JP2015051751A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire improved in steering stability performance while keeping wet performance.SOLUTION: A pneumatic tire is provided with a pair of shoulder main grooves 4 on a tread portion 2, thereby dividing a shoulder land part 10, and designating an installing direction to a vehicle. The pair of the shoulder main grooves 4 includes inside shoulder main grooves 4A. The inside shoulder main groove 4A has the minimum groove width of the main grooves. The shoulder land part 10 includes an inside shoulder land part 11. The inside shoulder land part 11 is provided with a plurality of inside shoulder lateral grooves 13. The inside shoulder lateral groove 13 includes an inside portion 14; and an outside portion 15 ranging to the tire axial direction outside of the inside portion 14, and tilting to a tire circumferential direction by a larger angle than the inside portion 14. The outside portion 15 has larger groove width than that of the inside portion 14.

Description

  The present invention relates to a pneumatic tire having improved steering stability performance while maintaining wet performance.

  There has been proposed a pneumatic tire in which a tread portion is provided with a main groove extending continuously in the tire circumferential direction and a lateral groove extending in the tire axial direction. Such a pneumatic tire exhibits excellent wet performance due to the main grooves and the lateral grooves. On the other hand, the main groove and the lateral groove decrease the rigidity of the tread portion and decrease the steering stability performance.

  For example, the following Patent Document 1 discloses the arrangement of ribs, the groove width of a main groove, the shape of a sipe, and the like for a pneumatic tire in which the mounting direction to a vehicle is specified in order to achieve both wet performance and steering stability performance. Propose to improve.

JP 2004-90752 A

  However, even the pneumatic tire disclosed in Patent Document 1 has room for further improvement in terms of both wet performance and steering stability performance.

  The present invention has been devised in view of the actual situation as described above, and maintains wet performance on the basis of improving the groove width of the main groove and the shape of the lateral groove arranged on the inner side of the vehicle when the vehicle is mounted. On the other hand, the main object is to provide a pneumatic tire with improved steering stability.

  The present invention relates to a pneumatic tire in which the direction of mounting on a vehicle is specified, and extends continuously to the tread portion in the tire circumferential direction on the most tread grounding end side, and is the inner side of the vehicle when mounted on the vehicle By providing the shoulder main groove, the inner shoulder land portion is divided on the outer side in the tire axial direction of the inner shoulder main groove, and the inner shoulder main groove extends continuously in the tire circumferential direction provided in the tread portion. The main groove has the smallest groove width, and the inner shoulder land portion has a plurality of inner shoulder lateral grooves extending in the tire axial direction, and the inner shoulder lateral grooves are inclined with respect to the tire circumferential direction. And an outer portion that is connected to the outer side in the tire axial direction of the inner portion and is inclined at an angle greater than the inner portion with respect to the tire circumferential direction. It is characterized by having a larger groove width than the inner portion.

  In the pneumatic tire according to the present invention, the inner shoulder lateral groove includes a first inner shoulder lateral groove extending from a tread ground end to the inner shoulder main groove, and extending inward in the tire axial direction from the tread ground end and the inner shoulder land. Preferably, the first inner shoulder lateral groove and the second inner shoulder lateral groove are alternately arranged in the tire circumferential direction.

  In the pneumatic tire according to the present invention, each inner shoulder lateral groove has a corner portion to which the inner portion and the outer portion are connected, and the corner portion of the first inner shoulder lateral groove is the first portion. 2 It is desirable to be provided on the outer side in the tire axial direction than the corner portion of the inner shoulder lateral groove.

  In the pneumatic tire according to the present invention, the length of the inner portion of the first inner shoulder lateral groove is the length from the inner end in the tire axial direction of the outer portion of the first inner shoulder lateral groove to the tread grounding end. Preferably, the length of the inner portion of the second inner shoulder lateral groove is smaller than the length from the inner end in the tire axial direction of the second inner shoulder lateral groove to the tread ground contact end. .

  In the pneumatic tire according to the present invention, it is preferable that the inner shoulder land portion is provided with a vertical sipe extending in the tire circumferential direction by connecting the inner portions adjacent in the tire circumferential direction.

  In the pneumatic tire according to the present invention, it is preferable that the groove width of the outer portion gradually decreases toward the outer side in the tire axial direction.

  The shoulder main groove of the pneumatic tire of the present invention includes an inner shoulder main groove disposed on the vehicle inner side when the vehicle is mounted. The inner shoulder main groove has the smallest groove width among the main grooves continuously extending in the tire circumferential direction provided in the tread portion. In general, when a tire is mounted on a vehicle with a negative camber, a large ground pressure acts on the inner shoulder main groove, but with the above configuration, a large rubber volume is given to the land portion inside the vehicle, and the land portion Stiffness is improved. For this reason, excellent steering stability performance is exhibited.

  The shoulder land portion of the pneumatic tire of the present invention includes an inner shoulder land portion that is disposed on the vehicle inner side when the vehicle is mounted. A plurality of inner shoulder lateral grooves extending in the tire axial direction are provided in the inner shoulder land portion. The inner shoulder lateral groove discharges water between the inner shoulder land portion and the road surface to the outer side in the tire axial direction during wet traveling. For this reason, wet performance improves.

  The inner shoulder lateral groove has an inner portion that is inclined with respect to the tire circumferential direction and an outer portion that is continuous with the outer side in the tire axial direction of the inner portion and is inclined at an angle greater than the inner portion with respect to the tire circumferential direction. Part. Such an inner shoulder lateral groove effectively discharges water in the inner portion to the outer side in the tire axial direction during wet running. Moreover, the inner shoulder lateral grooves make the tire circumferential rigidity on the tire equator side of the inner shoulder land portion larger than the rigidity on the tread ground contact end side. Since a larger ground pressure acts on the tire equator side of the inner shoulder land portion than on the tread ground end side, the inner shoulder land portion as described above can effectively improve the steering stability performance. .

  The outer part has a larger groove width than the inner part. Therefore, the outer portion discharges water between the inner shoulder land portion and the road surface to the outer side in the tire axial direction more effectively during wet traveling. For this reason, wet performance is maintained. Moreover, the inner shoulder lateral groove gives a large rubber volume to the inner side in the tire axial direction of the inner shoulder land portion. For this reason, the rigidity inside the tire axial direction of the inner shoulder land portion is improved, and excellent steering stability performance is exhibited.

  As described above, the pneumatic tire of the present invention can improve the steering stability performance while maintaining the wet performance.

It is an expanded view of the tread part of the pneumatic tire of this embodiment. It is AA sectional drawing of FIG. It is an enlarged view of the inner side shoulder land part of FIG. It is an enlarged view of the outer side shoulder land part of FIG. It is an enlarged view of the inner middle land part of FIG. It is an enlarged view of the outer middle land part of FIG. It is an enlarged view of the center land part of FIG.

  As shown in FIG. 1, a pneumatic tire (hereinafter, simply referred to as “tire”) 1 of the present embodiment is a pneumatic tire in which the direction of mounting on a vehicle is specified. In FIG. 1, when the tire 1 is mounted on a vehicle, the left side is the vehicle outer side and the right side is the vehicle inner side. The tire of the present embodiment is asymmetric at the tire equator C. The tire 1 of this embodiment is suitably used as a radial tire for passenger cars, for example.

  The tread portion 2 of the tire 1 is provided with a pair of center main grooves 3 and a pair of shoulder main grooves 4.

  The tread portion 2 is a region between the outer tread grounding end Te1 positioned on the vehicle outer side and the inner tread grounding end Te2 when the vehicle is mounted. The tread grounding ends Te1 and Te2 mean positions on the outermost side in the tire axial direction when a normal load is loaded on a normal tire and grounded on a plane with a camber angle of 0 degrees.

  The “normal state” is a no-load state in which the tire 1 is assembled to a normal rim (not shown) and filled with a normal internal pressure. In the present specification, unless otherwise specified, the dimension of each part of the tire 1 is a value measured in a normal state.

  The “regular rim” is a rim defined 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, For ETRTO, "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. In the normal state, the distance in the tire axial direction between the tread ground contact ends Te1 and Te2 is the tread ground contact width.

  The center main groove 3 is provided on both sides of the tire equator C. The center main groove 3 extends continuously in the tire circumferential direction. The center main groove 3 has a substantially constant groove width W1. The groove width W1 of the center main groove 3 is, for example, 5 to 7% of the tread ground contact width TW. The center main groove 3 includes an inner center main groove 3A disposed on the vehicle inner side when the vehicle is mounted and an outer center main groove 3B disposed on the outer side of the vehicle when the vehicle is mounted. In the present embodiment, the inner center main groove 3A and the outer center main groove 3B have the same groove width.

  As shown in FIG. 1, the shoulder main groove 4 continuously extends in the tire circumferential direction on both sides of the tire equator C and on the tread ground contact ends Te1 and Te2 side. The shoulder main groove 4 includes an inner shoulder main groove 4A disposed on the vehicle inner side and an outer shoulder main groove 4B disposed on the vehicle outer side when the vehicle is mounted. Each shoulder main groove 4A, 4B of this embodiment has a substantially constant groove width and is linear.

  The groove width W2 of the inner shoulder main groove 4A is, for example, 4 to 6% of the tread ground contact width TW. Such an inner shoulder main groove 4 </ b> A improves wet performance while suppressing a decrease in rigidity of the tread portion 2.

  The groove width W2 of the inner shoulder main groove 4A is the smallest among the main grooves provided in the tread portion 2 and continuously extending in the tire circumferential direction. That is, the groove width W2 of the inner shoulder main groove 4A is smaller than the groove width W1 of the center main groove 3 and the groove width W3 of the outer shoulder main groove 4B. In the present specification, the “main groove” means a groove extending continuously in the tire circumferential direction and having a groove width of 3% or more of the tread ground contact width TW. In general, when the tire is attached to the vehicle with a negative camber, a large ground pressure acts around the inner shoulder main groove 4A, but the above configuration gives a large rubber volume to the land portion inside the vehicle, The rigidity of the land is improved. For this reason, excellent steering stability performance is exhibited.

  The groove width W3 of the outer shoulder main groove 4B is, for example, 6 to 8% of the tread ground contact width TW. It is desirable that the groove width W3 of the outer shoulder main groove 4B is larger than the groove width W1 of the center main groove 3. The groove width W3 of the outer shoulder main groove 4B is preferably 1.2 times or more, more preferably 1.3 times or more, and preferably 1.4 times or less of the groove width W1 of the center main groove 3. Such an outer shoulder main groove 4B exhibits excellent drainage performance while maintaining the rigidity of the tread portion 2. Therefore, the wet performance is improved while maintaining the steering stability performance.

  The ratio W2 / W3 between the groove width W2 of the inner shoulder main groove 4A and the groove width W3 of the outer shoulder main groove 4B is preferably 0.65 or more, more preferably 0.70 or more, and preferably 0.80 or less. More preferably, it is 0.75 or less. When the ratio W2 / W3 is smaller than 0.65, the tread portion 2 may be unevenly worn. Conversely, if the ratio W2 / W3 is greater than 0.80, the steering stability performance may be reduced.

  FIG. 2 is a cross-sectional view taken along the line AA in FIG. As shown in FIG. 2, the groove depth d1 of the center main groove 3 and the groove depth d2 of the shoulder main groove 4 are preferably 5 to 10 mm in the case of a passenger car tire, for example. The center main groove 3 and the shoulder main groove 4 exhibit excellent wet performance while maintaining the rigidity of the tread portion 2.

  The groove wall surface 5 of the outer shoulder main groove 4 </ b> B of the present embodiment includes, for example, a gentle slope portion 6. The gentle slope portion 6 of the present embodiment is a curved surface that is recessed in a circular arc shape having a center outside the tire. As a result, the outer shoulder main groove 4B has a large groove volume and exhibits excellent wet performance.

  As shown in FIG. 1, by providing the center main groove 3 and the shoulder main groove 4 in the tread portion 2, a pair of shoulder land portions 10, a pair of middle land portions 30, and a center land portion 50 are provided. It is divided.

  Each shoulder land portion 10 is formed on the outer side in the tire axial direction of the shoulder main groove 4, and includes an inner shoulder land portion 11 and an outer shoulder land portion 12. The inner shoulder land portion 11 is divided between the inner shoulder main groove 4A and the tread ground contact Te2. It is divided between the outer shoulder main groove 4B and the tread ground contact end Te1.

  FIG. 3 shows an enlarged view of the inner shoulder land portion 11. As shown in FIG. 3, the inner shoulder land portion 11 has a substantially constant width W4. W4 of the inner shoulder land portion 11 is preferably not less than 0.16 times, more preferably not less than 0.18 times, preferably not less than 0.18 times the tread ground contact width TW (shown in FIG. 1 and the same shall apply hereinafter). 24 times or less, More preferably, it is 0.22 times or less. Such an inner shoulder land portion 11 achieves both wet performance and steering stability performance.

  The inner shoulder land portion 11 is provided with a plurality of inner shoulder lateral grooves 13. The inner shoulder lateral groove 13 includes an inner portion 14 provided on the inner side in the tire axial direction and an outer portion 15 provided on the outer side in the tire axial direction.

  The inner part 14 extends linearly, for example. The inner portion 14 is inclined at an angle θ1 of, for example, 35 to 65 ° with respect to the tire circumferential direction. The angle θ1 is preferably 40 ° or more, more preferably 45 ° or more, preferably 60 ° or less, more preferably 55 ° or less. Such an inner portion 14 increases the rigidity of the land portion in the tire circumferential direction as compared with a case where a groove substantially parallel to the tire axial direction is provided. For this reason, steering stability performance improves.

  The inner part 14 has, for example, a substantially constant groove width W5. The groove width W5 of the inner portion 14 is preferably 0.20 times or more, more preferably 0.25 times or more, preferably 0.35 times or less, more preferably, the groove width W2 of the inner shoulder main groove 4A. Is 0.30 times or less. Thereby, wet performance and steering stability performance are compatible.

  The outer portion 15 extends linearly, for example. The outer portion 15 is continuous to the outer side in the tire axial direction of the inner portion 14. The outer portion 15 preferably extends at least to the tread grounding end Te2. The outer portion 15 of the present embodiment extends outward in the tire axial direction beyond the tread ground contact Te2.

  The outer portion 15 is inclined at an angle θ2 larger than the inner portion 14 with respect to the tire circumferential direction. The inner shoulder lateral groove 13 including the inner portion 14 and the outer portion 15 effectively discharges water in the inner portion 14 to the outer side in the tire axial direction during wet running. Moreover, the inner portion 14 and the outer portion 15 make the rigidity in the tire circumferential direction on the tire equator C side of the inner shoulder land portion 11 larger than the rigidity on the tread ground contact end Te2 side. Since a larger ground pressure acts on the tire equator C side of the inner shoulder land portion 11 than on the tread ground end Te2 side, the inner shoulder land portion 11 as described above effectively improves the steering stability performance. Can be made.

  The angle θ2 of the outer portion 15 with respect to the tire circumferential direction is preferably 80 ° or more, more preferably 83 ° or more, preferably 90 ° or less, and more preferably 87 ° or less. Such an outer portion 15 increases the rigidity in the tire axial direction of the land portion near the tread ground contact Te2. Therefore, for example, the steering stability performance during a sudden turn is improved.

  The outer portion 15 has a larger groove width W6 than the inner portion 14. Therefore, the outer side part 15 discharges | emits the water between the inner side shoulder land part 11 and a road surface more effectively to a tire axial direction outer side at the time of wet driving | running | working. For this reason, wet performance is maintained. Moreover, the outer portion 15 and the inner portion 14 give a large rubber volume to the inner side in the tire axial direction of the inner shoulder land portion 11. For this reason, the rigidity on the inner side in the tire axial direction of the inner shoulder land portion 11 is improved, and excellent steering stability performance is exhibited.

  The ratio W5 / W6 between the groove width W5 of the inner part 14 and the groove width W6 of the outer part 15 is preferably 0.55 or more, more preferably 0.60 or more, preferably 0.75 or less, more preferably 0.70 or less. Thereby, the partial wear of the inner side shoulder land part 11 is suppressed.

  It is desirable that the groove width W6 of the outer portion 15 gradually decreases toward the outer side in the tire axial direction. Thereby, the rubber | gum chipping etc. which started from the tread grounding edge Te2 vicinity of the inner side shoulder land part 11 are suppressed, improving steering stability performance.

  The inner shoulder lateral groove 13 includes a first inner shoulder lateral groove 16 and a second inner shoulder lateral groove 17. The first inner shoulder lateral groove 16 extends at least from the tread grounding end Te2 to the inner shoulder main groove 4A. The second inner shoulder lateral groove 17 extends at least inward in the tire axial direction from the tread grounding end Te2 and terminates in the inner shoulder land portion 11 without communicating with the inner shoulder main groove 4A. The first inner shoulder lateral grooves 16 and the second inner shoulder lateral grooves 17 are alternately arranged in the tire circumferential direction. Thereby, the rigidity of the inner side shoulder land portion 11 on the inner side in the tire axial direction is increased, and excellent steering stability performance is exhibited.

  The length L1 of the inner portion 14 of the first inner shoulder lateral groove 16 is preferably larger than the length L2 from the inner end 15e in the tire axial direction of the outer portion 15 of the first inner shoulder lateral groove 16 to the tread ground contact end Te2. . The ratio L1 / L2 between the length L1 and the length L2 is preferably 1.8 or more, more preferably 1.85 or more, preferably 2.0 or less, more preferably 1.95 or less. . Thereby, the length of the inner side part 14 connected to 4 A of inner side shoulder main grooves is ensured, and the outstanding wet performance is exhibited.

  The length L3 of the inner portion 14 of the second inner shoulder lateral groove 17 is preferably smaller than the length L4 from the inner end 15e in the tire axial direction of the outer portion 15 of the second inner shoulder lateral groove 17 to the tread ground contact end Te2. . The ratio L3 / L4 between the length L3 and the length L4 is preferably 0.80 or more, more preferably 0.85 or more, preferably 0.95 or less, more preferably 0.90 or less. . Thereby, the rigidity of the inner side in the tire axial direction of the inner shoulder land portion 11 is increased while maintaining the wet performance, and excellent steering stability performance is exhibited.

  The inner shoulder lateral groove 13 has a corner portion 18 to which the inner portion 14 and the outer portion 15 are connected. The corner portion 18 of this embodiment is formed by sharp bending of the inner shoulder lateral groove 13. The corner portion 18 may be formed in, for example, an arc shape that smoothly curves.

  It is desirable that the corner portions 18 adjacent in the tire circumferential direction are displaced from each other in the tire axial direction. In the present embodiment, the corner portion 18 a of the first inner shoulder lateral groove 16 is provided on the outer side in the tire axial direction than the corner portion 18 b of the second inner shoulder lateral groove 17. Thereby, since each corner part 18 does not align in a linear form, the local deformation | transformation of the inner side shoulder land part 11 is suppressed. Therefore, excellent steering stability performance and wear resistance performance are exhibited.

  A vertical sipe 19 is provided in the inner shoulder land portion 11 of the present embodiment. The longitudinal sipe 19 extends in the tire circumferential direction by connecting adjacent inner portions 14 in the tire circumferential direction. Such a longitudinal sipe 19 improves wet performance while maintaining the rigidity of the inner shoulder land portion 11 in the tire circumferential direction. In this specification, “sipe” means a cut having a width of 0.5 to 1.5 mm.

  FIG. 4 shows an enlarged view of the outer shoulder land portion 12. As shown in FIG. 4, the outer shoulder land portion 12 has a substantially constant width W7. The width W7 of the outer shoulder land portion 12 in the tire axial direction is preferably 0.18 times or more, more preferably 0.20 times or more, preferably 0.24 times or less, more preferably 0, of the tread ground contact width TW. .22 times or less. Thereby, wet performance and steering stability performance are compatible.

  The outer shoulder land portion 12 is provided with an outer shoulder sipe 27. For example, the outer shoulder sipe 27 extends continuously in the tire circumferential direction. The outer shoulder sipe 27 of the present embodiment is linear.

  The outer shoulder land portion 12 is divided into a first outer shoulder land portion 21 and a second outer shoulder land portion 22 by an outer shoulder sipe 27. The first outer shoulder land portion 21 is provided on the inner side in the tire axial direction. The second outer shoulder land portion 22 is provided on the outer side in the tire axial direction.

  The first outer shoulder land portion 21 is a rib that extends continuously in the tire circumferential direction. The 1st outer side shoulder land part 21 of this embodiment is a plain rib in which a groove | channel and a sipe are not provided at all. Such a 1st outer side shoulder land part 21 improves the rigidity of the tire circumferential direction of the outer side shoulder land part 12, and improves steering stability performance.

  The width W8 in the tire axial direction of the first outer shoulder land portion 21 is preferably 0.25 times or more, more preferably 0.30 times or more, preferably 0.40 times the width W7 of the outer shoulder land portion 12. Hereinafter, it is more preferably 0.35 times or less. As a result, the steering stability performance and the ride comfort performance are improved in a well-balanced manner.

  The second outer shoulder land portion 22 is provided with an outer shoulder lateral groove 23 extending in the tire axial direction. The outer shoulder lateral groove 23 includes a first outer shoulder lateral groove 24 and a second outer shoulder lateral groove 25. The first outer shoulder lateral groove 24 extends at least from the tread grounding end Te1 to the outer shoulder sipe 27. The second outer shoulder lateral groove 25 extends at least from the tread ground contact end Te <b> 1 toward the inner side in the tire axial direction and terminates in the outer shoulder land portion 12. The first outer shoulder lateral groove 24 and the second outer shoulder lateral groove 25 improve the wet performance while maintaining the rigidity of the outer shoulder land portion 12.

  As shown in FIG. 1, each middle land portion 30 is provided between the center main groove 3 and the shoulder main groove 4. The middle land portion 30 includes an inner middle land portion 31 and an outer middle land portion 32. The inner middle land portion 31 is divided between the inner center main groove 3A and the inner shoulder main groove 4A. The outer middle land portion 32 is divided between the outer center main groove 3B and the outer shoulder main groove 4B.

  FIG. 5 shows an enlarged view of the inner middle land portion 31. As shown in FIG. 5, the inner middle land portion 31 has a substantially constant width W9.

  The width W9 of the inner middle land portion 31 in the tire axial direction is preferably 0.11 times or more, more preferably 0.13 times or more, preferably 0.17 times or less, more preferably 0, of the tread ground contact width TW. .15 times or less. Such an inner middle land portion 31 achieves both wet performance and steering stability performance.

  In the inner middle land portion 31, for example, a first middle lug groove 33, a second middle lug groove 34, and a middle sipe 35 are provided. The first middle lug groove 33 extends outward from the center main groove 3 in the tire axial direction and terminates in the inner middle land portion 31. The second middle lug groove 34 extends inward in the tire axial direction from the shoulder main groove 4 and terminates in the inner middle land portion 31. The first middle lug grooves 33 and the second middle lug grooves 34 are alternately provided in the tire circumferential direction. The middle sipe 35 communicates with the first middle lug groove 33.

  The first middle lug groove 33 is inclined with respect to the tire circumferential direction, for example. The first middle lug groove 33 has a substantially constant groove width W10. The groove width W10 of the first middle lug groove 33 is, for example, 0.33 to 0.42 times the groove width W1 of the center main groove 3.

  The second middle lug groove 34 is linear. The second middle lug groove 34 is inclined in the same direction as the first middle lug groove 33 with respect to the tire circumferential direction. The second middle lug groove 34 includes an outer groove portion 37 and a central groove portion 38. The outer groove portion 37 communicates with the shoulder main groove 4. The central groove portion 38 is continuous with the inner side of the outer groove portion 37 in the tire axial direction. The central groove portion 38 has a groove width smaller than that of the outer groove portion 37. Accordingly, the second middle lug groove 34 improves the wet performance while maintaining the rigidity of the inner middle land portion 31.

  The middle sipe 35 extends from the outer end 33 o of the first middle lug groove 33 in the tire axial direction to the shoulder main groove 4. The middle sipe 35 is inclined in the same direction as the first middle lug groove 33 with respect to the tire circumferential direction. In the present embodiment, the middle sipe 35 is inclined at the same angle as the first middle lug groove 33 with respect to the tire circumferential direction. Such a middle sipe 35 improves wet performance while suppressing uneven wear of the inner middle land portion 31.

  FIG. 6 shows an enlarged view of the outer middle land portion 32. As shown in FIG. 6, the outer middle land portion 32 has a substantially constant width. The width W12 in the tire axial direction of the outer middle land portion 32 is preferably 0.09 to 0.13 times the tread ground contact width TW. Such an outer middle land portion 32 exhibits excellent steering stability performance while maintaining wet performance.

  An outer middle sipe 41 is provided in the outer middle land portion 32. The outer middle sipe 41 extends from the center main groove 3 to the shoulder main groove 4. Such an outer middle sipe 41 improves the wet performance while maintaining the rigidity of the outer middle land portion 32.

  The outer middle sipe 41 includes a first inclined portion 42 that is inclined with respect to the tire axial direction, and a second inclined portion 43 that is inclined in a direction opposite to the first inclined portion 42. Thereby, the edge effect is exhibited in multiple directions, and the wet performance is improved.

  FIG. 7 shows an enlarged view of the center land portion 50. As shown in FIG. 7, the center land portion 50 is provided between the pair of center main grooves 3. The center land portion 50 has a substantially constant width W14. The width W14 of the center land portion 50 is, for example, 0.10 to 0.15 times the tread ground contact width TW.

  The center land portion 50 is a block row in which center blocks 52 divided by center lateral grooves 51 are arranged in the tire circumferential direction.

  The center lateral groove 51 communicates with the pair of center main grooves 3 at both ends. The center lateral groove 51 is inclined with respect to the tire axial direction and extends linearly. The center lateral groove 51 has a substantially constant groove width W15. The groove width W15 of the center lateral groove is, for example, 0.30 to 40 times the groove width W1 of the center main groove 3.

  The center block 52 is formed in, for example, a substantially parallelogram shape. For example, a center lug groove 53 is provided in the center block 52. The center lug groove 53 has one end 53o communicating with the inner center main groove 3A and the other end 53i terminating in the center land portion 50. Such a center lug groove 53 improves drainage performance while maintaining the rigidity of the center land portion 50. For this reason, wet performance and steering stability performance are improved in a well-balanced manner.

  As mentioned above, although the pneumatic tire of this invention was demonstrated in detail, it cannot be overemphasized that this invention can be changed into various aspects, without being limited to said specific embodiment.

A pneumatic tire of size 215 / 60R17 having the basic pattern of FIG. The common specifications and test methods for each tire are as follows.
Wearing rim: 17 × 6.5J
Tire internal pressure: 240kPa
Test vehicle: 4-wheel drive vehicle, displacement 2400cc
Tire mounting position: all wheels

<Wet performance>
The test vehicle is entered while gradually increasing the speed to the following test course, the lateral acceleration (lateral G) of the front wheels of the test vehicle is measured, and the average lateral G of the front wheels at a speed of 55 to 80 km / h is calculated. It was done. The results are displayed as an index with Example 1 as 100. It shows that it is excellent in wet performance, so that a numerical value is large.
Test course: Circulation course with a radius of 100 m Road surface: A water pool with a depth of 6 mm and a length of 6 m is installed on the asphalt road surface

<Steering stability>
Steering performance was evaluated by the driver's sensory evaluation when the test vehicle circulated on the asphalt test course. A result is a score which sets Example 1 to 100, and shows that it is excellent in steering stability performance, so that a numerical value is large.
The test results are shown in Table 1.

  As a result of the test, it was confirmed that the pneumatic tire of the example had improved steering stability performance while maintaining wet performance.

2 Tread part 4 Shoulder main groove 4A Inner shoulder main groove 10 Shoulder land part
11 Inner shoulder land portion 13 Inner shoulder lateral groove 14 Inner portion 15 Outer portion

Claims (6)

A pneumatic tire with a specified orientation for mounting on a vehicle,
An inner shoulder main groove that extends continuously in the tire circumferential direction on the tread ground end side and that is on the inner side of the vehicle when mounted on the vehicle is provided on the tread portion so that the inner shoulder main groove is on the inner side in the tire axial direction. Shoulder land is divided,
The inner shoulder main groove has the smallest groove width among the main grooves continuously extending in the tire circumferential direction provided in the tread portion,
The inner shoulder land portion is provided with a plurality of inner shoulder lateral grooves extending in the tire axial direction,
The inner shoulder lateral groove is connected to the inner side inclined with respect to the tire circumferential direction and the outer side in the tire axial direction of the inner side, and is inclined with respect to the tire circumferential direction at a larger angle than the inner side part. And including an outer portion,
The pneumatic tire according to claim 1, wherein the outer portion has a larger groove width than the inner portion. The inner shoulder lateral groove includes a first inner shoulder lateral groove extending from the tread ground end to the inner shoulder main groove, and a second inner shoulder lateral groove extending inward in the tire axial direction from the tread ground end and terminating in the inner shoulder land portion. Including
The pneumatic tire according to claim 1, wherein the first inner shoulder lateral grooves and the second inner shoulder lateral grooves are alternately arranged in the tire circumferential direction. Each inner shoulder lateral groove has a corner portion to which the inner portion and the outer portion are connected,
The pneumatic tire according to claim 2, wherein the corner portion of the first inner shoulder lateral groove is provided on the outer side in the tire axial direction than the corner portion of the second inner shoulder lateral groove. The length of the inner side portion of the first inner shoulder lateral groove is larger than the length from the inner end in the tire axial direction of the outer side portion of the first inner shoulder lateral groove to the tread grounding end,
The length of the said inner part of the said 2nd inner side shoulder horizontal groove is smaller than the length from the inner end of the tire axial direction of the said outer side part of the said 2nd inner side shoulder horizontal groove to the said tread grounding end. Pneumatic tire.   The pneumatic tire according to claim 1, wherein the inner shoulder land portion is provided with a vertical sipe extending in the tire circumferential direction by connecting the inner portions adjacent in the tire circumferential direction.   The pneumatic tire according to any one of claims 1 to 5, wherein the groove width of the outer portion is gradually reduced toward the outer side in the tire axial direction.

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