JP2018079903A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire that can improve steering stability on a wet road surface while securing steering stability on a dry road surface.SOLUTION: The pneumatic tire comprises communication lug grooves 40 which when a land part 30 of a plurality of land parts 30 which is adjacent to a tire equator surface CL side with respect to a main groove 22 in an outer outermost peripheral direction is defined as an outer second land part 32, a land part 30 adjacent to outside in a width direction of a tire is defined as an outer shoulder land part 31, and a land part 30 of the plurality of land parts 30 which is adjacent to the tire equator surface CL side with respect to a main groove 23 in an inner outermost peripheral direction is defined as an inner second land part 33, and a land part 30 adjacent to outside in the width direction of the tire is defined as an inner shoulder land part 34, start from the outer shoulder land part 31 across the tire equator surface CL and extend continuously to the inner second land part 33, and terminate in the inner second land part 33. The inner second land part 33 is provided with sub grooves 50 which pass through terminating end parts 45 of the communication lug grooves 40 and separate from the main groove 23 in the inner outermost peripheral direction.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire.

  In a pneumatic tire, 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. This may cause noise generated from the ground contact area of the pneumatic tire during driving, or may lead to a decrease in steering stability. For this reason, some of the conventional pneumatic tires are designed to reduce the noise by suppressing the shape and arrangement of the grooves, and to ensure steering stability while suppressing the deterioration of drainage. is there.

  For example, in the pneumatic tire described in Patent Document 1, at least two of a plurality of land portion rows defined by a plurality of circumferential grooves have one end opened in the circumferential groove and the other end landed. It has lug grooves that terminate in the section, and the lengths of the center lines of the lug grooves provided in at least two land section rows are different from each other, thereby reducing tire noise without impairing steering stability. . Further, in the pneumatic tire described in Patent Document 1, sipes are formed between the lug grooves in the adjacent land portion rows through the circumferential grooves by forming sipes along the lug grooves. Yes. The pneumatic tire described in Patent Document 2 is provided with a pair of center main grooves extending in the circumferential direction on both sides of the tire equatorial plane and a pair of shoulder main grooves extending in the circumferential direction on the outer side of the center main groove. And an inner inclined lateral main groove extending from the outer side in the tire axial direction to the inner side in the tire axial direction from the outer side in the tire axial direction than the tread grounding end on the inner side of the vehicle, and being interrupted without intersecting the center main groove on the outer side of the vehicle. Thus, the steering stability is improved while suppressing a decrease in wet performance.

JP 2007-237816 A JP 2013-112061 A

  Here, there is a demand for further performance on the wet performance in the market. However, since the handling stability on the wet road surface and the driving stability on the dry road surface are contradictory, it is very difficult to improve the wet performance while ensuring the driving stability on the dry road surface. It has become a thing.

  This invention is made | formed in view of the above, Comprising: It aims at providing the pneumatic tire which can improve wet handling nature, ensuring dry handling nature.

  In order to solve the above-described problems and achieve the object, the pneumatic tire according to the present invention is divided into three or more circumferential main grooves extending in the tire circumferential direction on the tread surface and the circumferential main grooves. It is a pneumatic tire provided with four or more rows of land portions, and among the plurality of circumferential main grooves, two circumferential main grooves positioned on the outermost side in the tire width direction are arranged in the outermost circumferential direction. Of the two outermost circumferential main grooves, the outermost circumferential main groove located on one side of the tire equatorial plane in the tire width direction is defined as a first outermost circumferential main groove and is located on the other side. The outermost circumferential main groove is a second outermost circumferential main groove, and the land portion adjacent to the tire equatorial plane side with respect to the first outermost circumferential main groove among the plurality of land portions is the first land. And the land portion adjacent to the outside in the tire width direction as a first shoulder land portion, Among the plurality of land portions, the land portion adjacent to the tire equatorial plane side with respect to the second outermost circumferential main groove is the second land portion, and the land portion adjacent to the outer side in the tire width direction is the second land portion. The shoulder land portion includes a communication lug groove that extends from the first shoulder land portion to the tire equator plane and extends continuously to the second land portion and terminates in the second land portion. The two land portions are provided with sub-grooves that pass through the end portions of the communication lug grooves and are separated from the second outermost circumferential main grooves.

  In the pneumatic tire, a tire width direction length component W1 of a portion included in the contact area of the tread surface in the communication lug groove and a contact width CW which is a width of the contact area in the tire width direction are 0. It is preferable to satisfy the relationship of 6 ≦ (W1 / CW) ≦ 0.8.

  In the pneumatic tire described above, a distance LL in the tire circumferential direction between the end portions in the second land portion between the communication lug grooves adjacent in the tire circumferential direction, and a tire circumferential direction between both end portions of the sub-groove. It is preferable that the distance L1 satisfies the relationship of (L1 / LL) ≧ 0.5.

  In the pneumatic tire, the communication lug groove is formed with respect to a tire width direction of a straight line a connecting an intersection point of the communication lug groove with the ground contact end of the tread surface and the terminal end portion in the second land portion. The angle θ1 is preferably in the range of 25 ° ≦ θ1 ≦ 45 °.

  In the pneumatic tire, it is preferable that an angle θ2 of the sub groove with respect to a tire circumferential direction of a straight line b connecting both ends of the sub groove satisfies θ2 ≦ 20 °.

  In the pneumatic tire, it is preferable that the sub-groove is terminated at a position passing through the terminal portion of the communication lug groove.

  In the pneumatic tire, the sub-groove defines a side opposite to a side defined by the second outermost circumferential main groove among the circumferential main grooves that divides both sides in the tire width direction of the second land portion. It is preferable to open to the circumferential main groove.

  In the pneumatic tire, it is preferable that at least one end portion of the sub-groove terminates in the second land portion.

  In the pneumatic tire, the communication lug groove is inclined in the tire circumferential direction while extending in the tire width direction, and the sub-groove is extended inward in the tire width direction from the end portion of the communication lug groove. It is inclined in the circumferential direction, the inclination direction in the tire circumferential direction with respect to the tire width direction is the same direction as the inclination direction of the communication lug groove, and the inclination angle with respect to the tire width direction is the inclination angle of the communication lug groove Is preferably larger.

  In the pneumatic tire, it is preferable that the sub-groove is continuously formed over one circumference in the tire circumferential direction.

  In the pneumatic tire, it is preferable that a groove formed in the second land portion does not open at an edge portion on the second outermost circumferential main groove side in the second land portion.

  In the pneumatic tire, the second land portion is adjacent to the edge portion on the second outermost circumferential main groove side in the second land portion, and the groove is not formed continuously from the edge portion. The plane portion has a plane portion, and the plane portion has a minimum width Wgmin in the tire width direction of 0.1 ≦ (Wgmin / Wg) with respect to the width Wg of the second land portion in the tire width direction. ) ≦ 0.5 is preferable.

  In the pneumatic tire, a mounting direction of the pneumatic tire with respect to a vehicle is defined, and the first outermost circumferential main groove, the first land portion, and the first shoulder land portion are formed from the tire equatorial plane. It is also preferable that the second outermost circumferential main groove, the second land portion, and the second shoulder land portion are located on the inner side in the vehicle mounting direction than the tire equator plane.

  The pneumatic tire according to the present invention has an effect that wet handling can be improved while ensuring dry handling.

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 the inner second land portion shown in FIG. FIG. 4 is a detailed view of the plane portion of the inner second land portion. FIG. 5 is a modified example of the pneumatic tire according to the embodiment, and is an explanatory view showing a case where the secondary groove is bent. FIG. 6 is a modified example of the pneumatic tire according to the embodiment, and is an explanatory view showing a case where the auxiliary groove terminates in the inner second land portion. FIG. 7 is a modified example of the pneumatic tire according to the embodiment, and is an explanatory diagram illustrating a case where the sub-groove terminates in the inner second land portion. FIG. 8 is a modified example of the pneumatic tire according to the embodiment, and is an explanatory view showing a case where the auxiliary groove is formed over one circumference in the tire circumferential direction. FIG. 9A is a chart showing the results of a performance test of a pneumatic tire. FIG. 9B is a chart showing the results of the performance test of the pneumatic tire. FIG. 9C is a chart showing the results of the performance test of the pneumatic tire. FIG. 9D 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 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.

[Pneumatic tire]
FIG. 1 is a meridional cross-sectional view showing a main part of a pneumatic tire according to an embodiment. Here, the pneumatic tire 1 shown in FIG. 1 defines a mounting direction with respect to the vehicle, that is, a direction when the vehicle is mounted. That is, in the pneumatic tire 1 shown in FIG. 1, the side facing the inside of the vehicle when the vehicle is mounted is the inside of the vehicle mounting direction, and the side facing the outside of the vehicle when the vehicle is mounted is the outside of the vehicle mounting direction. In addition, designation | designated of a vehicle mounting direction inner side and a vehicle mounting direction outer side is not restricted to the case where it mounts on a vehicle. For example, when the rim is assembled, the orientation of the rim with respect to the inner side and the outer side of the vehicle is determined in the tire width direction. Therefore, when the rim is assembled, the pneumatic tire 1 includes the inner side and the vehicle mounting direction in the tire width direction when the rim is assembled. The direction with respect to the outside in the mounting direction is designated. The pneumatic tire 1 also has a mounting direction display unit (not shown) that indicates a mounting direction with respect to the vehicle. The mounting direction display part is constituted by, for example, marks or irregularities attached to the sidewall part 4 of the tire. For example, ECER 30 (European Economic Commission Regulation Article 30) obligates the installation of a mounting direction display section on the side wall section 4 that is on the outer side of the vehicle mounting direction when the vehicle is mounted. The pneumatic tire 1 according to this embodiment is a pneumatic tire 1 mainly used for passenger cars.

  When the pneumatic tire 1 according to the present embodiment is viewed in the meridional section, the tread portion 2 composed of the tread rubber 15 is disposed on the outermost portion in the tire radial direction. The outer peripheral surface constitutes the contour of the pneumatic tire 1. The outer peripheral surface of the tread portion 2 is a surface that comes into contact with the road surface when the vehicle on which the pneumatic tire 1 is mounted travels, and this outer peripheral surface is formed as a tread surface 3. The tread surface 3 is formed with three or more circumferential main grooves 20 extending in the tire circumferential direction. The tread surface 3 is provided with four or more rows of land portions 30 that are divided into three or more circumferential main grooves 20. Specifically, four circumferential main grooves 20 are provided side by side in the tire width direction, and the land portions 30 defined by the circumferential main grooves 20 are formed in five rows aligned in the tire width direction. ing. The four circumferential main grooves 20 are disposed two on each side of the tire equatorial plane CL in the tire width direction.

  Shoulder portions 5 are located at both ends of the tread portion 2 in the tire width direction, and sidewall portions 4 made of sidewall rubber 16 are disposed inside the shoulder portion 5 in the tire radial direction. That is, the sidewall portions 4 are disposed at two places on both sides of the pneumatic tire 1 in the tire width direction.

  A bead portion 10 is located on the inner side in the tire radial direction of each sidewall portion 4 located on both sides in the tire width direction. Similar to the sidewall portion 4, the bead portion 10 is disposed at two locations on both sides of the tire equatorial plane CL. Each bead portion 10 is provided with a bead core 11, and a bead filler 12 is provided outside the bead core 11 in the tire radial direction. The bead core 11 is an annular member formed by bundling a plurality of bead wires, and the bead filler 12 is a rubber member disposed on the outer side in the tire radial direction of the bead core 11.

  A plurality of belt layers 14 are provided on the inner side in the tire radial direction of the tread portion 2. The belt layer 14 is provided by laminating a plurality of cross belts 141 and 142 and a belt cover 143. Among them, the cross belts 141 and 142 are formed by rolling a plurality of belt cords made of steel or organic fiber material with a coating rubber and having a belt angle of 20 ° to 55 ° in absolute value. Composed. Further, the plurality of cross belts 141 and 142 are different in belt angle defined as an inclination angle of the fiber direction of the belt cord with respect to the tire circumferential direction, and are laminated by crossing the fiber directions of the belt cords. It is configured as a so-called cross-ply structure. The belt cover 143 is formed by rolling one or a plurality of cords made of steel coated with a coat rubber or an organic fiber material, and has a belt angle of 0 ° to 10 ° in absolute value. Further, the belt cover 143 is formed by winding one or a plurality of cords constituting the belt cover 143 around the outer circumferential surface of the cross belts 141 and 142 a plurality of times in the tire circumferential direction and spirally. 141 and 142 are stacked on the outer side in the tire radial direction.

  A carcass 13 containing a radial ply cord is continuously provided on the inner side in the tire radial direction of the belt layer 14 and on the tire equatorial plane CL side of the sidewall portion 4. The carcass 13 has a single-layer structure composed of a single carcass ply or a multilayer structure formed by laminating a plurality of carcass plies, and is bridged in a toroidal manner between bead cores 11 disposed on both sides in the tire width direction. Passed to form the tire skeleton. Specifically, the carcass 13 is disposed from one bead portion 10 to the other bead portion 10 among the bead portions 10 located on both sides in the tire width direction, and the bead so as to wrap the bead core 11 and the bead filler 12. The part 10 is wound back along the bead core 11 outward in the tire width direction. In addition, the carcass ply of the carcass 13 is formed by rolling a plurality of carcass cords made of steel or organic fiber materials such as aramid, nylon, polyester, rayon and the like with a coat rubber, and the carcass with respect to the tire circumferential direction. The carcass angle, which is the inclination angle of the cord in the fiber direction, is formed in an absolute value of 80 ° to 95 °.

  A rim cushion rubber 17 constituting a contact surface of the bead portion 10 with respect to the rim flange is disposed on the inner side in the tire radial direction and the outer side in the tire width direction of the rewind portion of the bead core 11 and the carcass 13 in the bead portion 10. An inner liner 18 is formed along the carcass 13 on the inner side of the carcass 13 or on the inner side of the carcass 13 in the pneumatic tire 1.

[Tread pattern]
FIG. 2 is an AA arrow view of FIG. Of the plurality of circumferential main grooves 20, the two circumferential main grooves 20 positioned on the outermost side in the tire width direction are formed as outermost circumferential main grooves 21. When viewed from the tire equatorial plane CL, when one side in the tire width direction is the outer side in the vehicle mounting direction and the other side is the inner side in the vehicle mounting direction, out of the two outermost circumferential main grooves 21, the outer side in the vehicle mounting direction The outermost circumferential main groove 21 positioned is an outermost outermost main groove 22 that is a first outermost circumferential main groove. Of the two outermost circumferential main grooves 21, the outermost circumferential main groove 21 positioned on the inner side in the vehicle mounting direction is an innermost outermost circumferential main groove 23 that is a second outermost circumferential main groove. Further, of the plurality of circumferential main grooves 20, the two circumferential main grooves 20 positioned on the inner side in the tire width direction of the two outermost circumferential main grooves 21 are formed as inner circumferential main grooves 24. . The two inner circumferential main grooves 24 are disposed on both sides of the tire equatorial plane CL in the tire width direction.

  Here, the main groove is a groove having a display requirement of a wear indicator defined in JATMA, and is generally a groove having a groove width of 5.0 mm or more and a groove depth of 6.5 mm or more. For this reason, the circumferential main groove 20 is a groove having a groove width of 5.0 mm or more and a groove depth of 6.5 mm or more and extending in the tire circumferential direction. The circumferential main groove 20 may not strictly extend in the tire circumferential direction, and may be curved or bent in the tire width direction while extending in the tire circumferential direction.

  The groove width in this case is measured as the maximum value of the distance between the groove walls at the position where the pneumatic tire 1 is opened on the tread surface 3 in a no-load state in which the pneumatic tire 1 is mounted on the specified rim and filled with the specified internal pressure. In the configuration in which the land portion 30 has a notch portion or a chamfered portion at the edge portion, the groove is defined with respect to the intersection of the tread surface 3 and the extension line of the groove wall in a cross-sectional view in which the groove length direction is a normal direction. The width is measured. Further, when the groove is repeatedly bent or bent to be formed into a wave shape or a zigzag shape, the groove width is measured using the center line of the amplitude of the groove wall as a measurement point.

  Further, the groove depth is measured as the maximum value of the distance from the tread surface 3 to the groove bottom in an unloaded state in which the pneumatic tire 1 is mounted on the specified rim and filled with the specified internal pressure. Moreover, in the structure which a groove | channel has a partial uneven | corrugated | grooved part and a sipe in a groove bottom, groove depth is measured except these.

  The specified rim refers to an “applied rim” defined in JATMA, a “Design Rim” defined in TRA, or a “Measuring Rim” defined in ETRTO. The specified internal pressure means “maximum air pressure” specified by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” specified by TRA, or “INFLATION PRESSURES” specified by ETRTO.

  Among the plurality of land portions 30, the land portion 30 adjacent to the tire equatorial plane CL side with respect to the outermost outermost circumferential main groove 22 is an outer second land portion 32 that is a first land portion, and is the outermost outermost land portion 32. The land portion 30 adjacent to the outer circumferential direction main groove 22 on the outer side in the tire width direction is an outer shoulder land portion 31 that is a first shoulder land portion. Of the plurality of land portions 30, the land portion 30 adjacent to the tire equatorial plane CL side with respect to the innermost outermost circumferential main groove 23 is an inner second land portion 33, which is the second land portion, The land portion 30 adjacent to the outer circumferential direction main groove 23 on the outer side in the tire width direction is an inner shoulder land portion 34 which is a second shoulder land portion. Further, among the plurality of land portions 30, the land portion 30 that is located between the two inner circumferential main grooves 24 and that is divided on both sides in the tire width direction by the two inner circumferential main grooves 24, It is the center land part 35. The center land portion 35 is located on the tire equator plane CL.

  Since the direction at the time of vehicle mounting is prescribed | regulated, the pneumatic tire 1 which concerns on this embodiment among the circumferential direction main groove 20 or the land part 30, the outermost outermost direction main groove 22, the outer side second land part 32, an outer side shoulder. The land portion 31 is located on the outer side in the vehicle mounting direction than the tire equator plane CL when the vehicle is mounted. On the other hand, the innermost outermost circumferential main groove 23, the inner second land portion 33, and the inner shoulder land portion 34 are located on the inner side in the vehicle mounting direction than the tire equatorial plane CL when the vehicle is mounted.

[Communication lug groove]
The tread surface 3 is formed with a communication lug groove 40 that extends in the tire width direction and is inclined in the tire circumferential direction. The communication lug groove 40 straddles the tire equatorial plane CL from the outer shoulder land portion 31 and continuously extends to the inner second land portion 33 and terminates in the inner second land portion 33. Thus, the communication lug groove 40 formed from the outer shoulder land portion 31 to the inner second land portion 33 is formed in the outer shoulder lug groove 41 formed in the outer shoulder land portion 31 and the outer second land portion 32. The outer second lug groove 42, the center lug groove 43 formed in the center land portion 35, and the inner second lug groove 44 formed in the inner second land portion 33 are configured. The outer shoulder lug groove 41, the outer second lug groove 42, the center lug groove 43, and the inner second lug groove 44 are all inclined in the tire circumferential direction while extending in the tire width direction. The inclination direction to the tire circumferential direction is the same in all of the outer shoulder lug groove 41, the outer second lug groove 42, the center lug groove 43, and the inner second lug groove 44.

  Among these, the outer shoulder lug groove 41 is formed across the ground contact end T of the tread surface 3, and the inner end portion in the tire width direction is open to the outermost outer circumferential direction main groove 22. In this case, the ground contact edge T corresponds to 88% of the specified load when the pneumatic tire 1 is assembled to the specified rim and filled with air with an internal pressure of 180 kPa and placed perpendicular to the flat plate in a stationary state. The outermost ends in the tire width direction of the region in contact with the flat plate on the tread surface 3 when a load to be applied is applied, and is continuous in the tire circumferential direction. The ground contact end T is located on the outer shoulder land portion 31 and the inner shoulder land portion 34.

  The specified load refers to the “maximum load capacity” defined in JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined in TRA, or “LOAD CAPACITY” defined in ETRTO.

  The outer second lug groove 42 is formed so as to penetrate the outer second land portion 32 in the tire width direction. That is, the outer side second lug groove 42 has an end on the outer side in the tire width direction that opens to the outermost outermost main groove 22, and an end on the outer side in the tire width direction of the two inner peripheral direction main grooves 24. Opening is made in the inner circumferential main groove 24 on the side defining the outer second land portion 32.

  The center lug groove 43 is formed so as to penetrate the center land portion 35 in the tire width direction. That is, both ends of the center lug groove 43 open into the two inner circumferential main grooves 24 that define the center land portion 35.

  The inner second lug groove 44 has an inner end in the tire width direction that opens to the inner circumferential main groove 24 on the side of the two inner circumferential main grooves 24 that defines the inner second land portion 33. The outer end in the tire width direction terminates in the inner second land portion 33.

  A plurality of outer shoulder lug grooves 41, outer second lug grooves 42, center lug grooves 43, and inner second lug grooves 44 formed as described above are formed side by side in the tire circumferential direction. At that time, the outer shoulder lug groove 41 and the outer second lug groove 42 are provided with the same number in the tire circumferential direction at substantially the same intervals. On the other hand, the center lug groove 43 and the inner second lug groove 44 have an interval in the tire circumferential direction that is approximately twice the interval in the tire circumferential direction of the outer shoulder lug groove 41 and the outer second lug groove 42. 41 and half of the number of outer side second lug grooves 42 are provided. That is, the center lug groove 43 and the inner second lug groove 44 are provided with the same number in the tire circumferential direction at substantially the same intervals.

  The outer shoulder lug grooves 41 and the outer second lug grooves 42, which are provided with the same number at substantially the same interval, are disposed on an extension line. Further, the center lug groove 43 and the inner second lug groove 44, which are provided with the same number at substantially the same interval, are disposed on an extension line. Furthermore, the center lug groove 43 and the inner second lug groove 44 are extensions of the outer shoulder lug groove 41 and the outer second lug groove 42 every other one in the tire circumferential direction of the outer shoulder lug groove 41 and the outer second lug groove 42. It is arranged on the line.

  The communication lug groove 40 is configured by an outer shoulder lug groove 41, an outer second lug groove 42, a center lug groove 43, and an inner second lug groove 44 that are arranged on an extension line as described above. In other words, the outer shoulder lug groove 41, the outer second lug groove 42, the center lug groove 43, and the inner second lug groove 44 that are disposed on the extension line constitute one communication lug groove 40. That is, all the center lug grooves 43 and the inner second lug grooves 44 constitute the communication lug grooves 40, respectively, and the outer shoulder lug grooves 41 and the outer second lug grooves 42 are every other one in the tire circumferential direction. A communication lug groove 40 is formed. The communication lug groove 40 configured as described above is inclined in the direction toward the tire circumferential direction while being directed in the tire width direction, and is gently curved as a whole. The plurality of communication lug grooves 40 are formed substantially parallel to each other.

[Center non-through lug groove]
In addition to the center lug groove 43, a plurality of center non-through lug grooves 46 are formed in the center land portion 35. The same number of center non-through lug grooves 46 as the center lug grooves 43 are formed in the center land portion 35, and each center non-through lug groove 46 is disposed between the center lug grooves 43. Further, the center non-penetrating lug groove 46 is inclined in the tire circumferential direction while extending in the tire width direction and is formed across the tire equatorial plane CL. Specifically, the center non-penetrating lug groove 46 has an end on the side where the outer second land portion 32 is positioned in the tire width direction, which opens to the inner circumferential main groove 24 that defines the outer second land portion 32. The other end of the non-through lug groove 46 terminates in the center land portion 35.

  The center non-penetrating lug groove 46 is on an extension line of the outer second lug groove 42 that is not in an extension line with the inner second lug groove 44 among the plurality of outer second lug grooves 42. It is arranged. In other words, the center non-through lug groove 46 is formed with respect to the outer second lug groove 42 and the outer shoulder lug groove 41 that do not constitute the communication lug groove 40 among the plurality of outer second lug grooves 42 and the outer shoulder lug grooves 41. These are arranged in a positional relationship located on the extension lines. The lug grooves formed as described above are lateral grooves extending in the tire width direction, each having a groove width within a range of 1.0 mm to 2.5 mm and within a range of 2.0 mm to 8.0 mm. The groove depth is as follows. In addition, the groove width and groove depth may change within one lug groove, and the opening width changes within one lug groove by forming a chamfer in part. It may be.

[Secondary groove]
The inner second land portion 33 is formed with a sub-groove 50 that passes through the terminal end 45 of the communication lug groove 40 and is not opened to the inner outermost circumferential main groove 23 and is separated from the inner outermost circumferential main groove 23. Yes. The secondary groove 50 is a groove disposed in the inner second land portion 33 with a groove width within a range of 1.0 mm to 2.5 mm and a groove depth within a range of 2.0 mm to 8.0 mm. It has become. The sub-groove 50 is terminated at a position where one end 51 passes through the terminal 45 of the communication lug groove 40. The other end 51 is an inner side that defines the opposite side of the inner main land 20 that divides both sides of the inner second land portion 33 in the tire width direction. The circumferential main groove 24 opens. That is, one end 51 of the secondary groove 50 is connected to the terminal end 45 in the inner second land portion 33 in the communication lug groove 40, that is, the terminal end 45 of the inner second lug groove 44. The end 51 opens into the inner circumferential main groove 24 that defines the inner second land portion 33 of the two inner circumferential main grooves 24.

  Specifically, in the secondary groove 50, the inclination direction in the tire circumferential direction with respect to the tire width direction is the same direction as the inclination direction in the tire circumferential direction of the inner second lug groove 44, and the terminal portion 45 of the communication lug groove 40. The inner second lug groove 44 is inclined in the tire circumferential direction at an angle larger than the inclination angle of the inner second lug groove 44 in the tire circumferential direction with respect to the tire width direction. The main groove 24 is open. In other words, in the secondary groove 50, the inner second lug groove 44 opens from the terminal portion 45 of the inner second lug groove 44 that extends outward in the tire width direction from the inner circumferential main groove 24 that defines the inner second land portion 33. The inner second lug groove 44 and the sub-groove 50 are formed in a substantially V shape in plan view, and are formed so as to be turned inward in the tire width direction toward the inner circumferential main groove 24. The sub-groove 50 is gently curved in a direction that protrudes away from the inner second lug groove 44.

[Inner shoulder lug groove]
Further, in the inner shoulder land portion 34, the inner shoulder lug groove formed across the ground contact end T located on the inner shoulder land portion 34, similarly to the outer shoulder lug groove 41 formed in the outer shoulder land portion 31. 47 is formed. The inner shoulder lug groove 47 is inclined in the tire circumferential direction while extending in the tire width direction, and an inner end portion in the tire width direction is open to the inner outermost circumferential main groove 23. The inclination direction of the inner shoulder land portion 34 in the tire circumferential direction with respect to the tire width direction is the same direction as the inclination direction of the communication lug groove 40 in the region on the inner side of the ground contact end T in the inner shoulder land portion 34 in the tire width direction. In addition, by curving in a region outside in the tire width direction from the ground contact end T, in the vicinity of the outer end in the tire width direction, the inclination direction to the tire circumferential direction is the opposite direction.

[Circumferential narrow groove]
In addition, a circumferential narrow groove 70 extending in the tire circumferential direction is formed in the inner shoulder land portion 34 at a position on the inner side in the tire width direction from the ground contact end T. The circumferential narrow groove 70 is formed over the entire circumference of the inner shoulder land portion 34 and intersects the inner shoulder lug groove 47. That is, each inner shoulder lug groove 47 straddles the circumferential narrow groove 70, or the circumferential narrow groove 70 is formed straddling all the inner shoulder lug grooves 47 arranged side by side in the tire circumferential direction. Has been.

[Sipe]
A plurality of sipes are formed on the tread surface 3. Here, the sipe is a cut formed in the tread surface 3, generally having a sipe width of less than 1.0 mm and a sipe depth of 2.0 mm or more, and is closed at the tire ground contact surface. The sipe width is measured as the maximum value of the sipe opening width on the tread of the land portion 30 in a no-load state in which a tire is mounted on a specified rim and filled with a specified internal pressure. The tire contact surface is the air when the pneumatic tire 1 is attached to the specified rim and applied with the specified internal pressure, and is placed perpendicular to the flat plate in a stationary state and applied with a load corresponding to the specified load. It is defined as a contact surface between the entering tire 1 and a flat plate.

  The sipe includes an outer shoulder sipe 61 formed on the outer shoulder land portion 31, an inner shoulder sipe 62 formed on the inner shoulder land portion 34, an outer second sipe 63 formed on the outer second land portion 32, and a center. A center sipe 64 formed in the land portion 35 is provided. Of these, the outer shoulder sipes 61 are disposed between the adjacent outer shoulder lug grooves 41 and extend in the tire width direction across the ground contact edge T located on the outer shoulder land portion 31, and in the tire width direction. The inner end of the outer shoulder land portion 31 terminates. The inner shoulder sipe 62 is disposed between the adjacent inner shoulder lug grooves 47 and extends in the tire width direction across the ground contact edge T located on the inner shoulder land portion 34. The inner end terminates within the inner shoulder land 34.

  Further, the outer second sipe 63 is disposed between the adjacent outer second lug grooves 42 and is curved in the tire circumferential direction while extending in the tire width direction, and the outer end portion in the tire width direction is the outer second lug groove. The inner end in the tire width direction is connected to the inner circumferential main groove 24 that defines the outer second land portion 32. The center sipe 64 is disposed between the adjacent center lug grooves 43 and extends in the tire width direction at a position on the extension line of the outer second sipe 63, and the outer end portion in the tire width direction is attached to the vehicle. It is connected to the inner circumferential main groove 24 on the outer side in the direction, and the inner end in the tire width direction terminates at a position in the center land portion 35 in the vicinity of the tire equatorial plane CL.

[Communication lug groove length and angle]
The communication lug groove 40 has a tire width direction length component W1 included in the contact area of the tread surface 3 in the communication lug groove 40 and a contact width CW which is a width of the contact area in the tire width direction. The relationship of ≦ (W1 / CW) ≦ 0.8 is satisfied. In this case, the ground contact area is an area between the ground contact ends T on both sides in the tire width direction, and the ground contact width CW is an interval between the ground contact ends T in the tire width direction. Further, the tire width direction length component W1 of the portion included in the contact area of the tread surface 3 in the communication lug groove 40 is the tire between the contact end T where the communication lug groove 40 intersects and the end portion 45 of the communication lug groove 40. It is an interval in the width direction. Specifically, the tire width direction length component W1 of the portion included in the ground contact region in the communication lug groove 40 includes the communication lug at the position of the ground contact end T where the communication lug groove 40 intersects and the end portion 45 of the communication lug groove 40. The distance between the groove 40 and the groove center line in the tire width direction. The communication lug groove 40 straddling the ground contact end T located on the outer shoulder land portion 31 has a tire width direction length component W1 of a portion included in the ground contact region of 0.6 ≦ (W1 / CW) ≦ 0.8.

  Further, the communication lug groove 40 is a tire of a straight line a that connects the intersection point P of the communication lug groove 40 with the grounding end T of the tread surface 3 and the terminal end 45 of the communication lug groove 40 in the inner second land portion 33. The angle θ1 formed with respect to the width direction is in the range of 25 ° ≦ θ1 ≦ 45 °. In other words, the communication lug groove 40 has a gently curved shape and extends in the tire width direction and is inclined in the tire radial direction, but the intersection P with the ground contact end T where the communication lug groove 40 intersects with the inner second land portion. An angle of inclination θ1 of the straight line a connecting the end portion 45 of the communication lug groove 40 in the tire 33 with respect to the tire width direction is formed in a range of 25 ° ≦ θ1 ≦ 45 °.

[Relationship between communication lug groove and secondary groove]
FIG. 3 is a detailed view of the inner second land portion shown in FIG. Further, the communication lug groove 40 and the sub-groove 50 are the pitch lengths LL between the communication lug grooves 40, that is, the terminal end portions 45 in the inner second land portion 33 between the communication lug grooves 40 adjacent in the tire circumferential direction. The distance L1 in the tire circumferential direction and the distance L1 in the tire circumferential direction between both end portions 51 of the sub-groove 50 which is the tire circumferential direction length component L1 of the sub-groove 50 are (L1 / LL) ≧ 0.5. Meet the relationship. In other words, the communication lug groove 40 and the sub-groove 50 are such that the distance L1 in the tire radial direction between the one end 51 and the other end 51 of the sub-groove 50 is located on both sides of the sub-groove 50 in the tire direction. The two communication lug grooves 40 are formed in a relationship satisfying (L1 / LL) ≧ 0.5 with respect to the distance LL in the tire circumferential direction between the end portions 45.

  The distance LL in the tire circumferential direction between the end portions 45 of the communication lug grooves 40 is the distance in the tire circumferential direction between the groove center lines of the communication lug grooves 40 at the positions of the end portions 45 of the respective communication lug grooves 40. It has become. Further, the distance L1 in the tire circumferential direction between both end portions 51 of the sub-groove 50 is the distance in the tire circumferential direction between the groove center lines of the sub-groove 50 at the position of the end portion 51 of the sub-groove 50. The relationship between the distance L1 between the two end portions 51 of the sub-groove 50 and the distance LL in the tire circumferential direction between the end portions 45 of the communication lug groove 40 is 0.6 ≦ (L1 / LL) ≦ 1.2. It is preferable to be within the range.

[Angle of minor groove]
Further, in the sub-groove 50, an angle θ2 formed with respect to the tire circumferential direction of the straight line b connecting the both end portions 51 of the sub-groove 50 satisfies θ2 ≦ 20 °. That is, the secondary groove 50 formed in the inner second land portion 33 is curved and extends in the tire width direction while being curved, and is inclined in the tire radial direction, but one end portion 51 and the other end portion 51 of the secondary groove 50. Is formed in a shape that satisfies an inclination angle θ2 with respect to the tire circumferential direction satisfying θ2 ≦ 20 °.

  The sub-groove 50 preferably has an inclination angle θ2 of the straight line b with respect to the tire circumferential direction within a range of 5 ° ≦ θ2 ≦ 15 °. Further, the sub-groove 50 is formed such that the angle θ3 of the straight line b with respect to the straight line a of the communication lug groove 40 is in the range of 25 ° ≦ θ3 ≦ 85 °.

[Plain part]
FIG. 4 is a detailed view of the plane portion of the inner second land portion. In addition, a groove formed in the inner second land portion 33 is not opened in the edge portion 33a on the innermost outermost circumferential main groove 23 side in the inner second land portion 33, and from the inner second land portion 33 side, None of the grooves is connected to the outermost circumferential main groove 23. Therefore, the inner second land portion 33 is a plane portion that is adjacent to the edge portion 33a on the innermost outer circumferential direction main groove 23 side in the inner second land portion 33 and is a region where no groove is continuously formed from the edge portion 33a. 80. In other words, the plane portion 80 has an outer end portion in the tire width direction defined by the edge portion 33a on the innermost outermost circumferential main groove 23 side of the inner second land portion 33, and an inner end portion in the tire width direction is the inner end portion. This is a region defined by the edge portion 33 b of the second land portion 33 on the inner circumferential main groove 24 side, the sub-groove 50, and the inner second lug groove 44.

  The plane portion 80 has a minimum width Wgmin in the tire width direction within a range of 0.1 ≦ (Wgmin / Wg) ≦ 0.5 with respect to the width Wg of the inner second land portion 33 in the tire width direction. Is formed. Specifically, the distance between the inner side second land portion 33 and the edge portion 33a on the innermost outermost circumferential direction main groove 23 side of the inner portion in the tire width direction of the plain portion 80 is the smallest. Is the end portion 45 of the inner second lug groove 44. For this reason, the minimum value Wgmin of the width in the tire width direction of the plain portion 80 is the tire between the edge portion 33a on the innermost outermost circumferential main groove 23 side of the inner second land portion 33 and the end portion 45 of the inner second lug groove 44. It is the distance in the width direction.

  Further, the width Wg of the inner second land portion 33 in the tire width direction is equal to the edge portion 33a on the innermost outermost circumferential main groove 23 side of the inner second land portion 33 and the inner circumferential main groove 24 side of the inner second land portion 33. It is the distance in the tire width direction from the edge portion 33b. In the plane portion 80, the relationship between the minimum width value Wgmin in the tire width direction and the width Wg in the tire width direction of the inner second land portion 33 is 0.1 ≦ (Wgmin / Wg) ≦ It is in the range of 0.5.

  Further, in the plane portion 80, the position in the tire width direction of the edge portion 33a on the innermost outermost circumferential main groove 23 side of the inner second land portion 33 and the position in the tire width direction of the terminal portion 45 of the inner second lug groove 44 The area in between is an area in which no groove is formed over one circumference in the tire circumferential direction. That is, grooves are formed at any position in the tire circumferential direction in the region formed over the circumference of the tire circumferential direction in the range where the width in the tire width direction of the plane portion 80 shows the minimum value Wgmin. Absent.

  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 communication lug groove 40, and the like. Drive while draining water. 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.

  At that time, the communication lug groove 40 is formed across the tire equatorial plane CL from the outer shoulder land portion 31 by extending in the tire width direction, so that water between the tread surface 3 and the road surface is It is possible to discharge more reliably. That is, the communication lug groove 40 crosses the ground contact end T located on the outer shoulder land portion 31 and the plurality of circumferential main grooves 20 by being formed across the tire equatorial plane CL from the outer shoulder land portion 31. doing. For this reason, when the water between the tread surface 3 and the road surface enters the communication lug groove 40, the communication lug groove 40 causes the water to flow in the communication lug groove 40 along the communication lug groove 40. It can flow through the circumferential main groove 20 intersecting the communication lug groove 40 or can flow outside the ground contact end T in the tire width direction. Thereby, the communication lug groove 40 can discharge a wider range of water between the tread surface 3 and the road surface from between the tread surface 3 and the road surface, and can improve drainage. Therefore, the steering stability on the wet road surface can be improved.

  In addition, the inner second land portion 33 where the end portion 45 of the communication lug groove 40 is located has a sub-groove 50 that passes through the end portion 45 of the communication lug groove 40, so that the water in the communication lug groove 40 is subsidized. By flowing into the groove 50 or flowing the water in the sub-groove 50 into the communication lug groove 40, the water between the vicinity of the inner second land portion 33 on the tread surface 3 and the road surface is transferred between the tread surface 3 and the road surface. It can be discharged from between. Thereby, drainage can be further improved.

  In addition, the communication lug groove 40 terminates in the inner second land portion 33, and the sub-groove 50 does not open to the inner outermost circumferential main groove 23 but is separated from the inner outermost circumferential main groove 23. The position near the innermost outermost circumferential main groove 23 in the portion 33 has rigidity without being lowered by the groove. For this reason, even when receiving a large load when traveling on a dry road surface, the inner second land portion 33 can receive this load without being greatly bent. Thereby, steering stability on a dry road surface can be ensured. As a result, the wet operability can be improved while ensuring the dry operability.

  Further, the tire width direction length component W1 of the portion included in the contact area of the tread surface 3 in the communication lug groove 40 and the contact width CW of the contact area satisfy 0.6 ≦ (W1 / CW) ≦ 0.8. In order to satisfy the relationship, the rigidity of the land portion 30 located in the ground contact area and the drainage can be more reliably achieved. That is, when the relationship between the tire width direction length component W1 of the communication lug groove 40 and the contact width CW is (W1 / CW) <0.6, the communication lug groove with respect to the contact width CW of the tread surface 3 Since 40 is too long in the tire width direction, the region where the groove in the land portion 30 is not formed becomes too small, and it may be difficult to ensure the rigidity of the land portion 30. In this case, it may be difficult to ensure the driving stability on the dry road surface. When the relationship between the length component W1 in the tire width direction of the communication lug groove 40 and the contact width CW is (W1 / CW)> 0.8, the communication lug groove with respect to the contact width CW of the tread surface 3 Since 40 is too short in the tire width direction, it may be difficult to secure drainage using the communication lug groove 40. In this case, it may be difficult to effectively improve the steering stability on the wet road surface.

  On the other hand, when the relationship between the length component W1 in the tire width direction of the communication lug groove 40 and the contact width CW is within the range of 0.6 ≦ (W1 / CW) ≦ 0.8, the tread is more reliably performed. While securing the rigidity of the land portion 30 located in the ground contact area of the surface 3, it is possible to ensure drainage using the communication lug groove 40. As a result, the wet operability can be improved while ensuring the dry operability more reliably.

  Further, the distance LL in the tire circumferential direction between the terminal end portions 45 in the inner second land portion 33 between the communication lug grooves 40 adjacent in the tire circumferential direction, and the distance in the tire circumferential direction between both end portions 51 of the sub-groove 50 Since L1 satisfies the relationship of (L1 / LL) ≧ 0.5, the water between the tread surface 3 and the road surface can be more reliably drained by the auxiliary groove 50 and the communication lug groove 40. . That is, when the relationship between the distance LL between the end portions 45 of the communication lug groove 40 and the distance L1 between the both end portions 51 of the sub-groove 50 is (L1 / LL) <0.5, adjacent communication lugs Since the length of the auxiliary groove 50 in the tire circumferential direction is too short compared to the interval between the grooves 40, water between the tread surface 3 and the road surface becomes difficult to enter the auxiliary groove 50, There is a possibility that water will not easily flow into the secondary groove 50. In this case, it may be difficult to effectively improve the steering stability on the wet road surface. On the other hand, when the relationship between the distance LL between the end portions 45 of the communication lug groove 40 and the distance L1 between the both end portions 51 of the sub-groove 50 is (L1 / LL) ≧ 0.5, they are adjacent to each other. Since the length of the auxiliary groove 50 in the tire circumferential direction is longer than the interval between the communication lug grooves 40, water between the vicinity of the inner second land portion 33 and the road surface on the tread surface 3 communicates with the auxiliary groove 50. With the lug groove 40, it can drain more reliably. As a result, wet maneuverability can be improved more reliably.

  Further, the communication lug groove 40 is an angle formed with respect to the tire width direction of the straight line a connecting the intersection P with the ground contact end T of the tread surface 3 in the communication lug groove 40 and the terminal end 45 in the inner second land portion 33. Since θ1 is in the range of 25 ° ≦ θ1 ≦ 45 °, it is possible to more reliably achieve both steering stability on a dry road surface and steering stability on a wet road surface. That is, when the angle θ1 of the straight line a with respect to the tire width direction is less than 25 °, it is difficult to secure the length of the communication lug groove 40, and thus it is difficult to ensure drainage using the communication lug groove 40. There is. Further, when the angle θ1 of the straight line a with respect to the tire width direction exceeds 45 °, the inclination angle of the communication lug groove 40 in the tire circumferential direction is too large, so the tire width direction of the land portion 30 adjacent to the communication lug groove 40 The width at may be reduced. In this case, since the rigidity of the land part 30 falls, the steering stability on a dry road surface may fall. In contrast, when the angle θ1 of the straight line a with respect to the tire width direction is within a range of 25 ° ≦ θ1 ≦ 45 °, the rigidity of the land portion 30 is ensured while ensuring the length of the communication lug groove 40 more reliably. Can be secured. As a result, the wet operability can be improved while ensuring the dry operability more reliably.

  In the sub-groove 50, since the angle θ2 formed with respect to the tire circumferential direction of the straight line b connecting the both end portions 51 of the sub-groove 50 satisfies θ2 ≦ 20 °, the rigidity of the land portion 30 can be ensured more reliably. It is possible to ensure steering stability on a dry road surface. That is, when the angle θ2 of the straight line b with respect to the tire circumferential direction exceeds 20 °, the angle with respect to the communication lug groove 40 when the sub groove 50 is connected to the communication lug groove 40 may be too small. . In this case, the angle of the portion where the sub-groove 50 and the communication lug groove 40 are connected in the region between the sub-groove 50 and the communication lug groove 40 in the inner second land portion 33 becomes too acute. There is a possibility that the rigidity of the land portion 33 is lowered and the steering stability on the dry road surface is lowered. On the other hand, when the angle θ2 formed with respect to the tire circumferential direction of the straight line b connecting the both end portions 51 of the sub-groove 50 satisfies θ2 ≦ 20 °, the shape becomes an acute angle in plan view of the land portion 30. Since it can suppress that the part which passes is generated, the rigidity of the land part 30 can be ensured more reliably. As a result, dry operability can be more reliably ensured.

  Moreover, since the secondary groove 50 is terminated at a position passing through the terminal end 45 of the communication lug groove 40, the flow of water between the secondary groove 50 and the communication lug groove 40 can be ensured more reliably. The drainage by the sub-groove 50 and the communication lug groove 40 can be ensured more reliably. As a result, wet maneuverability can be improved more reliably.

  Further, the sub-groove 50 is an inner circumferential direction that divides the opposite side to the side that is defined by the innermost outermost circumferential main groove 23 among the circumferential main grooves 20 that divide both sides in the tire width direction of the inner second land portion 33. Since the main groove 24 opens, the rigidity of the portion of the inner second land portion 33 near the innermost outer circumferential direction main groove 23 is secured, and the water that has entered the sub-groove 50 is not only connected to the communication lug groove 40 but also to the inner periphery. It can also flow in the direction main groove 24. Thereby, it is possible to more reliably achieve both steering stability on a dry road surface and steering stability on a wet road surface. As a result, the wet operability can be improved while ensuring the dry operability more reliably.

  The sub-groove 50 is inclined in the tire circumferential direction while extending inward in the tire width direction from the end portion 45 of the communication lug groove 40, and the inclination direction in the tire circumferential direction with respect to the tire width direction is the communication lug groove 40. Since the inclination angle with respect to the tire width direction is larger than the inclination angle of the communication lug groove 40, the auxiliary groove 50 of the inner second land portion 33 where the auxiliary groove 50 is formed is the same as the inclination direction of the tire. By securing the length of the sub-groove 50 while ensuring the rigidity of the outer portion in the tire width direction and the rigidity of the portion between the sub-groove 50 and the communication lug groove 40, drainage can be ensured. . As a result, the wet operability can be improved while ensuring the dry operability more reliably.

  Further, since the groove formed in the inner second land portion 33 does not open in the edge portion 33a on the innermost outermost circumferential main groove 23 side in the inner second land portion 33, the innermost land portion 33 in the inner second land portion 33 is more surely provided. Rigidity at a position near the outer circumferential main groove 23 can be ensured. As a result, dry operability can be more reliably ensured.

  Further, the inner second land portion 33 has a plane portion 80 adjacent to the edge portion 33a on the innermost outer circumferential direction main groove 23 side in the inner second land portion 33, and the plane portion 80 has a width in the tire width direction. Since the minimum value Wgmin is within the range of 0.1 ≦ (Wgmin / Wg) ≦ 0.5 with respect to the width Wg of the inner second land portion 33 in the tire width direction, the rigidity of the inner second land portion 33 is ensured. It is possible to more reliably balance drainage. That is, when the relationship between the minimum width Wgmin of the plain portion 80 in the tire width direction and the width Wg of the inner second land portion 33 is (Wgmin / Wg) <0.1, the tire in the plain portion 80 Since the width at the position where the width in the width direction is the smallest is too small, it may be difficult to effectively secure the rigidity of the inner second land portion 33. In this case, the steering stability on the dry road surface may be lowered. When the relationship between the minimum width Wgmin of the plain portion 80 in the tire width direction and the width Wg of the inner second land portion 33 is (Wgmin / Wg)> 0.5, the inner second land portion 33 Since the length of the inner secondary lug groove 44 that constitutes the communication lug groove 40 at the position of the formed secondary groove 50 and the inner second land portion 33 is too short, the drainage performance by the auxiliary groove 50 and the communication lug groove 40 is ensured. Can be difficult.

  On the other hand, the relationship between the minimum width Wgmin of the plain portion 80 in the tire width direction and the width Wg of the inner second land portion 33 is in the range of 0.1 ≦ (Wgmin / Wg) ≦ 0.5. In this case, the drainage by the sub-groove 50 and the communication lug groove 40 can be ensured more reliably while ensuring the rigidity of the inner second land portion 33. As a result, the wet operability can be improved while ensuring the dry operability more reliably.

  The outermost outermost main groove 22, the outer second land portion 32, and the outer shoulder land portion 31 are located on the outer side in the vehicle mounting direction than the tire equator plane CL, and the innermost outermost direction main groove 23 and the inner second land portion 33. Since the inner shoulder land portion 34 is located on the inner side in the vehicle mounting direction than the tire equator plane CL, the drainage can be secured by the communication lug groove 40 at a position outside the tire equator plane CL in the vehicle mounting direction. The rigidity of the land portion 30 can be ensured by securing the rigidity of the inner second land portion 33 at a position on the inner side in the vehicle mounting direction from the tire equator plane CL. As a result, a large load is likely to act on the outer region in the vehicle mounting direction than the tire equator surface CL on the tread surface 3, and drainage performance during turning of the vehicle can be ensured. Therefore, when traveling on a wet road surface Turning performance can be ensured. In addition, since the load on the tread surface 3 is more likely to act on the inner side of the tire equatorial plane CL than the tire equatorial plane CL, and the rigidity of the land portion 30 can be secured when the vehicle is traveling straight, the vehicle travels on a dry road surface. Steering stability at the time can be ensured. As a result, the wet operability can be improved while ensuring the dry operability more reliably.

[Modification]
FIG. 5 is a modified example of the pneumatic tire according to the embodiment, and is an explanatory view showing a case where the secondary groove is bent. In the pneumatic tire 1 according to the above-described embodiment, the secondary groove 50 is gently curved in a direction that protrudes in a direction away from the adjacent inner second lug groove 44, but the secondary groove 50 has a shape other than the curved shape. May be formed. For example, as shown in FIG. 5, the secondary groove 50 may be bent at a bent portion 55 in a direction away from the adjacent inner second lug groove 44. Further, the sub-groove 50 may be formed in a wave shape or a zigzag shape by repeating the bending and bending not only once but multiple times.

  FIG. 6 and FIG. 7 are modified examples of the pneumatic tire according to the embodiment, and are explanatory views showing a case where the secondary groove terminates in the inner second land portion. In the pneumatic tire 1 according to the above-described embodiment, the sub-groove 50 has one end portion 51 connected to the terminal end portion 45 of the communication lug groove 40 and the other end portion 51 defining the inner second land portion 33. However, at least one end 51 of the sub-groove 50 may terminate in the inner second land portion 33. For example, as shown in FIG. 6, the sub-groove 50 may have one end 51 connected to the inner circumferential main groove 24 and the other end 51 terminating in the inner second land portion 33. . In this case, as shown in FIG. 6, the sub-groove 50 is connected to the end portion 45 through the end portion 45 of the communication lug groove 40 in the vicinity of the end portion 51 on the side terminating in the inner second land portion 33. Thus, the sub-groove 50 and the communication lug groove 40 are connected.

  Alternatively, as shown in FIG. 7, the sub-groove 50 has one end portion 51 connected to the end portion 45 of the communication lug groove 40 and the other end portion 51 terminating in the inner second land portion 33. Also good. Even when the end portion 51 of the sub-groove 50 terminates in the inner second land portion 33, the sub-groove 50 is connected to the communication lug groove 40 and separated from the innermost outermost circumferential main groove 23. Since both the rigidity of the land portion 30 can be ensured, the wet operability can be improved while ensuring the dry operability.

  FIG. 8 is a modified example of the pneumatic tire according to the embodiment, and is an explanatory view showing a case where the auxiliary groove is formed over one circumference in the tire circumferential direction. Further, in the pneumatic tire 1 according to the above-described embodiment, the auxiliary groove 50 includes the end 51 on the side connected to the terminal end 45 of the communication lug groove 40 and the side connected to the inner circumferential main groove 24. Although it has the end part 51, the subgroove 50 does not have the end part 51, or the position of the both end parts 51 may correspond. That is, as shown in FIG. 8, the sub-groove 50 may extend in the tire circumferential direction and be continuously formed over one circumference in the tire circumferential direction. Thus, even when the auxiliary groove 50 is formed continuously over the circumference in the tire circumferential direction, the auxiliary groove 50 passes through the terminal end 45 of the communication lug groove 40 and extends from the innermost outermost circumferential main groove 23. They are formed apart. Further, in this case, the plane portion 80 is formed in a rib shape in which both sides in the tire width direction are partitioned by the innermost outermost circumferential main groove 23 and the sub-groove 50.

  In addition, when the sub-groove 50 is continuously formed over the circumference in the tire circumferential direction, it extends in the tire circumferential direction while curving or bending in the tire width direction, thereby forming a wavy or zigzag shape. It may be formed. Thus, even when the sub-groove 50 is continuously formed over the circumference in the tire circumferential direction, the sub-groove 50 is connected to the communication lug groove 40 and is separated from the innermost outermost circumferential main groove 23. Thereby, since both drainage property and the rigidity of the land part 30 can be ensured, wet operability can be improved while ensuring dry operability.

  In the pneumatic tire 1 according to the above-described embodiment, the mounting direction with respect to the vehicle is defined, the outermost outermost main groove 22 that is the first outermost circumferential main groove, and the outer second land that is the first land portion. The outer shoulder land portion 31 that is the portion 32 and the first shoulder land portion is located on the outer side in the vehicle mounting direction with respect to the tire equator plane CL, and the inner outermost circumferential main groove 23 that is the second outermost circumferential main groove, the second The inner second land portion 33 that is the land portion and the inner shoulder land portion 34 that is the second shoulder land portion are located on the inner side in the vehicle mounting direction than the tire equator plane CL, but the mounting direction with respect to the vehicle is not defined. Alternatively, the mounting direction with respect to the vehicle may be defined in the opposite direction. That is, in the pneumatic tire 1 having the communication lug groove 40 and the auxiliary groove 50, the first outermost circumferential main groove, the first land portion, and the first shoulder land portion are located on the inner side in the vehicle mounting direction than the tire equatorial plane CL. The second outermost circumferential main groove, the second land portion, and the second shoulder land portion may be located on the outer side in the vehicle mounting direction than the tire equator plane CL.

  When the first outermost circumferential main groove, the first land portion, and the first shoulder land portion are located on the inner side in the vehicle mounting direction than the tire equator plane CL, the communication lug groove 40 is formed when the vehicle goes straight. Since the position is easily grounded, drainage can be ensured, and steering stability when traveling straight on a wet road surface can be ensured. Further, the second outermost circumferential main groove, the second land portion, and the second shoulder land portion are located on the outer side in the vehicle mounting direction than the tire equator plane CL, so that the plane portion 80 is formed when the vehicle turns. Since the position is easily grounded, it is possible to ensure the rigidity of the land portion 30 where a large load is easily applied during turning, and to ensure steering stability when turning on a dry road surface.

  In the pneumatic tire 1 according to the above-described embodiment, four circumferential main grooves 20 are provided, but the circumferential main grooves 20 may be other than four. For example, the circumferential main groove 20 may be three or five. At least three circumferential main grooves 20 are formed, and the two outer circumferential main grooves 20 positioned on the outermost side in the tire width direction are outermost circumferential main grooves 21, and the tire equatorial plane is formed from the first shoulder land portion. The communication lug groove 40 that extends over the CL to the second land portion and terminates in the second land portion, and the sub-groove 50 that passes through the terminal portion 45 of the communication lug groove 40 and is separated from the second outermost circumferential main groove. The mounting direction of the pneumatic tire 1 with respect to the vehicle does not matter.

[Example]
9A to 9D 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. In the performance evaluation test, tests were performed on wet steering stability indicating steering stability when traveling on a wet road surface and dry steering stability indicating steering stability when traveling on a dry road surface.

  In the performance evaluation test, a pneumatic tire 1 of 215 / 55R17 94W size specified by JATMA is assembled on a rim wheel of a 17 × 7 JJ size JATMA standard rim, and the air pressure is adjusted to 230 kPa. A front-wheel-drive passenger car having an amount of 1600 cc was used as a test vehicle, and the test tires were mounted on all the wheels of the test vehicle for test running.

  As for the evaluation method of each test item, as for wet maneuvering stability, the test driver runs on an asphalt road sprinkled at a water depth of 1 mm at a speed of 40 km / h. Sensory evaluation of stability at the time was performed. The wet maneuvering stability is displayed with a score of 100 as a conventional example, which will be described later. The larger the numerical value, the better the maneuvering stability. With regard to dry handling stability, a test course on a dry road surface with a flat circuit is run at 60 km / h to 100 km / h by a test vehicle, and the test driver is steerable during race change and cornering, and when driving straight Sensory evaluation of the stability was performed. The dry maneuvering stability is displayed with a score of 100 as a conventional example to be described later, and the larger the numerical value, the better the dry maneuvering stability.

  An evaluation test compares with the pneumatic tire of the conventional example which is an example of the conventional pneumatic tire 1, Examples 1-7 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 16 types of pneumatic tires of Comparative Examples 1 to 8 which are pneumatic tires. Among these pneumatic tires 1, the conventional pneumatic tire is not provided with lug grooves that straddle a plurality of land portions, and is not provided with sub-grooves in the inner second land portion 33. The pneumatic tires of Comparative Examples 1 to 8 have a communication lug groove 40 straddling a plurality of land portions 30, or a sipe that straddles the tire equatorial plane CL from one shoulder land portion, and a plurality of land portions. The communication lug groove 40 straddling 30 differs from the shoulder land portion over the tire equatorial plane CL, and the terminal position of the communication lug groove 40 is different. Further, in the pneumatic tires of Comparative Examples 1 to 8, whether or not the secondary groove 50 is provided in the inner second land portion 33, whether or not the secondary groove 50 is connected to the communication lug groove 40, The presence or absence of an opening in the outermost circumferential main groove 21 is different.

  On the other hand, Examples 1-7 which are examples of the pneumatic tire 1 which concerns on this invention all straddle the tire equator surface CL from one shoulder land part, and the communication lug groove | channel 40 which terminates in the inner side second land part 33. The inner second land portion 33 is provided with a sub-groove 50 that is connected to the communication lug groove 40 and does not open in the outermost circumferential main groove 21. Moreover, the pneumatic tire 1 which concerns on Examples 1-7 WHEREIN: Ratio (W1 / CW) of the tire width direction length component W1 of the communication lug groove 40 and the contact width CW, the tire circumferential direction length component of the subgroove 50 The ratio (L1 / LL) between L1 and the pitch length LL of the communication lug groove 40, the angle θ1 of the communication lug groove 40 with respect to the tire width direction, and the angle θ2 of the auxiliary groove 50 with respect to the tire circumferential direction are different.

  As a result of performing an evaluation test using these pneumatic tires 1, as shown in FIGS. 9A to 9D, the pneumatic tires 1 of Examples 1 to 7 are compared with the conventional examples and Comparative Examples 1 to 8. It was found that the wet steering stability can be improved while maintaining the same level of performance as that of the conventional example at least for the dry steering stability. That is, the pneumatic tire 1 according to Examples 1 to 7 can improve the wet operability while ensuring the dry operability.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Tread surface 4 Side wall part 5 Shoulder part 10 Bead part 11 Bead core 12 Bead filler 13 Carcass 14 Belt layer 141, 142 Cross belt 143 Belt cover 20 Circumferential main groove 21 Outermost peripheral main groove 22 Outside outermost main groove (first outermost main groove)
23 innermost outermost main groove (second outermost main groove)
24 inner circumferential main groove 30 land portion 31 outer shoulder land portion (first shoulder land portion)
32 Outer second land (first land)
33 Inner second land (second land)
33a, 33b Edge portion 34 Inner shoulder land portion (second shoulder land portion)
35 Center land portion 40 Communication lug groove 41 Outer shoulder lug groove 42 Outer second lug groove 43 Center lug groove 44 Inner second lug groove 45 Terminal portion 46 Center non-penetrating lug groove 47 Inner shoulder lug groove 50 Sub groove 51 End portion 70 Circumferential direction Narrow groove 80 Plain part

Claims (13)

A pneumatic tire comprising three or more circumferential main grooves extending in the tire circumferential direction on a tread surface and four or more rows of land portions defined by the circumferential main grooves,
Of the plurality of circumferential main grooves, the two circumferential main grooves positioned on the outermost side in the tire width direction are outermost circumferential main grooves,
Of the two outermost circumferential main grooves, the outermost circumferential main groove located on one side of the tire equatorial plane in the tire width direction is the first outermost circumferential main groove, and the outermost circumferential direction is located on the other side. The main groove is the second outermost circumferential main groove,
Among the plurality of land portions, the land portion adjacent to the tire equatorial plane side with respect to the first outermost circumferential main groove is defined as a first land portion, and the land portion adjacent to the outer side in the tire width direction is defined as the first land portion. Shoulder land,
Among the plurality of land portions, the land portion adjacent to the tire equatorial plane side with respect to the second outermost circumferential main groove is the second land portion, and the land portion adjacent to the outer side in the tire width direction is the second land portion. When the shoulder land
A communication lug groove extending from the first shoulder land portion over the tire equatorial plane and continuously extending to the second land portion and terminating in the second land portion;
The pneumatic tire according to claim 1, wherein the second land portion includes a sub-groove that passes through a terminal portion of the communication lug groove and is separated from the second outermost circumferential main groove.   A tire width direction length component W1 of a portion included in the contact area of the tread surface in the communication lug groove and a contact width CW which is a width of the contact area in the tire width direction are 0.6 ≦ (W1 / CW). 2) The pneumatic tire according to claim 1, which satisfies a relationship of ≦ 0.8.   Between the communication lug grooves adjacent in the tire circumferential direction, a distance LL in the tire circumferential direction between the end portions in the second land portion, and a distance L1 in the tire circumferential direction between both end portions of the sub-groove, The pneumatic tire according to claim 1 or 2, satisfying a relationship of (L1 / LL) ≧ 0.5.   In the communication lug groove, an angle θ1 formed with respect to the tire width direction of a straight line a connecting the intersection of the communication lug groove with the grounded end of the tread surface and the terminal portion in the second land portion is 25 °. The pneumatic tire according to any one of claims 1 to 3, which is within a range of?? 1? 45 °.   5. The pneumatic tire according to claim 1, wherein an angle θ <b> 2 formed with respect to the tire circumferential direction of a straight line b connecting both ends of the sub-groove satisfies the θ <b> 2 ≦ 20 °. .   The pneumatic tire according to any one of claims 1 to 5, wherein the sub-groove is terminated at a position passing through the terminal portion of the communication lug groove.   The sub-groove is a circumferential main groove that defines a side opposite to a side defined by the second outermost circumferential main groove among the circumferential main grooves that define both sides of the second land portion in the tire width direction. A pneumatic tire given in any 1 paragraph of Claims 1-6 opened to.   The pneumatic tire according to any one of claims 1 to 7, wherein at least one end of the sub-groove terminates in the second land portion. The communication lug groove is inclined in the tire circumferential direction while extending in the tire width direction,
The sub-groove is inclined in the tire circumferential direction while extending inward in the tire width direction from the end portion of the communication lug groove, and an inclination direction in the tire circumferential direction with respect to the tire width direction is an inclination of the communication lug groove. The pneumatic tire according to any one of claims 1 to 8, wherein an inclination angle with respect to a tire width direction is larger than an inclination angle of the communication lug groove in the same direction as the direction.   The pneumatic tire according to any one of claims 1 to 5, wherein the auxiliary groove is formed continuously over one circumference in the tire circumferential direction.   The pneumatic tire according to any one of claims 1 to 10, wherein a groove formed in the second land portion does not open at an edge portion on the second outermost circumferential main groove side in the second land portion. . The second land portion is a plane portion that is adjacent to the edge portion on the second outermost circumferential main groove side in the second land portion and is a region where the groove is not formed continuously from the edge portion. Have
The plain portion has a minimum width Wgmin in the tire width direction within a range of 0.1 ≦ (Wgmin / Wg) ≦ 0.5 with respect to the width Wg of the second land portion in the tire width direction. Item 12. The pneumatic tire according to Item 11. The pneumatic tire has a specified mounting direction with respect to the vehicle,
The first outermost circumferential main groove, the first land portion, and the first shoulder land portion are located outside the tire equator plane in the vehicle mounting direction,
The air according to any one of claims 1 to 12, wherein the second outermost circumferential main groove, the second land portion, and the second shoulder land portion are located on the inner side in the vehicle mounting direction than the tire equator plane. Enter tire.

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