JP2018192959A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire that can make both on-ice performance and on-snow performance compatible.SOLUTION: A pneumatic tire comprises: second lug grooves 32 connected to a center main groove 21 and a shoulder main groove 22; a circumferential narrow groove 50 positioned between the center main groove 21 and the shoulder main groove 22 and extended in a tire circumferential direction; a first block region 15 partitioned by the two second lug grooves 32, the center main groove 21 and the circumferential narrow groove 50; a second block region 17 partitioned by the two second lug grooves 32, the shoulder main groove 22 and the circumferential narrow groove 50; first sub lug grooves 41, both ends of which are connected to the center main groove 21 and the circumferential narrow groove 50, which divide a land part of the first block region 15 into a plurality of first blocks 16; and second sub lug grooves 42, both ends of which are connected to the shoulder main groove 22 and the circumferential narrow groove 50, which divide a land part of the second block region 17 into a plurality of second blocks 18. The number of the second lug grooves 42 arranged are more than the number of the first sub lug grooves 41 arranged.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire.

  Pneumatic tires have grooves on the tread surface for the purpose of ensuring drainage, etc.However, if there are too many grooves, noise is likely to be generated, and the rigidity of the land part will be reduced and steering stability will be reduced. Some conventional pneumatic tires are designed to improve these contradictory performances by devising the arrangement of grooves in order to reduce wear resistance.

  For example, in the pneumatic tire described in Patent Document 1, the adjacent vertical main grooves are connected by the horizontal main grooves, and the divided vertical fine grooves that connect the adjacent horizontal main grooves are provided. The hydroplaning performance is improved while substantially maintaining the noise performance by disposing the lateral auxiliary grooves at positions where the positions in the tire circumferential direction are different between the vertical main grooves and the divided vertical thin grooves. Moreover, the pneumatic tire described in Patent Document 2 has a plurality of middle lateral grooves extending in the tire circumferential direction and joining adjacent main grooves, and a circumferential groove joining the middle lateral grooves adjacent in the tire circumferential direction. Thereby, turning performance and uneven wear resistance performance can be improved while ensuring straight running stability.

Japanese Patent No. 3682269 JP2015-74289A

  Here, among the pneumatic tires, there is a so-called studless tire that requires running performance on ice or snow. The studless tire uses a relatively soft rubber on the tread surface to increase the adhesive frictional force and provide a large number of sipes to improve the running performance on ice and snow. In recent years, in such a studless tire, it is more and more important to achieve both on-snow performance and on-ice performance. For example, with respect to on-ice performance, there are increasing demands for improving braking performance and turning performance. Generally, to improve the performance on ice, it is effective to reduce the groove area of the tread pattern and increase the contact surface. To improve the performance on snow, the groove area is increased and the snow on the road surface is increased. It has become good to drain snow by the groove. Thus, since the on-ice performance and the on-snow performance are contradictory to the tendency of an effective tread pattern, it has been very difficult to achieve both performances.

  This invention is made | formed in view of the above, Comprising: It aims at providing the pneumatic tire which can make performance on ice and performance on snow compatible.

  In order to solve the above-described problems and achieve the object, a pneumatic tire according to the present invention includes a first main groove extending in the tire circumferential direction and a tire width direction extending in the tire circumferential direction and more than the first main groove. A second main groove located outside and adjacent to the first main groove; a plurality of main lug grooves extending in the tire width direction and having both ends connected to the first main groove and the second main groove; A circumferentially thin line extending between the first main groove and the second main groove in the tire width direction and extending in the tire circumferential direction with a groove width narrower than the groove widths of the first main groove and the second main groove. A groove, a first block region defined by the two main lug grooves adjacent to each other in the tire circumferential direction, the first main groove, and the circumferential narrow groove, and the two main adjacent to each other in the tire circumferential direction. A second block region defined by a lug groove, the second main groove, and the circumferential narrow groove; A land portion extending in the tire width direction between one main groove and the circumferential narrow groove and having both ends connected to the first main groove and the circumferential narrow groove and having a plurality of land portions located in the first block region. A first auxiliary lug groove that is divided into blocks, and extends in the tire width direction between the second main groove and the circumferential narrow groove, and both ends thereof are connected to the second main groove and the circumferential narrow groove; A second sub lug groove that divides a land portion located in the second block region into a plurality of blocks, and the second sub lug groove disposed in one second block region includes the one The number of the first sub lug grooves disposed in the first block region is greater than the number of the first sub lug grooves.

  In the pneumatic tire, the distance between the first main groove and the second main groove in the tire width direction from the tire equatorial plane is in a range of 3% to 50% of the tire ground contact width. preferable.

  In the pneumatic tire, the outer side of the second main groove in the tire width direction is formed at a position extending in the tire width direction and extending from the main lug groove, and an inner end portion in the tire width direction is the second end. A first outer lug groove connected to the main groove, and an inner end portion in the tire width direction that extends in the tire width direction and has a position in the tire circumferential direction that is different from the position in the tire circumferential direction of the main lug groove. And a second outer lug groove connected to the second main groove.

  In the pneumatic tire, it is preferable that the first auxiliary lug groove and the second auxiliary lug groove are arranged at equal intervals between the main lug grooves adjacent in the tire circumferential direction.

  In the pneumatic tire, the circumferential narrow groove is bent in the tire width direction while extending in the tire circumferential direction, and the second auxiliary lug groove is connected to a bent portion of the circumferential narrow groove to be bent. It is preferable.

  In the pneumatic tire, the first auxiliary lug groove and the second auxiliary lug groove are both inclined in the tire circumferential direction while extending in the tire width direction, and an inclination angle in the tire width direction with respect to the tire circumferential direction is It is preferably within the range of 40 ° to 85 °.

  In the pneumatic tire, it is preferable that a groove width of the second sub lug groove is in a range of 30% to 70% of a groove width of the first sub lug groove.

  In the pneumatic tire, both the first sub lug groove and the second sub lug groove may be shallow within a range of 1 mm to 5 mm with respect to the groove depth of the main lug groove. preferable.

  The pneumatic tire according to the present invention has an effect that it is possible to achieve both performance on ice and performance on snow.

FIG. 1 is a plan view showing a tread surface of a pneumatic tire according to an embodiment. FIG. 2 is a detailed view of part A of FIG. FIG. 3 is an explanatory diagram of the first sub lug groove and the second sub lug groove shown in FIG. 2. 4 is a cross-sectional view taken along line BB in FIG. 5 is a cross-sectional view taken along the line CC of FIG. FIG. 6 is an explanatory diagram showing the relationship between one block unit and a shoulder block. FIG. 7A is a chart showing the results of a performance test of a pneumatic tire. FIG. 7B is a chart showing the results of the performance test of the pneumatic tire. FIG. 7C is a chart showing the results of the performance test of the pneumatic tire. FIG. 7D is a chart showing the results of the performance test of the 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 radial direction refers to a direction orthogonal to the rotational axis of the pneumatic tire 1, the tire radial inner side is the side toward the rotational axis in the tire radial direction, and the tire radial outer side is the tire radial direction. Means the side away from the rotation axis. Further, the tire circumferential direction refers to a circumferential direction with the rotation axis as the central axis. Further, the tire width direction means a direction parallel to the rotation axis, the inner side in the tire width direction means the side toward the tire equator plane (tire equator line) CL in the tire width direction, and the outer side in the tire width direction means in the tire width direction. The side away from the tire equatorial plane CL. The tire equatorial plane CL is a plane that is orthogonal to the rotation axis of the pneumatic tire 1 and passes through the center of the tire width of the pneumatic tire 1. The tire width is the width in the tire width direction between the portions located outside in the tire width direction, that is, the distance between the portions farthest from the tire equatorial plane CL in the tire width direction. The tire equator line is a line along the tire circumferential direction of the pneumatic tire 1 on the tire equator plane CL.

  FIG. 1 is a plan view showing a tread surface 3 of a pneumatic tire 1 according to an embodiment. A pneumatic tire 1 shown in FIG. 1 is provided with a tread portion 2 at the outermost portion in the tire radial direction, and the surface of the tread portion 2, that is, a vehicle on which the pneumatic tire 1 is mounted (not shown). The portion that comes into contact with the road surface during travel is formed as a tread surface 3. A plurality of circumferential main grooves 20 extending in the tire circumferential direction and lug grooves 30 extending in the tire width direction are formed on the tread surface 3, and the tread surface 3 includes the tread surface 3 and the tread surface 3. A plurality of blocks 10 that are land portions are formed on the surface 3.

  Specifically, four circumferential main grooves 20 are formed side by side in the tire width direction, and a center main groove 21 that is two first main grooves located on both sides of the tire equatorial plane CL in the tire width direction. Also, shoulder main grooves 22, which are two second main grooves adjacent to the center main groove 21, are provided on the outer sides in the tire width direction of the two center main grooves 21.

  The center main groove 21 and the shoulder main groove 22 have a tire ground contact width TW of 3 in which the distance in the tire width direction from the tire equatorial plane CL is the distance in the tire width direction between the ground contact ends T of the tread surface 3. % To 50% or less. In this case, the ground contact end T is assembled with a normal rim by assembling the pneumatic tire 1 with a normal rim, and is placed perpendicular to the flat plate in a stationary state and applied with a load equivalent to 88% of the normal load. The outermost ends in the tire width direction of the region in contact with the flat plate on the tread surface 3 when being applied, are continuous in the tire circumferential direction.

  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 normal load is “maximum load capacity” defined by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “LOAD CAPACITY” defined by ETRTO.

  The lug groove 30 is a second lug which is a center lug groove 31 located between two center main grooves 21 and a main lug groove located between adjacent center main grooves 21 and shoulder main grooves 22. A groove 32 and a shoulder lug groove 33 located on the outer side in the tire width direction of the shoulder main groove 22 are provided. The circumferential main groove 20 here has a groove width in the range of 3 mm to 15 mm and a groove depth in the range of 7 mm to 10 mm. The lug groove 30 has a groove width in the range of 2 mm to 12 mm and a groove depth in the range of 7 mm to 10 mm.

  Among the plurality of lug grooves 30, the center lug groove 31 is formed extending in the tire width direction between the two center main grooves 21, and both ends thereof are connected to the center main groove 21. The second lug groove 32 is formed to extend in the tire width direction between the adjacent center main groove 21 and shoulder main groove 22, and the inner end in the tire width direction is connected to the center main groove 21. The outer end in the width direction is connected to the shoulder main groove 22. Further, the shoulder lug groove 33 is formed to extend in the tire width direction at a position outside the shoulder main groove 22 in the tire width direction, and an inner end portion in the tire width direction is connected to the shoulder main groove 22. Moreover, the shoulder lug groove 33 has the 1st shoulder lug groove 34 which is a 1st outer side lug groove, and the 2nd shoulder lug groove 35 which is a 2nd outer side lug groove. Among these, the 1st shoulder lug groove 34 is arrange | positioned on the extension to the tire width direction outer side of the 2nd lug groove 32, and the 2nd shoulder lug groove 35 is the 1st shoulder lug groove 34 adjacent in a tire circumferential direction. It is arranged between each other.

  Specifically, the first shoulder lug groove 34 is formed at a position extending from the second lug groove 32, and includes an opening 34a to the shoulder main groove 22 and an opening 32a to the shoulder main groove 22 of the second lug groove 32. At least a part of the range in the tire circumferential direction is overlapped, and at least a part is opposed in the tire width direction. The second shoulder lug groove 35 is formed at a position where the position in the tire circumferential direction is different from the position in the tire circumferential direction of the second lug groove 32, the opening 35 a to the shoulder main groove 22, and the shoulder of the second lug groove 32. The position in the tire circumferential direction differs between the opening 32a to the main groove 22. The first shoulder lug grooves 34 and the second shoulder lug grooves 35 are alternately arranged in the tire circumferential direction at substantially the same intervals in the tire circumferential direction.

  The lug grooves 30 are each curved in the tire circumferential direction or inclined while extending in the tire width direction. The form of the lug groove 30 such as a curve or an inclination in the tire circumferential direction with respect to the tire width direction is appropriately set according to a target tread pattern.

  The block 10 is partitioned by a circumferential main groove 20 and a lug groove 30. As the block 10, a center block 11 positioned between two center main grooves 21, an adjacent center main groove 21, and a shoulder main The second block 12 located between the groove 22 and the shoulder block 13 located on the outer side in the tire width direction of the shoulder main groove 22 are provided.

  Among these, the center block 11 is located on the tire equatorial plane CL, and is partitioned by the center main groove 21 and the center lug groove 31. In the center block 11, a notch 36 is formed at a position close to a position where the second drag groove 32 is extended. The notch 36 has one end connected to the center main groove 21 and the other end terminating in the center block 11. The notches 36 formed in this way are provided on both sides of the two center main grooves 21 that define the center block 11.

  The second block 12 is disposed on both sides of the center block 11 in the tire width direction, and is formed adjacent to the center block 11 via the center main groove 21. Further, the second block 12 is partitioned by a center main groove 21 and a shoulder main groove 22 that are adjacent in the tire width direction, and two second lug grooves 32 that are adjacent in the tire circumferential direction.

  The shoulder block 13 is disposed outside the second block 12 in the tire width direction, and is formed adjacent to the second block 12 via the shoulder main groove 22. The shoulder block 13 is partitioned by a shoulder main groove 22 and a shoulder lug groove 33. Specifically, the first shoulder lug groove 34 and the second shoulder lug groove 35 that are adjacent in the tire circumferential direction, and the shoulder It is partitioned by the main groove 22.

  A large number of sipes 55 are formed on the tread surface 3. The sipe 55 is formed in each block 10 of the center block 11, the second block 12, and the shoulder block 13, and has a zigzag shape that extends in the tire width direction and swings in the tire circumferential direction.

  Here, the sipe 55 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 the normal internal pressure condition. When the narrow groove is located in the part of the ground contact surface formed on the flat plate when loaded in the vertical direction on the flat plate, or when the land part where the narrow groove is formed falls, The wall surface which comprises the said fine groove, or at least one part of the site | part provided in a wall surface says what mutually contacts by deformation | transformation of a land part. In the present embodiment, the sipe 55 has a width in the range of 0.2 mm to 1.0 mm and a depth in the range of 3 mm to 10 mm.

  FIG. 2 is a detailed view of part A of FIG. In the tread surface 3, a circumferential narrow groove 50, a first sub lug groove 41, and a second sub lug groove 42 are formed between the adjacent center main groove 21 and shoulder main groove 22. Among these, the circumferential narrow groove 50 is located between the center main groove 21 and the shoulder main groove 22 in the tire width direction, and has a groove width narrower than the groove width of the center main groove 21 and the shoulder main groove 22. It extends in the tire circumferential direction. The first sub lug groove 41 is formed to extend in the tire width direction between the center main groove 21 and the circumferential narrow groove 50, and both ends thereof are connected to the center main groove 21 and the circumferential narrow groove 50. Yes. The second auxiliary lug groove 42 is formed to extend in the tire width direction between the shoulder main groove 22 and the circumferential narrow groove 50, and both ends thereof are connected to the shoulder main groove 22 and the circumferential narrow groove 50. Yes.

  The second block 12 positioned between the adjacent center main groove 21 and shoulder main groove 22 is partitioned into a first block region 15 and a second block region 17 by a circumferential narrow groove 50. Among these, the first block region 15 is partitioned by two second lug grooves 32 adjacent to each other in the tire circumferential direction, the center main groove 21, and the circumferential narrow groove 50. Further, the second block region 17 is partitioned by two second lug grooves 32 adjacent to each other in the tire circumferential direction, the shoulder main groove 22, and the circumferential narrow groove 50.

  The first sub lug groove 41 and the second sub lug groove 42 divide land portions located in the first block region 15 and the second block region 17 into a plurality of blocks 10, respectively. That is, the first sub lug groove 41 divides the land portion located in the first block region 15 into the first blocks 16 that are the plurality of blocks 10. Similarly, the second sub lug groove 42 divides the land portion located in the second block region 17 into the second blocks 18 that are the plurality of blocks 10. As described above, the second block 12 includes the block unit 14 including the first block region 15 and the second block region 17 between the two second lug grooves 32 adjacent in the tire circumferential direction. The shoulder block 13 located on the outer side in the tire width direction of the shoulder main groove 22 is adjacent to the second block region 17 in the block unit 14 of the second block 12 via the shoulder main groove 22.

  In one block unit 14, the first sub lug grooves 41 that divide the block 10 in the first block area 15 and the second sub lug grooves 42 that divide the block 10 in the second block area 17 are arranged in different numbers. The number of second sub lug grooves 42 provided in one second block region 17 is greater than the number of first sub lug grooves 41 provided in one first block region 15. It is arranged. That is, the second secondary lug groove 42 disposed in one second block region 17 is disposed in the first block region 15 adjacent to the second block region 17 via the circumferential narrow groove 50. The number is larger than that of the one sub lug groove 41. For this reason, in one block unit 14, the number of the second blocks 18 included in the second block region 17 is larger than that of the first blocks 16 included in the first block region 15. Accordingly, the length of the first block 16 and the second block 18 in the tire circumferential direction is shorter in the length of the second block 18 than in the length of the first block 16.

  In the present embodiment, the number of the second sub lug grooves 42 included in the second block region 17 of one block unit 14 is twice that of the first sub lug grooves 41 included in the first block region 15. Specifically, one first sub lug groove 41 is disposed in the first block region 15, and two second sub lug grooves 42 are disposed in the second block region 17. For this reason, the first block area 15 has two first blocks 16, and the second block area 17 has three second blocks 18.

  As described above, the first sub lug grooves 41 and the second sub lug grooves 42 arranged in different numbers are respectively arranged at equal intervals between the second lug grooves 32 adjacent in the tire circumferential direction. ing. That is, the first sub lug groove 41 is disposed at a position that bisects the two second lug grooves 32 adjacent in the tire circumferential direction. The second auxiliary lug groove 42 is disposed at a position that divides the two second lug grooves 32 adjacent in the tire circumferential direction into approximately three equal parts. For this reason, the first sub lug groove 41 and the second sub lug groove 42 have different positions in the tire circumferential direction at the respective ends connected to the circumferential narrow groove 50. That is, the tire of the outer side end 41o that is the outer end in the tire width direction of the first secondary lug groove 41 connected to the circumferential narrow groove 50 and the second secondary lug groove 42 connected to the circumferential narrow groove 50. The position in the tire circumferential direction is different from the inner end portion 42i that is the end portion on the inner side in the width direction.

  Further, since the first sub lug grooves 41 and the second sub lug grooves 42 are arranged in different numbers between the second lug grooves 32 adjacent in the tire circumferential direction, one first block region 15 is provided. The number is different between the first block 16 having and the second block 18 having one second block region 17. That is, among the first block area 15 and the second block area 17 included in one block unit 14, the first block area 15 includes two first blocks 16, whereas the second block area 17 has three second blocks 18.

  FIG. 3 is an explanatory diagram of the first sub lug groove 41 and the second sub lug groove 42 shown in FIG. The first secondary lug groove 41 disposed in the first block region 15 and the second secondary lug groove 42 disposed in the second block region 17 are each inclined in the tire circumferential direction while extending in the tire width direction. doing. Specifically, the inclination angle α of the first auxiliary lug groove 41 in the tire width direction with respect to the tire circumferential direction is in the range of 40 ° to 85 °. Similarly, the second auxiliary lug groove 42 also has an inclination angle β in the tire width direction with respect to the tire circumferential direction in the range of 40 ° to 85 °. In addition, the inclination direction in the tire circumferential direction with respect to the tire width direction is the same in the second lug groove 32, the first sub lug groove 41, and the second sub lug groove 42.

  In this case, the inclination angle α of the first sub lug groove 41 is determined by the end connected to the center main groove 21 and the end connected to the circumferential narrow groove 50 in the first sub lug groove 41. The angle of the straight line connecting the centers of the first auxiliary lug grooves 41 in the groove width direction with respect to the tire circumferential direction. Similarly, the inclination angle β of the second secondary lug groove 42 is different between the end portion connected to the shoulder main groove 22 and the end portion connected to the circumferential narrow groove 50 in the second secondary lug groove 42. The angle of the straight line connecting the centers in the groove width direction of the second auxiliary lug groove 42 with respect to the tire circumferential direction. In addition, the inclination angle α of the first sub lug groove 41 and the inclination angle β of the second sub lug groove 42 are preferably in the range of 60 ° to 75 °.

  The first sub lug groove 41 and the second sub lug groove 42 have different groove widths, and the groove width W2 of the second sub lug groove 42 is larger than the groove width W1 of the first sub lug groove 41. The direction is narrower. Specifically, the groove width W2 of the second sub lug groove 42 is in the range of 30% to 70% of the groove width W1 of the first sub lug groove 41.

  4 is a cross-sectional view taken along line BB in FIG. 5 is a cross-sectional view taken along the line CC of FIG. The first sub lug groove 41 and the second sub lug groove 42 have a groove depth shallower than the groove depth of the second lug groove 32. That is, the groove depth D1 of the first auxiliary lug groove 41 and the groove depth D2 of the second auxiliary lug groove 42 are both within the range of 1 mm or more and 5 mm or less with respect to the groove depth DS of the second lug groove 32. It is shallow. Further, in the first sub lug groove 41 and the second sub lug groove 42, the groove depth D2 of the second sub lug groove 42 is shallower than the groove depth D1 of the first sub lug groove 41. That is, the second lug groove 32, the first sub lug groove 41, and the second sub lug groove 42 have a groove depth that decreases in the order of the second lug groove 32, the first sub lug groove 41, and the second sub lug groove 42. ing.

  Of the first sub lug groove 41 and the second sub lug groove 42 formed as described above, the first sub lug groove 41 has a groove width W1 in the range of 2 mm to 7 mm, and the groove depth The length D1 is in the range of 5 mm to 10 mm. The second sub lug groove 42 has a groove width W2 in the range of 1 mm to 5 mm and a groove depth D2 in the range of 3 mm to 8 mm.

  Further, the circumferential narrow grooves 50 are repeatedly bent in the tire width direction while extending in the tire circumferential direction, and are bent in the same number as the number of the second auxiliary lug grooves 42 positioned between the adjacent second lug grooves 32. doing. In other words, the circumferential narrow groove 50 that connects the adjacent second lug grooves 32 has two bent portions 51 that are bent portions in the present embodiment. Specifically, the bent portion 51 of the circumferential narrow groove 50 is bent in a direction shifted in the groove width direction of the circumferential narrow groove 50 while the circumferential narrow groove 50 faces the extending direction of the circumferential narrow groove 50. It is formed by. The two bent portions 51 formed in this way are formed at positions that divide the two second lug grooves 32 adjacent in the tire circumferential direction into approximately three equal parts. As for the 2nd sub lug groove 42 connected to the circumferential direction fine groove 50, the inner side edge part 42i is connected to the bending part 51 of the circumferential direction fine groove 50, respectively. The circumferential narrow groove 50 has a groove width in the range of 2 mm to 7 mm, and a groove depth in the range of 3 mm to 8 mm.

  The circumferential narrow groove 50 is disposed between the adjacent center main groove 21 and the shoulder main groove 22, and the position thereof is from the center of the center main groove 21 and the shoulder main groove 22 in the tire width direction. Also, the position is closer to the center main groove 21. For this reason, the first block 16 included in the first block region 15 and the second block 18 included in the second block region 17 have substantially the same area. In other words, the circumferential narrow groove 50 is disposed at a position where the areas of the first blocks 16 of the first block region 15 and the second blocks 18 of the second block region 17 are approximately the same. ing. The area of one first block 16 and the area of one second block 18 are preferably within a range of ± 5% of each other. That is, for example, the area a1 of the first block 16 is preferably in the range of 95% to 105% with respect to the area a2 of the second block 18.

  FIG. 6 is an explanatory diagram showing the relationship between one block unit 14 and the shoulder block 13. The shoulder lug groove 33 includes a first shoulder lug groove 34 disposed at a position extending the second lug groove 32 and a second shoulder lug disposed at a position different from the second lug groove 32 in the tire circumferential direction. The grooves 35 are alternately arranged. For this reason, two shoulder blocks 13 are formed between the first shoulder lug grooves 34 adjacent to each other with the second shoulder lug groove 35 interposed therebetween. On the other hand, the interval between the first shoulder lug grooves 34 adjacent to each other across the second shoulder lug groove 35 and the interval between the second lug grooves 32 adjacent in the tire circumferential direction are the same interval. For this reason, the length in the tire circumferential direction in which the two shoulder blocks 13 and the second shoulder lug groove 35 positioned therebetween are combined and the length in the tire circumferential direction of one block unit 14 are substantially the same length. It has become.

  In other words, one block unit 14 is disposed in substantially the same range as the range in which the two shoulder blocks 13 are disposed in the tire circumferential direction. For this reason, three second blocks 18 in the second block region 17 of the block unit 14 are arranged in the range in which the two shoulder blocks 13 are arranged, that is, the second block 18 has a tire circumference. The number in the predetermined range in the direction is arranged in a number larger than the number of shoulder blocks 13 in the same range.

  In this case, the same range means that when the second lug groove 32 and the first shoulder lug groove 34 that are located on the extension are made one continuous lug groove, they are located between the adjacent lug grooves. The range to do. That is, since the second lug groove 32 and the first shoulder lug groove 34 are both inclined in the tire width direction, the positions of the adjacent second lug grooves 32 in the tire circumferential direction, and the adjacent first shoulder lug grooves 34. The position in the tire circumferential direction differs depending on the position in the tire width direction. For this reason, in the case where the second lug groove 32 and the first shoulder lug groove 34 positioned on the extension are used as one lug groove, the range located between the adjacent lug grooves is referred to as the same range here. To do.

  In addition, the center main groove 21 has two edges that form openings to the tread surface 3 having different shapes. Of the edges of the center main groove 21, the inner edge 21i located on the inner side in the tire width direction is formed linearly along the tire circumferential direction. On the other hand, of the edges of the center main groove 21, the outer edge 21o located on the outer side in the tire width direction is repeatedly bent in the tire width direction while extending in the tire circumferential direction. For this reason, the groove width of the opening portion of the center main groove 21 changes depending on the position in the tire circumferential direction as the outer edge 21o is repeatedly bent in the tire width direction while extending in the tire circumferential direction.

  Specifically, the center main groove 21 has a constant groove width at the groove bottom, and a notch that extends in the tire circumferential direction and bends in the tire width direction is formed on the outer edge 21o side of the opening. As a result, the outer edge 21o of the center main groove 21 is bent and the groove width at the groove bottom is constant, while the groove width of the opening changes depending on the position in the tire circumferential direction.

  The outer edge 21o of the center main groove 21 is convex in the direction in which the groove width of the center main groove 21 increases, that is, the bent portion 23 that is convex and bent outward in the tire width direction, One place is formed between the adjacent second lug grooves 32, and one bent portion 23 is located near the center between the second lug grooves 32. The first sub lug groove 41 connected to the center main groove 21 is connected to a portion where the inner end 41 i, which is the inner end in the tire width direction, is located at the bent portion 23 of the outer edge 21 o in the center main groove 21. ing.

  In the present embodiment, the center main groove 21 is formed with a notch on the outer edge 21o side of the opening to form a bent portion 23 on the outer edge 21o. Not only the position near the opening in the wall is bent, but the entire groove wall may be bent. That is, in the present embodiment, the shape of the center main groove 21 is different between the opening and the groove bottom, but the opening and the groove bottom may be formed in the same shape.

  When the pneumatic tire 1 configured as described above is mounted on a vehicle and 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, the lug groove 30, and the like, and water between the tread surface 3 and the road surface in these grooves. Drive while draining. 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.

  Further, when traveling on a snowy road surface, the pneumatic tire 1 compresses the snow on the road surface with the tread surface 3, and the snow on the road surface enters the circumferential main grooves 20 and the lug grooves 30. Will be pressed into the groove. In this state, a driving force or a braking force is applied to the pneumatic tire 1 or a force in the tire width direction is applied by turning of the vehicle, whereby the shearing force is applied to the snow in the groove. A so-called snow column shear force is generated between the pneumatic tire 1 and snow. When traveling on a snowy road surface, resistance is generated between the pneumatic tire 1 and the road surface by the snow column shear force, so that driving force and braking force can be transmitted to the road surface. It becomes possible to run on.

  Further, when traveling on a snowy road surface or an icy road surface, the vehicle travels using the edge effect of the circumferential main groove 20, the lug groove 30 and the sipe 55. That is, when traveling on a snowy road surface or on an ice surface, the vehicle travels using resistance caused by the edge of the circumferential main groove 20, the edge of the lug groove 30, and the edge of the sipe 55 being caught on the snow surface or ice surface. Further, when traveling on an icy road surface, water on the surface of the icy road surface is absorbed by the sipe 55, and the water film between the icy road surface and the tread surface 3 is removed so that the icy road surface and the tread surface 3 are in contact with each other. It becomes easy to do. As a result, the tread surface 3 is increased in resistance between the road surface on ice due to frictional force and edge effect, and the traveling performance of the vehicle equipped with the pneumatic tire 1 can be ensured.

  As described above, when driving on a snowy road surface, the contribution of the snow column shearing force generated by the snow entering the groove is high. Therefore, in order to improve the performance on snow, grooves such as the circumferential main groove 20 and the lug groove 30 are provided. It is effective to increase the area. On the other hand, when driving on an icy road surface, the contribution of frictional force and edge effect when the tread surface 3 contacts the road surface is high, so in order to improve the performance on ice, the groove area is reduced and the ground contact area is increased. It is effective to do. That is, the preferable tendency is contradictory between the tread pattern for improving the performance on snow and the tread pattern for improving the performance on ice.

  Here, the inventors of the present application conducted intensive research on the tread pattern for improving the performance on ice, and as a result, the edge amount in the intermediate region between the tire equatorial plane CL and the ground contact edge T on the tread surface 3 is It was found that the contribution to performance was the highest. That is, the same amount of edge is added to the region near the tire equator plane CL, to the region near the ground contact edge T, and to the intermediate region between the tire equator plane CL and the ground contact edge T. When compared with the case, it was found that the addition to the intermediate region between the tire equatorial plane CL and the ground contact edge T can improve the performance on ice efficiently.

  For this reason, in the pneumatic tire 1 according to the present embodiment, the center main groove 21 and the shoulder main groove 22 are used in order to increase the edge amount in the intermediate region between the tire equatorial plane CL and the ground contact end T on the tread surface 3. 1st sub lug groove 41, 2nd sub lug groove 42, and the circumferential direction narrow groove 50 are formed between these. As a result, it is possible to increase the edge amount of the region effective for improving the performance on ice while suppressing the decrease in the contact area of the entire tread surface 3 as much as possible. Moreover, in the area | region between the center main groove 21 and the shoulder main groove 22, since a groove area increases, a snow column shear force can be increased and on-snow performance can be improved. Thereby, both on-ice performance and on-snow performance can be improved.

  Further, in the region between the center main groove 21 and the shoulder main groove 22, the second secondary lug groove 42 disposed in one second block region 17 is disposed in one first block region 15. Since the number of the first sub lug grooves 41 is greater than the number of the first sub lug grooves 41, the running performance during running on the ice road surface can be further enhanced. That is, when a relatively large load is applied to the tread surface 3 during braking or turning during traveling of the vehicle, the large load is likely to be applied to a position closer to the outer side in the tire width direction on the tread surface 3. . For this reason, when the number of the second sub lug grooves 42 disposed on the outer side in the tire width direction from the first sub lug grooves 41 is larger than the number of the first sub lug grooves 41, a large load acts. The edge of the area which becomes easy can be increased, and the performance on ice can be improved. As a result, on-ice performance can be improved while significantly improving on-ice performance, and both on-ice performance and on-snow performance can be achieved.

  Further, the center main groove 21 and the shoulder main groove 22 are disposed within a range of 3% to 50% of the tire ground contact width TW in the tire width direction from the tire equatorial plane CL. 21 and the shoulder main groove 22, the first sub lug groove 41, the second sub lug groove 42, and the circumferential narrow groove 50 are disposed, so that the edge amount of the region having a high contribution to the performance on ice can be further increased. It can be surely increased. As a result, the on-ice performance can be improved more reliably, and both on-ice performance and on-snow performance can be achieved.

  The second secondary lug groove 42 disposed between the second lug grooves 32 is a second shoulder lug located between the first shoulder lug grooves 34 disposed on the extension of the second lug groove 32. A larger number than the grooves 35 is provided. For this reason, the edge amount in the intermediate region between the tire equatorial plane CL and the ground contact end T, which has a high contribution to the performance on ice, can be increased more reliably. As a result, the on-ice performance can be improved more reliably, and both on-ice performance and on-snow performance can be achieved.

  Moreover, since the 1st sub lug groove 41 and the 2nd sub lug groove 42 are each arrange | positioned at equal intervals between the second lug grooves 32 adjacent in a tire circumferential direction, the 1st block area | region 15 has. The sizes of the first blocks 16 and the sizes of the second blocks 18 included in the second block region 17 can be made substantially the same. As a result, the block rigidity can be made substantially uniform between the first blocks 16 and the second blocks 18, and it is possible to prevent the occurrence of blocks where the block rigidity becomes too small. It is possible to prevent the performance on ice from deteriorating due to the large deformation of the block at the time of grounding. Moreover, since it is possible to prevent the occurrence of a block in which the block rigidity is too small, it is possible to suppress the occurrence of uneven wear due to the difference in block rigidity. As a result, on-ice performance can be improved more reliably while suppressing uneven wear.

  Further, since the circumferential narrow groove 50 is bent in the tire width direction while extending in the tire circumferential direction, the edge length of the circumferential narrow groove 50 can be increased and the edge effect of the circumferential narrow groove 50 can be increased. The direction to be exhibited can be a plurality of directions. Thereby, the performance on ice can be improved more reliably. Moreover, since the 2nd sub lug groove 42 is connected to the bending part 51 of the circumferential direction fine groove 50, the opening area of the connection part of the circumferential direction fine groove 50 and the 2nd secondary lug groove 42 can be enlarged. . As a result, snow travels into the circumferential narrow groove 50 and the second secondary lug groove 42 when running on a snowy road surface to exert a snow column shearing force, and then the circumferential narrow groove 50 and the second secondary lug on the tread surface 3. When the position where the groove 42 is formed is separated from the road surface on the snow, the snow in the groove can be easily removed. That is, since the snow removal performance of the circumferential narrow groove 50 and the second secondary lug groove 42 can be improved, the position where the circumferential narrow groove 50 and the second secondary lug groove 42 are formed on the tread surface 3 is on the snow. When touching the road surface, snow on the road surface can sequentially enter the circumferential narrow groove 50 and the second auxiliary lug groove 42, and the snow column shearing force can be more reliably exhibited. As a result, both on-ice performance and on-snow performance can be improved more reliably.

  Further, since the first sub lug groove 41 and the second sub lug groove 42 have the inclination angles α and β in the tire width direction with respect to the tire circumferential direction within the range of 40 ° to 85 °, the rigidity difference between the blocks The edge effect can be exerted in more directions while suppressing the occurrence of. That is, when the inclination angles α and β of the first sub lug groove 41 and the second sub lug groove 42 are less than 40 °, the first sub lug groove 41 and the second sub lug groove 42 are in the tire width direction. Therefore, the effect of the edge effect by the first sub lug groove 41 and the second sub lug groove 42 in the tire circumferential direction may be reduced. In this case, it may be difficult to improve the traction performance and braking performance on the road surface on ice. When the first sub lug groove 41 and the second sub lug groove 42 are excessively inclined in the tire circumferential direction with respect to the tire width direction, the first sub lug groove 41 and the second sub lug groove 42 and the shoulder main groove 22 and the relative angle with the connection part with the circumferential direction fine groove 50 may become small too much, and the part where block rigidity becomes too low may generate | occur | produce. In this case, uneven wear is likely to occur due to the locally low block rigidity. When the inclination angles α and β of the first sub lug groove 41 and the second sub lug groove 42 exceed 85 °, the tire in the tire width direction of the first sub lug groove 41 and the second sub lug groove 42 Since the inclination in the circumferential direction is too small, the effect of the edge effect by the first sub lug groove 41 and the second sub lug groove 42 in the tire width direction may be reduced. In this case, it may be difficult to improve the turning performance on the road surface on ice.

  On the other hand, when the inclination angles α and β of the first sub lug groove 41 and the second sub lug groove 42 are within the range of 40 ° or more and 85 ° or less, a portion where the block rigidity is locally reduced occurs. The edge effect of the 1st sub lug groove 41 and the 2nd sub lug groove 42 can be exhibited with respect to more directions, suppressing doing. As a result, the performance on ice can be more reliably improved while suppressing a decrease in uneven wear resistance.

  Further, since the groove width W2 of the second sub lug groove 42 is within the range of 30% or more and 70% or less of the groove width W1 of the first sub lug groove 41, it is between the center main groove 21 and the shoulder main groove 22. The edge effect of the second secondary lug groove 42 can be ensured while securing the ground contact area of the region. That is, when the groove width W2 of the second secondary lug groove 42 is less than 30% of the groove width W1 of the first secondary lug groove 41, the groove width W2 of the second secondary lug groove 42 is too narrow. There is a possibility that the edge of the secondary lug groove 42 does not function sufficiently and the edge effect of the second secondary lug groove 42 is not sufficiently exhibited. In this case, it may be difficult to effectively improve the performance on ice. In addition, when the groove width W2 of the second sub lug groove 42 exceeds 70% of the groove width W1 of the first sub lug groove 41, the groove area of the second block region 17 having the second sub lug groove 42 is large. Due to the fact that the contact area becomes too small, it is difficult to effectively improve the performance on ice.

  On the other hand, when the groove width W2 of the second sub lug groove 42 is in the range of 30% to 70% of the groove width W1 of the first sub lug groove 41, the center where the second block region 17 is located. The groove width W2 of the second sub lug groove 42 can be made large enough to exhibit the edge effect while securing the contact area of the region between the main groove 21 and the shoulder main groove 22. . That is, by setting the groove width W2 of the second auxiliary lug groove 42 having a relatively large number, the edge component can be increased while ensuring the contact area, and the performance on ice such as braking on ice can be improved. Can do. Moreover, by setting the groove width W1 of the first sub lug grooves 41 having a relatively small number, the snow column shearing force can be increased while ensuring the contact area, and the performance on snow while ensuring the performance on ice. Can be improved. As a result, both on-ice performance and on-snow performance can be improved more reliably.

  Further, since the first sub lug groove 41 and the second sub lug groove 42 are both shallow in the range of the groove depth DS of the second lug groove 32 within the range of 1 mm or more and 5 mm or less, the first block The snow column shear force can be secured while securing the block rigidity of the 16 and the second block 18. That is, when the depth of the first sub lug groove 41 and the second sub lug groove 42 is shallower than the groove depth DS of the second lug groove 32 is less than 1 mm, Since the groove depths D1 and D2 of the lug groove 41 and the second auxiliary lug groove 42 are too deep, the block rigidity of the first block 16 and the second block 18 may be excessively lowered. In this case, it is difficult to appropriately receive the load acting on the first block 16 and the second block 18, and it may be difficult to improve the performance on ice. Further, when the groove depths D1 and D2 of the first sub lug groove 41 and the second sub lug groove 42 are shallower than the groove depth DS of the second lug groove 32 by 5 mm or more, the first sub lug groove 41 and the second sub lug groove 41 Since the groove depths D <b> 1 and D <b> 2 of the second sub lug groove 42 are too shallow, it may be difficult to secure the snow column shear force in the first sub lug groove 41 and the second sub lug groove 42. In this case, it may be difficult to improve the performance on snow.

  On the other hand, the groove depth D1 of the first auxiliary lug groove 41 and the groove depth D2 of the second auxiliary lug groove 42 are within a range of 1 mm or more and 5 mm or less with respect to the groove depth DS of the second lug groove 32. When it is shallow, the groove depths D1 and D2 of the first sub lug groove 41 and the second sub lug groove 42 are suppressed while preventing the block rigidity of the first block 16 and the second block 18 from becoming too low. The depth can ensure the snow column shearing force. As a result, both on-ice performance and on-snow performance can be improved more reliably.

  Further, the center main groove 21 is formed with a bent portion 23 that is bent in a convex direction in the direction in which the groove width of the center main groove 21 is increased at the outer edge 21o, and the first sub lug groove 41 is the center main groove 21. Therefore, the opening area of the connecting portion between the center main groove 21 and the first sub lug groove 41 can be increased. As a result, when snow travels on the snowy road surface, snow enters the center main groove 21 or the first sub lug groove 41 to exert a snow column shear force, and then the center main groove 21 or the first sub lug groove 41 on the tread surface 3. When the position where the is formed is separated from the road surface on the snow, the snow in the groove can be easily removed. That is, since the snow drainage performance of the center main groove 21 and the first sub lug groove 41 can be improved, the position where the center main groove 21 and the first sub lug groove 41 are formed on the tread surface 3 is the road surface on the snow. When grounded, snow on the road surface can sequentially enter the center main groove 21 and the first auxiliary lug groove 41, and the snow column shearing force can be more reliably exhibited. As a result, the performance on snow can be improved more reliably.

  In the pneumatic tire 1 according to the above-described embodiment, the circumferential main groove 20 includes a total of four center main grooves 21 and two shoulder main grooves 22. The number of main grooves 20 may be other than four. Further, the configuration of the lug groove 30 may be a configuration other than the embodiment. Regardless of the number of the circumferential main grooves 20 and the configuration of the lug grooves 30, between the two circumferential main grooves 20 adjacent to each other disposed on the same direction side in the tire width direction with respect to the tire equatorial plane CL. A first block region 15 having a plurality of first blocks 16 and a second block region 17 having a plurality of second blocks 18 by the first sub lug grooves 41, the second sub lug grooves 42 and the circumferential narrow grooves 50. If it is formed, the form of the circumferential direction main groove 20 or the lug groove 30 will not be ask | required.

  Moreover, in the pneumatic tire 1 which concerns on embodiment mentioned above, although the block unit 14 which has the 1st block area | region 15 and the 2nd block area | region 17 is arrange | positioned at the both sides of the tire equatorial plane CL in a tire width direction. The block unit 14 may be disposed only on one side of the tire equatorial plane CL in the tire width direction. When the block unit 14 is disposed only on one side of the tire equatorial plane CL in the tire width direction, the block unit 14 is disposed on the inner side in the vehicle mounting direction when the pneumatic tire 1 is mounted on the vehicle. Is preferred.

  Further, in the pneumatic tire 1 according to the above-described embodiment, one block unit 14 has one first sub lug groove 41 and two second sub lug grooves 42. The number of the 1st sub lug groove 41 and the 2nd sub lug groove 42 may be other than this. If the number of the second sub lug grooves 42 is greater than the number of the first sub lug grooves 41 in one block unit 14, the number of each is not limited.

  In the pneumatic tire 1 according to the above-described embodiment, the center main groove 21 has the inner edge 21i formed in a straight line and the outer edge 21o repeatedly bent in the tire width direction. Both the edge 21o may be linear, or both the inner edge 21i and the outer edge 21o may be repeatedly bent in the tire width direction. Similarly, the shoulder main groove 22 may be formed in a shape other than a linear shape along the tire circumferential direction.

〔Example〕
7A to 7D are tables showing results of performance tests of pneumatic tires. Hereinafter, with respect to the pneumatic tire 1 described above, the performance of the conventional pneumatic tire, the pneumatic tire 1 according to the present invention, and the pneumatic tire of the comparative example compared with the pneumatic tire 1 according to the present invention. The evaluation test will be described. The performance evaluation test was conducted on ice braking indicating braking performance on ice, turning performance on ice indicating steering stability on ice, and snow handling stability indicating steering stability on snow.

  In the performance evaluation test, a pneumatic tire of 195 / 65R15 91Q size specified by JATMA was assembled on a rim wheel of a 15 × 6.0J size JATMA standard rim, and the air pressure was adjusted to 210 kPa. The test was carried out by mounting on a test vehicle.

  As for the evaluation method of each test item, the braking on ice was evaluated by performing a braking test by a test driver on a test course on an ice surface, and expressing the reciprocal of the braking distance by an index with a conventional example as 100 described later. The larger the value, the shorter the braking distance and the better the braking on ice. Further, the turning property on ice was evaluated by measuring the turning time when the test vehicle on the ice road surface was run with a test vehicle, and expressing the reciprocal of the turning time by an index with the conventional example as 100 described later. The larger the value, the faster the turning time and the better the turning ability on ice. Further, the snow maneuverability was evaluated by performing a sensory evaluation by a test driver when traveling on a test course on a snowy road surface with a test vehicle, and expressing the sensory evaluation as an index with the conventional example described later as 100. The larger the value, the better the snow maneuverability.

  An evaluation test is a pneumatic tire compared with the conventional example which is an example of the conventional pneumatic tire, Examples 1-18 which are the pneumatic tire 1 which concerns on this invention, and the pneumatic tire 1 which concerns on this invention. It carried out about 20 types of pneumatic tires of a comparative example. Among these pneumatic tires, in the conventional pneumatic tire, the lug groove in the region between the center main groove 21 and the shoulder main groove 22 is the second lug groove in the above-described embodiment (in FIGS. 7A to 7D). This is constituted by a groove corresponding to 32 and the second auxiliary lug groove 42, and a groove corresponding to the first auxiliary lug groove 41 is not provided. In the pneumatic tire of the comparative example, the lug groove in the region between the center main groove 21 and the shoulder main groove 22 corresponds to the second lug groove 32, the first sub lug groove 41, and the second sub lug groove 42. Although constituted by grooves, the number of grooves corresponding to the first auxiliary lug grooves 41 and the number of grooves corresponding to the second auxiliary lug grooves 42 are the same, one each.

  On the other hand, in Examples 1-18 which are examples of the pneumatic tire 1 which concerns on this invention, all the lug grooves of the area | region between the center main groove 21 and the shoulder main groove 22 are the second lug groove 32, and 1st. The sub-lag grooves 41 and the second sub-lug grooves 42 are configured, and the number of the second sub-lag grooves 42 is larger than that of the first sub-lug grooves 41. The pneumatic tire 1 according to Examples 1 to 18 includes the number of the first sub lug grooves 41 and the second sub lug grooves 42, the first sub lug grooves 41 and the second sub lug grooves with respect to the circumferential narrow groove 50. The inclination angles α and β of 42, the groove widths W1 and W2, and the groove depths D1 and D2 of the first and second sub-lag grooves 41 and 42 are different from each other.

  As a result of performing an evaluation test using these pneumatic tires, as shown in FIGS. 7A to 7D, the pneumatic tires 1 of Examples 1 to 18 are braked on ice and on ice as compared with the conventional example and the comparative example. It was found that both turning performance and snow maneuverability can be improved. That is, the pneumatic tire 1 according to Examples 1 to 18 can achieve both on-ice performance and on-snow performance.

1 Pneumatic tire 2 Tread part 3 Tread surface 10 blocks (Land part)
11 center block 12 second block 13 shoulder block 14 block unit 15 first block area 16 first block 17 second block area 18 second block 20 circumferential main groove 21 center main groove (first main groove)
22 Shoulder main groove (second main groove)
23, 51 Bent part 30 Lug groove 31 Center lug groove 32 Second lug groove (main lug groove)
33 Shoulder lug groove 34 First shoulder lug groove (first outer lug groove)
35 Second shoulder lug groove (second outer lug groove)
36 Notch part 41 1st sub lug groove 42 2nd sub lug groove 50 Circumferential thin groove 55 Sipe

Claims (8)

A first main groove extending in the tire circumferential direction;
A second main groove that extends in the tire circumferential direction and is located on the outer side in the tire width direction of the first main groove and adjacent to the first main groove;
A plurality of main lug grooves extending in the tire width direction and having both ends connected to the first main groove and the second main groove;
A circumferentially thin line extending between the first main groove and the second main groove in the tire width direction and extending in the tire circumferential direction with a groove width narrower than the groove widths of the first main groove and the second main groove. Groove,
A first block region defined by two main lug grooves adjacent to each other in the tire circumferential direction, the first main groove, and the circumferential narrow groove;
A second block region defined by the two main lug grooves adjacent to each other in the tire circumferential direction, the second main groove, and the circumferential narrow groove;
A land portion that extends in the tire width direction between the first main groove and the circumferential narrow groove, has both ends connected to the first main groove and the circumferential narrow groove, and is located in the first block region. A first auxiliary lug groove that is divided into a plurality of blocks;
A land portion extending in the tire width direction between the second main groove and the circumferential narrow groove and having both ends connected to the second main groove and the circumferential narrow groove and located in the second block region. A second auxiliary lug groove divided into a plurality of blocks;
With
The second sub lug grooves disposed in one second block region are disposed in a number larger than the number of the first sub lug grooves disposed in one first block region. Pneumatic tire characterized by.   2. The pneumatic according to claim 1, wherein the first main groove and the second main groove are arranged such that a distance in a tire width direction from a tire equatorial plane is within a range of 3% to 50% of a tire ground contact width. tire. On the outer side in the tire width direction of the second main groove,
A first outer lug groove formed in a position extending in the tire width direction and extending from the main lug groove, and having an inner end in the tire width direction connected to the second main groove;
A second outer side extending in the tire width direction and having a position in the tire circumferential direction different from a position in the tire circumferential direction of the main lug groove, and an inner end in the tire width direction being connected to the second main groove Lug grooves,
The pneumatic tire according to claim 1 or 2, wherein   The first sub lug groove and the second sub lug groove are arranged at equal intervals between the main lug grooves adjacent in the tire circumferential direction, respectively. The described pneumatic tire. The circumferential narrow groove is bent in the tire width direction while extending in the tire circumferential direction,
The pneumatic tire according to claim 1, wherein the second sub lug groove is connected to a bent portion of the circumferential narrow groove that is bent.   The first auxiliary lug groove and the second auxiliary lug groove are both inclined in the tire circumferential direction while extending in the tire width direction, and an inclination angle in the tire width direction with respect to the tire circumferential direction is not less than 40 ° and not more than 85 °. The pneumatic tire according to any one of claims 1 to 5, wherein the pneumatic tire is within a range of.   The pneumatic tire according to any one of claims 1 to 6, wherein a groove width of the second sub lug groove is in a range of 30% to 70% of a groove width of the first sub lug groove.   The first auxiliary lug groove and the second auxiliary lug groove are both shallow in the range of 1 mm to 5 mm in depth relative to the groove depth of the main lug groove. The pneumatic tire according to item 1.

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