tire

Abstract

To provide a tire having improved steering stability performance and drainage performance during high-load traveling such as circuit traveling.SOLUTION: A tire 1 has a tread part 2. The tread part 2 includes a second land part 8 and a third land part 9 sequentially adjacent to a first land part 7. A plurality of second lateral grooves 31 is disposed on the second land part 8. A plurality of third sipings 41 is disposed on the third land part 9. The second lateral grooves 31, in a tread plan view, are formed so as to completely enclose a virtual extension line 41c on which the third sipings 41 extend on the second land part 8 along a longitudinal direction thereof. A siping 6 and a lateral groove 5 which traverse the third land part 9, excluding the third sipings 41, are not disposed on the third land part 9.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] The following Patent Document 1 describes a tire whose mounting direction on a vehicle is specified. The tread portion of this tire is provided with a second main groove, a first main groove, and a third main groove, in that order, from the inner tread edge to the outer side of the vehicle. The arrangement of the first main groove to the third main groove is specified, and the groove width of the third main groove is made smaller than the groove widths of the first main groove and the second main groove. Such a tire is said to exhibit excellent wet performance while maintaining dry grip performance during high-load driving such as on a circuit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-167717 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 steering stability and drainage performance during high-load driving, such as circuit driving.

[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 can improve steering stability and drainage performance during high-load driving such as circuit driving. [Means for solving the problem]

[0006] The present disclosure relates to a tire having a tread portion whose mounting orientation on a vehicle is specified, the tread portion including a first tread edge and a second tread edge located on the vehicle outer side and vehicle inner side, respectively, when mounted on the vehicle, and a plurality of main grooves extending continuously in the tire circumferential direction between the first tread edge and the second tread edge, the plurality of main grooves including two inner main grooves whose groove center lines are located on the second tread edge side of the tire equator, and one outer main groove whose groove center line is located on the first tread edge side of the tire equator, and the tread portion is located axially outboard of the outer main groove. The tire is divided into a first land portion disposed on the tread surface of the tire, and a second land portion, a third land portion, and a fourth land portion adjacent to the first land portion in that order, the second land portion is provided with a plurality of second lateral grooves crossing the second land portion, and the third land portion is provided with a plurality of third sipes crossing the third land portion, and in a plan view of the tread, the plurality of second lateral grooves are formed so as to completely encompass imaginary extension lines extending the plurality of third sipes along their longitudinal direction onto the second land portion, and the third land portion is not provided with sipes or lateral grooves crossing the third land portion, except for the plurality of third sipes. Effect of the Invention

[0007] By employing the above-described configuration, the tire of the present disclosure can improve the steering stability and drainage performance during high-load driving such as circuit driving. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a development view of a tread portion of the tire of the present embodiment. [Diagram 2] 2 is a cross-sectional view taken along line AA in FIG. 1. [Diagram 3] 2A is a cross-sectional view taken along line BB in FIG. 1, and FIG. 2B is a cross-sectional view taken along line CC in FIG. [Figure 4] 2 is an enlarged view of a first land portion and a second land portion of FIG. 1. [Diagram 5] FIG. 2 is a cross-sectional view taken along line DD in FIG. [Figure 6] 2 is an enlarged view of a second land portion and a third land portion of FIG. 1. [Figure 7] FIG. 2 is an enlarged view of a fourth land portion in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, one embodiment of the present disclosure will be described with reference to the drawings. 1 is a plan view showing an expanded tread portion 2 of a tire 1 according to an embodiment of the present disclosure. The tire 1 according to the present disclosure is used, for example, as a pneumatic tire for passenger cars that can be used for normal driving on public roads as well as high-speed driving on a circuit. However, the tire 1 according to the present disclosure can also be used, for example, as a pneumatic tire for heavy loads or motorcycles, or as a non-pneumatic tire that is not filled with compressed air.

[0010] The mounting direction of the tread portion 2 on a vehicle is specified. Thus, the tread portion 2 has a first tread edge To located on the outer side of the vehicle when the tire 1 is mounted on the vehicle, and a second tread edge Ti located on the inner side of the vehicle.

[0011] In the case of a pneumatic tire, the first tread edge To and the second tread edge Ti are the axially outermost contact points when a normal load is applied to the tire 1 in a normal state and the tire touches the ground on a flat surface with a camber angle of 0°. The "normal state" refers to a state in which the tire is mounted on a normal rim, inflated to a normal internal pressure, and no load is applied. In this specification, unless otherwise specified, the dimensions of each part of the tire 1 are values ​​measured in the normal state. The axial distance between the first tread edge To and the second tread edge Ti is the tread width TW.

[0012] 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" in the case of JATMA, a "Design Rim" in the case of TRA, and a "Measuring Rim" in the case of ETRTO.

[0013] 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.

[0014] The "normal load" is a load determined for each tire by each standard in a 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 described 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.

[0015] The tread portion 2 of the present embodiment includes a plurality of main grooves 3 that extend continuously in the tire circumferential direction between a first tread edge To and a second tread edge Ti.

[0016] In this embodiment, the main grooves 3 include two inner main grooves 3A whose groove center lines 3c are located closer to the second tread edge Ti than the tire equator C, and one outer main groove 3B located closer to the first tread edge To than the tire equator C. These main grooves 3 divide the tread portion 2 into a first land portion 7 located axially outboard of the outer main groove 3B, and a second land portion 8, a third land portion 9, and a fourth land portion 10 adjacent to the first land portion 7 in that order. The groove center line 3c is a line passing through the center of the groove width.

[0017] In this embodiment, the tread portion 2 is provided with a plurality of lateral grooves 5 extending in the tire axial direction, and a plurality of sipes 6 extending in the tire axial direction. In this specification, the sipes 6 are formed as slits with a width of less than 1.5 mm. In this specification, the main grooves 3 and the lateral grooves 5 are formed as grooves with a groove width of 1.5 mm or more. In addition, in this specification, "extending in the tire axial direction" includes extending at an angle of 80 degrees or less with respect to the tire axial direction.

[0018] In this embodiment, the lateral grooves 5 include a first lateral groove 30 arranged in the first land portion 7, a second lateral groove 31 arranged in the second land portion 8, and a fourth lateral groove 32 arranged in the fourth land portion 10. The sipes 6 include a second sipe 40 arranged in the second land portion 8, a third sipe 41 arranged in the third land portion 9, and a fourth sipe 42 arranged in the fourth land portion 10.

[0019] Fig. 6 is a plan view of the second land portion 8 and the third land portion 9. As shown in Fig. 6, the second lateral groove 31 includes a second transverse lateral groove 31A. The second transverse lateral groove 31A crosses the second land portion 8. The third sipe 41 is formed as a third transverse sipe 41A crossing the third land portion 9. In other words, both ends of each of the second transverse lateral groove 31A and the third transverse sipe 41A are connected to the main groove 3. This improves the flow of water and improves drainage performance.

[0020] The second land portion 8 and the third land portion 9 located on the tire equator C side are less likely to discharge the water film on the tread surface T than the first land portion 7 adjacent to the first tread edge To and the fourth land portion 10 adjacent to the second tread edge Ti. In the tire 1 of the present disclosure, in a plan view of the tread, the second transverse groove 31A of the second land portion 8 is formed so as to completely include a virtual extension line 41c that extends the third transverse sipe 41A along its longitudinal direction onto the second land portion 8. Such second transverse groove 31A and third transverse sipe 41A are in continuous contact with the ground. This contact causes the second transverse groove 31A and the third transverse sipe 41A to deform so as to open widely from each other, so that the water film on the tread surface T of the second land portion 8 and the third land portion 9 can be collected in large amounts and discharged to the outer main groove 3B and the inner main groove 3A. This provides excellent drainage performance. In this specification, the "imaginary extension line" is a line extending from the groove center line of the groove or the center line of the sipe. The "completely encompassing" in this specification means that the imaginary extension line is located on the groove continuously from the inner end to the outer end of the groove in the axial direction of the tire.

[0021] The third land portion 9 does not have any lateral grooves 5 or sipes 6 that cross the third land portion 9, except for the third transverse sipes 41A. This prevents a decrease in the rigidity of the third land portion 9, which is subjected to a large ground contact pressure during straight driving, and therefore provides excellent steering stability.

[0022] FIG. 2 is a cross-sectional view taken along line AA in FIG. 1. FIG. 2 shows a cross section of the outer main groove 3B. As shown in FIG. 2, the outer main groove 3B includes a pair of groove walls 13 and a groove bottom 14. Each of the pair of groove walls 13 includes a first groove wall portion 15 extending from the groove bottom 14 toward the tire radial direction, and a second groove wall portion 16 located outside the tire radial direction from the first groove wall portion 15 and inclined at an angle θ2 larger than that of the first groove wall portion 15 with respect to the tread normal n. The angle θ2 of the second groove wall portion 16 is preferably 40 to 75 degrees (°). Such a second groove wall portion 16 suppresses rolling in, in which the groove edge 3e of the outer main groove 3B is rolled up like a tread surface, and uneven ground pressure due to this rolling in, even when a large lateral force is applied, thereby improving steering stability. In addition, the second groove wall portion 16 increases the lateral rigidity of the first land portion 7 and the second land portion 8 near the outer main groove 3B, and thus suppresses the reduction in groove volume due to the deformation of the outer main groove 3B when subjected to a lateral force. This improves drainage performance. Furthermore, since the angle θ2 is 40 degrees or more, the roll-in and the unevenness of the ground pressure caused by the roll-in are further suppressed. Since the angle θ2 is 75 degrees or less, the volume of the first land portion 7 and the second land portion 8 is secured, and the rigidity is maintained high. From this viewpoint, the angle θ2 is more preferably 50 degrees or more, and even more preferably 70 degrees or less. The tread normal n is a normal to the tread surface T of the land portion, or, in the portion where the tread surface T is not formed by the lateral grooves 5 and the sipes 6 described later, to the virtual tread surface Ta obtained by filling these.

[0023] Although not particularly limited, the difference (θ2-θ1) between the angle θ2 of the second groove wall portion 16 and the angle θ1 of the first groove wall portion 15 relative to the tread normal n is preferably 40 degrees or more, more preferably 45 degrees or more, and more preferably 70 degrees or less, and even more preferably 65 degrees or less.

[0024] In this embodiment, the first groove wall 15 and the second groove wall 16 are connected via a bent portion K that is convex toward the groove center line 3c. The bent portion K may be formed by, for example, the intersection of two straight lines, or may be formed in an arc shape. In this embodiment, the first groove wall 15 and the second groove wall 16 extend linearly.

[0025] As shown in Fig. 1, the inner main groove 3A and the outer main groove 3B each extend linearly along the tire circumferential direction. Such inner main groove 3A and outer main groove 3B help to smoothly flow water in the groove. The inner main groove 3A and outer main groove 3B may each extend in a zigzag or wavy shape, for example.

[0026] The groove width W1 of the outer main groove 3B is smaller than the groove width W2 of the inner main groove 3A. Such an outer main groove 3B maintains high rigidity of the tread portion 2 on the outer side of the vehicle, where a large lateral force acts during cornering, and maintains high drainage performance during straight driving. Although not particularly limited, the groove width W1 of the outer main groove 3B is preferably 0.6 times or more, more preferably 0.7 times or more, more preferably 0.9 times or less, and more preferably 0.8 times or less of the groove width W2 of the inner main groove 3A. In the case of a main groove 3 having a second groove wall portion, the groove width in this specification is the length including the second groove wall portion.

[0027] As shown in Fig. 2, the groove width W1 of the outer main groove 3B is equal to or greater than the groove depth d1 of the outer main groove 3B. This suppresses deformation such as axial collapse of the first land portion 7 and the second land portion 8 during cornering, thereby further improving steering stability. In addition, suppressing deformation of the land portions 7 and 8 prevents the groove volume of the outer main groove 3B from decreasing, thereby providing high drainage performance during high-load driving.

[0028] In order to improve drainage performance while maintaining high rigidity of the first land portion 7 and the second land portion 8, the groove width W1 of the outer main groove 3B is preferably 1.5 times or more, more preferably 1.8 times or more, and more preferably 3.0 times or less, and even more preferably 2.7 times or less, of the groove depth d1 of the outer main groove 3B.

[0029] The groove bottom 14 of the outer main groove 3B includes, for example, a maximum depth portion 14A where the groove depth is maximum, and a pair of raised portions 14B that are connected to both sides of the maximum depth portion 14A and have a convex arc shape toward the outside of the outer main groove 3B. In this embodiment, the groove bottom 14 of the outer main groove 3B is formed into a substantially U-shape. The shape of the groove bottom 14 is not limited to this embodiment.

[0030] Although not particularly limited, it is preferable that the width W3 (shown in FIG. 1) of the second groove wall portion 16 of the outer main groove 3B satisfies the following formula (1) when the angle θ2 (°) of the second groove wall portion 16 of the outer main groove 3B is used. The smaller the angle θ2, the larger the width W3 is set, so that a reduction in groove volume due to deformation of the outer main groove 3B is suppressed. In this specification, the width W3 is the length of the outer main groove 3B in the groove width direction. It is preferable that the width W3 is 2.0 to 4.0 mm. 1×cosθ2≦W3(mm)≦7×cosθ2…(1)

[0031] The height h1 of the second groove wall portion 16 in the tire radial direction is, for example, desirably 15% or more of the groove depth d1 of the outer main groove 3B, more desirably 20% or more, and desirably 35% or less, and even more desirably 30% or less.

[0032] Although not particularly limited, the angle θ1 of the first groove wall portion 15 is preferably 0 degrees or more, more preferably 5 degrees or more, and is preferably 20 degrees or less, and even more preferably 15 degrees or less.

[0033] 1, the inner main groove 3A includes, for example, a first inner main groove 11 and a second inner main groove 12 located closer to the second tread edge Ti than the first inner main groove 11. For example, the first inner main groove 11 is closest to the tire equator C among the main grooves 3.

[0034] The groove width W2a of the first inner main groove 11 is larger than the groove width W2b of the second inner main groove 12. This improves the drainage performance near the tire equator C where drainage is difficult, and provides excellent drainage performance. Although not particularly limited, the groove width W2a of the first inner main groove 11 is preferably 1.1 times or more, more preferably 1.2 times or more, more preferably 1.5 times or less, and more preferably 1.4 times or less, of the groove width W2b of the second inner main groove 12.

[0035] The first inner main groove 11 includes a pair of groove edges 18 extending in the longitudinal direction. Each groove edge 18 includes an outer groove edge 18a located on the side of the first tread end To. The axial separation distance La between the outer groove edge 18a and the tire equator C is 2% or less of the tread width TW. This allows the above-mentioned effects to be effectively achieved. In this embodiment, the outer groove edge 18a is located on the tire equator C.

[0036] FIG. 3(a) is a cross-sectional view of line BB in FIG. 1. FIG. 3(a) shows a cross section of the first inner main groove 11. As shown in FIG. 3(a), the first inner main groove 11 includes a pair of groove walls 20 and a groove bottom 21. The groove wall 20 of the first inner main groove 11 includes a first outer groove wall 20A located on the side of the first tread edge To and a first inner groove wall 20B located on the side of the second tread edge Ti. The groove bottom 21 of the first inner main groove 11 includes a maximum depth portion 21A where the groove depth is maximum, and a pair of raised portions 21B that are connected to both sides of the maximum depth portion 21A and have a convex arc shape toward the outside of the first inner main groove 11, similar to the groove bottom 14 of the outer main groove 3B. The groove bottom 21 of the first inner main groove 11 is formed, for example, in a substantially U-shape.

[0037] The first outer groove wall 20A includes a first groove wall portion 23 extending radially outward from the groove bottom 21, and a second groove wall portion 24 located radially outward of the first groove wall portion 23 and inclined at an angle θ4 with respect to the tread normal n larger than the first groove wall portion 23. This suppresses rolling-in of the outer groove edge 18a connected to the first outer groove wall 20A into a tread-like shape and uneven ground contact pressure caused by this rolling-in, thereby improving steering stability.

[0038] The first inner groove wall 20B extends, for example, linearly outward in the tire radial direction from the groove bottom 21. In this embodiment, the first inner groove wall 20B extends linearly between the groove bottom 21 and the tread surface T.

[0039] The angle θ3 of the first groove wall portion 23 of the first outer groove wall 20A relative to the tread normal n is smaller than the angle θ5 of the first inner groove wall 20B relative to the tread normal n. This ensures the volume of the second land portion 8 located relatively on the vehicle outer side. Also, the groove volume can be increased on the third land portion 9 side of the first inner main groove 11. The angle θ3 of the first outer groove wall 20A is preferably 25 degrees or more, more preferably 35 degrees or more, more preferably 55 degrees or less, and even more preferably 45 degrees or less.

[0040] Also, the angle θ3 of the first groove wall portion 23 of the first outer groove wall 20A of the first inner main groove 11 is formed larger than the angle θ1 of the first groove wall portion 15 of the outer main groove 3B. This ensures the volume of the first land portion 7 arranged relatively on the vehicle outer side. Also, the groove volume can be increased on the second land portion 8 side of the first inner main groove 11. The difference (θ3-θ1) between the angle θ3 of the first groove wall portion 23 of the first outer groove wall 20A and the angle θ1 of the first groove wall portion 15 of the outer main groove 3B is preferably 15 degrees or more, more preferably 20 degrees or more, more preferably 35 degrees or less, and even more preferably 30 degrees or less.

[0041] The angle θ5 (°) of the first inner groove wall 20B of the first inner main groove 11 is, for example, desirably 5% or more of the tread width TW (mm), more desirably 10% or more, and desirably 20% or less, and even more desirably 10% or less.

[0042] The angle θ4 of the second groove wall portion 24 of the first inner main groove 11 is formed to be larger than the angle θ5 of the first inner groove wall 20B. Such a second groove wall portion 24 more effectively suppresses rolling in like a tread surface and uneven ground pressure caused by this rolling in. The difference (θ4-θ5) between the angle θ4 of the second groove wall portion 24 and the angle θ5 of the first inner groove wall 20B is preferably 10 degrees or more, more preferably 15 degrees or more, more preferably 30 degrees or less, and more preferably 25 degrees or less. The angle θ4 of the second groove wall portion 24 is preferably, for example, 45 degrees or more, more preferably 55 degrees or more, more preferably 75 degrees or less, and more preferably 65 degrees or less. The angle θ5 of the first inner groove wall 20B is preferably, for example, 25 degrees or more, more preferably 35 degrees or more, more preferably 55 degrees or less, and more preferably 45 degrees or less.

[0043] Although not particularly limited, the radial height h2 of the second groove wall portion 24 is desirably 40% or more of the groove depth d2a of the first inner main groove 11, more desirably 45% or more, preferably 60% or less, and even more desirably 55% or less.

[0044] FIG. 3(b) is a cross-sectional view taken along the line CC in FIG. 1. FIG. 3(b) shows a cross section of the second inner main groove 12. As shown in FIG. 3(b), the second inner main groove 12 includes a pair of groove walls 27 and a groove bottom 28. The groove bottom 28 includes, for example, a maximum depth portion 28A where the groove depth is maximum, and a pair of raised portions 28B, 28B that are connected to both sides of the maximum depth portion 28A and have a convex arc shape toward the outside of the second inner main groove 12. In this embodiment, the groove bottom 28 is formed in a substantially U-shape. For example, the pair of groove walls 27 each extend linearly from the groove bottom 21 toward the outside in the tire radial direction. In this embodiment, each groove wall 27 extends from the groove bottom 28 to the tread surface T.

[0045] In this manner, in this embodiment, the pair of groove walls 13 of the outer main groove 3B and the first outer groove wall 20A of the first inner main groove 11 are formed to include the first groove wall portion and the second groove wall portion. Also, the first inner groove wall 20B of the first inner main groove 11 and each groove wall 27 of the second inner main groove 12 are formed without the second groove wall portion. This provides an excellent rigidity balance between the vehicle inner region and the vehicle outer region of the tread portion 2, thereby further improving steering stability and drainage performance during high-load driving.

[0046] The pair of groove walls 27 of the second inner main groove 12 includes a second inner groove wall 27A located on the side of the first tread edge To and a second outer groove wall 27B located on the side of the second tread edge Ti. The angle θ6 of the second inner groove wall 27A with respect to the tread normal n is smaller than the angle θ7 of the second outer groove wall 27B with respect to the tread normal n. The angle θ6 of the second inner groove wall 27A is preferably 60% or more of the angle θ7 of the second outer groove wall 27B, more preferably 65% ​​or more, more preferably 90% or less, and more preferably 85% or less. The angle θ7 (°) of the second outer groove wall 27B is, for example, preferably 5% or more of the tread width TW (mm), more preferably 10% or more, more preferably 20% or less, and more preferably 15% or less. The angle θ7 of the second outer groove wall 27B is preferably, for example, 30 degrees or more, more preferably 35 degrees or more, and is preferably 50 degrees or less, and more preferably 45 degrees or less. The angle θ7 of the second outer groove wall 27B is preferably the same as the angle θ5 of the first inner groove wall 20B of the first inner main groove 11.

[0047] The groove width W2a (shown in FIG. 1) of the first inner main groove 11 is, for example, greater than or equal to the groove depth d2a (shown in FIG. 3(a)) of the first inner main groove 11. The groove width W2b (shown in FIG. 1) of the second inner main groove 12 is, for example, greater than or equal to the groove depth d2b of the second inner main groove 12. This reduces the change in rigidity of the land portions 8-10, and maintains high steering stability during high load running. In this embodiment, the groove width W2a of the first inner main groove 11 is greater than the groove depth d2a of the first inner main groove 11. In this embodiment, the groove width W2b of the second inner main groove 12 is greater than the groove depth d2b of the second inner main groove 12.

[0048] 1, the tire axial width Wa of the first land portion 7 is formed larger than the tire axial widths Wb, Wc, Wd of the second land portion 8, the third land portion 9, and the fourth land portion 10, respectively. This increases the lateral rigidity of the first land portion 7, which receives the largest lateral force during cornering, thereby improving the steering stability during high-load driving.

[0049] In order to improve steering stability during high-load driving, the width Wa of the first land portion 7 is desirably 1.3 times or more the width Wc of the narrowest land portion, that is, in this embodiment, the third land portion 9, more desirably 1.5 times or more, preferably 2.1 times or less, and even more desirably 1.9 times or less.

[0050] In order to improve steering stability and drainage performance in a well-balanced manner, the tire axial width Wa of the first land portion 7 is preferably 25% to 35% of the tread width TW. The tire axial width Wb of the second land portion 8 is preferably 15% to 25% of the tread width TW. The tire axial width Wb of the second land portion 8 is more preferably 16% or more of the tread width TW, even more preferably 17% or more, still more preferably 24% or less, and even more preferably 21% or less. The tire axial width Wc of the third land portion 9 is preferably 8% to 22% of the tread width TW. The tire axial width Wd of the fourth land portion 10 is preferably 18% to 28% of the tread width TW.

[0051] At least one of the lateral grooves 5 and the sipes 6 is arranged to intersect with the tire axial line X at any position in the tire circumferential direction. This provides a drainage effect at any position in the tire circumferential direction. This configuration also reduces the change in lateral rigidity of the tread portion 2 in the tire circumferential direction, thereby providing higher steering stability.

[0052] Each of the lateral grooves 5 is inclined in the same direction relative to the tire axial direction. For example, the lateral grooves 5 are inclined in a first direction (upward to the right in FIG. 1 ) relative to the tire axial direction. This allows water in the lateral grooves 5 to be smoothly discharged toward one side in the tire axial direction by utilizing the rotation of the tire 1. Each of the sipes 6 is also inclined in the same direction relative to the tire axial direction. For example, the sipes 6 are inclined in the first direction.

[0053] The angle α of each of the lateral grooves 5 and the sipes 6 relative to the tire axial direction is preferably, for example, 5 to 60 degrees. Since the angle α is 5 degrees or more, water in the lateral grooves 5 and the sipes 6 can be smoothly discharged by utilizing the rotation of the tire 1. Since the angle α is 60 degrees or less, a decrease in the lateral rigidity of each of the land portions 7 to 10 can be suppressed. To effectively exert such effects, the angle α is more preferably 15 degrees or more, and more preferably 45 degrees or less.

[0054] Fig. 4 is an enlarged plan view of the first land portion 7 and the second land portion 8. As shown in Fig. 4, the first lateral groove 30 includes a first transverse lateral groove 30A that crosses the first land portion 7 and a first interrupted lateral groove 30B that is interrupted within the first land portion 7.

[0055] The first transverse lateral grooves 30A and the first interrupted lateral grooves 30B are positioned at equal pitches P1 in the tire circumferential direction. In this specification, equal pitches include those in which the difference between the maximum and minimum pitches is within 10% of the maximum pitch.

[0056] The first transverse groove 30A includes an inner first portion 33A extending from the outer main groove 3B at the same angle α1 with respect to the tire axial direction, and an outer first portion 33B continuing to the inner first portion 33A and extending at a smaller angle α2 with respect to the tire axial direction than the inner first portion 33A. The outer first portion 33B is connected to the first tread edge To.

[0057] The first interrupted lateral groove 30B includes an inner second portion 34A extending at the same angle α3 with respect to the tire axial direction, and an outer second portion 34B connecting the inner second portion 34A and the first tread edge To. The outer second portion 34B is inclined at an angle α4 smaller than that of the inner second portion 34A, for example.

[0058] Although not particularly limited, the axial length L1 of the first interrupted lateral groove 30B is preferably 65% ​​or more of the width Wa (shown in FIG. 1) of the first land portion 7, more preferably 70% or more, and more preferably 85% or less, and even more preferably 80% or less.

[0059] The inner first portion 33A and the inner second portion 34A extend, for example, linearly. In this embodiment, the inner first portion 33A and the inner second portion 34A extend parallel to each other. In this specification, the term "parallel" includes an absolute value of the difference between the angles of inclination of each portion being 0 degrees, as well as 10 degrees or less. The angle α1 of the inner first portion 33A and the angle α3 of the inner second portion 34A are preferably, for example, 10 degrees or more, more preferably 15 degrees or more, more preferably 30 degrees or less, and even more preferably 25 degrees or less. The outer first portion 33B and the outer second portion 34B extend, for example, parallel to each other.

[0060] In this embodiment, the second lateral groove 31 further includes a second interrupted lateral groove 31B. The second transverse lateral grooves 31A and the second interrupted lateral grooves 31B are alternately provided along the tire circumferential direction. The second transverse lateral grooves 31A and the second interrupted lateral grooves 31B are arranged at equal pitches P2 in the tire circumferential direction. The second transverse lateral grooves 31A adjacent to each other in the tire circumferential direction are also arranged at equal pitches P3 in the tire circumferential direction.

[0061] In this embodiment, the second interrupted lateral groove 31B extends from the first inner main groove 11 toward the first tread edge To and terminates within the second land portion 8. The second transverse lateral groove 31A and the second interrupted lateral groove 31B are inclined in the same direction with respect to the tire axial direction, for example. This suppresses the rigidity step of the second land portion 8. The second transverse lateral groove 31A and the second interrupted lateral groove 31B extend parallel to each other in this embodiment. The angle α5 of the second transverse lateral groove 31A with respect to the tire axial direction is, for example, preferably 10 degrees or more, more preferably 15 degrees or more, more preferably 30 degrees or less, and more preferably 25 degrees or less.

[0062] The second sipes 40 are formed as second interrupted sipes 40A with at least one end terminating within the second land portion 8. The second interrupted sipes 40A connect the outer main groove 3B and the second interrupted lateral grooves 31B. The second interrupted sipes 40A connect to the axially outer ends 31e of the second interrupted lateral grooves 31B. The width Wf of the second interrupted sipes 40A is constant along the longitudinal direction.

[0063] In the plan view of the tread, the second transverse groove 31A is formed so as to completely include a virtual extension line 30c that extends the first transverse groove 30A along its longitudinal direction onto the second land portion 8. As a result, one virtual groove including the second transverse groove 31A and the first transverse groove 30A is formed, improving drainage performance. In addition, since the first transverse groove 30A and the second transverse groove 31A come into contact with the ground at the same time, these grooves 30A, 31A are deformed to be widely open, and the apparent groove volume is increased. This further improves drainage performance.

[0064] The second transverse grooves 31A extend, for example, in a straight line, which prevents the separation phenomenon when water flows through the grooves and reduces the resistance to water flow, thereby maintaining high drainage performance.

[0065] In the present embodiment, the second interrupted lateral groove 31B is formed so as to completely include an imaginary extension line 40c that extends onto the second land portion 8 from the second interrupted sipe 40A along its longitudinal direction in a plan view of the tread.

[0066] The length L2 of the second interrupted lateral grooves 31B in the tire axial direction is preferably 40% to 60% of the width Wb of the second land portion 8. Since the length L2 of the second interrupted lateral grooves 31B is 40% or more of the width Wb of the second land portion 8, drainage performance is maintained. Since the length L2 of the second interrupted lateral grooves 31B is 60% or less of the width Wb of the second land portion 8, steering stability performance is maintained. For this reason, the length L2 of the second interrupted lateral grooves 31B is more preferably 45% or more of the width Wb of the second land portion 8, and more preferably 55% or less.

[0067] The groove width W7 of the second interrupted lateral groove 31B is, for example, the same as the groove width W6 of the second transverse lateral groove 31A. This maintains a small rigidity step in the second land portion 8. In this embodiment, the maximum value of the groove width W7 of the second interrupted lateral groove 31B is the same as the maximum value of the groove width W6 of the second transverse lateral groove 31A. In this specification, the term "same" includes not only a difference in the groove widths of the lateral grooves being 0 mm, but also an absolute value of the difference being within 3 mm.

[0068] The second interrupted lateral groove 31B includes, for example, a junction 35 that connects to the second interrupted lateral groove 40A. In this embodiment, the junction 35 includes an axially outer end 31e of the second interrupted lateral groove 31B. The junction 35 is a portion where the groove width W7 of the second interrupted lateral groove 31B continuously decreases toward the second interrupted lateral sipe 40A.

[0069] Fig. 5 is a cross-sectional view taken along line DD in Fig. 1. Fig. 5 shows a longitudinal section of the second interrupted lateral groove 31B and the second interrupted sipe 40A. As shown in Fig. 5, the depth d6 of the second interrupted lateral groove 40A may be smaller than the groove depth d5 ​​of the second interrupted lateral groove 31B.

[0070] In the longitudinal section of the second interrupted lateral groove 31B, the groove bottom 35s of the joint 35 is formed in a convex arc shape toward the inside in the tire radial direction. Such a joint 35 reduces the rigidity step of the second land portion 8, thereby improving the steering stability. The curvature radius R of the groove bottom 35s of the joint 35 is preferably 5 mm or more, more preferably 7 mm or more, more preferably 12 mm or less, and even more preferably 9 mm or less.

[0071] Although not particularly limited, the depth d6 of the second interrupted sipe 40A is desirably 20% or more of the groove depth d1 of the outer main groove 3B, more desirably 35% or more, preferably 80% or less, and even more desirably 65% ​​or less.

[0072] 1, in this embodiment, the second transverse groove 31A and the first transverse groove 30A are formed to include the imaginary extension line 41c that extends the third transverse sipe 41A to the first land portion 7 and the second land portion 8. This makes it possible to more effectively exert the above-mentioned effects.

[0073] In this embodiment, the third land portion 9 includes a recess 45 connected to the inner main groove 3A. The recess 45 includes a first recess 45A connected to the first inner main groove 11 and a second recess 45B connected to the second inner main groove 12. Such a recess 45 serves to increase the groove volume of the inner main groove 3A.

[0074] In this embodiment, the third transverse sipe 41A extends so as to connect the first recess 45A and the second recess 45B. As a result, the third transverse sipe 41A and each recess 45 come into contact with the ground at the same time, so that both deform to open widely, and the apparent volume increases, improving drainage performance.

[0075] The recess 45 has, for example, a tire circumferential length Lb that decreases toward an axially intermediate position 9c of the third land portion 9. In this embodiment, the tire circumferential length Lb of the recess 45 continuously decreases toward the intermediate position 9c of the third land portion 9. In a plan view of the tread, the recess 45 has, for example, a triangular shape. Such a recess 45 suppresses a decrease in land portion rigidity of the third land portion 9. The recess 45 is not limited to this shape.

[0076] The maximum value of the length Lb of the recess 45 is preferably 120% or more of the axial length Lc of the recess 45, more preferably 130% or more, more preferably 160% or less, and more preferably 150% or less. The axial length Lc of the recess 45 is preferably 10% or more of the width Wc of the third land portion 9, more preferably 15% or more, more preferably 30% or less, and more preferably 25% or less. The depth d7 of the recess 45 (shown in FIG. 3(b)) is preferably 30% or more of the groove depths d2a, d2b of the inner main groove 3A, more preferably 40% or more, more preferably 70% or less, and more preferably 60% or less.

[0077] Fig. 7 is a plan view of the fourth land portion 10. As shown in Fig. 7, the fourth lateral groove 32 of the fourth land portion 10 includes a fourth outer lateral groove 32A that is connected to the second tread edge Ti and terminates at the fourth land portion 10, and a fourth inner lateral groove 32B that is connected to the second inner main groove 12 and terminates at the fourth land portion 10. The fourth sipe 42 of the fourth land portion 10 is a fourth interrupted sipe 42A that is connected to the second tread edge Ti and terminates at the fourth land portion 10. In this embodiment, the fourth interrupted sipe 42A connects the fourth inner lateral groove 32B and the second tread edge Ti.

[0078] The axially inner end 32i of the fourth outer lateral groove 32A is located axially inside of the axially outer end 32e of the fourth inner lateral groove 32B. In other words, the fourth land portion 10 has an overlapping portion Y where the outer lateral groove 32A and the fourth inner lateral groove 32B overlap in the axial direction. Such an overlapping portion Y can suitably drain the water film on the tread surface of the fourth land portion 10. In order to improve the steering stability performance and the drainage performance in a well-balanced manner, the axial length Ld of the overlapping portion Y is preferably 3% or more of the width Wd of the fourth land portion 10, more preferably 5% or more, more preferably 15% or less, and even more preferably 10% or less. The inner end 32i and the outer end 32e are positions on the groove center line 32c of each lateral groove 32A, 32B.

[0079] In plan view of the tread, the fourth inner lateral groove 32B is formed so as to completely include a virtual extension line 42c that extends the fourth interrupted sipe 42A along its longitudinal direction onto the fourth land portion 10. As a result, the fourth inner lateral groove 32B and the fourth interrupted sipe 42A come into contact with the ground at the same time, so that the groove 32B and the sipe 42A are deformed to open widely, and the apparent groove volume and sipe volume are increased. This improves drainage performance.

[0080] The angle α7 of the fourth lateral groove 32 and the fourth sipe 42 relative to the tire axial direction is larger than, for example, the angle α6 (shown in FIG. 6) of the first lateral groove 30, the second lateral groove 31, the second sipe 40, and the third sipe 41 relative to the tire axial direction. In other words, the angle α7 of the lateral groove 5 and the sipe 6 formed in the fourth land portion 10 is larger than the angle α6 of the lateral groove 5 and the sipe 6 formed in the first land portion 7 to the third land portion 9. Although not particularly limited, the angle α7 of the fourth lateral groove 32 and the fourth sipe 42 is preferably 25 degrees or more, more preferably 30 degrees or more, more preferably 45 degrees or less, and even more preferably 40 degrees or less.

[0081] The land-sea ratio (S / L) of the tread portion 2 of this embodiment is preferably 15% or more, more preferably 20% or more, and more preferably 35% or less, and even more preferably 30% or less. The land-sea ratio is the ratio of the sum (L) of the areas of the tread surfaces T of the land portions 7 to 10 to the sum (S) of the areas of the grooves between both tread ends To and Ti at the same height as the tread surfaces T.

[0082] Although one embodiment of the present disclosure has been described in detail above, the present disclosure is not limited to the above specific embodiment and can be modified and implemented in various aspects. EXAMPLES

[0083] Tires having the basic pattern shown in Fig. 1 were prototyped based on the specifications in Table 1. Then, each test tire was tested for steering stability and drainage performance. The common specifications and test methods for each test tire are as follows.

[0084] <Handling stability> Each test tire was mounted on all wheels of the following test vehicle. A test driver drove the test vehicle at high speed on a test course with a dry asphalt road surface. The steering stability performance based on the stability and operability at this time was evaluated by the test driver's senses. The results are shown as a score with Comparative Example 1 being 100. The higher the value, the better the tire is, and if it is 90 or less, the tire is rejected. Tire size: 245 / 40R18 Rim: 18×8.5J Internal pressure (kPa): 220 (all wheels) Vehicle: 2000cc four-wheel drive vehicle

[0085] <Drainage performance> A test driver drove the test vehicle on an asphalt road surface with a radius of 100 m, on which puddles of 5 mm depth were placed. The lateral acceleration of the front wheels at this time was measured. The lateral acceleration is the average lateral G of the front wheels at a speed of 55 to 80 km / h. The results are expressed as an index, with the average lateral G value of Comparative Example 1 being set at 100. The higher the value, the better, and if it is 90 or less, the tire is rejected. The test results are shown in Tables 1 to 4. An "A" in each table means that the second transverse groove completely encompasses the imaginary extension of the third transverse sipe. "B" means that the second transverse groove does not completely encompass the imaginary extension of the third transverse sipe. "※1" means that there are no lateral grooves or sipes crossing the third land portion. "※2" means that a horizontal ditch is provided that crosses the third land area. A negative "La / TW" indicates that the first inner lateral groove extends to the tire equator. There are three main grooves. The groove widths of each of the main grooves and each of the lateral grooves are the same.

[0086] [Table 1]

[0087] [Table 2]

[0088] [Table 3]

[0089] [Table 4]

[0090] [Table 5]

[0091] As a result of the tests, it is understood that the tires of the examples have improved steering stability and drainage performance compared to the tires of the comparative examples.

[0092] [Note] The present disclosure includes the following aspects.

[0093] [Disclosure 1] A tire having a tread portion whose mounting direction on a vehicle is specified, The tread portion is a first tread edge and a second tread edge positioned on an outer side and an inner side of the vehicle, respectively, when the tire is mounted on the vehicle; a plurality of main grooves extending continuously in a tire circumferential direction between the first tread edge and the second tread edge, The plurality of main grooves include two inner main grooves whose groove centerlines are located closer to the second tread edge than the tire equator, and one outer main groove whose groove centerline is located closer to the first tread edge than the tire equator, The tread portion is divided into a first land portion located on an outer side of the outer main groove in the tire axial direction, and a second land portion, a third land portion, and a fourth land portion adjacent to the first land portion in this order, The second land portion is provided with a plurality of second lateral grooves crossing the second land portion, A plurality of third sipes crossing the third land portion are provided in the third land portion, In a plan view of the tread, the second lateral grooves are formed so as to completely include imaginary extension lines extending from the third sipes along their longitudinal directions onto the second land portion, The third land portion is not provided with any sipes or lateral grooves crossing the third land portion, except for the plurality of third sipes. tire. [Disclosure 2] The inner main groove includes a first inner main groove and a second inner main groove located closer to the second tread edge than the first inner main groove, The second land portion is provided with a second interrupted lateral groove extending from the first inner main groove toward the first tread edge and terminating within the second land portion, The tire according to Disclosure 1, wherein the second lateral groove and the second interrupted lateral groove are inclined in the same direction relative to the tire axial direction. [Disclosure 3] The tire according to Disclosure 2, wherein the length in the tire axial direction of the second interrupted lateral groove is 40% to 60% of the width in the tire axial direction of the second land portion. [Disclosure 4] The second land portion is provided with a second interrupted sipe connecting the second interrupted lateral groove and the outer main groove, The tire according to Disclosure 2 or 3, wherein, in a plan view of the tread, the second interrupted lateral groove is formed so as to completely encompass an imaginary extension line that extends the second interrupted sipe along its longitudinal direction onto the second land portion. [Disclosure 5] The tire according to Disclosure 4, wherein a depth of the second interrupted sipes is smaller than a groove depth of the second interrupted lateral grooves. [Disclosure 6] The second interrupted lateral groove includes a joint portion connected to the second interrupted sipe, The tire according to Disclosure 4 or 5, wherein in a longitudinal section of the second interrupted lateral groove, the groove bottom at the joining portion has an arc shape with a radius of curvature of 5 to 12 mm. [Disclosure 7] The tire according to Disclosure 6, wherein, in the joint portion, the groove width of the second interrupted lateral groove continuously decreases toward the second interrupted sipe. [Disclosure 8] The first inner main groove includes a pair of groove walls and a groove bottom, The pair of groove walls of the first inner main groove include a first outer groove wall located on the side of the first tread edge, the first outer groove wall includes a first groove wall portion extending radially outward from the groove bottom, and a second groove wall portion located radially outward of the first groove wall portion and inclined at a larger angle with respect to a tread normal than the first groove wall portion, The tire according to any one of claims 2 to 7, wherein the angle of the second groove wall portion is 45 to 75 degrees. [Disclosure 9] The pair of groove walls of the first inner main groove include a first inner groove wall located on the second tread edge side, The tire according to disclosure 8, wherein the angle of the first inner groove wall with respect to the tread normal is 25 to 55 degrees. [Disclosure 10] The first inner main groove includes a pair of groove edges extending in a longitudinal direction, The pair of groove edges includes an outer groove edge located on the side of the first tread edge, The tire according to any one of claims 2 to 9, wherein the axial distance between the outer groove edge and the tire equator is 2% or less of the tread width. [Disclosure 11] The tire according to any one of claims 1 to 10, wherein the second land portion has an axial width of 16% to 24% of the tread width. [Disclosure 12] The tire according to any one of the disclosures 1 to 11, wherein a groove width of the outer main groove is smaller than a groove width of the inner main groove. [Explanation of symbols]

[0094] 1 Tire 2 Tread section 5 Yokomizo 6 Sipe 7 1st Land Department 8 2nd Land Department 9 3rd Land Department 31 Second Yokomizo 41 3rd sipe 41c Virtual extension line

Claims

1. A tire having a tread portion whose mounting direction on a vehicle is specified, The tread portion is a first tread edge and a second tread edge positioned on an outer side and an inner side of the vehicle, respectively, when the tire is mounted on the vehicle; a plurality of main grooves extending continuously in a tire circumferential direction between the first tread edge and the second tread edge, The plurality of main grooves include two inner main grooves whose groove centerlines are located closer to the second tread edge than the tire equator, and one outer main groove whose groove centerline is located closer to the first tread edge than the tire equator, The tread portion is divided into a first land portion located on an outer side of the outer main groove in the tire axial direction, and a second land portion, a third land portion, and a fourth land portion adjacent to the first land portion in this order, The second land portion is provided with a plurality of second lateral grooves crossing the second land portion, A plurality of third sipes crossing the third land portion are provided in the third land portion, In a plan view of the tread, the second lateral grooves are formed so as to completely include imaginary extension lines extending from the third sipes along their longitudinal directions onto the second land portion, The third land portion is not provided with any sipes or lateral grooves crossing the third land portion, except for the plurality of third sipes. tire.

2. The inner main groove includes a first inner main groove and a second inner main groove located closer to the second tread edge than the first inner main groove, The second land portion is provided with a second interrupted lateral groove extending from the first inner main groove toward the first tread edge and terminating within the second land portion, The tire according to claim 1 , wherein the second lateral groove and the second interrupted lateral groove are inclined in the same direction relative to the tire axial direction.

3. The tire according to claim 2, wherein the length in the tire axial direction of the second interrupted lateral groove is 40% to 60% of the width in the tire axial direction of the second land portion.

4. The second land portion is provided with a second interrupted sipe connecting the second interrupted lateral groove and the outer main groove, The tire according to claim 2 or 3, wherein, in a plan view of the tread, the second interrupted lateral groove is formed so as to completely include an imaginary extension line that extends the second interrupted sipe along its longitudinal direction onto the second land portion.

5. The tire according to claim 4 , wherein a depth of the second interrupted sipes is smaller than a groove depth of the second interrupted lateral grooves.

6. The second interrupted lateral groove includes a joint portion connected to the second interrupted sipe, The tire according to claim 4 or 5, wherein in a longitudinal section of the second interrupted lateral groove, a groove bottom at the joint portion has an arc shape having a radius of curvature of 5 to 12 mm.

7. The tire according to claim 6 , wherein, in the joint portion, a groove width of the second interrupted lateral groove continuously decreases toward the second interrupted sipe.

8. The first inner main groove includes a pair of groove walls and a groove bottom, The pair of groove walls of the first inner main groove include a first outer groove wall located on a side of the first tread edge, the first outer groove wall includes a first groove wall portion extending radially outward from the groove bottom, and a second groove wall portion located radially outward of the first groove wall portion and inclined at a larger angle with respect to a tread normal than the first groove wall portion, The tire according to any one of claims 2 to 7, wherein the angle of the second groove wall portion is between 45 and 75 degrees.

9. The pair of groove walls of the first inner main groove include a first inner groove wall located on the second tread edge side, 9. The tire of claim 8, wherein the angle of said first inner groove wall relative to the tread normal is between 25 and 55 degrees.

10. The first inner main groove includes a pair of groove edges extending in a longitudinal direction, the pair of groove edges includes an outer groove edge located on a side of the first tread edge, 10. The tire according to claim 2, wherein the axial separation between the outer groove edge and the tire equator is 2% or less of the tread width.

11. The tire according to any one of claims 1 to 10, wherein the second land portion has an axial width of 16% to 24% of the tread width.

12. The tire according to claim 1 , wherein a groove width of the outer main groove is smaller than a groove width of the inner main groove.

Images