tire

Abstract

To provide a tire further improved in on-ice performance and on-snow performance.SOLUTION: A tire 1 comprises a tread part 2. The tread part 2 includes a first land part 4 and first lateral grooves 6 extending in a tire axis direction on the first land part 4. A pair of groove edges 7 and 7 of the first lateral grooves 6 respectively include trough parts 10 protruding toward groove-width center lines 6c of the first lateral grooves 6 and crest parts 11 protruding in a direction in which the parts get away from the groove-width center lines 6c. The respective trough parts 10 of the pair of groove edges 7 and 7 are arranged at substantially same positions in a longitudinal direction of the groove-width center lines 6c. The respective crest parts 11 of the pair of groove edges 7 and 7 are arranged at the substantially same positions in the longitudinal direction of the groove-width center lines 6c.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 below describes a pneumatic tire that is expected to have improved performance on snow. This pneumatic tire includes at least one longitudinal groove, multiple lateral grooves, multiple sipes, a first semi-blind groove that intersects with the sipe and opens into one of the lateral grooves, and a second semi-blind groove that intersects with the sipe and opens into the other lateral groove. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-18450 A Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a demand for further improvements in the performance on ice and snow of such tires.

[0005] The present disclosure has been devised in view of the above circumstances, and has as its main object to provide a tire that can further improve performance on ice and snow. [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 and a first lateral groove extending through the first land portion in the tire axial direction, the first lateral groove including a pair of groove edges extending in a wave-like manner on the tread surface of the first land portion, each of the pair of groove edges including a valley portion that is convex toward a groove width center line of the first lateral groove and a peak portion that is convex away from the groove width center line, the valley portions of each of the pair of groove edges being arranged at substantially the same position in the longitudinal direction of the groove width center line, and the peak portions of each of the pair of groove edges being arranged at substantially the same position in the longitudinal direction of the groove width center line. [Effects of the Invention]

[0007] By employing the above-described configuration, the tire of the present disclosure can further improve its performance on ice and on snow. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a plan view of a first land portion according to an embodiment of the present disclosure. [Figure 2] FIG. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] FIG. [Figure 6] FIG. [Figure 7] FIG. [Figure 8] 10(a) is a plan view of a first land portion of another embodiment, and FIG. 10(b) is a plan view of a first land portion of yet another embodiment. [Figure 9] 10(a) is a plan view of a first land portion of still another embodiment, and FIG. 10(b) is a plan view of a first land portion of still another embodiment. [Figure 10] FIG. 10 is a plan view of a first land portion according to still another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is an enlarged plan view of a tread portion 2 of a tire 1 according to this embodiment. The present disclosure is suitable for use as, for example, a winter tire. In this specification, the term "winter tire" refers to a tire 1 suitable for driving on snow or ice, including studless tires, snow tires, and all-season tires. The present disclosure may also be applied to pneumatic tires 1 for passenger cars and heavy-duty vehicles, as well as tires 1 of other categories.

[0010] As shown in FIG. 1, the tread portion 2 of this embodiment includes a first land portion 4 and a first lateral groove 6 extending through the first land portion 4 in the tire axial direction. In this specification, the term "extending in the tire axial direction" includes the first lateral groove 6 having a groove width center line 6c inclined so as to have an axial component. The angle θ1 of the groove width center line 6c relative to the tire axial direction is preferably 45 degrees or less, more preferably 30 degrees or less, and even more preferably 15 degrees or less. In this embodiment, the angle θ1 is 0 degrees.

[0011] The first lateral grooves 6 include a pair of groove edges 7, 7 that extend in a wave-like pattern on the tread surface 4a of the first land portion 4. Each of the pair of groove edges 7, 7 includes a valley portion 10 that is convex toward the groove width center line 6c of the first lateral groove 6, and a peak portion 11 that is convex in a direction away from the groove width center line 6c. Such first lateral grooves 6 have a larger edge length per unit groove length than those having straight groove edges (not shown), and the increased edge length improves on-ice performance.

[0012] The valleys 10 of each pair of groove edges 7, 7 are arranged at substantially the same position in the longitudinal direction of the groove width centerline 6c. The peaks 11 of each pair of groove edges 7, 7 are arranged at substantially the same position in the longitudinal direction of the groove width centerline 6c. As a result, in a plan view of the tread, the first lateral grooves 6 include a portion (shown by imaginary lines in FIG. 1) that is formed like a cross, which exerts a large snow column shear force in the tire axial and circumferential directions, improving on-snow performance. In this embodiment, the valleys 10 of each pair of groove edges 7, 7 are arranged at the same position in the longitudinal direction of the groove width centerline 6c. In this embodiment, the peaks 11 of each pair of groove edges 7, 7 are arranged at the same position in the longitudinal direction of the groove width centerline 6c.

[0013] The phrase "substantially the same position" means that the longitudinal separation distance La between the apexes 10a, 10a of the valley portions 10 of each groove edge 7 and the longitudinal separation distance Lb between the apexes 11a, 11a of the peak portions 11 of each groove edge 7 and the groove width center line 6c is 10% or less of the separation distance L1 between the apexes 10a, 11a. In this specification, the valley portions 10 and the peak portions 11 are separated by a midpoint t between the apex 10a of the valley portion 10 and the apex 11a of the peak portion 11. The midpoint t is determined in a direction perpendicular to the groove width center line 6c.

[0014] Each of the pair of groove edges 7, 7 includes a plurality of wave patterns 12 in one cycle, in which valleys 10 and peaks 11 are alternately arranged. This makes the above-mentioned effect even more effective. In this embodiment, each of the pair of groove edges 7, 7 has two wave patterns 12.

[0015] In this embodiment, the wave pattern 12 is formed in a sinusoidal wave shape. In this specification, the sinusoidal wave shape refers to a shape in which the valleys 10 and peaks 11 are each formed in an arc shape and are smoothly connected.

[0016] The first lateral grooves 6, for example, completely cross the first land portion 4. Such first lateral grooves 6 exert an even greater snow column shear force.

[0017] Both ends 6e, 6e of the first lateral grooves 6 are, for example, other than the peaks 11. This prevents a decrease in the land rigidity of the first land portions 4, thereby maintaining high steering stability. Furthermore, such first lateral grooves 6 reduce noise due to air column resonance generated from the first lateral grooves 6. In this embodiment, the both ends 6e, 6e are the valleys 10 excluding the peaks 10a of the valleys 10.

[0018] The first lateral grooves 6 include a maximum groove width portion 13 where the groove width is maximum, and a minimum groove width portion 14 where the groove width is minimum. The maximum groove width portion 13 is formed, for example, between the apexes 11a, 11a of both crest portions 11 of each groove edge 7. The minimum groove width portion 14 is formed, for example, between the apexes 10a, 10a of both valley portions 10 of each groove edge 7. The groove width (minimum groove width) Wm of the minimum groove width portion 14 is preferably 30% or more, more preferably 35% or more, more preferably 50% or less, and even more preferably 45% or less of the groove width (maximum groove width) Wx of the maximum groove width portion 13. The maximum groove width Wx is preferably 10% or more, more preferably 15% or more, more preferably 30% or less, and even more preferably 25% or less of the width Wa of the first land portion 4 in the tire axial direction.

[0019] The first pitch P1 between adjacent valley portions 10, 10 in the longitudinal direction of the groove width centerline 6c is formed at the same pitch as the second pitch P2 between adjacent peak portions 11, 11 in the longitudinal direction of the groove width centerline 6c. In this specification, the term "same" means that the absolute value |P1-P2| of the difference between the first pitch P1 and the second pitch P2 is not necessarily 0 mm, but is preferably 5 mm or less, and more preferably 3 mm or less. The first pitch P1 and the second pitch P2 are preferably 200% or more of the maximum groove width Wx, more preferably 230% or more, more preferably 350% or less, and even more preferably 320% or less. Such first lateral grooves 6 further improve on-snow performance while maintaining steering stability.

[0020] Although not particularly limited, the groove depth (not shown) of the first transverse grooves 6 is, for example, 6.0 to 9.0 mm.

[0021] 2 is a plan view showing the entire tire axial direction of the tread portion 2. The mounting orientation of the tread portion 2 on a vehicle is specified in this embodiment. As shown in FIG. 2, the tread portion 2 has a first tread edge T1 located on the outer side of the vehicle when the tire 1 is mounted on the vehicle, and a second tread edge T2 located on the inner side of the vehicle.

[0022] In the case of a pneumatic tire, the first tread edge T1 and the second tread edge T2 are the axially outermost contact points when the tire 1 in a normal state is loaded with a normal load and contacts the ground flatly with a camber angle of 0°. The "normal state" refers to a state in which the tire 1 is mounted on a normal rim (not shown), inflated to a normal internal pressure, and no load is applied. Unless otherwise specified, the dimensions of each part of the tire 1 in this specification are values ​​measured in the normal state. The axial distance between the first tread edge T1 and the second tread edge T2 is the tread width TW.

[0023] The "genuine rim" is a rim that is defined for each tire by a standard system that includes the standard on which tire 1 is based, such as a "standard rim" for JATMA, a "design rim" for TRA, or a "measuring rim" for ETRTO.

[0024] The "normal internal pressure" is the air pressure determined for each tire by each standard in a standard system including the standard on which tire 1 is based, and is the "maximum air pressure" in the case of JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the case of TRA, and the "INFLATION PRESSURE" in the case of ETRTO.

[0025] The "normal load" is the load determined for each tire by each standard in the standard system including the standard on which tire 1 is based, and is the "maximum load capacity" in the case of JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the case of TRA, and the "LOAD CAPACITY" in the case of ETRTO.

[0026] The tread portion 2 of this embodiment includes an outer shoulder main groove 3A, an outer crown main groove 3B, an inner crown main groove 3C, and an inner shoulder main groove 3D. The outer shoulder main groove 3A is located closest to the first tread edge T1. The inner shoulder main groove 3D is located closest to the second tread edge T2. The outer crown main groove 3B is located between the outer shoulder main groove 3A and the tire equator C. The inner crown main groove 3C is located between the inner shoulder main groove 3D and the tire equator C.

[0027] In this embodiment, the outer shoulder main groove 3A, inner crown main groove 3C, and inner shoulder main groove 3D extend linearly and parallel to the tire circumferential direction. The outer crown main groove 3B extends, for example, in a zigzag pattern in the tire circumferential direction. The outer crown main groove 3B includes a first portion 19a inclined to one side with respect to the tire circumferential direction and a second portion 19b connected to the first portion 19a and inclined in the opposite direction to the first portion 19a. The first portions 19a and the second portions 19b are alternately arranged in the tire circumferential direction. The tire circumferential length L10 of the first portion 19a is preferably 15% or more of the tread width TW, more preferably 20% or more, more preferably 35% or less, and even more preferably 30% or less. The tire circumferential length L11 of the second portion 19b is preferably 2% or more of the length L10 of the first portion 19a, more preferably 3% or more, more preferably 7% or less, and even more preferably 6% or less. Although not particularly limited, the angle α1 of the first portion 19a with respect to the tire circumferential direction is preferably 2 degrees or more, more preferably 3 degrees or more, and is preferably 10 degrees or less, and even more preferably 9 degrees or less.

[0028] The groove width W3 of the inner crown main groove 3C is larger than the groove width W1 of the outer shoulder main groove 3A, the groove width W2 of the outer crown main groove 3B, and the groove width W4 of the inner shoulder main groove 3D. The groove width W3 of the inner crown main groove 3C is preferably 2% or more of the tread width TW, more preferably 3% or more, and preferably 6% or less, and even more preferably 5% or less. The groove width W1 of the outer shoulder main groove 3A, the groove width W2 of the outer crown main groove 3B, and the groove width W4 of the inner shoulder main groove 3D are preferably 50% or more of the groove width W3 of the inner crown main groove 3C, more preferably 60% or more, and preferably 90% or less, and even more preferably 80% or less.

[0029] The tread portion 2 includes, for example, an outer shoulder land portion 5A, an outer middle land portion 5B, a crown land portion 5C, an inner middle land portion 5D, and an inner shoulder land portion 5E. The outer shoulder land portion 5A includes a first tread edge T1 and is separated by the first tread edge T1 and the outer shoulder main groove 3A. The outer middle land portion 5B is separated by the outer shoulder main groove 3A and the outer crown main groove 3B. The crown land portion 5C is separated by the outer crown main groove 3B and the inner crown main groove 3C. The inner middle land portion 5D is separated by the inner crown main groove 3C and the inner shoulder main groove 3D. The inner shoulder land portion 5E is separated by the inner shoulder main groove 3D and the second tread edge T2.

[0030] The maximum axial width Wa of the outer shoulder land portion 5A is larger than the maximum axial widths Wb and We of the outer middle land portion 5B, crown land portion 5C, inner middle land portion 5D, and inner shoulder land portion 5E. The maximum widths Wb and We of the outer middle land portion 5B and inner shoulder land portion 5E are larger than the maximum widths Wc and Wd of the crown land portion 5C and inner middle land portion 5D. However, the maximum widths Wa and We of the land portions 5A to 5E are not limited to these.

[0031] Although not particularly limited, the maximum width Wa of the outer shoulder land portion 5A is preferably 15% or more of the tread width TW, more preferably 20% or more, and preferably 35% or less, and even more preferably 30% or less. The maximum width Wb of the outer middle land portion 5B and the maximum width We of the inner shoulder land portion 5E are preferably 70% or more of the maximum width Wa of the outer shoulder land portion 5A, more preferably 75% or more, and preferably 95% or less, and even more preferably 90% or less. The maximum width Wc of the crown land portion 5C and the maximum width Wd of the inner middle land portion 5D are preferably 45% or more of the maximum width Wa of the outer shoulder land portion 5A, more preferably 50% or more, and preferably 65% ​​or less, and even more preferably 69% or less.

[0032] In this embodiment, the first land portion 4 is formed in the outer shoulder land portion 5A (shown in FIG. 3). The outer shoulder land portion 5A is a land portion that receives a relatively large lateral force compared to the other land portions 5B to 5E. By using the first lateral grooves 6 located in the outer shoulder land portion 5A in the manner described herein, on-snow performance can be more effectively improved. Note that the first lateral grooves 6 are not limited to those formed in the outer shoulder land portion 5A, and may be formed in the inner shoulder land portion 5E, for example. Even in this case, on-snow performance during cornering is improved. The first land portion 4 may also be formed in the other land portions 5B to 5D.

[0033] Figure 3 is a plan view of the outer shoulder land portion 5A. As shown in Figure 3, the outer shoulder land portion 5A is divided into outer shoulder blocks B1 by multiple first lateral grooves 6. In this embodiment, each outer shoulder block B1 is provided with an outer shoulder longitudinal narrow groove 20 that runs longitudinally through the outer shoulder block B1. The outer shoulder longitudinal narrow groove 20 extends from each of the first lateral grooves 6 located on both sides in the tire circumferential direction and includes a pair of main portions 20a, 20a that are inclined to one side with respect to the tire circumferential direction, and a sub-portion 20b that connects the pair of main portions 20a and is inclined in the opposite direction to the main portions 20a.

[0034] The outer shoulder longitudinal narrow groove 20 is located at the axial middle c1 of the outer shoulder land portion 5A. The middle c1 of the outer shoulder land portion 5A refers to a position axially spaced 40% to 60% of the maximum width Wa of the outer shoulder land portion 5A from the first tread edge T1 toward the tire equator C. The groove width W6 of the outer shoulder longitudinal narrow groove 20 is preferably 5% or more of the maximum groove width Wx of the first lateral groove 6, more preferably 10% or more, and more preferably 25% or less, and even more preferably 20% or less.

[0035] The circumferential length L8 of the main portion 20a is preferably 40% or more of the maximum circumferential length L7 of the outer shoulder block B1, more preferably 45% or more, and preferably 60% or less, and more preferably 55% or less. The angle θ4 of the main portion 20a with respect to the axial direction of the tire is preferably 2 degrees or more, more preferably 3 degrees or more, and preferably 8 degrees or less, and more preferably 7 degrees or less. The circumferential length L9 of the sub-portion 20b is preferably 5% or more of the length L8 of the main portion 20a, more preferably 7% or more, and preferably 15% or less, and more preferably 13% or less.

[0036] Fig. 4 is a plan view of the outer middle land portion 5B. As shown in Fig. 4, the outer middle land portion 5B of this embodiment is provided with a first outer middle lateral groove 21 that crosses the outer middle land portion 5B and a second outer middle lateral groove 22 that extends from the outer crown main groove 3B toward the first tread edge T1. As a result, the outer middle land portion 5B is divided into a plurality of outer middle blocks B2 that are divided into the outer shoulder main grooves 3A, the outer crown main grooves 3B, and the first outer middle lateral groove 21.

[0037] In this embodiment, the first outer middle lateral groove 21 includes a first outer middle portion 21a connected to the outer crown main groove 3B, a second outer middle portion 21b connected to the outer shoulder main groove 3A, and a third outer middle portion 21c connecting the first outer middle portion 21a and the second outer middle portion 21b. The first outer middle portion 21a and the second outer middle portion 21b are inclined, for example, to one side (upward and to the left in the figure) with respect to the tire axial direction. The third outer middle portion 21c is formed with a groove width larger than that of the first outer middle portion 21a and the second outer middle portion 21b.

[0038] The absolute value of the difference |θ5a-θ5b| between the angle θ5a of the first outer middle portion 21a relative to the tire axial direction and the angle θ5b of the second outer middle portion 21b relative to the tire axial direction is preferably 20 degrees or less, and more preferably 10 degrees or less. The angle θ5a of the first outer middle portion 21a and the angle θ5b of the second outer middle portion 21b are preferably, for example, 10 degrees or more, more preferably 15 degrees or more, and preferably 30 degrees or less, and more preferably 25 degrees or less.

[0039] The maximum groove width W10 of the first outer middle lateral groove 21 is, for example, smaller than the maximum groove width Wx (shown in FIG. 3) of the first lateral groove 6. The maximum groove width W10 of the first outer middle lateral groove 21 is preferably 50% or more of the maximum groove width Wx of the first lateral groove 6, more preferably 55% or more, and more preferably 70% or less, and even more preferably 65% ​​or less.

[0040] The second outer middle lateral grooves 22 have a groove width that continuously decreases from the outer crown main groove 3B toward the first tread edge T1. The second outer middle lateral grooves 22 have ends that terminate within the outer middle land portion 5B, for example.

[0041] In this embodiment, the second outer middle lateral grooves 22 are inclined in the same direction as the first outer middle portion 21a. The absolute value |θ6-θ5a| of the difference between the angle θ6 of the second outer middle lateral grooves 22 relative to the tire axial direction and the angle θ5a of the first outer middle portion 21a is preferably 20 degrees or less, and more preferably 10 degrees or less.

[0042] The axial length L10 of the second outer middle lateral grooves 22 is preferably 35% or more, more preferably 40% or more, and preferably 55% or less, and more preferably 50% or less of the maximum width Wb of the outer middle land portion 5B. The maximum groove width W11 of the second outer middle lateral grooves 22 is preferably 60% or more, more preferably 65% ​​or more, and preferably 80% or less, and more preferably 75% or less of the maximum groove width W10 of the first outer middle lateral grooves 21.

[0043] FIG. 5 is a plan view of a crown land portion 5C. As shown in FIG. 5, the crown land portion 5C of this embodiment includes a first crown lateral groove 23, a second crown lateral groove 24, and a third crown lateral groove 25. The first crown lateral groove 23 traverses the crown land portion 5C. This divides the crown land portion 5C into crown blocks B3, each divided by the outer crown main groove 3B, the inner crown main groove 3C, and the first crown lateral groove 23. The second crown lateral groove 24 connects to the outer crown main groove 3B and terminates within the crown land portion 5C. The third crown lateral groove 25 connects to the inner crown main groove 3C and terminates within the crown land portion 5C. For example, each of the second crown lateral groove 24 and the third crown lateral groove 25 is arranged one by one in the crown block B3.

[0044] The first crown lateral grooves 23 include a first crown portion 23a whose groove width W12 continuously decreases from the outer crown main groove 3B toward the second tread edge T2, and a second crown portion 23b that is inclined toward the other side (upward to the right in the drawing) with respect to the tire axial direction. The second crown portion 23b connects the first crown portion 23a to the inner crown main groove 3C, for example.

[0045] The first crown portion 23a extends, for example, so as to be located on an imaginary line 22K extending from one of the groove edges 22e of the second outer middle lateral grooves 22. In this embodiment, the imaginary line 22K is located on the intersection of the first crown portion 23a and the outer crown main groove 3B. The first crown portion 23a, together with the second outer middle lateral groove 22 and the outer crown main groove 3B, forms a single imaginary lateral groove, improving on-snow performance.

[0046] The second crown lateral grooves 24 extend so as to be located on an imaginary line 21K that is an extension of the groove width centerline 21s of the first outer middle lateral groove 21 toward the second tread edge T2. The imaginary line 21K is located on the intersection of the second crown lateral groove 24 and the outer crown main groove 3B. The second crown lateral grooves 24, together with the first outer middle lateral groove 21 and the outer crown main groove 3B, form a single imaginary lateral groove, improving on-snow performance. The groove width of the second crown lateral grooves 24 continuously decreases from the outer crown main groove 3B toward the second tread edge T2.

[0047] The second crown lateral grooves 24 and the third crown lateral grooves 25 are located at a circumferential intermediate position c2 of the crown block B3. The intermediate position c2 is located 50% of the circumferential maximum length L11 of the crown block B3 from one circumferential end b1 of the crown block B3. The axial length L12 of the second crown lateral grooves 24 and the axial length L13 of the third crown lateral grooves 25 are preferably 15% or more of the maximum width Wc of the crown land portion 5C, more preferably 20% or more, and more preferably 35% or less, and even more preferably 30% or less.

[0048] Fig. 6 is a plan view of the inner middle land portion 5D. As shown in Fig. 6, the inner middle land portion 5D of this embodiment includes a first inner middle lateral groove 26 that crosses the inner middle land portion 5D and a second inner middle lateral groove 27 that crosses the inner middle land portion 5D and has a groove width smaller than that of the first inner middle lateral groove 26.

[0049] The first inner middle lateral groove 26 extends, for example, linearly. The first inner middle lateral groove 26 is inclined, for example, in the same direction as the first outer middle lateral groove 21 (shown in FIG. 4). The angle θ9 of the first inner middle lateral groove 26 with respect to the tire axial direction is preferably 20 degrees or more, more preferably 25 degrees or more, and preferably 40 degrees or less, and more preferably 35 degrees or less. The groove width W15 of the first inner middle lateral groove 26 is, for example, smaller than the maximum groove width Wx (shown in FIG. 1) of the first lateral groove 6. The groove width W15 of the first inner middle lateral groove 26 is preferably 40% or more of the maximum groove width Wx of the first lateral groove 6, more preferably 45% or more, and more preferably 60% or less, and more preferably 55% or less.

[0050] The second inner middle lateral groove 27 includes, for example, a first inner middle portion 27a, a second inner middle portion 27b, and a third inner middle portion 27c. The first inner middle portion 27a extends, for example, from the inner crown main groove 3C toward the second tread edge T2 and is inclined in the opposite direction to the first inner middle lateral groove 26. The second inner middle portion 27b extends, for example, from the inner shoulder main groove 3D toward the first tread edge T1 and is inclined in the same direction as the first inner middle portion 27a. The third inner middle portion 27c connects, for example, the first inner middle portion 27a and the second inner middle portion 27b and is inclined in the opposite direction to the first inner middle portion 27a.

[0051] The groove width W16 of the first inner middle portion 27a and the groove width W17 of the second inner middle portion 27b are larger than the groove width W18 of the third inner middle portion 27c. The groove width W16 of the first inner middle portion 27a and the groove width W17 of the second inner middle portion 27b are preferably 1.5 times or more, more preferably 2.0 times or more, and preferably 3.5 times or less, and even more preferably 3.0 times or less, of the groove width W18 of the third inner middle portion 27c. Furthermore, the groove width W16 of the first inner middle portion 27a and the groove width W17 of the second inner middle portion 27b are preferably 65% ​​or more, more preferably 70% or more, and preferably 85% or less, and even more preferably 80% or less, of the groove width W15 of the first inner middle lateral groove 26.

[0052] The absolute value of the difference |θ10-θ11| between the angle θ10 of the first inner middle portion 27a relative to the tire axial direction and the angle θ11 of the second inner middle portion 27b relative to the tire axial direction is preferably 20 degrees or less, and more preferably 10 degrees or less. The angle θ10 of the first inner middle portion 27a and the angle θ11 of the second inner middle portion 27b are preferably, for example, 20 degrees or more, more preferably 25 degrees or more, and preferably 40 degrees or less, and more preferably 35 degrees or less. Although not particularly limited, the angle θ12 between the first inner middle portion 27a and the third inner middle portion 27c and the angle θ13 between the second inner middle portion 27b and the third inner middle portion 27c are preferably 80 degrees or more, more preferably 85 degrees or more, and preferably 100 degrees or less, and more preferably 95 degrees or less.

[0053] Fig. 7 is a plan view of the inner shoulder land portion 5E. As shown in Fig. 7, the inner shoulder land portion 5E of this embodiment is provided with a plurality of inner shoulder lateral grooves 28 that cross the inner shoulder land portion 5E, and an inner shoulder longitudinal narrow groove 29 that extends in the tire circumferential direction, connecting between circumferentially adjacent inner shoulder lateral grooves 28.

[0054] The inner shoulder lateral grooves 28 are formed, for example, with widened portions 28a in which the groove width W19 increases toward the second tread edge T2 and narrowed portions 28b in which the groove width W19 decreases toward the second tread edge T2, alternately arranged in the tire axial direction. In this embodiment, the inner shoulder lateral grooves 28 are inclined in the opposite direction to the first outer middle lateral grooves 21 (shown in FIG. 4).

[0055] The inner shoulder lateral groove 28 circumferentially overlaps, for example, the first inner middle lateral groove 26. In the present embodiment, the opening 28o of the inner shoulder lateral groove 28 at the inner shoulder main groove 3D overlaps, in the tire circumferential direction, with the opening 26o of the first inner middle lateral groove 26 at the inner shoulder main groove 3D.

[0056] The average groove width W19m of the inner shoulder lateral grooves 28 is smaller than, for example, the maximum groove width Wx (shown in FIG. 1) of the first lateral grooves 6. The average groove width W19m of the inner shoulder lateral grooves 28 is preferably 40% or more, more preferably 45% or more, and more preferably 60% or less, and even more preferably 55% or less of the maximum groove width Wx of the first lateral grooves 6. The average groove width W19m of the inner shoulder lateral grooves 28 is the average of the maximum and minimum values ​​of the inner shoulder lateral grooves 28.

[0057] The inner shoulder longitudinal narrow groove 29 extends, for example, linearly. The inner shoulder longitudinal narrow groove 29 extends parallel to the tire circumferential direction. The inner shoulder longitudinal narrow groove 29 is located at a middle point c3 of the inner shoulder land portion 5E in the tire axial direction. The middle point c3 of the inner shoulder land portion 5E refers to a position axially spaced from the second tread edge T2 toward the inner shoulder main groove 3D by 40% to 60% of the maximum width We of the inner shoulder land portion 5E.

[0058] Although not particularly limited, the groove width W20 of the inner shoulder longitudinal narrow groove 29 is preferably 10% or more of the average groove width W19m of the inner shoulder lateral grooves 28, more preferably 15% or more, and more preferably 30% or less, and even more preferably 25% or less.

[0059] As shown in FIG. 2, the outer shoulder land portion 5A, the outer middle land portion 5B, the crown land portion 5C, the inner middle land portion 5D, and the inner shoulder land portion 5E each have a plurality of sipes S. In this embodiment, the sipes S extend in a zigzag pattern. However, the sipes S may also extend linearly. In this specification, the sipes S are notched bodies having a width perpendicular to the longitudinal direction of less than 1.5 mm. Grooves including the outer shoulder longitudinal narrow groove 20 and the inner shoulder longitudinal narrow groove 29 are groove-shaped bodies having a width perpendicular to the longitudinal direction of more than 1.5 mm.

[0060] Fig. 8(a) is a plan view of a first land portion 4 of another embodiment. The same components as those of this embodiment are designated by the same reference numerals, and their description may be omitted. As shown in Fig. 8(a), the first land portion 4 of this embodiment also has first lateral grooves 6. The first lateral grooves 6 of this embodiment have trapezoidal corrugations 12 on their groove edges 7. These first lateral grooves 6 also improve performance on ice and on snow.

[0061] FIG. 8(b) is a plan view of a first land portion 4 of yet another embodiment. The same components as those of the present embodiment are designated by the same reference numerals, and their description may be omitted. As shown in FIG. 8(b), the first land portion 4 of this embodiment also has a first transverse groove 6. In this embodiment, the first transverse groove 6 has a groove edge 7 with a corrugation 12 that is arc-shaped. More specifically, in this embodiment, each groove edge 7 is formed with a plurality of arc portions 16 that are convex in a direction away from the groove width center line 6c and are aligned in the longitudinal direction. In this embodiment, the valley portion 10 is formed by connecting adjacent arc portions 16 in the longitudinal direction. The valley portion 10 is formed, for example, such that the length Le between the arc portions 16, 16 parallel to the groove width center line 6c, decreases at a rate that increases toward the groove width center line 6c. In this embodiment, the number of corrugations 12 is different in each first transverse groove 6.

[0062] FIG. 9(a) is a plan view of a first land portion 4 of yet another embodiment. The same components as those of the present embodiment are designated by the same reference numerals, and their description may be omitted. As shown in FIG. 9(a), the first land portion 4 of this embodiment also has a first transverse groove 6. In this embodiment, the first transverse groove 6 has a V-shaped corrugation 12 on the groove edge 7. More specifically, in this embodiment, each groove edge 7 is formed by arranging multiple arc portions 17 convex toward the groove centerline 6c in the longitudinal direction. In this embodiment, the peak portion 11 is formed by connecting adjacent arc portions 17 in the longitudinal direction. The peak portion 11 is formed, for example, such that the length Lf between the arc portions 17, 17 parallel to the groove centerline 6c, decreases at a rate that increases in the direction away from the groove centerline 6c. In this embodiment, the number of corrugations 12 is different for each first transverse groove 6.

[0063] FIG. 9(b) is a plan view of a first land portion 4 of yet another embodiment. The same components as those of this embodiment are designated by the same reference numerals, and their description may be omitted. As shown in FIG. 9(b), the first land portion 4 of this embodiment also has a first lateral groove 6. The first lateral groove 6 has both ends 6e, 6e other than the valleys 10. This allows water resulting from melted ice on the tread surface 4a of the first land portion 4 to be smoothly discharged from the first lateral groove 6 to the first tread edge T1 or the outer shoulder main groove 3A, thereby improving performance on ice. In this embodiment, the both ends 6e, 6e are the peaks 11 excluding the peaks 11a of the peaks 11. Note that, of the both ends 6e, 6e, one end 6e may be other than the peak 11, and the other end 6e may be other than the valley 10 (not shown).

[0064] Fig. 10 is a plan view of a first land portion 4 of yet another embodiment. The same components as those of this embodiment are denoted by the same reference numerals, and their description may be omitted. As shown in Fig. 10, the first land portion 4 of this embodiment also has first transverse grooves 6. The first transverse grooves 6 include wavy first transverse grooves 6A, each groove edge 7 of which includes a wave shape 12 consisting of valleys 10 and peaks 11, as shown in Fig. 1, and linear first transverse grooves 6B, each groove edge 7 of which extends linearly.

[0065] Although particularly preferred embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the illustrated embodiments and can be modified and implemented in various forms. [Example]

[0066] Tires with the basic pattern shown in Figure 2 were prototyped based on the specifications in Table 1. Each test tire was then tested for snow performance, ice performance, and handling stability. The common specifications and test methods for each test tire are as follows: Tire size: 195 / 65R15 91H Rim size: 15 x 6.0J

[0067] <Snow performance, ice performance, handling stability> The test tires were mounted on all wheels of a passenger car with an engine displacement of 2000cc. A test driver drove the vehicle on test courses with snowy, icy, and dry asphalt surfaces, and evaluated the stability of the vehicle when traveling straight and when cornering on each surface based on the test driver's senses. The results of each test were expressed as a score, with Comparative Example 1 being given as 100. The higher the score, the better the driving performance on each road surface. The test results are shown in Table 1. In Table 1, "A" refers to the outer shoulder land portion, and "B" refers to the crown land portion. The "groove volume ratio of the first transverse grooves" is an index obtained by adding up the groove volumes of all the first transverse grooves in the first land portion, with the value of Comparative Example 1 being 100.

[0068] [Table 1]

[0069] The tires of the examples have improved snow performance and ice performance compared to the tires of the comparative examples. Furthermore, the tires of the examples maintain high levels of steering stability. Note that tire performance may be evaluated as overall performance indicated by the total score of the test results for snow performance, ice performance, and steering stability.

[0070] [Note] The present disclosure includes the following aspects.

[0071] [Disclosure 1] A tire having a tread portion, The tread portion includes a first land portion and a first lateral groove extending in the first land portion in the tire axial direction, The first lateral groove includes a pair of groove edges extending in a wave-like shape on the tread surface of the first land portion, each of the pair of groove edges includes a valley portion that is convex toward a groove width center line of the first transverse groove and a peak portion that is convex in a direction away from the groove width center line; the valleys of the pair of groove edges are disposed at substantially the same positions in the longitudinal direction of the groove width center line, the peaks of the pair of groove edges are disposed at substantially the same positions in the longitudinal direction of the groove width center line; tire. [Disclosure 2] The tire according to Disclosure 1, wherein each of the pair of groove edges includes a plurality of wave patterns in one cycle in which the valleys and the peaks are alternately arranged. [Disclosure 3] The tire of Disclosure 2, wherein the corrugation is sinusoidal. [Disclosure 4] The tire of Disclosure 2, wherein the corrugation is a trapezoidal corrugation. [Disclosure 5] The tire of Disclosure 2, wherein the corrugation is arc-shaped. [Disclosure 6] The tire of Disclosure 2, wherein the corrugation is V-shaped. [Disclosure 7] The tire according to any one of the first to sixth disclosures, wherein the first lateral groove completely crosses the first land portion in the tire axial direction. [Disclosure 8] The tire according to any one of the first to seventh disclosures, wherein both ends of the first lateral groove are other than the ridge portions. [Disclosure 9] The tire according to any one of the first to seventh disclosures, wherein both ends of the first lateral groove are other than the valley portions. [Disclosure 10] The tire according to any one of the present disclosures 1 to 9, wherein the tread portion includes a shoulder land portion located outermost in the tire axial direction, and the first land portion is the shoulder land portion. [Disclosure 11] A tire described in any one of Disclosures 1 to 10, wherein the tread portion has a specified orientation toward the vehicle and includes a first tread edge that is located on the outer side of the vehicle when mounted on the vehicle, and an outer shoulder land portion that includes the first tread edge, and the first land portion is the outer shoulder land portion. [Explanation of symbols]

[0072] 1 tire 2 Tread section 3 Vertical grooves 5 Land 5e First circumferential edge 5i Second circumferential edge 6 First Yokomizo 6i inner end 7 sipes 8 tie bars 10 First sipe section 11 Second sipe section

Claims

1. A tire having a tread portion, the tread portion includes a first land portion and a first lateral groove extending in the first land portion in the tire axial direction, The first lateral groove includes a pair of groove edges extending in a wave-like shape on the tread surface of the first land portion, each of the pair of groove edges includes a valley portion that is convex toward a groove width center line of the first transverse groove and a peak portion that is convex in a direction away from the groove width center line, the valleys of the pair of groove edges are disposed at substantially the same positions in the longitudinal direction of the groove width center line, the peaks of the pair of groove edges are disposed at substantially the same positions in the longitudinal direction of the groove width center line, Each of the pair of groove edges includes a plurality of wave patterns each having one period in which the valley portions and the peak portions are alternately arranged, Each groove edge is formed so that a plurality of arc portions convex in a direction away from the groove width center line or a plurality of arc portions convex in a direction toward the groove width center line are arranged in the longitudinal direction. tire.

2. A tire as described in claim 1, wherein the wave shape is arc-shaped.

3. A tire as described in claim 1, wherein the wave shape is V-shaped.

4. A tire as described in any one of claims 1 to 3, wherein the first lateral groove completely traverses the first land portion in the tire axial direction.

5. A tire described in any one of claims 1 to 4, wherein both ends of the first lateral groove are other than the ridge portion.

6. A tire described in any one of claims 1 to 4, wherein both ends of the first lateral groove are other than the valley portion.

7. The tread portion includes a shoulder land portion located outermost in the tire axial direction, The tire according to claim 1 , wherein the first land portion is the shoulder land portion.

8. The tread portion has a specified orientation toward the vehicle and includes a first tread edge that is located on the outside of the vehicle when mounted on the vehicle, and an outer shoulder land portion that includes the first tread edge; The tire according to claim 1 , wherein the first land portion is the outer shoulder land portion.

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