatic tire 1 when the tire chain is mounted. The rigidity of the shoulder block 12 can be ensured to an appropriate size while securing the chain to the two lug grooves 80, and uneven wear can be suppressed. As a result, uneven wear resistance and chain hooking properties can be ensured more reliably.

  Further, the relationship between the groove depth D11 of the outer region A11 of the first lug groove 70 and the groove depth D21 of the outer region A21 of the second lug groove 80 is 0.2 ≦ (D21 / D11) ≦ 0.5. Therefore, uneven wear can be suppressed while securing the chain hooking property more reliably. That is, when the relationship between the groove depth D11 and the groove depth D21 is (D21 / D11) <0.2, the groove depth D11 of the first lug groove 70 and the groove depth D21 of the second lug groove 80 are set. Therefore, the difference in rigidity between the position near the first lug groove 70 and the position near the second lug groove 80 in the shoulder block 12 becomes too large, and it may be difficult to suppress uneven wear. is there. Further, when the relationship between the groove depth D11 and the groove depth D21 is (D21 / D11)> 0.5, the groove depth D11 of the first lug groove 70 may be too shallow, and the pneumatic tire 1 When the tire chain is attached to the first lug groove 70, the chain may be difficult to be caught.

  On the other hand, when the relationship between the groove depth D11 of the first lug groove 70 and the groove depth D21 of the second lug groove 80 is within the range of 0.2 ≦ (D21 / D11) ≦ 0.5. In addition, it is possible to secure the chain hooking property to the first lug groove 70 while suppressing the uneven wear caused by the rigidity difference of the shoulder block 12 becoming too large. As a result, uneven wear resistance and chain hooking properties can be ensured more reliably.

  Further, since the relationship between the maximum groove depth D15 of the first lug groove 70 and the maximum groove depth D25 of the second lug groove 80 is within the range of 0.1 ≦ (D25 / D15) ≦ 0.5, Uneven wear can be suppressed while ensuring the chain engagement more reliably. That is, when the relationship between the maximum groove depth D15 of the first lug groove 70 and the maximum groove depth D25 of the second lug groove 80 is (D25 / D15) <0.1, the first lug groove 70 and the first lug groove 70 2 Since the difference between the maximum groove depths with the lug groove 80 is too large, the difference in rigidity between the position near the first lug groove 70 and the position near the second lug groove 80 in the shoulder block 12 becomes too large, resulting in uneven wear. There is a risk that it will be difficult to suppress this. When the relationship between the maximum groove depth D15 of the first lug groove 70 and the maximum groove depth D25 of the second lug groove 80 is (D25 / D15)> 0.5, the groove of the first lug groove 70 The depth D11 may be too shallow, and when the tire chain is attached to the pneumatic tire 1, the chain may not be easily caught in the first lug groove 70.

  On the other hand, the relationship between the maximum groove depth D15 of the first lug groove 70 and the maximum groove depth D25 of the second lug groove 80 is in the range of 0.1 ≦ (D25 / D15) ≦ 0.5. In this case, it is possible to secure the chain hooking property to the first lug groove 70 while suppressing uneven wear due to the rigidity difference of the shoulder block 12 becoming too large. As a result, uneven wear resistance and chain hooking properties can be ensured more reliably.

  Further, the first lug groove 70 and the second lug groove 80 have the groove depths D13 and D23 at a position Pin near the end on the inner side in the tire width direction within the range of 1 mm or more and 5 mm or less. The rigidity at the position closer to the inner side in the tire width direction can be made comparable between the first lug groove 70 side and the second lug groove 80 side. Thereby, the partial wear resulting from the rigidity difference of the shoulder block 12 can be suppressed more reliably. Further, the first lug groove 70 has a groove depth D14 at a position Pout near the outer end in the tire width direction within a range of 6 mm or more and 15 mm or less, and the second lug groove 80 is an end on the outer side in the tire width direction. Since the groove depth D24 at the position Pout closer to the portion is in the range of 1 mm or more and 5 mm or less, the groove depth of the first lug groove 70 is set to an appropriate size with respect to the groove depth of the second lug groove 80. Can be deep. Thereby, when the tire chain of the pneumatic tire 1 is mounted, it is possible to more surely secure the ease of hanging the chain on the first lug groove 70. As a result, uneven wear resistance and chain hooking properties can be ensured more reliably.

  The relationship between the groove depth D12 in the defined region A12 of the first lug groove 70 and the groove depth DC of the shoulder circumferential main groove 22 is in the range of 0.6 ≦ (D12 / DC) ≦ 1.0. Therefore, uneven wear can be suppressed while securing the chain hooking property more reliably. That is, when the relationship between the groove depth D12 of the first lug groove 70 and the groove depth DC of the shoulder circumferential main groove 22 is (D12 / DC) <0.6, the groove depth of the first lug groove 70 The length D12 may be too shallow, and when the tire chain is mounted on the pneumatic tire 1, the chain may not be easily caught in the first lug groove 70. Further, when the relationship between the groove depth D12 of the first lug groove 70 and the groove depth DC of the shoulder circumferential main groove 22 is (D12 / DC)> 1.0, the groove depth of the first lug groove 70 There is a possibility that the depth D12 is too deep, and the rigidity of the position near the first lug groove 70 in the shoulder block 12 becomes too low, and it may be difficult to suppress uneven wear.

  On the other hand, when the relationship between the groove depth D12 of the first lug groove 70 and the groove depth DC of the shoulder circumferential main groove 22 is in the range of 0.6 ≦ (D12 / DC) ≦ 1.0. Can secure the chain hooking property to the first lug groove 70 while suppressing uneven wear due to the rigidity of the shoulder block 12 near the first lug groove 70 being too low. As a result, uneven wear resistance and chain hooking properties can be ensured more reliably.

  Further, the relationship between the groove width W12 at the outer end in the tire width direction of the first lug groove 70 and the groove width W22 at the outer end in the tire width direction of the second lug groove 80 is 1.1 ≦ (W12 / Since it is within the range of W22) ≦ 1.3, it is possible to suppress uneven wear while securing the chain hooking property more reliably. That is, when the relationship between the groove width W12 of the first lug groove 70 and the groove width W22 of the second lug groove 80 is (W12 / W22) <1.1, the groove width W12 of the first lug groove 70 is There is a possibility that the chain is too small, and when the tire chain is mounted on the pneumatic tire 1, the chain may not be easily caught in the first lug groove 70. When the relationship between the groove width W12 of the first lug groove 70 and the groove width W22 of the second lug groove 80 is (W12 / W22)> 1.3, the groove width W12 of the first lug groove 70 is Since the difference with the groove width W22 of the second lug groove 80 is too large, the difference in rigidity between the position near the first lug groove 70 and the position near the second lug groove 80 in the shoulder block 12 becomes too large. There is a possibility that stress concentration is likely to occur at the time of twelve grounding. In this case, it may be difficult to effectively suppress uneven wear of the shoulder block 12.

  On the other hand, if the relationship between the groove width W12 of the first lug groove 70 and the groove width W22 of the second lug groove 80 is within the range of 1.1 ≦ (W12 / W22) ≦ 1.3, the air While securing the chain to the first lug groove 70 when the tire chain is attached to the entering tire 1, the shoulder block 12 can have an appropriate rigidity and suppress uneven wear. Can do. As a result, uneven wear resistance and chain hooking properties can be ensured more reliably.

  In addition, the first lug groove 70 and the second lug groove 80 have a portion in which the groove depth at the same position in the tire width direction is the same in a predetermined range AH on the inner side in the tire width direction. It can be suppressed more reliably that the difference in rigidity between the position near the first lug groove 70 and the position near the second lug groove 80 in the block 12 becomes too large. Thereby, the partial wear resulting from the rigidity difference of the shoulder block 12 can be suppressed more reliably. In addition, since it is possible to prevent the groove depth at the position near the shoulder circumferential main groove 22 in the first lug groove 70 from becoming too deep, the sound generated when the tread surface 3 contacts the ground is changed from the shoulder circumferential main groove 22 to the first lug groove 70. It can suppress more reliably that it flows through the 1 lug groove 70 to the tire width direction outer side. Thereby, the passing sound at the time of driving | running | working of a vehicle can be reduced more reliably. As a result, noise can be reduced more reliably while ensuring uneven wear resistance.

  The fourth lug grooves 60 are the fourth lug grooves 60 provided in the center ribs 11 adjacent to each other in the tire width direction across the center circumferential main groove 21, and the opening position to the center circumferential direction main groove 21 is a tire. Since it has shifted | deviated 10 mm or more in the circumferential direction, it can suppress that the sound which generate | occur | produces at the time of the earthing | grounding of the tread surface 3 flows between 4th lug grooves 60 of the adjacent center rib 11. FIG. Thereby, the sound generated in the region located on one side in the tire width direction with respect to the center circumferential main groove 21 on the tread surface 3 flows more reliably through the fourth lug groove 60 to the other side. Can be suppressed. As a result, noise reduction can be achieved more reliably.

[Modification]
In the pneumatic tire 1 according to the above-described embodiment, only the circumferential main groove 20 and the lug groove 40 are provided on the tread surface 3, but the circumferential main groove 20 and the lug are provided on the tread surface 3. Other than the groove 40 may be provided. FIG. 18 is an explanatory diagram in the case where the sipe 100 is formed on the tread surface 3 as a modification of the pneumatic tire 1 according to the embodiment. A plurality of sipes 100 may be formed on the tread surface 3. As the sipe 100, for example, as shown in FIG. 18, a bent sipe 101 or a lug groove sipe 102 may be provided on the center rib 11, or a rib edge sipe 103 may be provided on the shoulder block 12. . Among them, the bent sipe 101 is a so-called closed sipe that ends in the center rib 11 at both ends, and the positions in the tire circumferential direction are adjacent to the third lug groove 50 and the fourth lug groove 60 in the tire circumferential direction. Is located between. The bending sipe 101 is formed in a crank shape by being bent at two locations while extending in the tire width direction.

  Similarly to the bent sipe 101, the lug groove sipe 102 is a closed sipe where both ends terminate in the center rib 11, and the position in the tire circumferential direction is the position of the third lug groove 50 in the tire circumferential direction, The four lug grooves 60 are disposed at the same position as the position in the tire circumferential direction. Specifically, the lug groove sipe 102 is disposed along the extending direction of the third lug groove 50 and the fourth lug groove 60, and a part thereof overlaps the third lug groove 50 and the fourth lug groove 60. Yes. That is, a part of the lug groove sipe 102 is formed at the groove bottom of the third lug groove 50 or the fourth lug groove 60.

  The rib edge sipe 103 is formed at the edge of the shoulder block 12 that is defined by the shoulder circumferential main groove 22. The rib edge sipe 103 extends in the tire width direction with a short length and opens at one end in the shoulder circumferential main groove 22. The other end terminates in the shoulder block 12. In the example shown in FIG. 18, two rib edge sipes 103 are disposed between the first lug groove 70 and the second lug groove 80 adjacent to each other in the tire circumferential direction.

  The sipe 100 here is formed in a narrow groove shape on the tread surface 3, and the pneumatic tire 1 is assembled on a regular rim to form a narrow groove when no load is applied under normal internal pressure conditions. The wall surfaces to be touched do not contact each other, but when the narrow groove is located in the portion of the grounding surface formed on the flat plate when loaded in the vertical direction on the flat plate, or when the land portion 10 where the narrow groove is formed falls In addition, the wall surfaces constituting the narrow groove, or at least a part of the portion provided on the wall surface are in contact with each other by deformation of the land portion 10.

  The regular rim is “standard rim” defined by JATMA, “Design Rim” defined by TRA, or “Measuring Rim” defined by ETRTO. The normal internal pressure is “maximum air pressure” defined by JATMA, the maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO.

  The tread surface 3 is provided with a sipe 100 such as a bent sipe 101, a lug groove sipe 102, and a rib edge sipe 103, thereby adjusting the rigidity of the land portion 10 and ensuring the rigidity of each part to a desired size more reliably. Therefore, uneven wear can be more reliably suppressed. Further, since the sipe 100 is closed when the tread surface 3 on which the sipe 100 is formed is grounded, it is possible to suppress the sound generated when the tread surface 3 is grounded from flowing through the sipe 100 to the outside in the tire width direction. As a result, noise can be reduced more reliably while ensuring uneven wear resistance.

  In the above-described embodiment, the widened portion 72 of the first lug groove 70 and the widened portion 82 of the second lug groove 80 have a groove width that increases from the inner side to the outer side in the tire width direction. As for 72 and 82, the groove width does not necessarily need to become large as it goes to the outer side from the inner side in a tire width direction. The widened portion 72 of the first lug groove 70 and the widened portion 82 of the second lug groove 80 may have a region where the groove width is constant, for example. If the wide portions 72 and 82 have groove widths at the end portions of the wide portions 72 and 82 on the outer side in the tire width direction, the groove widths at the end portions on the inner side in the tire width direction are larger. The groove width of the region between the end portions of the widened portions 72 and 82 may be changed in any manner.

  In the above-described embodiment, the first lug groove 70 and the second lug groove 80 have constant width portions 71 and 81 that are formed with a constant groove width inside the bent portions 73 and 83 in the tire width direction. However, the groove width inner sides of the bent portions 73 and 83 may not be formed with a constant groove width. On the inner side in the tire width direction of the bent portions 73 and 83, a portion where the groove width becomes constant and a portion where the groove width changes may be mixed, or the way of changing the groove width at the widened portions 72 and 82 The groove width may be changed in a different manner.

  In the above-described embodiment, three circumferential main grooves 20 are provided, but the number of circumferential main grooves 20 may be other than three. A plurality of circumferential main grooves 20 may be provided, and a shoulder circumferential direction is formed on the outer side in the tire width direction of the shoulder circumferential main groove 22 located on the outermost side in the tire width direction among the plurality of circumferential main grooves 20. The number of the circumferential main grooves 20 is not limited as long as the first lug grooves 70 and the second lug grooves 80 that open to the main groove 22 and have different depths are alternately arranged in the tire circumferential direction.

〔Example〕
19A to 19D are tables showing the results of performance tests of pneumatic tires. Hereinafter, the performance evaluation test performed on the pneumatic tire 1 of the conventional example and the pneumatic tire 1 according to the present invention will be described. The performance evaluation test includes uneven wear resistance, which is a performance against uneven wear of the tread surface 3, passing noise which is performance with respect to noise generated with the rolling of the pneumatic tire 1, and the tire of the pneumatic tire 1. A test was conducted on the chain hanging property, which is the performance of the chain when the chain is mounted.

  In the performance evaluation test, a pneumatic tire 1 with a tire size specified by JATMA of 205 / 85R16 size is assembled to a regular rim, the air pressure is adjusted to a regular internal pressure, and a 2-D test vehicle (tractor head) The test was carried out by wearing it. As for the evaluation method of each test item, with respect to uneven wear resistance, the wear amount of heel & toe wear after running 30,000 km on the test vehicle, that is, the difference in wear amount between the kicking side and the stepping side of the shoulder block 12 Was measured, and the difference in the measured amount of wear was displayed as an index with the conventional example described later as 100. The larger this value, the smaller the difference in wear amount between the kicking side and the stepping side of the shoulder block 12, that is, the smaller the heel and toe wear, and the better the uneven wear resistance.

  The passing noise was evaluated based on the magnitude of the passing sound measured outside the vehicle according to the tire noise test method defined in ECE R117-02 (ECE Regulation No. 117 Revision 2). In this test, the maximum noise value dB (frequency in a frequency range of 800 Hz to 1200 Hz) in the noise measurement section when the test vehicle is run sufficiently before the noise measurement section, the engine is stopped before the section, and the coasting is made. Value) was measured at a plurality of speeds in which a speed range of ± 10 km / h with respect to the reference speed was divided into eight or more at almost equal intervals, and the average was defined as vehicle outside noise. The maximum noise value dB was measured through an A characteristic frequency correction circuit using a stationary microphone installed at a height of 7.5 m to the side of the running center line and 1.2 m from the road surface at an intermediate point in the noise measurement section. Sound pressure dB (A). For the passing noise, this measurement result was expressed as a difference in sound pressure dB with respect to the passing noise of the conventional example with reference to the passing noise of the conventional example described later. The smaller the sound pressure dB with respect to the passing noise of the conventional example, the better the performance with respect to the passing noise.

  As for chain hookability, the tire chain is mounted on a test tire mounted on a test vehicle, and the deviation of the tire chain with respect to the test tire is visually evaluated after three braking tests from 20 km / h are performed. did. The chain hooking property is expressed by an index with the conventional example described later as 100, and the larger the numerical value, the smaller the amount of deviation of the tire chain and the better the chain hooking property.

  The evaluation test was performed on 26 types of pneumatic tires of a conventional pneumatic tire which is an example of the conventional pneumatic tire 1 and Examples 1 to 25 which are the pneumatic tire 1 according to the present invention. Among these pneumatic tires 1, the conventional pneumatic tire has a first lug groove and a second lug groove, and the groove of the first lug groove with respect to the groove depth of the second lug groove. Although the depth is deeper, the first lug grooves and the second lug grooves are not alternately arranged, and are arranged corresponding to the size of the block pitch as in Patent Document 1. .

  On the other hand, Examples 1-25 which are examples of the pneumatic tire 1 which concerns on this invention have all the 1st lug grooves 70 and the 2nd lug grooves 80, and are the grooves of the 2nd lug grooves 80 The depth of the first lug groove 70 is deeper than the depth, and the first lug grooves 70 and the second lug grooves 80 are alternately arranged. Further, in the pneumatic tire 1 according to Examples 1 to 25, the presence or absence of the third lug groove 50, the relative relationship between the groove depths of the first lug groove 70 and the third lug groove 50, the tire of the first lug groove 70 The ratio (W12 / W11) between the groove width W12 and the minimum groove width W11 at the outer end in the width direction, and the ratio between the groove width W22 and the minimum groove width W21 at the outer end in the tire width direction of the second lug groove 80 ( W22 / W21), the ratio (D21 / D11) of the groove depth D11 of the outer region A11 of the first lug groove 70 and the groove depth D21 of the outer region A21 of the second lug groove 80, the definition of the first lug groove 70 The ratio (D12 / DC) of the groove depth D12 in the region A12 and the groove depth DC of the shoulder circumferential main groove 22, the groove width W12 in the outer opening 75 of the first lug groove 70, and the outer side of the second lug groove 80. Ratio (W12 / W22) with groove width W22 at opening 85 The presence or absence of the same groove depth between the first lug groove 70 and the second lug groove 80, the opening position of the first lug groove 70 relative to the shoulder circumferential main groove 22, and the opening position of the second lug groove 80 The ratio between the distance L12 and the distance L13 between the opening position of the third lug groove 50 and the opening position of the first lug groove 70 relative to the shoulder circumferential main groove 22 (L13 / L12), and each of the adjacent third lug grooves 50 Distance L33 between the opening positions of the shoulder circumferential main groove 22, the opening position of the third lug groove 50 with respect to the shoulder circumferential main groove 22, and the opening position of the fourth lug groove 60 with respect to the center circumferential main groove 21. The ratio between the distance L34 (L34 / L33) and the ratio between the minimum groove depth D31 of the constant width portion 51 of the third lug groove 50 and the groove depth D21 of the outer region A21 of the second lug groove 80 (D31 / D21). , One of the fourth lug groove 60 The ratio (D41 / D21) between the minimum groove depth D41 of the width portion 61 and the groove depth D21 of the outer region A21 of the second lug groove 80 is formed in the center ribs 11 on both sides of the center circumferential main groove 21. The shift amounts of the opening positions of the fourth lug groove 60 with respect to the center circumferential main groove 21 are different.

  As a result of performing an evaluation test using these pneumatic tires 1, as shown in FIGS. 19A to 19D, the pneumatic tires 1 of Examples 1 to 25 are more resistant to uneven wear and chains than conventional examples. It was found that the passing noise was reduced without reducing the hooking property. That is, the pneumatic tire 1 according to Examples 1 to 25 can achieve low noise while ensuring uneven wear resistance and chain hooking property.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Tread surface 4 Shoulder part 5 Side wall part 6 Carcass 7 Belt layer 8 Inner liner 10 Land part 11 Center rib 12 Shoulder block 13 Shoulder block row 20 Circumferential main groove 21 Center circumferential main groove 22 Shoulder circumferential main groove 30 Bead portion 40 Lug groove 41 Center lug groove 42 Shoulder lug groove 50 Third lug groove 51, 61 Constant width portion 52, 62 Widened portion 53, 63 Open portion 54, 64 End portion 60 Fourth lug groove 70 First lug groove 71, 81 Constant width portion 72, 82 Widened portion 73, 83 Bent portion 74, 84 Inner opening 75, 85 Outer opening 76, 86 Groove bottom 80 Second lug groove 90 Notch 91 First cut Notch 95 Second notch 100 Sipe 101 Bending sipe 102 Lug groove sipe 103 Bedge sipe

Claims (15)

A plurality of circumferential main grooves formed on the tread surface and extending in the tire circumferential direction;
A plurality of lug grooves formed on the tread surface and extending in the tire width direction;
A plurality of land portions in which at least one end portion in the tire width direction is partitioned by the circumferential main groove;
With
Of the plurality of circumferential main grooves, the circumferential main groove located on the outermost side in the tire width direction is a shoulder circumferential main groove,
When the lug groove located outside the shoulder circumferential main groove in the tire width direction and opening from the outer side in the tire width direction to the shoulder circumferential main groove among the plurality of lug grooves is a shoulder lug groove ,
On the outer side in the tire width direction of the shoulder circumferential main groove, a shoulder block row in which shoulder blocks that are the land portions defined by the shoulder circumferential main groove and the shoulder lug groove are arranged in the tire circumferential direction is arranged. Established,
The shoulder lug groove has a first lug groove and a second lug groove having different groove depths, and the groove depth of the first lug groove is deeper than the groove depth of the second lug groove. And
The pneumatic tire according to claim 1, wherein the first lug grooves and the second lug grooves are alternately arranged in a tire circumferential direction.   Among the plurality of land portions, the land portion adjacent to the shoulder circumferential main groove from the inner side in the tire width direction has one end opened in the shoulder circumferential main groove and the other end terminated in the land portion. The pneumatic tire according to claim 1, wherein a third lug groove, which is the lug groove whose groove depth is shallower than the groove depth of the first lug groove, is provided. The first lug groove, the second lug groove and the third lug groove are:
The distance in the tire circumferential direction from the position where the first lug groove opens to the shoulder circumferential main groove to the position where the second lug groove opens to the shoulder circumferential main groove is L12,
When the distance in the tire circumferential direction from the position where the third lug groove opens to the shoulder circumferential main groove to the position where the first lug groove opens to the shoulder circumferential main groove is L13,
The pneumatic tire according to claim 2, wherein the relationship between the distance L12 and the distance L13 is in a range of 0.2≤ (L13 / L12) ≤0.8. In the land portion where the third lug groove is provided, one end of the land portion is opened in the circumferential main groove defining the inner side in the tire width direction of the land portion, and the other end is the lug groove terminating in the land portion. A fourth lug groove is provided,
The third lug groove and the fourth lug groove are arranged in a staggered arrangement by alternately providing the third lug groove and the fourth lug groove in the tire circumferential direction. The pneumatic tire according to 2 or 3. The distance in the tire circumferential direction of the opening position to the shoulder circumferential main groove between the third lug grooves adjacent in the tire circumferential direction is L33,
An opening position of the third lug groove to the shoulder circumferential main groove in the third lug groove and the fourth lug groove adjacent to each other in the tire circumferential direction, and the fourth lug groove to the circumferential main groove When the distance in the tire circumferential direction from the opening position of L is L34,
The pneumatic tire according to claim 4, wherein a relationship between the distance L33 and the distance L34 is in a range of 0.3 ≦ (L34 / L33) ≦ 0.5. The second lug groove has a bent portion that is a position where the groove width changes within a range of 40% to 60% of the width of the shoulder block in the tire width direction from the end portion in the tire width direction. And, the groove width is formed constant from the bent part in the tire width direction inside, and the groove width becomes wider from the bent part to the tire width direction outer side toward the tire width direction outer side,
The groove depth of the second lug groove in the region from the position of the bent portion in the second lug groove to the outer end in the tire width direction is D21,
The groove depth of the third lug groove is D31,
When the groove depth of the fourth lug groove is D41,
The third lug groove and the fourth lug groove have groove depths D31 and D41 of 0.8 ≦ (D31 / D21) ≦ 1.2, respectively, with respect to the groove depth D21 of the second lug groove. The pneumatic tire according to claim 4 or 5, which is in a range of 0.8 ≦ (D41 / D21) ≦ 1.2.   The first lug groove has a narrowest groove width at a portion located within a range of 40% to 60% of the width of the shoulder block in the tire width direction from the end in the tire width direction as the minimum groove width W11. Further, the relationship between the groove width W12 and the minimum groove width W11 at the end portion on the outer side in the tire width direction is within a range of 1.3 ≦ (W12 / W11) ≦ 1.7. The pneumatic tire according to item 1.   The second lug groove has a narrowest groove width as a minimum groove width W21 in a portion located in the range of 40% to 60% of the width of the shoulder block in the tire width direction from the end in the tire width direction. Further, the relationship between the groove width W22 at the outer end in the tire width direction and the minimum groove width W21 is in the range of 1.1 ≦ (W22 / W21) ≦ 1.5. The pneumatic tire according to item 1. The first lug groove and the second lug groove are positions where the groove width changes within a range of 40% to 60% of the width of the shoulder block in the tire width direction from the end in the tire width direction. Each has a bent portion, and the groove width is constant from the bent portion to the inner side in the tire width direction, and the groove width increases from the bent portion to the outer side in the tire width direction toward the outer side in the tire width direction. And
The groove depth of the first lug groove in the region from the position of the bent portion in the first lug groove to the outer end in the tire width direction is D11,
When the groove depth of the second lug groove in the region from the position of the bent portion in the second lug groove to the outer end in the tire width direction is D21,
The relationship between the groove depth D11 of the first lug groove and the groove depth D21 of the second lug groove is in the range of 0.2 ≦ (D21 / D11) ≦ 0.5. A pneumatic tire given in any 1 paragraph.   In the first lug groove and the second lug groove, the relationship between the maximum groove depth D15 of the first lug groove and the maximum groove depth D25 of the second lug groove is 0.1 ≦ (D25 / D15 The pneumatic tire according to any one of claims 1 to 9, which is within a range of ≦ 0.5. The first lug groove and the second lug groove have a groove depth of 1 mm or more and 5 mm at a position of 20% of the width of the shoulder block in the tire width direction from the inner end in the tire width direction to the outer side in the tire width direction. Within the following range:
The first lug groove has a groove depth in the range of 6 mm or more and 15 mm or less at a position of 20% of the width in the tire width direction of the shoulder block from the end on the tire width direction outer side to the tire width direction inner side,
The second lug groove has a groove depth in a range of 1 mm or more and 5 mm or less at a position of 20% of the width of the shoulder block in the tire width direction on the inner side in the tire width direction from an end portion on the outer side in the tire width direction. Item 11. The pneumatic tire according to any one of Items 1 to 10.   The first lug groove and the shoulder circumferential main groove are a groove depth D12 in a region 10 mm inward in the tire width direction from an end on the tire width direction outer side of the first lug groove, and the shoulder circumferential main groove. The pneumatic tire according to any one of claims 1 to 11, wherein a relationship with the groove depth DC is in a range of 0.6 ≦ (D12 / DC) ≦ 1.0.   The first lug groove and the second lug groove include a groove width W12 at an end portion on the outer side in the tire width direction of the first lug groove, and a groove width W22 at an end portion on the outer side in the tire width direction of the second lug groove. The pneumatic tire according to claim 1, wherein the relationship is 1.1 ≦ (W12 / W22) ≦ 1.3.   The first lug groove and the second lug groove have the same position in the tire width direction within a range of 40% of the width of the shoulder block in the tire width direction from the end in the tire width direction to the outer side in the tire width direction. The pneumatic tire according to any one of claims 1 to 13, which has a portion in which the groove depth at the position is the same. Three circumferential main grooves are provided side by side in the tire width direction,
The land portion is provided with four rows arranged in the tire width direction,
Of the plurality of land portions, the land portions other than the shoulder block rows are formed with grooves and sipes that open to both of the two circumferential main grooves that define both sides of the land portions in the tire width direction. Not
Among the three circumferential main grooves, one end of each of the land portions adjacent to each other in the tire width direction across the center circumferential main groove, which is the circumferential main groove at the center, has the center circumferential main groove. The lug grooves that are open at the other end and terminate in the land portion at the other end are respectively provided, and the lug grooves of the land portions in two rows are located between the lug grooves in the tire circumferential direction. The pneumatic tire according to any one of claims 1 to 14, which is deviated by 10 mm or more.

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