tire

Abstract

To provide a tire having improved braking performance or traction performance on a dry road surface while suppressing uneven wear.SOLUTION: A tire has a tread portion 2. A first land portion 11 is provided with a plurality of first lateral sipes 21 extending in a tire axial direction. Each of the plurality of first lateral sipes 21 includes a first sipe wall 21a and a second sipe wall 21b. Each of the plurality of first lateral sipes 21 is open in a tread surface 11s via a chamfered portion 36. The chamfered portion 36 includes a first chamfered surface 36a connected to the first sipe wall 21a and a second chamfered surface 36b connected to the second sipe wall 21b. In a plan view of the first land portion 11, a chamfer width W1 of the first chamfered surface 36a is greater than a chamfer width W2 of the second chamfered surface 36b.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to tires. [Background technology]

[0002] Patent Document 1 listed below proposes a tire that improves steering stability on dry roads and wet cornering performance by improving lateral grooves and sipes provided in the first land portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-137015 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, vehicle performance has been improving, and so tires are being required to have even better braking and traction performance on dry roads. At the same time, tires are also being required to have reduced uneven wear.

[0005] The present disclosure has been devised in consideration of the above-described circumstances, and has as its main object to provide a tire that suppresses uneven wear while improving braking performance or traction performance on dry roads. [Means for solving the problem]

[0006] The present disclosure relates to a tire having a tread portion, wherein the tread portion includes a first land portion having a first edge extending in the tire circumferential direction, a second edge extending in the tire circumferential direction, and a tread surface formed therebetween, wherein the first land portion is provided with a plurality of first lateral sipes extending in the tire axial direction, each of the plurality of first lateral sipes including a first sipe wall located on a first side in the tire circumferential direction and a second sipe wall located on a second side in the tire circumferential direction, each of the plurality of first lateral sipes opening at the tread surface via a chamfered portion, the chamfered portion including a first chamfered surface continuous with the first sipe wall and a second chamfered surface continuous with the second sipe wall, and wherein, in a plan view of the first land portion, a chamfer width W1 of the first chamfered surface is greater than a chamfer width W2 of the second chamfered surface. [Effects of the Invention]

[0007] By adopting the above-described configuration, the tire of the present disclosure can improve braking performance or traction performance on dry road surfaces while suppressing uneven wear. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a development view of a tread portion of a tire according to one embodiment of the present disclosure. [Figure 2] 2 is an enlarged view of the first land portion, the second land portion, and the third land portion in FIG. 1. [Figure 3] 3 is an enlarged view of the first and second transverse sipes in FIG. 2. FIG. [Figure 4] FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 5] FIG. 3 is a cross-sectional view taken along line BB in FIG. 2. [Figure 6] FIG. 3 is a cross-sectional view taken along line CC in FIG. 2. [Figure 7] FIG. 3 is a cross-sectional view taken along line DD in FIG. 2. [Figure 8] FIG. 3 is a cross-sectional view taken along the line EE in FIG. 2. [Figure 9] FIG. 3 is a cross-sectional view taken along the line FF in FIG. 2. [Figure 10] FIG. 2 is an enlarged view of the fourth land portion and the fifth land portion of FIG. [Figure 11] FIG. 2 is a development view of a tread portion of a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the present disclosure will be described below with reference to the drawings. Fig. 1 is a development view of a tread portion 2 of a tire 1 showing an embodiment of the present disclosure. The tire 1 of this embodiment is suitably used, for example, as a pneumatic tire for passenger cars. However, the present disclosure is not limited to such an embodiment and may also be applied to pneumatic tires for heavy loads and non-pneumatic tires that are not filled with pressurized air inside the tire.

[0010] 1, the tread portion 2 of this embodiment has a specified orientation for installation on a vehicle, for example, so that the tread portion 2 includes a first tread edge T1 intended to be on the outer side of the vehicle when installed on the vehicle, and a second tread edge T2 intended to be on the inner side of the vehicle when installed on the vehicle.

[0011] The first tread edge T1 and the second tread edge T2 each correspond to the edge of the contact patch when a normal load is applied to the tire 1 in a normal state and the tread portion 2 is brought into contact with a flat surface at a camber angle of 0°.

[0012] "Normal condition" means, in the case of a pneumatic tire for which various standards are established, that the tire is mounted on a normal rim, inflated to the normal internal pressure, and is in an unloaded state. In the case of a tire for which various standards are not established or a non-pneumatic tire, the normal condition means a standard use state according to the intended use of the tire, in which the tire is not mounted on a vehicle and is unloaded. In this specification, unless otherwise specified, the dimensions of each part of the tire are values ​​measured in the normal condition.

[0013] A "genuine rim" is a rim that is defined for each tire by the standard system that includes the standard on which the tire is based. For example, in the case of JATMA, it is called a "standard rim," in the case of TRA, it is called a "design rim," and in the case of ETRTO, it is called a "measuring rim."

[0014] "Normal internal pressure" is the air pressure specified for each tire by each standard in the standard system, including the standard on which the tire is based. For JATMA, it is the "maximum air pressure," for TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and for ETRTO, it is the "INFLATION PRESSURE."

[0015] For pneumatic tires for which various standards are established, "normal load" refers to the load specified for each tire in the standard system including the standard on which the tire is based. For JATMA, this is "maximum load capacity," for TRA, this is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and for ETRTO, this is "LOAD CAPACITY." For tires for which various standards are not established, "normal load" refers to the maximum load that can be applied when using the tire in accordance with the above standards.

[0016] The tread portion 2 includes a plurality of circumferential grooves 3 extending continuously in the tire circumferential direction between the first tread edge T1 and the second tread edge T2, and a plurality of land portions 4 separated by the plurality of circumferential grooves 3. The tire 1 of this embodiment is a so-called five-rib tire in which the tread portion 2 is configured with four circumferential grooves 3 and five land portions 4. However, the present disclosure is not limited to this aspect. In another embodiment of the tire 1 of the present disclosure, for example, the tread portion 2 may be a so-called four-rib tire in which the tread portion 2 is configured with three circumferential grooves 3 and four land portions 4.

[0017] The circumferential grooves 3 include, for example, a first circumferential groove 6, a second circumferential groove 7, a third circumferential groove 8, and a fourth circumferential groove 9. The first circumferential groove 6 and the second circumferential groove 7 are provided between the tire equator C and the second tread edge T2. The second circumferential groove 7 is provided between the first circumferential groove 6 and the second tread edge T2. The third circumferential groove 8 and the fourth circumferential groove 9 are provided between the tire equator C and the first tread edge T1. The fourth circumferential groove 9 is provided between the third circumferential groove 8 and the first tread edge T1. As a result, the first circumferential groove 6 and the third circumferential groove 8 are provided to sandwich the tire equator C, and the second circumferential groove 7 and the fourth circumferential groove 9 are provided to sandwich the first circumferential groove 6 and the third circumferential groove 8.

[0018] The axial distance L1 from the tire equator C to the groove center line of the first circumferential groove 6 or the third circumferential groove 8 is preferably, for example, 5% to 15% of the tread width TW. The axial distance L2 from the tire equator C to the groove center line of the second circumferential groove 7 or the fourth circumferential groove 9 is preferably, for example, 25% to 35% of the tread width TW. The tread width TW is the axial distance from the first tread edge T1 to the second tread edge T2 in the normal state.

[0019] Each circumferential groove 3 of this embodiment extends, for example, linearly in parallel to the tire circumferential direction. Each circumferential groove 3 may extend, for example, in a wavy shape.

[0020] The groove width Wa of each circumferential groove 3 is preferably at least 3 mm or more. Furthermore, the groove width Wa of each circumferential groove 3 is preferably 2.0% to 8.0% of the tread width TW. As a more preferable aspect in this embodiment, among the multiple circumferential grooves 3, the fourth circumferential groove 9 has the smallest groove width. However, the present disclosure is not limited to this aspect.

[0021] The multiple land portions 4 include a first land portion 11, a second land portion 12, a third land portion 13, a fourth land portion 14, and a fifth land portion 15. The first land portion 11 is defined between the first circumferential groove 6 and the second circumferential groove 7. The second land portion 12 is defined between the first circumferential groove 6 and the third circumferential groove 8, and is provided on the tire equator C in this embodiment. The third land portion 13 is defined on the axially outer side of the second circumferential groove 7, and in this embodiment, includes the second tread edge T2. The fourth land portion 14 is defined between the third circumferential groove 8 and the fourth circumferential groove 9. The fifth land portion 15 is defined on the axially outer side of the fourth circumferential groove 9, and includes the first tread edge T1 in this embodiment.

[0022] Fig. 2 shows an enlarged view of the first land portion 11, the second land portion 12, and the third land portion 13. As shown in Fig. 2, the first land portion 11 has a first edge 11a extending in the tire circumferential direction on the side of the first tread edge T1, a second edge 11b extending in the tire circumferential direction on the side of the second tread edge T2, and a tread surface 11s formed therebetween. The first land portion 11 also includes a first sidewall 11w1 on the side of the first edge 11a and a second sidewall 11w2 on the side of the second edge 11b.

[0023] A plurality of first lateral sipes 21 extending in the tire axial direction are provided in the first land portion 11. In this embodiment, a plurality of second lateral sipes 22 extending in the tire axial direction are also provided in the first land portion 11.

[0024] Fig. 3 shows an enlarged plan view of the first transverse sipes 21 and the second transverse sipes 22, and Fig. 4 shows an enlarged cross-sectional view of the first transverse sipe 21 taken along line AA in Fig. 2. As shown in Fig. 4, each of the plurality of first transverse sipes 21 includes a first sipe wall 21a located on a first side A1 in the tire circumferential direction and a second sipe wall 21b located on a second side A2 in the tire circumferential direction.

[0025] In this specification, a "sipe" refers to a small cut between two inner walls (first sipe wall 21a and second sipe wall 21b in FIG. 4) with a width of 1.5 mm or less. As will be described later, a sipe may open at the tread surface of a land portion via a chamfered portion. The bottom of the sipe may also be connected to a so-called flask bottom with an expanded width.

[0026] As shown in FIG. 4 , each of the multiple first lateral sipes 21 opens to the tread surface 11s of the first land portion 11 via a chamfered portion 36. The chamfered portion 36 includes a first chamfered surface 36a that connects to the first sipe wall 21a and a second chamfered surface 36b that connects to the second sipe wall 21b. The first chamfered surface 36a and the second chamfered surface 36b are configured, for example, as flat surfaces. In other embodiments, the first chamfered surface 36a and the second chamfered surface 36b may be configured as curved surfaces that convex outward from the tire.

[0027] 3, in a plan view of the first land portion 11, the chamfer width W1 of the first chamfered surface 36a is larger than the chamfer width W2 of the second chamfered surface 36b. By adopting the above-described configuration, the tire 1 of the present disclosure can improve braking performance or traction performance on dry roads (hereinafter, these performances may be collectively referred to as "dry performance") while suppressing uneven wear. The following mechanism is presumed to be the reason for this.

[0028] The chamfered portion 36 (shown in FIG. 4 ) of the present disclosure includes a first chamfered surface 36a and a second chamfered surface 36b, thereby effectively suppressing uneven wear around the first lateral sipe 21. Meanwhile, because the chamfer width W1 of the first chamfered surface 36a is larger than the chamfer width W2 of the second chamfered surface 36b, the first chamfered surface 36a is more likely to contact the ground during vehicle acceleration or deceleration, providing greater grip while suppressing a reduction in rubber volume due to the chamfered portion 36. This is expected to improve traction or braking performance on dry roads. It is believed that this mechanism in the present disclosure can improve at least one of braking performance or traction performance on dry roads while suppressing uneven wear.

[0029] The following describes the configuration of this embodiment in more detail. Note that each configuration described below represents a specific aspect of this embodiment. Therefore, it goes without saying that the present disclosure can achieve the above-described effects even if it does not include the configurations described below. Furthermore, even if any one of the configurations described below is applied alone to a tire of the present disclosure having the above-described characteristics, performance improvement corresponding to each configuration can be expected. Furthermore, when several of the configurations described below are applied in combination, combined performance improvement corresponding to each configuration can be expected.

[0030] As shown in FIG. 4, the total depth d1 of the first transverse sipe 21, including the chamfered portion 36, is, for example, 70% to 90% of the depth of the circumferential groove 3. The total depth d1 is preferably 2.0 to 2.5 times the depth d of the chamfered portion 37. The total depth d1 is the depth from the tread surface to the bottom of the sipe. Hereinafter, unless otherwise specified, the depth of the sipe refers to the depth including the chamfered portion. The depth d2 of the chamfered portion 37 is 2.0 mm or less, preferably 1.0 to 2.0 mm. Furthermore, as shown in FIG. 2, the opening width W5 of the chamfered portion 36 is, for example, 2.5 to 4.5 mm. However, the present invention is not limited to this embodiment.

[0031] As shown in Fig. 2, the multiple first lateral sipes 21 are inclined at an angle of, for example, 30 to 40° with respect to the tire axial direction. Also, as shown in Fig. 3, an obtuse-angled corner portion 34a is formed between the first sipe wall 21a, to which the first chamfered surface 36a having a large chamfer width is connected, and the first side wall 11w1 of the first land portion 11, in a tread plan view. Also, an acute-angled corner portion 34b is formed between the second sipe wall 21b, to which the second chamfered surface 36b is connected, and the first side wall 11w1 of the first land portion 11, in a tread plan view.

[0032] 2, it is desirable that the multiple first lateral sipes 21 communicate with the first edge 11a and have discontinued ends 21e within the tread surface 11s of the first land portion 11. Furthermore, the first lateral sipes 21 are discontinued, for example, closer to the first edge 11a than the axial center position of the first land portion 11. The axial length L3 of the first lateral sipes 21 is, for example, 25% to 40% of the width W6 of the tread surface 11s of the first land portion 11. Such first lateral sipes 21 can improve dry performance while suppressing uneven wear.

[0033] As shown in Fig. 3, the chamfer width W1 of the first chamfered surface 36a is constant over 70% or more of the range of the first sipe wall 21a in the sipe longitudinal direction. The chamfer width W2 of the second chamfered surface 36b is constant over 70% or more of the range of the second sipe wall 21b in the sipe longitudinal direction. In a more desirable embodiment, the chamfer width W1 and the chamfer width W2 are each constant over substantially the entire area of ​​the first lateral sipe 21. This ensures the above-described effects.

[0034] The chamfer width W1 of the first chamfered surface 36a is preferably 2.0 to 5.0 times, and more preferably 3.0 to 4.0 times, the width W7 (shown in FIG. 4) between the first sipe wall 21a and the second sipe wall 21b. The width W7 is, for example, 0.2 to 1.0 mm. Such a first chamfered surface 36a can improve uneven wear resistance and dry performance in a well-balanced manner.

[0035] From the same viewpoint, the angle θ1 of the first chamfered surface 36a with respect to the tire normal is, for example, 40 to 60° as shown in Fig. 4. However, the first chamfered surface 36a is not limited to this embodiment.

[0036] 3, the chamfer width W1 of the first chamfered surface 36a is preferably 1.5 times or more, more preferably 1.8 times or more, and preferably 3.5 times or less, more preferably 3.2 times or less, the chamfer width W2 of the second chamfered surface 36b. This improves uneven wear resistance and dry performance in a well-balanced manner.

[0037] From the same viewpoint, the angle θ2 of the second chamfered surface 36b with respect to the tire normal is set to, for example, 20 to 40° as shown in Fig. 4. In a desirable embodiment, the difference between the angle θ1 and the angle θ2 is set to 25° or less.

[0038] As shown in FIG. 2, the first land portion 11 of this embodiment is provided with a plurality of second lateral sipes 22 extending in the tire axial direction. The second lateral sipes 22 are inclined, for example, in the same direction as the first lateral sipes 21 with respect to the tire axial direction, and in this embodiment, these sipes are inclined at the same angle. Also, as shown in FIG. 3, an obtuse-angled corner portion 35b is formed between the second sipe wall 22b, to which the second chamfered surface 37b having a large chamfer width is connected, and the second sidewall 11w2 of the first land portion 11, in a tread plan view. Also, an acute-angled corner portion 35a is formed between the first sipe wall 22a, to which the first chamfered surface 37a is connected, and the second sidewall 11w2 of the first land portion 11, in a tread plan view.

[0039] 2, the second transverse sipes 22, for example, communicate with the second edge 11b and have a discontinuous end 22e within the tread surface 11s of the first land portion 11. The axial length L4 of the second transverse sipes 22 can be configured in the same manner as the length L3 of the first transverse sipes 21 described above.

[0040] In another embodiment (not shown), the axial length L3 of the first lateral sipes 21 may be greater than the axial length L4 of the second lateral sipes 22. In this case, the length L3 is, for example, 130% or less of the length L4, and is preferably 110% to 120%. This makes it possible to suppress uneven wear on the first edge 11a side of the first land portion 11.

[0041] Fig. 5 shows a cross-sectional view taken along line BB in Fig. 2 as a diagram illustrating a cross section of the second transverse sipes 22. As shown in Fig. 5, each of the second transverse sipes 22 includes a first sipe wall 22a located on a first side A1 in the tire circumferential direction and a second sipe wall 22b located on a second side A2 in the tire circumferential direction. Each of the multiple second transverse sipes 22 opens at the tread surface via a chamfered portion 37.

[0042] The chamfered portion 37 of the second transverse sipe 22 includes a first chamfered surface 37a that connects to the first sipe wall 22a and a second chamfered surface 37b that connects to the second sipe wall 22b. Also, as shown in Fig. 3, in a plan view of the first land portion 11, the chamfer width W3 of the first chamfered surface 37a of the second transverse sipe 22 is smaller than the chamfer width W4 of the second chamfered surface 37b. That is, in the second transverse sipe 22, the width of the chamfered surface located on the second side A2 in the tire circumferential direction is larger, and the size relationship of the chamfered surfaces is opposite to that of the first transverse sipe 21.

[0043] The tire 1 of this embodiment can improve both traction performance and braking performance on dry roads by virtue of such first lateral sipes 21 and second lateral sipes 22. That is, when the first chamfered surface 36a of the first lateral sipe 21 exerts a large gripping force during traction, the second chamfered surface 37b of the second lateral sipe 22 can exert a large gripping force during braking. Furthermore, even if the direction of rotation of the tire changes, the first lateral sipes 21 and the second lateral sipes 22 can alternate roles and exert the above-mentioned effects.

[0044] The chamfer width W3 of the first chamfered surface 37a of the chamfered portion 37 of the second transverse sipe 22 is constant over an area of ​​70% or more of the first sipe wall 22a in the sipe longitudinal direction. The chamfer width W4 of the second chamfered surface 37b of the chamfered portion 37 of the second transverse sipe 22 is constant over an area of ​​70% or more of the second sipe wall 22b in the sipe longitudinal direction. In a more desirable embodiment, the chamfer width W3 and the chamfer width W4 are each constant over substantially the entire area of ​​the second transverse sipe 22. This ensures the above-described effects.

[0045] The first chamfered surface 37a of the second transverse sipe 22 can be applied to the configuration of the second chamfered surface 36b of the first transverse sipe 21 described above. Also, the second chamfered surface 37b of the second transverse sipe 22 can be applied to the configuration of the first chamfered surface 36a of the first transverse sipe 21 described above. Therefore, a specific description of each chamfered surface of the second transverse sipe 22 will be omitted.

[0046] FIG. 6 shows a cross-sectional view taken along line CC in FIG. 2 as a view showing a cross-section along the length of the first transverse sipe 21. FIG. 7 shows a cross-sectional view taken along line DD in FIG. 2 as a view showing a cross-section along the length of the second transverse sipe 22. As shown in FIGS. 6 and 7, the first transverse sipe 21 has a depth that increases toward the discontinuous end 21e. The second transverse sipe 22 has a constant depth along its length. The maximum depth d4 of the second transverse sipe 22 is preferably smaller than the maximum depth d3 of the first transverse sipe 21. Specifically, the depth d4 is 70% to 90% of the depth d3. Such first transverse sipes 21 and second transverse sipes 22 are useful for improving dry performance and wet performance in a well-balanced manner.

[0047] As shown in Fig. 2, the first transverse sipes 21 and the second transverse sipes 22 are preferably offset from each other in the tire circumferential direction. Specifically, in a plan view of the tread, it is desirable that a virtual area 41 (shown by dots in Fig. 2) obtained by extending the first transverse sipes 21 in their length direction does not overlap with the second transverse sipes 22. Similarly, in a plan view of the tread, it is desirable that a virtual area 42 (shown by dots in Fig. 2) obtained by extending the second transverse sipes 22 in their length direction does not overlap with the first transverse sipes 21. Such a sipe arrangement can further improve uneven wear resistance.

[0048] The second transverse sipes 22 are arranged, for example, at the same one-pitch length as the first transverse sipes 21. In this embodiment, each second transverse sipe 22 is arranged closer to the first transverse sipe 21 adjacent to the second side A2 in the tire circumferential direction than to the first transverse sipe 21 adjacent to the first side A1 in the tire circumferential direction. This brings the first chamfered surface 36a of the first transverse sipe 21 and the second chamfered surface 37b of the second transverse sipe 22 closer to each other, further improving uneven wear resistance. In addition, the minimum distance L10 in the tire circumferential direction between the end of the first transverse sipe 21 on the first edge 11a side and the end of the second transverse sipe 22 on the second edge 11b side is, for example, 30% or less of the one-pitch length P1 of the first transverse sipe 21 or the second transverse sipe 22 in the tire circumferential direction, and is preferably 15% to 25%.

[0049] In a more desirable embodiment, the first land portion 11 of this embodiment has no grooves or sipes except for the above-described first lateral sipes 21 and second lateral sipes 22. This allows the first land portion 11 to extend continuously in the tire circumferential direction. Such a first land portion 11 can further improve dry performance.

[0050] A plurality of first shallow grooves 26 are provided in the second land portion 12. The first shallow grooves 26 extend, for example, from the first circumferential groove 6 and have discontinuous ends 26e within the tread of the second land portion 12. The first shallow grooves 26 are inclined in the same direction with respect to the tire axial direction as the first lateral sipes 21 and the second lateral sipes 22. The angle of the first shallow grooves 26 with respect to the tire axial direction is, for example, 30 to 40°.

[0051] The axial length L5 of the first shallow grooves 26 is, for example, 40% to 60% of the axial width W8 of the tread surface of the second land portion 12. In a desirable embodiment, the length L5 of the first shallow grooves 26 is greater than the axial length L3 of the first lateral sipes 21. Such first shallow grooves 26 are useful for improving uneven wear resistance and wet performance.

[0052] FIG. 8 shows a cross section of the first shallow groove 26 taken along line EE in FIG. 2. As shown in FIG. 8, the depth d5 ​​of the first shallow groove 26 is, for example, 0.5 to 1.5 mm. The groove width W14 of the first shallow groove 26 is, for example, 1.5 to 2.5 mm. In a more desirable embodiment, the first shallow groove 26 has a V-shaped cross section in which two groove walls 26w inclined relative to the tire radial direction are connected. The angle θ3 between the two groove walls 26w is, for example, 80 to 100°. When cornering on a wet road, for example, the groove walls 26w come into contact with the ground as the land portion deforms due to an increase in ground pressure, and this can improve dry and wet performance.

[0053] As shown in Fig. 2, in a plan view of the tread, a virtual region 43 (shown by a dot in Fig. 2) formed by extending the first shallow groove 26 in its length direction preferably overlaps with the first lateral sipe 21. Such a first shallow groove 26 can further improve the dry performance and the wet performance.

[0054] The third land portion 13 is provided with a plurality of second shallow grooves 27. The second shallow grooves 27 extend, for example, from the second circumferential groove 7 and have discontinuous ends 27e within the tread of the third land portion 13. The axial length L6 of the second shallow grooves 27 is 5% to 15% of the axial width W9 of the tread of the third land portion 13. In a desirable embodiment, the length L6 of the second shallow grooves 27 is shorter than the length L4 of the second lateral sipes 22. Such second shallow grooves 27 can improve dry performance while suppressing uneven wear of the third land portion 13.

[0055] The cross-sectional configuration of the first shallow groove 26 described above can be applied to the cross-sectional configuration of the second shallow groove 27. Therefore, a description of the cross-section of the second shallow groove 27 will be omitted.

[0056] It is desirable that the second lateral sipes 22 and the second shallow grooves 27 are misaligned in the tire circumferential direction. Specifically, in a plan view of the tread, a virtual region 44 formed by extending the second shallow grooves 27 in the length direction does not overlap with the second lateral sipes 22. This further improves uneven wear resistance.

[0057] In this embodiment, the third land portion 13 is provided with a plurality of first lateral grooves 31. For example, the first lateral grooves 31 extend so as to cross at least the second tread edge T2, and have discontinuous ends 31e within the third land portion 13. Such first lateral grooves 31 can improve uneven wear resistance and wet performance.

[0058] FIG. 9 shows a cross-sectional view taken along line FF in FIG. 2. As shown in FIG. 9, each first lateral groove 31 has a chamfered portion 38. The chamfered portion 38 includes a small-width chamfered surface 38a and a large-width chamfered surface 38b between the tread surface of the third land portion 13 and the groove wall 31w of the first lateral groove 31. The chamfer width W11 of the small-width chamfered surface 38a is smaller than the chamfer width W12 of the large-width chamfered surface 38b. Specifically, the chamfer width W11 is 40% to 60% of the chamfer width W12. The small-width chamfered surface 38a is located on the first circumferential side A1 of the large-width chamfered surface 38b. This arrangement of the chamfered surfaces allows for well-balanced enhancement of traction performance and braking performance on dry roads.

[0059] Fig. 10 shows an enlarged view of the fourth land portion 14 and the fifth land portion 15. As shown in Fig. 10, the fourth land portion 14 is provided with a plurality of third shallow grooves 28 and a plurality of third transverse sipes 23.

[0060] The third shallow grooves 28 extend, for example, from the third circumferential groove 8 and have discontinuous ends 28e within the fourth land portion 14. The axial length L7 of the third shallow grooves 28 is, for example, 15% to 25% of the tread width W13 of the fourth land portion 14. In a desirable aspect, the axial length L7 of the third shallow grooves 28 is shorter than the axial length L3 (shown in FIG. 2 ) of the first lateral sipes 21. Such third shallow grooves 28 can improve dry and wet performance while suppressing uneven wear of the fourth land portion 14.

[0061] The cross-sectional configuration of the third shallow groove 28 can be the same as that of the first shallow groove 26. Therefore, a description of the cross-section of the third shallow groove 28 will be omitted.

[0062] The third lateral sipes 23 extend, for example, from the fourth circumferential groove 9 and have a discontinued end 23e within the fourth land portion 14. The axial length L8 of the third lateral sipes 23 is 40% to 60% of the tread width W13 of the fourth land portion 14. In a desirable embodiment, the length L8 of the third lateral sipes 23 is greater than the axial length L3 (shown in FIG. 2 ) of the first lateral sipes 21. Such third lateral sipes 23 are useful for improving dry performance and wet performance in a well-balanced manner.

[0063] The third lateral sipes 23 open at the tread surface via chamfered portions 39. The chamfered portions 39 of the third lateral sipes 23 include two chamfered surfaces 40 that connect to each sipe wall. The chamfer width of each chamfered surface 40 increases continuously toward the fourth circumferential groove 9. The third lateral sipes 23 having such chamfered surfaces 40 can effectively guide a water film toward the fourth circumferential groove 9 when in contact with a wet road surface.

[0064] In a more desirable embodiment, the area of ​​one chamfered surface 46 is larger than the area of ​​the other chamfered surface 47. Furthermore, the one chamfered surface 46 is disposed on the first side A1 in the tire circumferential direction relative to the other chamfered surface 47. Such an arrangement of the chamfered surfaces 40, in cooperation with the first lateral sipes 21 and second lateral sipes 22, can improve braking performance and traction performance on dry roads in a well-balanced manner.

[0065] A plurality of second lateral grooves 32 are provided in the fifth land portion 15. The second lateral grooves 32 extend, for example, from the fourth circumferential groove 9 to a position beyond the first tread edge T1. Such second lateral grooves 32 can exhibit excellent wet performance.

[0066] The cross-sectional configuration of the second lateral grooves 32 can be the same as that of the first lateral grooves 31. In a preferred embodiment, the chamfered portion 50 of the second lateral grooves 32 includes a small-chamfered surface 50a and a large-chamfered surface 50b, and in the second lateral grooves 32, the large-chamfered surface 50b is located on the first circumferential side A1 of the small-chamfered surface 50a. This results in a difference in the positional relationship between the large-chamfered surface and the small-chamfered surface in the first lateral grooves 31 and 32, resulting in a balanced improvement in traction performance and braking performance on dry roads.

[0067] Although a tire according to one embodiment of the present disclosure has been described in detail above, the present disclosure is not limited to the above-described specific embodiment and can be modified and implemented in various aspects. [Example]

[0068] Pneumatic tires of size 235 / 35ZR19 having the basic pattern of FIG. 1 were prototyped based on the specifications in Table 1. Furthermore, as a comparative example, a tire was prototyped in which the first lateral sipe a, the second lateral sipe b, and the third lateral sipe c provided in the tread portion were not provided with chamfered portions, as shown in FIG. 11. The comparative tire was substantially the same as the example tire, except for the above-mentioned features. Furthermore, these test tires were tested for uneven wear resistance, as well as braking performance and traction performance on dry roads. The common specifications and test methods for each test tire are as follows: Rim: 19 x 8.0J Tire pressure: 260kPa on all wheels Test vehicle: 2000cc, 4-wheel drive Tire mounting position: All wheels

[0069] <Uneven wear resistance> After the test vehicle was driven a certain distance, the remaining land height of the first land portion on the first lateral sipe side was measured. The results were expressed as an index with the remaining land height of the comparative example being 100, and the larger the value, the better the uneven wear resistance.

[0070] <Braking and traction performance on dry roads> The braking performance and traction performance of the test vehicle when driven on a dry road were evaluated by the driver. The results were evaluated as a score based on the braking performance or traction performance of the comparative example being 100, with a higher score indicating better braking performance or traction performance. The test results are shown in Table 1.

[0071] [Table 1]

[0072] As shown in Table 1, it can be seen that the tires of each example exhibit excellent uneven wear resistance. Furthermore, it was confirmed that the tires of each example have improved both braking performance and traction performance on dry roads by having different widths of the chamfered portions in the first lateral sipes and the second lateral sipes.

[0073] [Note] The present disclosure includes the following aspects.

[0074] [Disclosure 1] A tire having a tread portion, the tread portion includes a first land portion having a first edge extending in the tire circumferential direction, a second edge extending in the tire circumferential direction, and a tread surface formed therebetween, The first land portion is provided with a plurality of first lateral sipes extending in the tire axial direction, Each of the plurality of first lateral sipes includes a first sipe wall located on a first side in the tire circumferential direction and a second sipe wall located on a second side in the tire circumferential direction, Each of the plurality of first lateral sipes is open at the tread surface via a chamfered portion, The chamfered portion includes a first chamfered surface that is continuous with the first sipe wall and a second chamfered surface that is continuous with the second sipe wall, In a plan view of the first land portion, a chamfer width W1 of the first chamfered surface is larger than a chamfer width W2 of the second chamfered surface. tire. [Disclosure 2] The tire according to Disclosure 1, wherein the chamfer width W1 of the first chamfered surface is constant over a range of 70% or more of the first sipe wall in the sipe longitudinal direction. [Disclosure 3] The tire according to Disclosure 1 or 2, wherein the chamfer width W1 is 1.5 to 3.5 times the chamfer width W2. [Disclosure 4] The first land portion is provided with a plurality of second lateral sipes extending in the tire axial direction, The first lateral sipe communicates with the first edge, The second lateral sipe communicates with the second edge, The tire according to any one of Disclosures 1 to 3, wherein the first lateral sipes and the second lateral sipes are inclined in the same direction relative to the tire axial direction. [Disclosure 5] The first land portion is provided with a plurality of second lateral sipes extending in the tire axial direction, Each of the plurality of second lateral sipes includes a first sipe wall located on the first side in the tire circumferential direction and a second sipe wall located on the second side in the tire circumferential direction, Each of the plurality of second transverse sipes is open at the tread surface via a chamfered portion, The chamfered portion includes a first chamfered surface that is continuous with the first sipe wall and a second chamfered surface that is continuous with the second sipe wall, In a plan view of the first land portion, a chamfer width W3 of the first chamfered surface of the second transverse sipe is smaller than a chamfer width W4 of the second chamfered surface, Each of the plurality of first lateral sipes communicates with the first edge and has an interrupted end within the tread surface of the first land portion, The tire according to any one of Disclosures 1 to 4, wherein each of the plurality of second lateral sipes communicates with the second edge and has a discontinuous end within the tread surface of the first land portion. [Disclosure 6] the first land portion includes a first side wall on the first edge side and a second side wall on the second edge side, An obtuse angled corner portion is formed between the first side wall and the first sipe wall of the first lateral sipe, and between the second side wall and the second sipe wall of the second lateral sipe, in a tread plan view, A tire described in the present disclosure 5, wherein acute corner portions are formed between the first side wall and the second sipe wall of the first lateral sipe, and between the second side wall and the first sipe wall of the second lateral sipe, respectively, in a plan view of the tread. [Disclosure 7] The tire according to any one of Disclosures 4 to 6, wherein the maximum depth of the second lateral sipes is smaller than the maximum depth of the first lateral sipes. [Disclosure 8] The tread portion includes a first tread edge that is located on the outer side of the vehicle when mounted on the vehicle, a second tread edge that is located on the inner side of the vehicle when mounted on the vehicle, four circumferential grooves that extend continuously in the tire circumferential direction between the first tread edge and the second tread edge, and five land portions that are divided by the four circumferential grooves, the five land portions include a second land portion disposed on the tire equator and a third land portion including the second tread edge, the first land portion is provided between the second land portion and the third land portion, The tire according to any one of the first to seventh disclosures, wherein the first edge is located closer to the tire equator than the second edge. [Disclosure 9] the circumferential groove includes a first circumferential groove between the first land portion and the second land portion, The second land portion is provided with a plurality of first shallow grooves extending from the first circumferential groove and having discontinued ends within the tread surface of the second land portion, In a plan view of the tread, a virtual area obtained by extending the plurality of first shallow grooves in the length direction overlaps with the first lateral sipe, The tire according to Disclosure 8, wherein the axial length of the first shallow groove is greater than the axial length of the first lateral sipe. [Disclosure 10] the circumferential groove includes a second circumferential groove between the first land portion and the third land portion, The first land portion is provided with a plurality of second lateral sipes that communicate with the second edge and have interrupted ends within the tread surface of the first land portion, The third land portion is provided with a plurality of second shallow grooves extending from the second circumferential groove and having discontinued ends within the tread surface of the third land portion, In a plan view of the tread, a virtual area obtained by extending the plurality of second shallow grooves in the length direction does not overlap with the second lateral sipe, The tire according to Disclosure 8 or 9, wherein the axial length of the second shallow groove is shorter than the axial length of the second lateral sipe. [Disclosure 11] The first land portion is provided with a plurality of second lateral sipes extending in the tire axial direction, The tire according to any one of claims 8 to 10, wherein the axial length of the first lateral sipes is greater than the axial length of the second lateral sipes. [Explanation of symbols]

[0075] 2 Tread section 11a First Edge 11b Second Edge 11s tread 21 First horizontal sipe 21a 1st sipe wall 21b Second sipe wall 36 Chamfered part 36a First chamfered surface 36b Second chamfered surface W1 Chamfer width of the first chamfer W2 Chamfer width of second chamfer

Claims

1. A tire having a tread portion, the tread portion includes a first land portion having a first edge extending in the tire circumferential direction, a second edge extending in the tire circumferential direction, and a tread surface formed therebetween, The first land portion is provided with a plurality of first lateral sipes extending in the tire axial direction, Each of the plurality of first lateral sipes includes a first sipe wall located on a first side in the tire circumferential direction and a second sipe wall located on a second side in the tire circumferential direction, Each of the plurality of first lateral sipes is open at the tread surface via a chamfered portion, the chamfered portion includes a first chamfered surface that is continuous with the first sipe wall and a second chamfered surface that is continuous with the second sipe wall, In a plan view of the first land portion, a chamfer width W1 of the first chamfered surface is larger than a chamfer width W2 of the second chamfered surface, The tread portion includes a first tread edge that is located on the outer side of the vehicle when mounted on the vehicle, a second tread edge that is located on the inner side of the vehicle when mounted on the vehicle, four circumferential grooves that extend continuously in the tire circumferential direction between the first tread edge and the second tread edge, and five land portions that are divided by the four circumferential grooves, the five land portions include a second land portion disposed on the tire equator and a third land portion including the second tread edge, the first land portion is provided between the second land portion and the third land portion, the first edge is located closer to the tire equator than the second edge, the circumferential groove includes a first circumferential groove between the first land portion and the second land portion, The second land portion is provided with a plurality of first shallow grooves extending from the first circumferential groove and having discontinued ends within the tread surface of the second land portion, In a plan view of the tread, a virtual region obtained by extending the plurality of first shallow grooves in the length direction overlaps with the first lateral sipe, The length of the first shallow groove in the tire axial direction is greater than the length of the first lateral sipe in the tire axial direction. tire.

2. A tire having a tread portion, the tread portion includes a first land portion having a first edge extending in the tire circumferential direction, a second edge extending in the tire circumferential direction, and a tread surface formed therebetween, The first land portion is provided with a plurality of first lateral sipes extending in the tire axial direction, Each of the plurality of first lateral sipes includes a first sipe wall located on a first side in the tire circumferential direction and a second sipe wall located on a second side in the tire circumferential direction, Each of the plurality of first lateral sipes is open at the tread surface via a chamfered portion, the chamfered portion includes a first chamfered surface that is continuous with the first sipe wall and a second chamfered surface that is continuous with the second sipe wall, In a plan view of the first land portion, a chamfer width W1 of the first chamfered surface is larger than a chamfer width W2 of the second chamfered surface, The tread portion includes a first tread edge that is located on the outer side of the vehicle when mounted on the vehicle, a second tread edge that is located on the inner side of the vehicle when mounted on the vehicle, four circumferential grooves that extend continuously in the tire circumferential direction between the first tread edge and the second tread edge, and five land portions that are divided by the four circumferential grooves, the five land portions include a second land portion disposed on the tire equator and a third land portion including the second tread edge, the first land portion is provided between the second land portion and the third land portion, the first edge is located closer to the tire equator than the second edge, the circumferential groove includes a second circumferential groove between the first land portion and the third land portion, The first land portion is provided with a plurality of second lateral sipes that communicate with the second edge and have interrupted ends within the tread surface of the first land portion, The third land portion is provided with a plurality of second shallow grooves that extend from the second circumferential groove and have discontinued ends within the tread surface of the third land portion, In a plan view of the tread, a virtual region obtained by extending the plurality of second shallow grooves in the length direction does not overlap with the second lateral sipe, The length of the second shallow groove in the tire axial direction is shorter than the length of the second lateral sipe in the tire axial direction. tire.

3. The first land portion is provided with a plurality of second lateral sipes extending in the tire axial direction, The tire according to claim 1 or 2, wherein the axial length of the first lateral sipes is greater than the axial length of the second lateral sipes.

4. The first land portion is provided with a plurality of second lateral sipes extending in the tire axial direction, The first lateral sipe communicates with the first edge, The second lateral sipe communicates with the second edge, The tire according to claim 1 , wherein the first lateral sipes and the second lateral sipes are inclined in the same direction relative to the tire axial direction.

5. A tire having a tread portion, the tread portion includes a first land portion having a first edge extending in the tire circumferential direction, a second edge extending in the tire circumferential direction, and a tread surface formed therebetween, The first land portion is provided with a plurality of first lateral sipes extending in the tire axial direction, Each of the plurality of first lateral sipes includes a first sipe wall located on a first side in the tire circumferential direction and a second sipe wall located on a second side in the tire circumferential direction, Each of the plurality of first lateral sipes is open at the tread surface via a chamfered portion, the chamfered portion includes a first chamfered surface that is continuous with the first sipe wall and a second chamfered surface that is continuous with the second sipe wall, In a plan view of the first land portion, a chamfer width W1 of the first chamfered surface is larger than a chamfer width W2 of the second chamfered surface, The first land portion is provided with a plurality of second lateral sipes extending in the tire axial direction, Each of the plurality of second lateral sipes includes a first sipe wall located on the first side in the tire circumferential direction and a second sipe wall located on the second side in the tire circumferential direction, Each of the plurality of second lateral sipes is open at the tread surface via a chamfered portion, the chamfered portion includes a first chamfered surface that is continuous with the first sipe wall and a second chamfered surface that is continuous with the second sipe wall, In a plan view of the first land portion, a chamfer width W3 of the first chamfered surface of the second transverse sipe is smaller than a chamfer width W4 of the second chamfered surface, Each of the plurality of first lateral sipes communicates with the first edge and has an interrupted end within the tread surface of the first land portion, Each of the plurality of second lateral sipes communicates with the second edge and has a discontinuous end within the tread surface of the first land portion. tire.

6. the first land portion includes a first sidewall on the first edge side and a second sidewall on the second edge side, an obtuse angled corner portion is formed between the first side wall and the first sipe wall of the first lateral sipe, and between the second side wall and the second sipe wall of the second lateral sipe, in a tread plan view; 6. The tire according to claim 5, wherein an acute angle is formed between the first side wall and the second sipe wall of the first lateral sipe, and between the second side wall and the first sipe wall of the second lateral sipe, in a tread plan view.

7. The tire according to claim 4 , wherein a maximum depth of the second lateral sipes is smaller than a maximum depth of the first lateral sipes.

8. A tire described in any one of claims 1 to 7, wherein the chamfer width W1 of the first chamfered surface is constant over a range of 70% or more of the sipe longitudinal direction of the first sipe wall.

9. A tire described in any one of claims 1 to 8, wherein the chamfer width W1 is 1.5 to 3.5 times the chamfer width W2.

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