JP2018140745A - tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire which has excellent uneven wear resistance while maintaining wet performance.SOLUTION: A tire has a tread part 2 in which a direction of attachment to a vehicle is specified. A first groove edge 16a and a second groove edge 16b of an outer shoulder lateral groove 16 provided at an outer shoulder land part 10 intersect with an outer tread end To at a first intersection point 21 and a second intersection point 22 respectively. A third groove edge 17a and a fourth groove edge 17b of an inner shoulder lateral groove 17 provided at an inner shoulder land part intersect with an inner tread end Ti at a third intersection point 23 and a fourth intersection point 24 respectively. The first intersection point 21 and the second intersection point 22 are respectively provided at different positions from the third intersection point 23 and the fourth intersection point 24 in a tire circumferential direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tire having excellent uneven wear resistance.

  For example, Patent Document 1 below proposes a tire having a tread portion in which the direction of mounting on a vehicle is specified. The tire has an outer shoulder land portion positioned on the vehicle outer side when the vehicle is mounted and an inner shoulder land portion positioned on the vehicle inner side when the vehicle is mounted. The outer shoulder land portion is provided with a plurality of outer shoulder lateral grooves extending inward in the tire axial direction from the tread end. The inner shoulder land portion is provided with a plurality of inner shoulder lateral grooves extending inward in the tire axial direction from the tread end. These shoulder lateral grooves discharge the water in the ground contact surface to the tread end side and improve the wet performance.

  In the tire, each outer shoulder lateral groove has a groove edge that intersects the tread end at the first intersection and the second intersection. Each inner shoulder lateral groove has its groove edge intersecting the tread end at the third intersection and the fourth intersection.

  In general, when the tire travels, the land portion slides relatively large with respect to the road surface at the moment when the positions of the first to fourth intersections of the lateral grooves touch the road surface and leave the road surface. Such slipping of the land portion leads to wear of the land portion. In particular, when the first intersection or the second intersection is in contact with the road surface or separated from the road surface at the same time as the third intersection or the fourth intersection, the inner and outer shoulder land portions slide simultaneously with respect to the road surface, and the land portion during tire traveling The amount of slip increases. Such repeated sliding tends to promote uneven wear (for example, heel and toe wear) in which the vicinity of the groove edge of the lateral groove of the tread portion is worn early.

Japanese Patent Laid-Open No. 2006-150601

  The present invention has been devised in view of the above problems, and has as its main object to provide a tire having excellent uneven wear resistance performance while maintaining wet performance.

  The present invention is a tire having a tread portion in which the direction of mounting on a vehicle is specified, and the tread portion includes an outer shoulder land portion including an outer tread end positioned on the outer side of the vehicle when the vehicle is mounted, An inner shoulder land portion including an inner tread end located inside the vehicle, wherein the outer shoulder land portion includes at least a plurality of outer shoulder lateral grooves extending inward in the tire axial direction from the outer tread end. The land portion is provided with at least a plurality of inner shoulder lateral grooves extending inward in the tire axial direction from the inner tread end, and each outer shoulder lateral groove is a first groove located in a first direction on one side of the tire circumferential direction. An edge, and a second groove edge located in a second direction opposite to the first direction in the tire circumferential direction, the first groove edge and the front The second groove edge intersects with the outer tread end at the first intersection and the second intersection, respectively, and each inner shoulder lateral groove has a third groove edge and a tire circumferential direction located in the first direction in the tire circumferential direction. A fourth groove edge located in the second direction, and the third groove edge and the fourth groove edge intersect the inner tread end at a third intersection point and a fourth intersection point, respectively, The second intersection point is provided at a position different from the third intersection point and the fourth intersection point in the tire circumferential direction.

  In the tire of the present invention, the first intersection point, the second intersection point, the third intersection point, and the first intersection point toward the second direction in the group of first to fourth intersection points that are closest to each other in the tire circumferential direction. It is desirable to line up in the tire circumferential direction in the order of the four intersections.

  In the tire of the present invention, the distance L1 in the tire circumferential direction between the second intersection and the third intersection is a groove width at the outer tread end of the outer shoulder lateral groove and the inner tread of the inner shoulder lateral groove. It is desirable that it is smaller than the groove width at the end.

  In the tire of the present invention, the distance L1 is preferably 0.2 to 1.0 mm.

  In the tire of the present invention, it is preferable that the outer shoulder lateral groove completely crosses the outer shoulder land portion.

  In the tire of the present invention, it is preferable that an inner end of the inner shoulder lateral groove in the tire axial direction is located in the inner shoulder land portion.

  In the tire of the present invention, the outer shoulder lateral groove and the inner shoulder lateral groove each have an angle of less than 10 ° with respect to the tire axial direction, and the maximum angle of the inner shoulder lateral groove with respect to the tire axial direction is the outer side. It is desirable that the angle is smaller than the maximum angle of the shoulder lateral groove with respect to the tire axial direction.

  In the tire according to the present invention, the outer shoulder sipe is provided with an outer shoulder sipe, the inner shoulder land is provided with an inner shoulder sipe, and the outer shoulder sipe and the inner shoulder sipe are each shallow. A bottom portion and a deep bottom portion having a depth larger than the shallow bottom portion, and the outer shoulder sipe is provided with the shallow bottom portion on the inner side in the tire axial direction of the deep bottom portion, and the inner shoulder sipe is the shallow shoulder sipe. It is desirable that the bottom portion is provided outside the deep bottom portion in the tire axial direction.

  Each outer shoulder lateral groove provided in the outer shoulder land portion of the tire of the present invention has a first groove edge located in the first direction which is one side of the tire circumferential direction, and is opposite to the first direction in the tire circumferential direction. A second groove edge located in the second direction on the side. The first groove edge and the second groove edge intersect with the outer tread end at the first intersection and the second intersection, respectively.

  Each inner shoulder lateral groove provided in the inner shoulder land portion has a third groove edge located in the first direction in the tire circumferential direction and a fourth groove edge located in the second direction in the tire circumferential direction. The third groove edge and the fourth groove edge intersect with the inner tread end at the third intersection point and the fourth intersection point, respectively.

  In the tire according to the present invention, the first intersection and the second intersection are provided at different positions in the tire circumferential direction from the third intersection and the fourth intersection, respectively. Therefore, according to the present invention, when the tire is running, the intersections are grounded at different timings, so that the inner and outer shoulder land portions can be prevented from sliding simultaneously with respect to the road surface. For this reason, according to the tire of the present invention, while maintaining the wet performance by the shoulder lateral groove, it is possible to reduce the slip amount of the shoulder land portions on both sides when the tire is running, thereby providing excellent uneven wear resistance performance. .

It is an expanded view of the tread part of the tire of one embodiment of the present invention. It is an enlarged view of the outer side shoulder land part of FIG. It is an enlarged view of the inner side shoulder land part of FIG. It is the elements on larger scale of the outer side shoulder horizontal groove and inner side shoulder horizontal groove of FIG. (A) is the sectional view on the AA line of FIG. 3, (b) is the sectional view on the BB line of FIG. 2, (c) is the sectional view on the CC line of FIG. . It is an enlarged view of the outer middle land part of FIG. FIG. 2 is a partially enlarged view of an outer shoulder lateral groove and an outer middle lateral groove of FIG. 1. (A) is the DD sectional view taken on the line of FIG. 6, (b) is the EE sectional view taken on the line of FIG. It is an enlarged view of the inner middle land part and crown land part of FIG. (A) is the FF sectional view taken on the line of FIG. 9, (b) is the GG sectional view of FIG. 9, (c) is the HH sectional view of FIG. (D) is the II sectional view taken on the line of FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a development view of the tread portion 2 of the tire 1 of the present embodiment. The tire 1 of the present embodiment can be used for various tires such as pneumatic tires for passenger cars and heavy loads, and non-pneumatic tires that are not filled with pressurized air inside the tires. The tire 1 of this embodiment is suitably used as a pneumatic tire for passenger cars, for example.

  As shown in FIG. 1, the tire 1 of the present embodiment includes, for example, a tread portion 2 in which the mounting direction to the vehicle is specified. The tread portion 2 has an outer tread end To positioned on the vehicle outer side when the tire 1 is mounted on the vehicle, and an inner tread end Ti positioned on the vehicle inner side when the vehicle is mounted. The direction of mounting on the vehicle is displayed, for example, with letters or symbols on a sidewall (not shown).

  In the case of a pneumatic tire, each tread end To, Ti is a grounding position on the outermost side in the tire axial direction when a regular load is applied to the regular tire 1 and grounded on a plane with a camber angle of 0 °. The normal state is a state in which the tire is assembled on the normal rim and is filled with the normal internal pressure, and further, there is no load. In this specification, when there is no notice in particular, the dimension of each part of a tire, etc. are values measured in the normal state.

  The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, “Standard Rim” for JATMA, “Design Rim” for TRA, and “ETRTO” If there is "Measuring Rim".

  “Regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. “JAMATA” is the “highest air pressure”, TRA is the table “TIRE LOAD LIMITS AT” The maximum value described in “VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” for ETRTO.

  “Regular load” is a load determined by each standard for each tire in the standard system including the standard on which the tire is based. “JATMA” is “Maximum load capacity”, TRA is “TIRE LOAD LIMITS” The maximum value described in “AT VARIOUS COLD INFLATION PRESSURES”, “LOAD CAPACITY” in the case of ETRTO.

  The tread portion 2 is provided with a plurality of main grooves extending continuously in the tire circumferential direction. The plurality of main grooves include, for example, an outer shoulder main groove 3, an inner shoulder main groove 4, an outer crown main groove 5, and an inner crown main groove 6. Each of the main grooves 3 to 6 of the present embodiment extends linearly, for example, but is not limited to such a mode, and may be, for example, a zigzag shape.

  The outer shoulder main groove 3 is provided, for example, on the outermost tread end To side among the plurality of main grooves. The inner shoulder main groove 4 is provided, for example, on the innermost tread end Ti side among the plurality of main grooves. The outer crown main groove 5 is provided between the outer shoulder main groove 3 and the tire equator C, for example. The inner crown main groove 6 is provided between the inner shoulder main groove 4 and the tire equator C, for example.

  In the outer shoulder main groove 3 and the inner shoulder main groove 4, for example, the distance L2 from the tire equator C to the groove center line is preferably 0.25 to 0.35 times the tread width TW. In the outer crown main groove 5 and the inner crown main groove 6, for example, the distance L3 from the tire equator C to the groove center line is preferably 0.05 to 0.15 times the tread width TW. The tread width TW is a distance in the tire axial direction from the outer tread end To to the inner tread end Ti in the normal state.

  The inner shoulder main groove 4, the outer crown main groove 5, and the inner crown main groove 6 preferably have, for example, groove widths W1a, W1b, and W1c that are 5 to 8% of the tread width TW. For example, the outer shoulder main groove 3 preferably has a groove width W1d smaller than the groove widths W1a to W1c. The groove width W1d of the outer shoulder main groove 3 is preferably 0.40 to 0.50 times the groove width W1a of the inner shoulder main groove 4, for example. Thereby, wet performance and steering stability are improved with good balance.

  The main grooves 3 to 6 desirably have a depth of, for example, about 5 to 10 mm in the case of a tire for a passenger car. Each of the main grooves 3 to 6 can improve wet performance and steering stability in a well-balanced manner. However, the dimensions of the main grooves 3 to 6 are not limited to such a range.

  By providing the main grooves 3 to 6 described above, the tread portion 2 has an outer shoulder land portion 10, an inner shoulder land portion 11, an outer middle land portion 12, an inner middle land portion 13, and a crown land portion. 14 is divided. The outer shoulder land portion 10 is sectioned on the outer side in the tire axial direction of the outer shoulder main groove 3 and includes an outer tread end To. The inner shoulder land portion 11 is sectioned on the outer side in the tire axial direction of the inner shoulder main groove 4 and includes an inner tread end Ti. The outer middle land portion 12 is divided between the outer shoulder main groove 3 and the outer crown main groove 5. The inner middle land portion 13 is divided between the inner shoulder main groove 4 and the inner crown main groove 6. The crown land portion 14 is divided between the outer crown main groove 5 and the inner crown main groove 6.

  An enlarged view of the outer shoulder land portion 10 is shown in FIG. As shown in FIG. 2, the outer shoulder land portion 10 is provided with a plurality of outer shoulder lateral grooves 16.

  Each outer shoulder lateral groove 16 extends inward in the tire axial direction from at least the outer tread end To. In the preferred embodiment, the outer shoulder transverse groove 16 completely traverses the outer shoulder land 10.

  Each outer shoulder lateral groove 16 has a first groove edge 16a and a second groove edge 16b. The first groove edge 16a is located in the first direction, which is one side in the tire circumferential direction. The second groove edge 16b is located in the second direction opposite to the first direction in the tire circumferential direction. The first groove edge 16a and the second groove edge 16b intersect the outer tread end To at the first intersection 21 and the second intersection 22, respectively.

  FIG. 3 shows an enlarged view of the inner shoulder land portion 11. As shown in FIG. 3, the inner shoulder land portion 11 is provided with a plurality of inner shoulder lateral grooves 17.

  Each inner shoulder lateral groove 17 extends at least inward in the tire axial direction from the inner tread end Ti. In a desirable mode, the inner end 17 i in the tire axial direction of the inner shoulder lateral groove 17 is located in the inner shoulder land portion 11.

  Each inner shoulder lateral groove 17 has a third groove edge 17a and a fourth groove edge 17b. The third groove edge 17a is located in the first direction in the tire circumferential direction. The fourth groove edge 17b is located in the second direction in the tire circumferential direction. The third groove edge 17a and the fourth groove edge 17b intersect the inner tread end Ti at the third intersection point 23 and the fourth intersection point 24, respectively.

  FIG. 4 shows a partially enlarged view of the outer shoulder lateral groove 16 and the inner shoulder lateral groove 17. As shown in FIG. 4, the first intersection 21 and the second intersection 22 are provided at different positions in the tire circumferential direction from the third intersection 23 and the fourth intersection 24, respectively. Therefore, according to the present invention, when the tire travels, the intersections 21 to 24 are grounded at different timings, so that the inner and outer shoulder land portions 10 and 11 can be prevented from slipping on the road surface at the same time. For this reason, according to the tire 1 of the present invention, while maintaining the wet performance by the shoulder lateral grooves 16 and 17, the amount of slip of the shoulder land portions 10 and 11 on both sides when the tire is running is reduced, and thus excellent uneven wear resistance. Can provide performance.

  In a desirable mode, in the group of the 1st-4th intersections 21-24 located closest in the tire peripheral direction, the 1st intersection 21, the 2nd intersection 22, the 3rd intersection 23, and the 4th toward the 2nd direction. They are arranged in the tire circumferential direction in the order of the intersection points 24. Such arrangement of the first to fourth intersections 21 to 24 can more reliably exhibit the above-described effects. However, the present invention is not limited to such an aspect. For example, the third intersection 23 may be located between the first intersection 21 and the second intersection 22 in the tire circumferential direction.

  The distance L1 in the tire circumferential direction between the second intersection point 22 and the third intersection point 23 is, for example, the groove width W2 (shown in FIG. 2) at the outer tread end To of the outer shoulder lateral groove 16 and the inner shoulder lateral groove 17. It is desirable to be smaller than the groove width W3 (shown in FIG. 3) at the inner tread end Ti. If the distance L1 is larger than these, the tire vibration may increase.

  More specifically, the distance L1 is preferably 0.2 mm or more, more preferably 0.4 mm or more, preferably 1.0 mm or less, more preferably 0.8 mm or less. Thereby, the shoulder lateral grooves 16 and 17 can cooperate to exhibit excellent drainage while exhibiting excellent uneven wear resistance.

  As shown in FIGS. 2 and 3, the groove width W2 of the outer shoulder lateral groove 16 and the groove width W3 of the inner shoulder lateral groove 17 are, for example, 0 of the groove width W1d (shown in FIG. 1) of the outer shoulder main groove 3. It is desirable to be 8 to 1.2 times. The ratio W2 / W3 between the groove width W2 and the groove width W3 is preferably 0.8 to 1.2, for example. Such outer shoulder lateral grooves 16 and inner shoulder lateral grooves 17 are useful for improving wet performance and uneven wear resistance in a well-balanced manner.

  Each of the outer shoulder lateral groove 16 and the inner shoulder lateral groove 17 desirably has an angle of preferably less than 20 °, more preferably less than 10 °, for example, with respect to the tire axial direction. In this specification, the angle of the groove with respect to the tire axial direction means the angle of the center line of the groove with respect to the tire axial direction. Such outer shoulder lateral grooves 16 and inner shoulder lateral grooves 17 can be combined with the above-described arrangement of the first to fourth intersections 21 to 24 to create a flow of water in the entire groove during wet running. Can increase the sex.

  In a desirable mode, the angle with respect to the tire axial direction of the outer shoulder lateral groove 16 and the inner shoulder lateral groove 17 gradually increases toward the tire equator C side. In a further desirable mode, the maximum angle θ2 of the inner shoulder lateral groove 17 with respect to the tire axial direction is smaller than the maximum angle θ1 of the outer shoulder lateral groove 16 with respect to the tire axial direction. Thereby, the abrasion resistance performance of the inner side shoulder land part 11 is improved.

  The inner shoulder lateral groove 17 desirably has a tire axial length L4 that is 0.75 to 0.85 times the tire axial width W4 of the inner shoulder land portion 11, for example. Such inner shoulder lateral grooves 17 can maintain the rigidity of the inner shoulder land portion 11 on the inner side in the tire axial direction. For this reason, wet performance and steering stability are improved with good balance.

  FIG. 5A shows a cross-sectional view taken along line AA of the inner shoulder lateral groove 17 of FIG. As shown in FIG. 5A, the inner shoulder lateral groove 17 has, for example, an inclined bottom surface 25 having an angle θ3 of 40 to 50 ° with respect to a normal passing through the tread at the inner end in the tire axial direction. Is desirable. Thereby, it is prevented that the rigidity of the inner shoulder land portion 11 is locally changed, and excellent uneven wear resistance performance is obtained.

  As shown in FIG. 2, the outer shoulder land portion 10 is provided with a plurality of outer shoulder sipes 18. In the present embodiment, the outer shoulder sipes 18 and the outer shoulder lateral grooves 16 are provided alternately in the tire circumferential direction. In this specification, “sipe” means a cut having a width of less than 3 mm.

  The outer shoulder sipe 18 of the present embodiment completely crosses the outer shoulder land portion 10, for example. For example, the outer shoulder sipe 18 is preferably inclined in the same direction as the outer shoulder lateral groove 16 with respect to the tire axial direction. In a desirable mode, the outer side shoulder sipe 18 is arranged at an angle θ4 of 5 to 10 ° with respect to the tire axial direction, for example.

  FIG. 5B is a cross-sectional view of the outer shoulder sipe 18 of FIG. As shown in FIG. 5B, the outer shoulder sipe 18 has, for example, a shallow bottom portion 26 and a deep bottom portion 27 having a depth larger than the shallow bottom portion 26. The shallow bottom portion 26 has, for example, a depth d2 that is 0.10 to 0.20 times the depth d1 of the outer shoulder main groove 3. The deep bottom portion 27 has, for example, a depth d3 that is 0.55 to 0.65 times the depth d1 of the outer shoulder main groove 3. In the outer shoulder sipe 18 of the present embodiment, for example, the shallow bottom portion 26 is provided inside the deep bottom portion 27 in the tire axial direction. Such an outer shoulder sipe 18 is useful for suppressing wear on the inner side in the tire axial direction of the outer shoulder land portion 10.

  As a more desirable mode, it is desirable that the outer shoulder sipe 18 of the present embodiment is provided with a shallow bottom portion 28 having a depth smaller than the deep bottom portion 27 even outside the outer tread end To. Such an outer shoulder sipe 18 can suppress uneven wear in the vicinity of the outer tread end To while improving wandering performance.

  As shown in FIG. 3, the inner shoulder land portion 11 is provided with a plurality of inner shoulder sipes 19. In the present embodiment, the inner shoulder sipes 19 and the inner shoulder lateral grooves 17 are alternately provided in the tire circumferential direction.

  For example, the inner shoulder sipe 19 of the present embodiment completely crosses the inner shoulder land portion 11. For example, the inner shoulder sipe 19 is preferably inclined in the same direction as the inner shoulder lateral groove 17. In a desirable mode, it is desirable that the inner shoulder sipe 19 is inclined at an angle θ5 of 5 to 10 ° with respect to the tire axial direction, for example.

  FIG. 5C is a cross-sectional view of the inner shoulder sipe 19 taken along the line CC. As shown in FIG. 5C, the inner shoulder sipe 19 includes, for example, a shallow bottom portion 31 and a deep bottom portion 32 having a depth larger than the shallow bottom portion 31. The shallow bottom portion 31 preferably has a depth d5 that is 0.10 to 0.20 times the depth d4 of the inner shoulder main groove 4, for example. The deep bottom portion 32 preferably has a depth d6 that is 0.55 to 0.65 times the depth d4 of the inner shoulder main groove 4, for example. In the inner shoulder sipe 19 of this embodiment, the shallow bottom portion 31 is provided on the outer side in the tire axial direction of the deep bottom portion 32. Such an inner shoulder sipe 19 maintains the rigidity in the vicinity of the inner tread end Ti of the inner shoulder land portion 11, and thus can prevent a decrease in steering stability.

  FIG. 6 shows an enlarged view of the outer middle land portion 12. As shown in FIG. 6, the outer middle land portion 12 is provided with, for example, a plurality of outer middle lateral grooves 35 and a plurality of outer middle sipes 36. In the present embodiment, the outer middle lateral grooves 35 and the outer middle sipes 36 are alternately provided in the tire circumferential direction.

  The outer middle lateral groove 35 extends from the outer shoulder main groove 3 inward in the tire axial direction and is interrupted in the outer middle land portion 12, for example. The outer middle lateral groove 35 preferably has a length L5 in the tire axial direction that is 0.55 to 0.65 times the width W5 of the outer middle land portion 12 in the tire axial direction, for example. Such outer middle lateral grooves 35 can improve wet performance while maintaining the rigidity of the outer middle land portion 12.

  FIG. 7 shows a partially enlarged view of the outer shoulder lateral groove 16 and the outer middle lateral groove 35. As shown in FIG. 7, it is desirable that the outer middle lateral groove 35 is smoothly continuous with the outer shoulder lateral groove 16 via, for example, the outer shoulder main groove 3. Thereby, during wet running, the outer middle lateral groove 35 and the outer shoulder lateral groove 16 can cooperate to discharge a large amount of water. In the present specification, “two grooves or sipes smoothly continue through the main groove” means that at least one of the grooves is smoothly extended in the length direction of the one groove. It is assumed that at least half of the groove width of the groove overlaps with the other groove.

  In the present embodiment, when each groove edge of the outer shoulder lateral groove 16 is smoothly extended in the length direction, a deviation amount P1 (not shown) of the outer middle lateral groove 35 with respect to each groove edge is determined by the outer middle lateral groove 35. It is desirable that it is not more than 0.10 times the groove width W6. In a more desirable mode, the shift amount P1 is 0.4 mm or less. Such outer middle lateral groove 35 can more smoothly guide the water in the groove toward the outer shoulder lateral groove 16 during wet running.

  FIG. 8A shows a cross-sectional view taken along line DD of the outer middle lateral groove 35 of FIG. As shown in FIG. 8A, the outer middle lateral groove 35 of the present embodiment has, for example, a gradually increasing portion 37 and an outer portion 38. The gradually increasing portion 37 gradually increases in depth toward the outer side in the tire axial direction. The outer portion 38 is disposed on the outer side in the tire axial direction of the gradually increasing portion 37 and has a certain depth. Such outer middle lateral grooves 35 prevent local changes in the rigidity of the outer middle land portion 12, and consequently uneven wear of the outer middle land portion 12 is suppressed.

  In order to further exert the above-described effects, the length L6 of the gradually increasing portion 37 in the tire axial direction is 0.35 to 0.45 times the width W5 (shown in FIG. 6) in the outer middle land portion 12 tire axial direction. It is desirable. For example, the bottom surface of the gradually increasing portion 37 is preferably inclined at an angle θ6 of 60 to 70 ° with respect to the normal passing through the tread surface of the land portion.

  As shown in FIG. 6, the outer middle sipe 36 completely crosses the outer middle land portion 12, for example. For example, the outer middle sipe 36 is preferably inclined in the same direction as the outer shoulder sipe 18 (shown in FIG. 2) with respect to the tire axial direction. The angle θ7 of the outer middle sipe with respect to the tire axial direction is preferably 5 to 15 °, for example.

  As shown in FIG. 7, it is desirable that the outer middle sipe 36 is smoothly continuous with the outer shoulder sipe 18 via, for example, the outer shoulder main groove 3. As a result, the outer middle sipe 36 and the outer shoulder sipe 18 are easily opened at the time of ground contact, and a high frictional force is obtained by these edges.

  FIG. 8B shows a cross-sectional view of the outer middle sipe 36 of FIG. As shown in FIG. 8B, the outer middle sipe 36 desirably has a shallow bottom portion 39 and a deep bottom portion 40 having a depth larger than the shallow bottom portion 39, for example. In the outer middle sipe 36 of the present embodiment, the shallow bottom portion 39 is provided outside the deep bottom portion 40 in the tire axial direction.

  The shallow bottom portion 39 depth d7 of the outer middle sipe 36 is preferably, for example, 0.10 to 0.20 times the depth d1 of the outer shoulder main groove 3. The depth d8 of the deep bottom portion 40 of the outer middle sipe 36 is preferably 0.55 to 0.65 times the depth d1 of the outer shoulder main groove 3, for example. Such an outer middle sipe 36 can improve wet performance while suppressing uneven wear of the outer middle land portion 12.

  FIG. 9 shows an enlarged view of the inner middle land portion 13 and the crown land portion 14. As shown in FIG. 9, the inner middle land portion 13 is provided with, for example, a plurality of inner middle sipes 42. In a desirable mode, only the inner middle sipe 42 is provided in the inner middle land portion 13 and no groove having a width of 3 mm or more is provided.

  The inner middle sipe 42 completely crosses the inner middle land portion 13, for example. For example, the inner middle sipe 42 is inclined in the direction opposite to the outer shoulder lateral groove 16 with respect to the tire axial direction. For example, the inner middle sipe 42 is preferably inclined at an angle θ8 of 20 to 30 ° with respect to the tire axial direction.

  The inner middle sipe 42 has, for example, a central portion 43 in the tire axial direction and end portions 44 extending from the central portion 43 to the main grooves on both sides. For example, the central portion 43 and the end portion 44 of the present embodiment have different depths.

  10A shows a cross-sectional view taken along line FF of the inner middle sipe 42 of FIG. 9, and FIG. 10B shows a cross-sectional view taken along line GG of the central portion 43 of FIG. Has been. As shown in FIGS. 10A and 10B, the central portion 43 has a depth d9 of, for example, 1.0 to 2.0 mm. The central portion 43 of the present embodiment is, for example, a tire axial length L7 (see FIG. 9) 0.30 to 0.40 times the width W7 (shown in FIG. 9) of the inner middle land portion 13 in the tire axial direction. It is desirable to have Thereby, the rigidity of the inner middle land portion 13 is maintained, and excellent steering stability is obtained.

  FIG. 10C shows a cross-sectional view taken along line HH of the end portion 44 of FIG. As shown in FIG. 10C, the end portion 44 of this embodiment includes, for example, a first portion 45 and a second portion 46. For example, the first portion 45 opens with the same width as the central portion 43. In a desirable mode, the 1st portion 45 has the same depth as central part 43, for example. The second portion 46 is disposed, for example, at the bottom of the first portion 45 and extends in the tire radial direction with a smaller width than the first portion 45. Such an end portion 44 can provide a large frictional force by the edge.

  In order to improve the wet performance and the steering stability with a good balance, it is desirable that the depth d10 of the end portion 44 is, for example, 0.35 to 0.45 times the depth d4 of the inner shoulder main groove 4.

  As shown in FIG. 9, the crown land portion 14 is provided with, for example, a plurality of crown sipes 47. In a desirable mode, the crown land portion 14 is provided with only the crown sipe 47 and is not provided with a groove having a width of 3 mm or more.

  The crown sipe 47 completely traverses the crown land portion 14, for example. The crown sipe 47 of the present embodiment includes, for example, a central portion 48 in the tire axial direction and end portions 49 extending from the central portion 48 to the main grooves on both sides. In the present embodiment, the central portion 48 of the crown sipe 47 has substantially the same cross-sectional shape as the central portion 43 (shown in FIG. 10B) of the inner middle sipe 42. The end portion 49 of the crown sipe 47 has substantially the same cross-sectional shape as the end portion 44 of the inner middle sipe 42 (shown in FIG. 10C).

  The central portion 48 of the crown sipe 47 of the present embodiment is inclined with respect to the tire axial direction, for example. In the preferred embodiment, the central portion 48 of the crown sipe 47 is inclined in the opposite direction to the inner middle sipe 42. The angle θ9 of the central portion 48 of the crown sipe 47 with respect to the tire axial direction is preferably 50 to 70 °, for example.

  For example, the end portion 49 of the crown sipe 47 is preferably inclined in the direction opposite to the central portion with respect to the tire axial direction. For example, the end portion 49 is preferably inclined at an angle θ10 of 20 to 30 ° with respect to the tire axial direction. The angle θ11 between the end portion 49 and the central portion 48 is preferably 80 to 100 °, for example. Such a crown sipe 47 can exert frictional forces in multiple directions by its edges.

  FIG. 10D shows a cross-sectional view taken along line II of the crown sipe 47 of FIG. As shown in FIG. 10D, the end portion 49 of the crown sipe 47 desirably has a depth d12 that is greater than the depth d11 of the central portion 48, for example. The depth d12 of the end portion 49 is preferably 3.0 to 3.5 times the depth d11 of the central portion 48, for example. Such a crown sipe 47 can improve wet performance while maintaining the wear resistance of the crown land portion 14.

  As mentioned above, although the tire of one embodiment of the present invention was explained in detail, the present invention is not limited to the above-mentioned specific embodiment, and can be carried out by changing to various modes.

A pneumatic tire of size 255 / 55R18 having the basic tread pattern of FIG. 1 was prototyped based on the specifications in Table 1. As a comparative example, a tire in which the second intersection and the third intersection are in the same position in the tire circumferential direction was manufactured. Each test tire was tested for uneven wear resistance and wet performance. The common specifications and test methods for each test tire are as follows.
Rims: 18 x 8.0J
Tire internal pressure: 240kPa

<Uneven wear resistance>
A wear energy measuring device was used to measure the wear energy of each shoulder land. The result is an index in which the wear energy of the comparative example is 100, and the smaller the value, the smaller the wear energy and the better the uneven wear resistance.

<Wet performance>
An inside drum tester was used, and the rate of occurrence of hydroplaning phenomenon was measured when each test tire traveled on a drum surface having a water depth of 5.0 mm under the following conditions. A result is an index | index which makes a comparative example 100, and shows that the said generation | occurrence | production speed | rate is high and wet performance is excellent, so that a numerical value is large.
Slip angle: 1.0 °
Longitudinal load: 4.2kN
The test results are shown in Table 1.

  As a result of the test, it was confirmed that the tires of the examples exhibited excellent uneven wear resistance performance while maintaining wet performance.

2 tread portion 10 outer shoulder land portion 11 inner shoulder land portion 16 outer shoulder lateral groove 16a first groove edge 16b second groove edge 17 inner shoulder lateral groove 17a third groove edge 17b fourth groove edge 21 first intersection point 22 second intersection point 23 3rd intersection 24 4th intersection To Outer tread edge Ti Inner tread edge

Claims (8)

A tire having a tread portion in which a direction of mounting on a vehicle is specified,
The tread portion includes an outer shoulder land portion including an outer tread end positioned on the vehicle outer side when the vehicle is mounted, and an inner shoulder land portion including an inner tread end positioned on the vehicle inner side when the vehicle is mounted.
The outer shoulder land portion includes at least a plurality of outer shoulder lateral grooves extending inward in the tire axial direction from the outer tread end.
The inner shoulder land portion includes at least a plurality of inner shoulder lateral grooves extending inward in the tire axial direction from the inner tread end,
Each outer shoulder lateral groove has a first groove edge located in a first direction which is one side in the tire circumferential direction, and a second groove located in a second direction opposite to the first direction in the tire circumferential direction. The first groove edge and the second groove edge intersect the outer tread end at a first intersection and a second intersection, respectively,
Each of the inner shoulder lateral grooves has a third groove edge located in the first direction in the tire circumferential direction and a fourth groove edge located in the second direction in the tire circumferential direction, and the third groove edge and the first groove The four groove edges intersect with the inner tread end at the third intersection and the fourth intersection, respectively.
The first intersection and the second intersection are tires provided at different positions in the tire circumferential direction from the third intersection and the fourth intersection, respectively.   In the group of first to fourth intersections that are closest to each other in the tire circumferential direction, the tire circumference in the order of the first intersection, the second intersection, the third intersection, and the fourth intersection toward the second direction. The tire according to claim 1 arranged in a direction.   The distance L1 in the tire circumferential direction between the second intersection and the third intersection is greater than the groove width at the outer tread end of the outer shoulder lateral groove and the groove width at the inner tread end of the inner shoulder lateral groove. The tire according to claim 2, which is small.   The tire according to claim 3, wherein the distance L1 is 0.2 to 1.0 mm.   The tire according to any one of claims 1 to 4, wherein the outer shoulder lateral groove completely crosses the outer shoulder land portion.   The tire according to any one of claims 1 to 5, wherein an inner end of the inner shoulder lateral groove in the tire axial direction is located in the inner shoulder land portion. Each of the outer shoulder lateral grooves and the inner shoulder lateral grooves has an angle of less than 10 ° with respect to the tire axial direction,
The tire according to any one of claims 1 to 6, wherein a maximum angle of the inner shoulder lateral groove with respect to the tire axial direction is smaller than a maximum angle of the outer shoulder lateral groove with respect to the tire axial direction. The outer shoulder land portion is provided with an outer shoulder sipe,
The inner shoulder land is provided with an inner shoulder sipe,
The outer shoulder sipe and the inner shoulder sipe each have a shallow bottom portion and a deep bottom portion having a depth larger than the shallow bottom portion,
In the outer shoulder sipe, the shallow bottom portion is provided inside the deep bottom portion in the tire axial direction,
The tire according to any one of claims 1 to 7, wherein the inner shoulder sipe has the shallow bottom portion provided on the outer side in the tire axial direction of the deep bottom portion.

Images