tire

Abstract

To provide a tire configured so that a tread rubber can be warmed earlier by running, while maintaining steering stability on a dry road surface.SOLUTION: A tire comprises a tread part 2 whose mounting direction on a vehicle is designated. An inner shoulder land part 6 is provided with a plurality of first inner shoulder lateral grooves 10 and a plurality of second inner shoulder lateral grooves 15. Each of the plurality of first inner shoulder lateral grooves 10 has a first terminating end 10a. A groove width of each of the plurality of first inner shoulder lateral grooves 10 gradually reduces from an inner circumferential groove 5 toward the first terminating end. Each of the plurality of second inner shoulder lateral grooves 15 has a second terminating end 15a. A groove width of each of the plurality of second inner shoulder lateral grooves 15 gradually reduces at least from a first inner grounding end T1i toward the second terminating end 15a.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a tire. [Background Art]

[0002] Conventionally, various tires that can travel on public roads and exhibit excellent performance during high-load traveling on circuits or the like have been proposed (see, for example, Patent Document 1 below). In the tire, by specifying grooves provided in a tread portion, excessive reduction in rigidity of a land portion is suppressed, and dry grip performance is maintained. [Prior Art Literature] [Patent Literature]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2018-167717 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] Generally, for a tire to sufficiently exert grip performance and steering stability, it is necessary for the tread rubber to generate heat up to an appropriate temperature. However, in the tire of Patent Document 1, since the rigidity of the tread portion is high, it takes a long time from the start of traveling for the tread rubber to reach an appropriate temperature, and consequently, there is room for further improvement in reducing lap time.

[0005] The present invention has been devised in view of the above actual situation, and a main object thereof is to provide a tire capable of quickly warming tread rubber by traveling while maintaining steering stability on a dry road surface. [Means for Solving the Problem]

[0006] The present invention relates to a tire having a tread portion whose orientation for mounting on a vehicle is specified, wherein the tread portion includes a tire equator, an outer tread portion located outside the vehicle beyond the tire equator when mounted on a vehicle, and an inner tread portion located inside the vehicle beyond the tire equator when mounted on a vehicle, wherein the outer tread portion is provided with only one outer circumferential groove as a circumferential groove extending continuously in the circumferential direction of the tire, and the inner tread portion is provided with only one inner circumferential groove as the circumferential groove, wherein the inner tread portion has an inner shoulder land portion on the tire axial side of the inner circumferential groove, wherein the inner shoulder land portion includes a first inner contact end which is the contact end when 70% of the normal load is applied, and a second inner contact end which is the contact end when 130% of the normal load is applied, and the second inner The tire is such that the contact end is located outward in the tire axial direction from the first inner contact end, the inner shoulder land portion is provided with a plurality of first inner shoulder lateral grooves extending outward in the tire axial direction from the inner circumferential groove, and a plurality of second inner shoulder lateral grooves crossing the first inner contact end, each of the plurality of first inner shoulder lateral grooves has a first interrupted end that ends before the second inner contact end, the groove width of each of the plurality of first inner shoulder lateral grooves decreases from the inner circumferential groove toward the first interrupted end, each of the plurality of second inner shoulder lateral grooves has a second interrupted end between the inner circumferential groove and the first inner contact end, and the groove width of each of the plurality of second inner shoulder lateral grooves decreases at least from the first inner contact end toward the second interrupted end. [Effects of the Invention]

[0007] By adopting the above-described configuration, the tire of the present invention can maintain handling stability on dry surfaces while quickly warming up the tread rubber during driving. Therefore, the tire of the present invention is useful in shortening driving times in circuit driving and the like. [Brief explanation of the drawing]

[0008] [Figure 1]This is an exploded view of the tire tread portion of one embodiment of the present invention. [Figure 2] This is a meridian cross-sectional view of the tread area in Figure 1. [Figure 3] This is an enlarged view of the inner shoulder land area of ​​Figure 1. [Figure 4] Figure 3 is an enlarged view of the first medial shoulder transverse groove. [Figure 5] Figure 3 is an enlarged view of the second medial shoulder transverse groove. [Figure 6] This is a cross-sectional view along line AA in Figure 3. [Figure 7] Figure 3 is a cross-sectional view along line BB. [Figure 8] Figure 3 is a cross-sectional view along the CC line. [Figure 9] This is an enlarged view of the outer shoulder land area of ​​Figure 1. [Figure 10] Figure 9 is an enlarged view of the first lateral shoulder transverse groove. [Figure 11] Figure 9 is an enlarged view of the second lateral shoulder transverse groove. [Figure 12] This is a magnified view of the Crown's track and field area. [Figure 13] This is an enlarged view of the inner circumferential groove, the first inner shoulder transverse groove, and the first inner crown transverse groove. [Figure 14] This is an enlarged view of the outer circumferential groove, the first outer shoulder transverse groove, and the outer crown transverse groove. [Modes for carrying out the invention]

[0009] Hereinafter, one embodiment of the present invention will be described with reference to the drawings. Figure 1 is an unfolded view of the tread portion 2 of a tire 1 showing one embodiment of the present invention. Figure 2 is a meridian cross-sectional view of the tread portion 2 of this embodiment including the axis of rotation of the tire 1. In each figure showing a plan view of the grooves in this specification, the grooves are marked with dots. As shown in Figures 1 and 2, the tire 1 of this embodiment is used, for example, as a pneumatic tire for a passenger car, and is particularly suitable for use as a high-performance tire intended for use on circuits and the like. For this reason, the tire 1 of this embodiment is required to exhibit minimum drainage performance when driving on public roads, while exhibiting excellent driving performance when driving under high load on circuits and the like. "During high load driving" means, for example, driving conditions that can shorten the lap time on a circuit as much as possible.

[0010] The tire 1 of the present invention has a specified orientation for mounting on a vehicle. In Figures 1 and 2, when the tire 1 is mounted on a vehicle, the left side faces the outside of the vehicle and the right side faces the inside of the vehicle.

[0011] As shown in Figure 1, the tread portion 2 of tire 1 includes a tire equator C, an outer tread portion 2B located outside the vehicle beyond the tire equator C when mounted on a vehicle, and an inner tread portion 2A located inside the vehicle beyond the tire equator C when mounted on a vehicle. The tread portion 2 also includes a first outer contact end T1o and a first inner contact end T1i, which correspond to the edges of the contact surface during normal driving, and a second outer contact end T2o and a second inner contact end T2i, which correspond to the edges of the contact surface during high-load driving. The second outer contact end T2o is located outside the tire axial direction of the first outer contact end T1o. The second inner contact end T2i is located outside the tire axial direction of the first inner contact end T1i.

[0012] The first outer contact end T1o and the first inner contact end T1i correspond to the edges of the contact surface when 70% of the normal load is applied to the tire 1 in its normal state and the tread portion 2 is in contact with a flat surface at a camber angle of 0°.

[0013] The "normal state" refers to, in the case of a pneumatic tire with various established standards, a state where the tire is assembled on a standard rim, filled with standard internal pressure, and is under no load. For tires for which no various standards are established, the aforementioned normal state means a standard use state corresponding to the intended use purpose of the tire and being in an unloaded state. In the present specification, unless otherwise specified, the dimensions and the like of each part of the tire are values measured in the aforementioned normal state.

[0014] "Standard rim" is a rim that is specified for each tire by the relevant standard in the standard system including the standard on which the tire is based. For example, it is "standard rim" for JATMA, "Design Rim" for TRA, and "Measuring Rim" for ETRTO.

[0015] "Standard internal pressure" is the air pressure that is specified for each tire by the relevant standard in the standard system including the standard on which the tire is based. It is "maximum air pressure" for JATMA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and "INFLATION PRESSURE" for ETRTO.

[0016] "Standard load" refers to, in the case of a pneumatic tire with various established standards, the load that is specified for each tire by the relevant standard in the standard system including the standard on which the tire is based. It is "maximum load capacity" for JATMA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and "LOAD CAPACITY" for ETRTO. In addition, for tires for which no various standards are established, "standard load" refers to the maximum load applicable when using the tire in accordance with the aforementioned standards.

[0017] The second outer ground contact edge T2o and the second inner ground contact edge T2i respectively correspond to the edges of the ground contact surface when a load of 130% of the standard load is applied to the tire 1 in the normal state, and the tread portion 2 is brought into contact with a flat surface at a camber angle of 0°.

[0018] The outer tread portion 2B is provided with only one outer circumferential groove 4, which is a circumferential groove 3 that extends continuously in the circumferential direction of the tire. The inner tread portion 2A is provided with only one inner circumferential groove 5, which is a circumferential groove 3. These circumferential grooves 3 extend in a straight line parallel to the circumferential direction of the tire. Each circumferential groove 3 may also extend in a zigzag or wavy pattern in the circumferential direction of the tire.

[0019] To ensure minimum drainage performance during road driving, the groove width W1 of the circumferential groove 3 is, for example, 3.0 mm or more, preferably 8.0 to 15.0 mm. Furthermore, to improve handling stability on dry surfaces while ensuring wet performance, the groove width W1 of the circumferential groove 3 is 3% to 7% of the tread contact width TW. The tread contact width TW corresponds to the distance in the tire axial direction from the first outer contact end T1o to the first inner contact end T1i in the normal state. The depth of the circumferential groove 3 is, for example, 5 to 10 mm.

[0020] In this specification, unless otherwise specified, "groove width" corresponds to the distance between two groove edges in a direction perpendicular to the groove centerline. Furthermore, the groove edge is the boundary between the groove opening and the plane when 70% of the normal load is applied to the tire 1 in a normal state and the tread portion 2 is in contact with a plane at a camber angle of 0°.

[0021] In this embodiment, the axial distance L1 from the groove centerline of the inner circumferential groove 5 to the tire equator C is preferably 45% to 75% of the tread half width TWh. The axial distance L2 from the groove centerline of the outer circumferential groove 4 to the tire equator C is preferably 5% to 35% of the tread half width TWh. This ensures wet performance while improving driving performance under high load. The tread half width TWh corresponds to the axial distance from the tire equator C to the first inner contact end T1i, or the axial distance from the tire equator C to the first outer contact end T1o.

[0022] The inner tread portion 2A includes an inner shoulder portion 6 located on the tire axial side of the inner circumferential groove 5. The inner shoulder portion 6 includes the first inner contact end T1i and the second inner contact end T2i described above. The outer tread portion 2B includes an outer shoulder portion 7 located on the tire axial side of the outer circumferential groove 4. The outer shoulder portion 7 includes the first outer contact end T1o and the second outer contact end T2o described above.

[0023] Figure 3 shows an enlarged view of the inner shoulder land portion 6. As shown in Figure 3, the inner shoulder land portion 6 is provided with a plurality of first inner shoulder lateral grooves 10 and a plurality of second inner shoulder lateral grooves 15. The first inner shoulder lateral grooves 10 extend outward in the tire axial direction from the inner circumferential groove 5. The second inner shoulder lateral grooves 15 cross the first inner contact end T1i.

[0024] Each of the multiple first inner shoulder lateral grooves 10 has a first interrupted end 10a that ends before the second inner contact end T2i. Furthermore, the groove width of each of the multiple first inner shoulder lateral grooves 10 decreases from the inner circumferential groove 5 toward the first interrupted end 10a. Each of the multiple second inner shoulder lateral grooves 15 has a second interrupted end 15a between the inner circumferential groove 5 and the first inner contact end T1i. The groove width of each of the multiple second inner shoulder lateral grooves 15 decreases at least from the first inner contact end T1i toward the second interrupted end 15a. By adopting the above configuration, the tire 1 of the present invention can warm up the tread rubber quickly through driving while maintaining handling stability on dry surfaces (hereinafter sometimes simply referred to as "handling stability"). The reason for this is as follows.

[0025] In this invention, the outer tread portion 2B is provided with only one outer circumferential groove 4 as a circumferential groove 3 that extends continuously in the circumferential direction of the tire, and the inner tread portion 2A is provided with only one inner circumferential groove 5 as the circumferential groove 3. As a result, the tire 1 of this invention can secure a large contact area and exhibit excellent performance in limit driving on circuits, etc. Furthermore, the tire of this invention can secure the drainage necessary for driving on public roads through the outer circumferential groove 4 and the inner circumferential groove 5.

[0026] Since the inner shoulder land portion 6 is provided with the first inner shoulder lateral groove 10 and the second inner shoulder lateral groove 15 described above, the inner shoulder land portion 6 deforms appropriately during running, generating heat easily and exhibiting excellent warming performance.

[0027] On the other hand, the first inner shoulder lateral groove 10 has a first interrupted end 10a, and the groove width decreases toward this first interrupted end 10a. Similarly, the second inner shoulder lateral groove 15 has a second interrupted end 15a, and the groove width decreases toward this second interrupted end 15a. As a result, the reduction in rigidity of the inner shoulder land portion 6 is suppressed, and handling stability on dry road surfaces can be maintained. For these reasons, the tire 1 of the present invention can warm the tread rubber quickly through driving while maintaining handling stability on dry road surfaces. Therefore, the tire 1 of the present invention is useful in shortening driving times in circuit driving and the like.

[0028] The configuration of this embodiment will be described in more detail below. Note that each configuration described below represents a specific aspect of this embodiment. Therefore, it goes without saying that the present invention can achieve the above-described effects even without the configurations described below. Furthermore, even if any one of the configurations described below is applied individually to a tire of the present invention having the above-described features, an improvement in performance corresponding to each configuration can be expected. Moreover, if several of the configurations described below are applied in combination, a combined improvement in performance corresponding to each configuration can be expected.

[0029] Figure 4 shows an enlarged view of the first inner shoulder transverse groove 10 in Figure 3. As shown in Figures 3 and 4, the width of each of the multiple first inner shoulder transverse grooves 10 decreases continuously from the inner circumferential groove 5 toward the first discontinuity 10a. In a preferred embodiment, the first inner shoulder transverse groove 10 includes two linearly extending groove edges, with an angle θ1 between them of 4 to 20°. Such a first inner shoulder transverse groove 10 helps to balance steering stability and warm-up performance.

[0030] The first inner shoulder transverse groove 10 has its maximum groove width W3 at the point where it communicates with the inner circumferential groove 5. The maximum groove width W3 of the first inner shoulder transverse groove 10 is, for example, 5 to 20 mm.

[0031] As shown in Figure 3, the first inner shoulder lateral groove 10 crosses at least the first inner contact end T1i. Furthermore, the first inner shoulder lateral groove 10 is interrupted without reaching the second inner contact end T2i. The axial length L3 of the first inner shoulder lateral groove 10 is, for example, 40% to 65% of the axial width W2 of the outer surface of the inner shoulder land area 6. The axial distance L4 from the first interrupted end 10a of the first inner shoulder lateral groove 10 to the first inner contact end T1i is 5% to 20% of the width W2 of the inner shoulder land area 6. Such a first inner shoulder lateral groove 10 helps maintain handling stability on dry surfaces while ensuring wet performance during public road driving. The width W2 of the inner shoulder land area 6 corresponds to the axial distance from the groove edge on the outer side of the inner circumferential groove 5 to the second inner contact end T2i.

[0032] In this embodiment, each of the multiple first inner shoulder lateral grooves 10 is inclined in the same direction with respect to the tire axis. Also, as shown in Figure 4, the angle θ2 of the first inner shoulder lateral groove 10 with respect to the tire axis is, for example, 10° or more, and preferably 20 to 35°. Such first inner shoulder lateral grooves 10 can exert the above-mentioned effects while suppressing uneven wear of the inner shoulder land portion 6. In this specification, the groove angle in a plan view of the tread is measured at the groove's centerline. Unless otherwise specified, the groove angle refers to the average groove angle. The average groove angle is the value obtained by dividing the groove's centerline into multiple equal minute regions and dividing the sum of the angles of each minute region by the number of minute regions. It is desirable that the minute regions be as small as possible, for example, having a length of 5 mm or less. The same applies to the angles of the groove walls, etc., which will be described later.

[0033] As shown in Figure 3, the pitch length P1 of the multiple first inner shoulder lateral grooves 10 in the tire circumferential direction is 100% to 200% of the width W2 of the inner shoulder land area 6. In this embodiment, the second inner shoulder lateral grooves 15 are also arranged with a similar pitch length. Furthermore, the first inner shoulder lateral grooves 10 and the second inner shoulder lateral grooves 15 are arranged alternately in the tire circumferential direction. In addition, the first inner shoulder lateral grooves 10 and the second inner shoulder lateral grooves 15 are inclined in the same direction with respect to the tire axial direction. This suppresses uneven wear of the inner shoulder land area 6.

[0034] The second interrupted end 15a of the second inner shoulder lateral groove 15 is located at least inward in the tire axial direction from the first interrupted end 10a of the first inner shoulder lateral groove 10. The axial distance L5 from the inner circumferential groove 5 to the second interrupted end 15a of the second inner shoulder lateral groove 15 is, for example, 20% to 30% of the width W2 of the inner shoulder land portion 6. Such a second inner shoulder lateral groove 15 can improve the heating performance near the first inner contact end T1i while maintaining the rigidity of the inner shoulder land portion 6.

[0035] The second inner shoulder lateral groove 15 extends, for example, to the vicinity of the second inner contact end T2i. The axial distance L6 from the outer end 15b of the second inner shoulder lateral groove 15 to the second inner contact end T2i is 2% to 5% of the width W2 of the inner shoulder land area 6. As a result, the axial length L7 of the second inner shoulder lateral groove 15 is 60% to 80% of the width W2 of the inner shoulder land area 6. Such a second inner shoulder lateral groove 15 helps to improve both handling stability and warm-up performance in a balanced way.

[0036] Figure 5 shows an enlarged view of the second inner shoulder lateral groove 15 in Figure 3. As shown in Figure 5, the second inner shoulder lateral groove 15 includes a first groove 16 that crosses the first inner contact end T1i and a second groove 17 that is connected to the first groove 16 on the axial side of the tire.

[0037] The angle θ3 of the first groove 16 with respect to the tire axis is, for example, 30 to 50°. The angle θ4 of the second groove 17 with respect to the tire axis is smaller than the angle θ3 of the first groove 16. Specifically, the angle θ4 is 15 to 30°. This increases the rigidity of the inner shoulder land portion 6 around the second groove 17. Therefore, the turning performance during high-load driving when the second groove 17 is in contact with the ground can be improved.

[0038] The first groove 16 has a continuously decreasing groove width towards the second interrupted end 15a. The first groove 16 also includes two groove edges that extend in a straight line, and the angle θ5 between them is 4 to 20°. As a result, as shown in Figure 3, the groove width of each of the multiple second inner shoulder transverse grooves 15 decreases continuously from the first inner grounding end T1i towards the second interrupted end 15a.

[0039] As shown in Figure 5, the second groove 17 includes two linearly extending groove edges that run parallel to each other. Therefore, the second groove 17 has a constant groove width. The length L8 of the second groove 17 in the tire axial direction is 60% to 80% of the length L7 (shown in Figure 3) of the second inner shoulder lateral groove 15. In this embodiment, the boundary between the first groove 16 and the second groove 17 is the position where the angle of the groove centerline changes.

[0040] Figure 6 shows a cross-sectional view along line AA in Figure 3. In Figure 6, the left side is the first side A1 in the tire circumferential direction, and the right side is the second side A2 in the tire circumferential direction. As shown in Figure 6, the first inner shoulder lateral groove 10 includes a first groove wall 13 on the first side A1 in the tire circumferential direction and a second groove wall 14 on the second side A2 in the tire circumferential direction. The angle θ6 of the first groove wall 13 of the first inner shoulder lateral groove 10 with respect to the tire radial direction is greater than the angle θ7 of the second groove wall 14 of the first inner shoulder lateral groove 10 with respect to the tire radial direction. Specifically, the angle θ6 is 25 to 35°, and the angle θ7 is 5° or less. Such a first inner shoulder lateral groove 10 allows the outer end of the second groove wall 14 in the tire radial direction to provide a large frictional force, which can improve braking performance and traction performance.

[0041] As shown in Figure 3, the above-mentioned relationship of groove wall angles is realized, for example, on the inner circumferential groove 5 side of the longitudinal center position of the first inner shoulder transverse groove 10. Near the first interrupted end 10a of the first inner shoulder transverse groove 10, the relationship of groove wall angles is as follows.

[0042] Figure 7 shows a cross-sectional view of line BB in Figure 3. As shown in Figure 7, near the first interrupted end 10a, the first groove wall 13 and the second groove wall 14 are arranged at the same angle θ8 with respect to the tire radial direction. The angle θ8 is, for example, 5° or less.

[0043] As shown in Figure 3, the first inner shoulder lateral groove 10 of this embodiment has the groove wall angle relationship shown in Figure 6 on the inner circumferential groove 5 side of its longitudinal center position, and the angle of the first groove wall 13 with respect to the tire radial direction decreases toward the first interrupted end 10a toward the first interrupted end 10a toward the first interrupted end 10a. Furthermore, at least at the first inner contact end T1i, the groove wall relationship shown in Figure 7 is realized. With such a groove wall, the first inner shoulder lateral groove 10 can maintain groove volume even near the first interrupted end 10a and maintain wet performance.

[0044] The groove wall angles shown in Figure 7 can be applied to the two groove walls of the first groove portion 16 of the second inner shoulder transverse groove 15. This improves wet performance.

[0045] Figure 8 shows a cross-sectional view of line CC in Figure 3. As shown in Figure 8, the second groove 17 of the second inner shoulder lateral groove 15 includes a first groove wall 18 on the first side A1 in the tire circumferential direction and a second groove wall 19 on the second side A2 in the tire circumferential direction. The angle θ9 of the first groove wall 18 of the second groove 17 with respect to the tire radial direction is smaller than the angle θ10 of the second groove wall 19 of the second groove 17 with respect to the tire radial direction. The angle θ9 is, for example, 5° or less. The angle θ10 is, for example, 25 to 35°. The second inner shoulder lateral groove 15 having such a second groove 17 can improve traction performance or braking performance.

[0046] Figure 9 shows an enlarged view of the outer shoulder land area 7 of Figure 1. As shown in Figure 9, the outer shoulder land area 7 is provided with multiple first outer shoulder lateral grooves 20. The first outer shoulder lateral grooves 20 make the outer shoulder land area 7 easily deformable and allow this land area to warm up quickly. The first outer shoulder lateral grooves 20 extend outward in the tire axial direction from the outer circumferential groove 4 and are interrupted without reaching the second outer contact end T2o. The width of each of the multiple first outer shoulder lateral grooves 20 decreases toward the outer circumferential groove 4. Such first outer shoulder lateral grooves 20 suppress the reduction in rigidity of the outer shoulder land area 7 and maintain handling stability on dry surfaces.

[0047] The pitch length P2 of the first outer shoulder lateral groove 20 in the tire circumferential direction is, for example, 80% to 100% of the width W4 of the outer shoulder land portion 7 in the tire axial direction. In this embodiment, multiple first outer shoulder lateral grooves 20 are arranged at the same pitch as multiple first inner shoulder lateral grooves 10 (shown in Figure 3). The width W4 of the outer shoulder land portion 7 corresponds to the distance in the tire axial direction from the groove edge on the outer circumferential side of the tire axial direction of the outer circumferential groove 4 to the second outer contact end T2o.

[0048] The opening width W5 in the outer circumferential groove 4 of the first outer shoulder lateral groove 20 is 4 mm or less. In a preferred embodiment, the opening width W5 is 10% to 40% of the maximum groove width W6 of the first outer shoulder lateral groove 20. This provides a good balance between improved handling stability and warm-up performance.

[0049] From a similar perspective, the maximum groove width W6 of the first outer shoulder transverse groove 20 is 15 mm or less, preferably 5 to 10 mm.

[0050] The first outer shoulder lateral groove 20 extends, for example, to the vicinity of the first outer contact end T1o. As a result, the axial length L9 of the first outer shoulder lateral groove 20 is 55% to 70% of the width W4 of the outer shoulder land portion 7. Also, the distance from the axially outer interrupted end 20a of the first outer shoulder lateral groove 20 to the first outer contact end T1o is, for example, 10% or less of the axial width W4 of the outer shoulder land portion 7. In a preferred embodiment, the interrupted end 20a of the first outer shoulder lateral groove 20 is positioned on the first outer contact end T1o. Such a first outer shoulder lateral groove 20 can improve handling stability during high-load driving while maintaining wet performance during public road driving.

[0051] The first outer shoulder lateral groove 20 is inclined, for example, in the same direction as the first inner shoulder lateral groove 10 (shown in Figure 3) with respect to the tire axis. However, the present invention is not limited to this embodiment.

[0052] Figure 10 shows an enlarged view of the first outer shoulder lateral groove 20. As shown in Figure 10, the first outer shoulder lateral groove 20 includes a first groove 21 connected to the outer circumferential groove 4 and a second groove 22 connected to the tire axial side of the first groove 21. The angle θ12 of the second groove 22 with respect to the tire axial direction is smaller than the angle θ11 of the first groove 21 with respect to the tire axial direction. Specifically, the angle θ11 of the first groove 21 is, for example, 25° or less, preferably 10 to 20°. The angle θ12 of the second groove 22 with respect to the tire axial direction is, for example, 5 to 15°. This increases the axial rigidity of the outer shoulder land portion 7 near the first outer contact end T1o, improving turning performance during high-load driving.

[0053] The groove width of the first groove 21 decreases continuously toward the outer circumferential groove 4. The first groove 21 also includes two linearly extending groove edges, with an angle θ13 between them of 5-10°. As a result, as shown in Figure 9, the groove width of each of the multiple first outer shoulder transverse grooves 20 decreases continuously toward the outer circumferential groove 4. Such first grooves 21 help to suppress uneven wear of the outer shoulder land area 7.

[0054] As shown in Figure 10, the second groove 22 includes two linearly extending groove edges that run parallel to each other. Therefore, the second groove 22 includes a portion that extends with a constant groove width. The length L10 of the second groove 22 in the tire axial direction is 30% to 45% of the length L9 (shown in Figure 9) of the first outer shoulder lateral groove 20. In this embodiment, the boundary between the first groove 21 and the second groove 22 is the position where the angle of the groove centerline changes.

[0055] As shown in Figure 9, the first outer shoulder lateral groove 20 of this embodiment includes a first groove wall 23 on the first side A1 in the tire circumferential direction and a second groove wall 24 on the second side A2 in the tire circumferential direction. Furthermore, in the region on the outermost circumferential groove 4 side when the first outer shoulder lateral groove 20 is divided into three equal parts in its longitudinal direction, the angle of the first groove wall 23 with respect to the tire radial direction and the angle of the second groove wall 24 with respect to the tire radial direction are the same, and specifically, it has the cross-sectional shape shown in Figure 7. This improves traction performance or braking performance. The features described in Figure 7 can be applied to the aforementioned region of the first outer shoulder lateral groove 20.

[0056] As shown in Figure 10, in the central region when the first outer shoulder lateral groove 20 is divided into three equal parts in the longitudinal direction, and in the region on the outer side in the tire axial direction, the angle of the first groove wall 23 with respect to the tire radius is greater than the angle of the second groove wall 24 with respect to the tire radius. As a result, at least in the second groove portion 22, the angle of the first groove wall 23 with respect to the tire radius is greater than the angle of the second groove wall 24 with respect to the tire radius. Specifically, the second groove portion 22 has the cross-sectional shape shown in Figure 6. The features described in Figure 6 can be applied to the second groove portion 22.

[0057] As shown in Figure 9, it is desirable that the outer shoulder land portion 7 is provided with a plurality of second outer shoulder lateral grooves 25 that cross the first outer contact end T1o and have a discontinuous end 25a between the first outer contact end T1o and the outer circumferential groove 4. The second outer shoulder lateral grooves 25 in this embodiment are arranged with a 1-pitch length similar to the first outer shoulder lateral grooves 20. The first outer shoulder lateral grooves 20 and the second outer shoulder lateral grooves 25 are arranged alternately in the circumferential direction of the tire. Furthermore, the first outer shoulder lateral grooves 20 and the second outer shoulder lateral grooves 25 are inclined in the same direction with respect to the tire axis. Such second outer shoulder lateral grooves 25 can improve wet performance while suppressing uneven wear of the outer shoulder land portion 7.

[0058] The end 25a of the second outer shoulder lateral groove 25 is located at least inward in the tire axial direction from the end 20a of the first outer shoulder lateral groove 20. The axial distance L11 from the outer circumferential groove 4 to the end 25a of the second outer shoulder lateral groove 25 is, for example, 45% to 55% of the width W4 of the outer shoulder land portion 7. Such a second outer shoulder lateral groove 25 helps to improve both handling stability and warm-up performance in a balanced way.

[0059] The second outer shoulder lateral groove 25 extends, for example, to the vicinity of the second outer contact end T2o. The axial distance L12 from the outer end 25b of the second outer shoulder lateral groove 25 to the second outer contact end T2o is 5% to 10% of the width W4 of the outer shoulder land portion 7. As a result, the axial length L13 of the second outer shoulder lateral groove 25 is 35% to 50% of the width W4 of the outer shoulder land portion 7.

[0060] Figure 11 shows an enlarged view of the second outer shoulder lateral groove 25 of Figure 9. As shown in Figure 11, the second outer shoulder lateral groove 25 includes a first groove 26 that crosses the first outer contact end T1o and a second groove 27 that is connected to the first groove 26 in the axial direction of the tire.

[0061] The angle θ14 of the first groove 26 with respect to the tire axis is, for example, 10 to 20°. The angle θ15 of the second groove 27 with respect to the tire axis is smaller than the angle θ14 of the first groove 26. Specifically, the angle θ15 is 5 to 15°. This makes it possible to improve handling stability while ensuring wet performance.

[0062] The first groove 26 has a continuously decreasing groove width toward the interrupted end 25a. The first groove 26 also includes two linearly extending groove edges, and the angle θ16 between them is 4 to 20°. As a result, as shown in Figure 9, the groove width of each of the multiple second outer shoulder transverse grooves 25 decreases continuously from at least the first outer contact end T1o toward the interrupted end 25a.

[0063] The second groove 27 includes two groove edges that extend in a straight line and are parallel to each other. Therefore, the second groove 27 has a constant groove width. The length L14 of the second groove 27 in the tire axial direction is 30% to 45% of the length L13 (shown in Figure 9) of the second outer shoulder lateral groove 25. In this embodiment, the boundary between the first groove 26 and the second groove 27 is the position where the angle of the groove centerline changes.

[0064] As shown in Figure 9, the second outer shoulder lateral groove 25 includes a first groove wall 28 on the first side A1 in the circumferential direction of the tire and a second groove wall 29 on the second side in the circumferential direction of the tire. In the region axially inward from the first outer contact end T1o, the first groove wall 28 and the second groove wall 29 of the second outer shoulder lateral groove 25 have the same angle with respect to the radial direction of the tire, and specifically have the cross-sectional shape shown in Figure 7. This allows for effective maintenance of wet performance. The features described in Figure 7 can be applied to the aforementioned region of the second outer shoulder lateral groove 25.

[0065] Further outward in the tire axial direction from the first outer contact end T1o, the angle of the first groove wall 28 of the second outer shoulder lateral groove 25 with respect to the tire radial direction is greater than the angle of the second groove wall 29 with respect to the tire radial direction. As a result, at least in the second groove portion 27, the angle of the first groove wall 28 with respect to the tire radial direction is greater than the angle of the second groove wall 29 with respect to the tire radial direction. Specifically, the second groove portion 27 of the second outer shoulder lateral groove 25 has the cross-sectional shape shown in Figure 6. The features described in Figure 6 can be applied to the second groove portion 27.

[0066] As shown in Figure 1, the tread portion 2 includes a crown land portion 8 divided between the inner circumferential groove 5 and the outer circumferential groove 4. The crown land portion 8 is adjacent to the inner shoulder land portion 6 via the inner circumferential groove 5, and is adjacent to the outer shoulder land portion 7 via the outer circumferential groove 4.

[0067] Figure 12 shows an enlarged view of the crown land area 8. As shown in Figure 12, the crown land area 8 is provided with a plurality of first inner crown lateral grooves 30, a plurality of second inner crown lateral grooves 35, and a plurality of outer crown lateral grooves 40. The first inner crown lateral grooves 30 and the second inner crown lateral grooves 35 extend from the inner circumferential grooves 5 and have abrupt ends within the crown land area 8. Furthermore, the first inner crown lateral grooves 30 and the second inner crown lateral grooves 35 are arranged alternately in the circumferential direction of the tire. The outer crown lateral grooves 40 extend from the outer circumferential grooves 4 and have abrupt ends within the crown land area 8.

[0068] The first inner crown lateral groove 30 crosses, for example, the center position of the crown land area 8 in the tire axial direction, and is interrupted without crossing the tire equator C. The length L15 of the first inner crown lateral groove 30 in the tire axial direction is, for example, 60% to 80% of the width W7 in the tire axial direction of the contact surface of the crown land area 8. Such a first inner crown lateral groove 30 can improve warm-up performance while maintaining handling stability.

[0069] The groove width of the first inner crown lateral groove 30 decreases towards the interrupted end 30a of the first inner crown lateral groove 30, and in a desirable embodiment, it decreases continuously. Such a first inner crown lateral groove 30 can improve the heating performance while suppressing a decrease in the rigidity of the crown land portion 8.

[0070] The first inner crown lateral groove 30 includes a first groove portion 31 that communicates with the inner circumferential groove 5 and a second groove portion 32 that communicates with the first groove portion 31. The first groove portion 31 is inclined, for example, in the same direction as the first inner shoulder lateral groove 10 (shown in Figure 3) with respect to the tire axis. On the other hand, the second groove portion 32 is inclined in the opposite direction to the first groove portion 31 with respect to the tire axis. The angle θ17 of the first groove portion 31 with respect to the tire axis is 20 to 35°. The angle θ18 of the second groove portion 32 with respect to the tire axis is 0 to 15°. The first inner crown lateral groove 30 having such a first groove portion 31 and second groove portion 32 can provide grip in multiple directions and can enhance handling stability.

[0071] Each of the first groove 31 and the second groove 32 has two groove edges that extend in a straight line. The angle θ19 between the two groove edges in the first groove 31 and the angle θ20 between the two groove edges in the second groove 32 are both between 4 and 20°.

[0072] The first inner crown lateral groove 30 includes a first groove wall 33 on the first side A1 in the tire circumferential direction and a second groove wall 34 on the second side A2 in the tire circumferential direction. In the first groove portion 31 of the first inner crown lateral groove 30, the angle of the first groove wall 33 with respect to the tire radial direction is smaller than the angle of the second groove wall 34 with respect to the tire radial direction. Specifically, the first groove portion 31 has the cross-sectional shape shown in Figure 8. That is, the relationship between the magnitude of the groove wall angles is the opposite of that of the first inner shoulder lateral groove 10. This suppresses excessive leaning of the ground portion around these lateral grooves, and consequently improves traction and braking performance. The features described in Figure 8 can be applied to the first groove portion 31.

[0073] In the second groove 32 of the first inner crown lateral groove 30, the angle of the first groove wall 33 with respect to the tire radial direction is the same as the angle of the second groove wall 34 with respect to the tire radial direction. Specifically, the second groove 32 has the cross-sectional shape shown in Figure 7. This ensures wet performance. The features described in Figure 7 can be applied to the second groove 32.

[0074] Figure 13 shows an enlarged view illustrating the positional relationship between the inner circumferential groove 5, the first inner shoulder lateral groove 10, and the first inner crown lateral groove 30. As shown in Figure 13, it is desirable that the end of the first inner crown lateral groove 30 on the inner circumferential groove 5 side overlaps with a virtual region that extends parallel to the tire axis direction from the end of the first inner shoulder lateral groove 10 on the inner circumferential groove 5 side. In a more desirable embodiment, the first groove portion 31 of the first inner crown lateral groove 30 and the first inner shoulder lateral groove 10 are arranged within a virtual belt 46 that extends linearly with a constant width W8, and the first groove portion 31 and the first inner shoulder lateral groove 10 are arranged such that the width W8 of this virtual belt 46 can be drawn with a width of 20 mm or less. This makes the areas around these grooves warm up more easily.

[0075] As shown in Figure 12, each of the multiple second inner crown lateral grooves 35 is inclined, for example, in the same direction as the first inner crown lateral groove 30 with respect to the tire axis. The angle θ21 of the second inner crown lateral groove 35 with respect to the tire axis is, for example, 20 to 35°. In a preferred embodiment, the second inner crown lateral groove 35 in this embodiment is substantially parallel to the first groove portion 31 of the first inner crown lateral groove 30. Such a second inner crown lateral groove 35 can improve warm-up performance while suppressing uneven wear of the crown land portion 8.

[0076] The groove width of the second inner crown transverse groove 35 decreases continuously toward the outer circumferential groove 4. The second inner crown transverse groove 35 in this embodiment includes two linearly extending groove edges, and the angle θ22 between them is 4 to 20°.

[0077] The second inner crown lateral groove 35 is preferably interrupted on the inner circumferential groove 5 side, rather than at the interrupted end 30a of the first inner crown lateral groove 30. The axial length L16 of the second inner crown lateral groove 35 is, for example, 25% to 40% of the axial width W7 of the crown land portion 8. Such a second inner crown lateral groove 35 can improve warm-up performance while maintaining handling stability.

[0078] Each of the multiple outer crown lateral grooves 40 is inclined, for example, in the same direction as the first inner crown lateral groove 30 with respect to the tire axis. The angle θ23 of the outer crown lateral groove 40 with respect to the tire axis is, for example, 20 to 35°. In a preferred embodiment, the outer crown lateral groove 40 of this embodiment is substantially parallel to the first groove portion 31 of the first inner crown lateral groove 30. Such a second inner crown lateral groove 35 can improve warm-up performance while suppressing uneven wear of the crown land portion 8.

[0079] The groove width of the outer crown transverse groove 40 decreases continuously toward the inner circumferential groove 5. The outer crown transverse groove 40 in this embodiment includes two linearly extending groove edges, and the angle θ24 between them is 5 to 15°.

[0080] The outer crown lateral groove 40 is preferably interrupted on the inner circumferential groove 5 side than the interrupted end 30a of the first inner crown lateral groove 30. Also, the interrupted end 40a of the outer crown lateral groove 40 is located on the outer circumferential groove 4 side than the interrupted end 35a of the second inner crown lateral groove 35. The axial length L17 of the outer crown lateral groove 40 is, for example, 40% to 60% of the axial width W7 of the crown land portion 8. Such an outer crown lateral groove 40 helps to improve both handling stability and warm-up performance in a balanced way.

[0081] The maximum depth of the second inner crown lateral groove 35 and the maximum depth of the outer crown lateral groove 40 are preferably smaller than, for example, the other lateral grooves. Specifically, the maximum depth of the second inner crown lateral groove 35 and the maximum depth of the outer crown lateral groove 40 are each smaller than the maximum depth of the first inner shoulder lateral groove 10 (shown in Figure 3), the maximum depth of the second inner shoulder lateral groove 15 (shown in Figure 3), the maximum depth of the first outer shoulder lateral groove 20 (shown in Figure 9), the maximum depth of the second outer shoulder lateral groove 25 (shown in Figure 9), and the maximum depth of the first inner crown lateral groove 30. This allows for the above-mentioned effects to be achieved while demonstrating excellent handling stability.

[0082] The second inner crown lateral groove 35 and the outer crown lateral groove 40 are positioned within a virtual belt 47 that extends linearly with a constant width W9. The second inner crown lateral groove 35 and the outer crown lateral groove 40 are positioned such that the width W9 of this virtual belt 47 is 20 mm or less. This makes the areas around these grooves more easily heated.

[0083] Figure 14 shows an enlarged view illustrating the positional relationship between the outer circumferential groove 4, the first outer shoulder lateral groove 20, and the outer crown lateral groove 40. As shown in Figure 14, it is desirable that the end of the outer crown lateral groove 40 on the outer circumferential groove 4 side overlaps with a virtual region that extends parallel to the tire axis direction from the end of the first outer shoulder lateral groove 20 on the outer circumferential groove 4 side. In a more desirable embodiment, the outer crown lateral groove 40 and the first outer shoulder lateral groove 20 are arranged within a virtual belt 48 that extends linearly with a constant width W10, and the outer crown lateral groove 40 and the first outer shoulder lateral groove 20 are positioned such that the width W10 of this virtual belt 48 can be drawn with a width of 20 mm or less. This further improves the warming performance.

[0084] Although a tire according to one embodiment of the present invention has been described in detail above, the present invention is not limited to the specific embodiments described above and can be implemented in various modified forms.

[0085] [Note] The present invention includes the following embodiments.

[0086] [Invention 1] A tire having a tread portion in which the orientation of mounting on the vehicle is specified, The tread portion includes a tire equator, an outer tread portion located outside the vehicle beyond the tire equator when mounted on the vehicle, and an inner tread portion located inside the vehicle beyond the tire equator when mounted on the vehicle. The outer tread portion is provided with only one outer circumferential groove, which extends continuously in the circumferential direction of the tire. The inner tread portion is provided with only one inner circumferential groove as the circumferential groove. The inner tread portion is provided with an inner shoulder land portion on the tire axial side of the inner circumferential groove, The inner shoulder land portion includes a first inner grounding end, which is the grounding end when 70% of the normal load is applied, and a second inner grounding end, which is the grounding end when 130% of the normal load is applied. The second inner contact end is located further outward in the tire axial direction than the first inner contact end. The inner shoulder land portion is provided with a plurality of first inner shoulder lateral grooves extending outward in the tire axial direction from the inner circumferential groove, and a plurality of second inner shoulder lateral grooves crossing the first inner contact end. Each of the plurality of first inner shoulder transverse grooves has a first interrupted end that is interrupted before the second inner grounding end, The width of each of the plurality of first inner shoulder transverse grooves decreases from the inner circumferential groove toward the first interrupted end. Each of the plurality of second inner shoulder transverse grooves has a second interrupted end between the inner circumferential groove and the first inner grounding end. The width of each of the plurality of second inner shoulder transverse grooves decreases at least from the first inner contact end toward the second interrupted end. tire. [2nd Invention] The tire according to the present invention 1, wherein the groove width of each of the plurality of first inner shoulder lateral grooves decreases continuously from the inner circumferential groove toward the first interrupted end. [Invention 3] The tire according to invention 1 or 2, wherein the groove width of each of the plurality of second inner shoulder lateral grooves decreases continuously from the first inner contact end to the second interrupted end. [Invention 4] The tire according to any one of claims 1 to 3 of the present invention, wherein the distance in the tire axial direction from the groove centerline of the inner circumferential groove to the tire equator is 45% to 75% of the tread half width from the tire equator to the first inner contact end. [5th ​​Invention] The tire according to claim 4, wherein the distance in the axial direction of the tire from the groove centerline of the outer circumferential groove to the tire equator is 5% to 35% of the tread half width. [Invention 6] The tire according to any one of claims 1 to 5 of the present invention, wherein the plurality of first inner shoulder lateral grooves and the plurality of second inner shoulder lateral grooves are alternately provided in the circumferential direction of the tire. [7th Invention] The tire according to any one of claims 1 to 6 of the present invention, wherein the plurality of first inner shoulder lateral grooves and the plurality of second inner shoulder lateral grooves are inclined in the same direction with respect to the tire axis. [8th Invention] At least one of the plurality of second inner shoulder lateral grooves includes a first groove portion that crosses the first inner contact end and a second groove portion that is connected to the tire axial side of the first groove portion, The tire according to any one of claims 1 to 7 of the present invention, wherein the angle of the second groove with respect to the tire axis is smaller than the angle of the first groove with respect to the tire axis. [Invention 9] The second groove portion includes a first groove wall on the first side in the tire circumferential direction and a second groove wall on the second side in the tire circumferential direction. The tire according to the present invention, wherein the angle of the first groove wall with respect to the tire radial direction is smaller than the angle of the second groove wall with respect to the tire radial direction. [10th Invention] At least one of the plurality of first inner shoulder lateral grooves includes a first groove wall on the first side in the tire circumferential direction and a second groove wall on the second side in the tire circumferential direction. The tire according to any one of claims 1 to 9 of the present invention, wherein the angle of the first groove wall with respect to the tire radial direction is greater than the angle of the second groove wall with respect to the tire radial direction. [Invention 11] The tread portion includes the inner shoulder portion and the adjacent crown portion via the inner circumferential groove, The tire according to any one of claims 1 to 5 of the present invention, wherein the crown land portion is provided with a plurality of first inner crown lateral grooves extending from the inner circumferential groove and having interrupted ends within the crown land portion. [Invention 12] The first inner crown lateral groove includes a first groove wall on the first side in the circumferential direction of the tire and a second groove wall on the second side in the circumferential direction of the tire. The tire according to invention 11, wherein the angle of the first groove wall with respect to the tire radial direction is smaller than the angle of the second groove wall with respect to the tire radial direction. [Explanation of Symbols]

[0087] 2 Tread section 2B Outer tread section 2A Inner tread section 3 Circumferential groove 4 Outer circumferential groove 5 Inner circumferential groove 6. Inner shoulder area 10. First medial shoulder transverse groove 10a First break 15. Second medial shoulder transverse groove 15a Second break T1i First Inner Grounding End T2i Second Inner Grounding End

Claims

1. A tire having a tread portion in which the orientation of mounting on the vehicle is specified, The tread portion includes a tire equator, an outer tread portion located outside the vehicle beyond the tire equator when mounted on the vehicle, and an inner tread portion located inside the vehicle beyond the tire equator when mounted on the vehicle. The outer tread portion is provided with only one outer circumferential groove, which extends continuously in the circumferential direction of the tire. The inner tread portion is provided with only one inner circumferential groove as the circumferential groove. The inner tread portion is provided with an inner shoulder land portion on the tire axial side of the inner circumferential groove, The inner shoulder land portion includes a first inner grounding end, which is the grounding end when 70% of the normal load is applied, and a second inner grounding end, which is the grounding end when 130% of the normal load is applied. The second inner contact end is located further outward in the tire axial direction than the first inner contact end. The inner shoulder land portion is provided with a plurality of first inner shoulder lateral grooves extending outward in the tire axial direction from the inner circumferential groove, and a plurality of second inner shoulder lateral grooves crossing the first inner contact end. Each of the plurality of first inner shoulder transverse grooves has a first interrupted end that is interrupted before the second inner grounding end, The width of each of the plurality of first inner shoulder transverse grooves decreases from the inner circumferential groove toward the first interrupted end. Each of the plurality of second inner shoulder transverse grooves has a second interrupted end between the inner circumferential groove and the first inner grounding end. The width of each of the plurality of second inner shoulder transverse grooves decreases at least from the first inner contact end toward the second interrupted end. tire.

2. The tire according to claim 1, wherein the width of each of the plurality of first inner shoulder lateral grooves decreases continuously from the inner circumferential groove toward the first interrupted end.

3. The tire according to claim 1 or 2, wherein the width of each of the plurality of second inner shoulder lateral grooves decreases continuously from the first inner contact end to the second interrupted end.

4. The tire according to claim 1 or 2, wherein the distance in the tire axial direction from the groove centerline of the inner circumferential groove to the tire equator is 45% to 75% of the tread half width from the tire equator to the first inner contact end.

5. The tire according to claim 4, wherein the distance in the tire axial direction from the groove centerline of the outer circumferential groove to the tire equator is 5% to 35% of the tread half width.

6. The tire according to claim 1 or 2, wherein the plurality of first inner shoulder lateral grooves and the plurality of second inner shoulder lateral grooves are alternately provided in the circumferential direction of the tire.

7. The tire according to claim 1 or 2, wherein the plurality of first inner shoulder lateral grooves and the plurality of second inner shoulder lateral grooves are inclined in the same direction with respect to the tire axis.

8. At least one of the plurality of second inner shoulder lateral grooves includes a first groove portion that crosses the first inner contact end and a second groove portion that is connected to the tire axial side of the first groove portion. The tire according to claim 1 or 2, wherein the angle of the second groove with respect to the tire axis is smaller than the angle of the first groove with respect to the tire axis.

9. The second groove portion includes a first groove wall on the first side in the tire circumferential direction and a second groove wall on the second side in the tire circumferential direction. The tire according to claim 8, wherein the angle of the first groove wall with respect to the tire radius is smaller than the angle of the second groove wall with respect to the tire radius.

10. At least one of the plurality of first inner shoulder lateral grooves includes a first groove wall on the first side in the tire circumferential direction and a second groove wall on the second side in the tire circumferential direction. The tire according to claim 1 or 2, wherein the angle of the first groove wall with respect to the tire radius direction is greater than the angle of the second groove wall with respect to the tire radius direction.

11. The tread portion includes the inner shoulder portion and the adjacent crown portion via the inner circumferential groove, The tire according to claim 1 or 2, wherein the crown land portion is provided with a plurality of first inner crown lateral grooves extending from the inner circumferential groove and having interrupted ends within the crown land portion.

12. The aforementioned first inner crown lateral groove includes a first groove wall on the first side in the circumferential direction of the tire and a second groove wall on the second side in the circumferential direction of the tire. The tire according to claim 11, wherein the angle of the first groove wall with respect to the tire radial direction is smaller than the angle of the second groove wall with respect to the tire radial direction.

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