Pneumatic tire

Abstract

To provide a pneumatic tire capable of improving steering stability on dry road surfaces and wet performance.SOLUTION: Provided is a pneumatic tire 1 having a tread portion. The axial width center of the central land portion 4C is positioned closer to the inner tread edge T2 than the tire equator C. Each of first outer lateral grooves 10 extends in a tire axial direction across an outer tread edge T1, terminates without reaching an outer circumferential groove 3A, and has an angle of 5 to 30 degrees with respect to the tire axial direction. Each of inner lateral grooves 8 extends inward in the tire axial direction across an inner tread edge T2, terminates without reaching an inner circumferential groove 3B, and has an angle of 0 to 40 degrees with respect to the axial direction of the tire. Each of first central lateral grooves 5 extends from an inner circumferential groove 3B toward the tire equator C, terminates without reaching the tire equator C, and has an angle of 5 to 35 degrees with respect to the tire axial direction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to pneumatic tires.

Background Art

[0002] Patent Document 1 below describes a tire having a tread portion. This tread portion includes three land portions divided by a first main groove and a second main groove. Among the three land portions, a plurality of intermediate sipes that completely cross the intermediate land portion are provided in the intermediate land portion between the first main groove and the second main groove.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the tire as described above, there was room for further improvement in terms of handling stability and wet performance on dry roads.

[0005] The present disclosure was devised in view of the above actual situation, and the main object is to provide a pneumatic tire capable of improving handling stability and wet performance on dry roads.

Means for Solving the Problems

[0006] The present disclosure relates to a pneumatic tire having a tread portion. The tread portion has a specified mounting direction on a vehicle, and thus includes an outer tread edge and an inner tread edge that face the outside and inside of the vehicle when mounted on the vehicle. The tread portion is divided into three land portions by two circumferential grooves. The two circumferential grooves are an outer circumferential groove that continuously extends in the tire circumferential direction on the side of the outer tread edge, and an inner circumferential groove that continuously extends in the tire circumferential direction on the side of the inner tread edge. The three land portions include an outer land portion including the outer tread edge, an inner land portion including the inner tread edge, and a central land portion between the outer land portion and the inner land portion. The width center of the central land portion in the tire axial direction is located on the side of the inner tread edge with respect to the tire equator. A plurality of first outer transverse grooves are provided in the outer land portion. Each of the first outer transverse grooves extends in the tire axial direction so as to cross the outer tread edge and terminates without reaching the outer circumferential groove. Each of the first outer transverse grooves has an angle of 5 to 30 degrees with respect to the tire axial direction. A plurality of inner transverse grooves are provided in the inner land portion. Each of the inner transverse grooves extends inward in the tire axial direction so as to cross the inner tread edge and terminates without reaching the inner circumferential groove. Each of the inner transverse grooves has an angle of 0 to 40 degrees with respect to the tire axial direction. A plurality of first central transverse grooves are provided in the central land portion. Each of the first central transverse grooves extends from the inner circumferential groove toward the tire equator side and terminates without reaching the tire equator. Each of the first central transverse grooves has an angle of 5 to 35 degrees with respect to the tire axial direction. It is a pneumatic tire.

Advantages of the Invention

[0007] By adopting the above configuration, the pneumatic tire of the present disclosure can improve the handling stability and wet performance on a dry road surface.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0009] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. It should be understood that the drawings include exaggerated expressions and expressions different from the dimensional ratios of actual structures in order to assist in understanding the content of the disclosure. Also, throughout each embodiment, the same or common elements are denoted by the same reference numerals, and redundant explanations are omitted. Furthermore, the specific configurations shown in the embodiments and the drawings are for the purpose of understanding the content of the present disclosure, and the present disclosure is not limited to the specific configurations shown.

[0010] [Pneumatic Tire] FIG. 1 is a developed view showing the tread portion 2 of the pneumatic tire (hereinafter sometimes simply referred to as "tire") 1 of the present embodiment. FIG. 2 is a sectional view taken along the line A-A of FIG. 1. The tire 1 of the present embodiment is used, for example, as a pneumatic tire for a passenger car, and is preferably used as a high-performance tire assuming use on a circuit or the like. Note that the tire 1 is not necessarily limited to such a passenger car use, and may be applied to tires of other categories.

[0011] The tire 1 of the present embodiment is used, for example, when mounted on a vehicle having a negative camber angle (such as a racing vehicle or a high-performance passenger vehicle). Here, the "vehicle having a negative camber angle" refers to a vehicle on which the tire 1 is mounted such that when the vehicle is viewed from the front, the upper sides of the left and right tires 1 are inclined inward of the vehicle to form a "V shape". The camber angle is not particularly limited, but is set to 2 to 5 degrees (in this example, 3 degrees). Note that the vehicle on which the tire 1 is mounted is not necessarily limited to a vehicle having a negative camber angle, and may be, for example, a vehicle having no camber angle.

[0012] [Tread portion] As shown in FIGS. 1 and 2, the tire 1 of the present embodiment has a tread portion 2. The tread portion 2 of the present embodiment has a specified mounting direction on the vehicle. Accordingly, the tread portion 2 includes an outer tread end T1 facing the outer side S1 of the vehicle when mounted on the vehicle, and an inner tread end T2 facing the inner side S2 of the vehicle.

[0013] The mounting direction on the vehicle is indicated, for example, by characters, figures, etc. on the sidewall portion (not shown) of the tire 1. When the tire 1 is mounted on the vehicle, the left side in FIGS. 1 and 2 corresponds to the outer side S1 of the vehicle. On the other hand, the right side in FIGS. 1 and 2 corresponds to the inner side S2 of the vehicle. Further, the outer tread end T1 and the inner tread end T2 are specified as the outermost ground contact positions in the tire axial direction when a normal load is applied to the tire 1 in a normal state and the tire is grounded on a plane with a camber angle of 0 degrees.

[0014] The normal state is a no-load state in which the tire 1 is rim-mounted on a normal rim and filled with a normal internal pressure. In this specification, unless otherwise specified, the dimensions, etc. of each part of the tire are indicated by values measured in the normal state.

[0015] The "regular rim" is the rim defined for each tire in the standard system including the standards on which Tire 1 is based. Therefore, the regular rim is, for example, the "standard rim" in JATMA, the "Design Rim" in TRA, and the "Measuring Rim" in ETRTO.

[0016] The "regular internal pressure" is the air pressure defined for each tire in the standard system including the standards on which Tire 1 is based. Therefore, the regular internal pressure is, for example, the "maximum air pressure" in JATMA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in TRA, and the "INFLATION PRESSURE" in ETRTO. When the tire is for a passenger car, the regular internal pressure is 180 kPa. Also, in the case of a tire for racing, when there are no applicable standards, the recommended rim and air pressure by the manufacturer are applied to the regular rim and the regular internal pressure.

[0017] The "regular load" is the load defined for each tire in the standard system including the standards on which Tire 1 is based. Therefore, the regular load is, for example, the "maximum load capacity" in JATMA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in TRA, and the "LOAD CAPACITY" in ETRTO. When the tire is for a passenger car, the regular load is a load corresponding to 88% of the said load.

[0018] As shown in FIG. 1, the tread portion 2 of the present embodiment is divided into three land portions 4 by two circumferential grooves 3. FIG. 3 is an enlarged view of the central land portion 4C. FIG. 4 is an enlarged view of the inner land portion 4B. FIG. 5 is an enlarged view of the outer land portion 4A.

[0019] [Two circumferential grooves] As shown in FIG. 1, the two circumferential grooves 3 are composed of an outer circumferential groove 3A and an inner circumferential groove 3B. The outer circumferential groove 3A extends continuously (linearly in this example) in the tire circumferential direction on the side of the outer tread end T1. On the other hand, the inner circumferential groove 3B extends continuously (linearly in this example) in the tire circumferential direction on the side of the inner tread end T2. Such outer circumferential groove 3A and inner circumferential groove 3B can efficiently discharge the water on the road surface along the tire circumferential direction, thus improving the wet performance.

[0020] FIG. 6 is a developed view showing the contact surface A1 (hereinafter sometimes simply referred to as "contact surface at a negative camber angle of 3 degrees") which is rim - assembled to a standard rim at a standard internal pressure, loaded with a standard load, and given a negative camber angle of 3 degrees. FIG. 7 is a developed view showing the contact surface A2 (hereinafter sometimes simply referred to as "contact surface at a camber angle of 0 degrees") which is rim - assembled to a standard rim at a standard internal pressure, loaded with a standard load, and given a camber angle of 0 degrees. FIG. 8 is a developed view showing the contact surface A1 during turning. In FIGS. 6 to 8, the contact surface A1 is indicated by a two - dot chain line. The camber angle of 0 degrees shown in FIG. 7 corresponds to the alignment of the tire 1, for example, at the initial stage of turning (between straight - running and turning) in a race vehicle or the like.

[0021] As shown in FIG. 1, the distance R2 in the tire axial direction from the groove center line L2 of the inner circumferential groove 3B to the tire equator C of the present embodiment is set larger than the distance R1 in the tire axial direction from the groove center line L1 of the outer circumferential groove 3A to the tire equator C. For this reason, the inner circumferential groove 3B is located at the central portion in the tire axial direction of the contact surface A1 at a negative camber angle of 3 degrees shown in FIG. 6, for example. Thereby, for example, when the vehicle is running straight in a race vehicle or the like, the water on the road surface is efficiently discharged from the inner circumferential groove 3B, improving the wet performance. In order to effectively exhibit such an effect, it is desirable that the distance R2 of the groove center line L2 of the inner circumferential groove 3B shown in FIG. 1 is located at 15% - 30% of the tread contact width TW. The tread contact width TW is the distance in the tire axial direction between the outer tread end T1 and the inner tread end T2.

[0022] On the one hand, the outer circumferential groove 3A is located within the ground contact surface A1 with a negative camber angle of 3 degrees shown in FIG. 6. Thereby, for example, when driving straight in a racing vehicle or the like, water on the road surface is efficiently discharged from the outer circumferential groove 3A, improving wet performance. In order to effectively exert such an effect, the distance R1 of the groove center line L1 of the outer circumferential groove 3A shown in FIG. 1 is desirably located at 0% to 10% of the tread ground contact width TW.

[0023] As shown in FIG. 1, the groove width W2 of the inner circumferential groove 3B of the present embodiment is set larger than the groove width W1 of the outer circumferential groove 3A. Thereby, on the ground contact surface A1 with a negative camber angle of 3 degrees shown in FIG. 6, water on the road surface is efficiently discharged from the inner circumferential groove 3B located at the central portion in the tire axis direction of the ground contact surface A1, improving wet performance. In order to effectively exert such an effect, the groove width W2 of the inner circumferential groove 3B shown in FIG. 1 is desirably set to 110% to 140% of the groove width W1 of the outer circumferential groove 3A.

[0024] Each groove width W1, W2 is not particularly limited as long as the above relationship is satisfied. Each groove width W1, W2 is appropriately set, for example, in the range of 5% to 10% of the tread ground contact width TW.

[0025] As shown in FIG. 2, in the present embodiment, the groove depth D2 of the outer circumferential groove 3A and the groove depth D1 of the inner circumferential groove 3B are set to be the same. Note that in order to improve wet performance, the groove depth D2 of the inner circumferential groove 3B may be set larger than the groove depth D1 of the outer circumferential groove 3A. These groove depths D1, D2 are set to about 6 to 16 mm.

[0026] [Three land portions] As shown in FIG. 1, the three land portions 4 of the present embodiment are configured to include an outer land portion 4A including the outer tread end T1, an inner land portion 4B including the inner tread end T2, and a central land portion 4C between the outer land portion 4A and the inner land portion 4B.

[0027] The outer land portion 4A, the inner land portion 4B, and the center land portion 4C are formed as rib bodies continuous in the tire circumferential direction. Here, "continuous" for the rib body means that it is not divided in the tire circumferential direction by transverse grooves (excluding sipes) that communicate between circumferential grooves adjacent in the tire axial direction or between a circumferential groove and a tread edge. These outer land portion 4A, inner land portion 4B, and center land portion 4C can increase the rigidity in the tire circumferential direction and the rigidity in the tire axial direction compared to, for example, a block row (not shown) divided by transverse grooves, so the handling stability on a dry road surface is improved.

[0028] In this specification, a "sipe" is a cut with an opening width on the tread surface of 2.0 mm or less, and is distinguished from a groove for drainage. The maximum depth of each sipe is, for example, 0.50 to 0.70 times the groove depth D1 of the outer circumferential groove 3A and the groove depth D2 of the inner circumferential groove 3B shown in FIG. 2.

[0029] [Center land portion] As shown in FIG. 1, the center land portion 4C of the present embodiment is divided by the outer circumferential groove 3A and the inner circumferential groove 3B. As shown in FIG. 3, the width center L3 in the tire axial direction of the center land portion 4C of the present embodiment is located on the side of the inner tread edge T2 (the inner side S2 of the vehicle) from the tire equator C. Thereby, for example, during straight running, at the initial stage of turning, and during turning in a racing vehicle or the like (shown in FIGS. 6 to 8), the center land portion 4C can be sufficiently grounded on the road surface, and thus the handling stability on a dry road surface is improved. In order to effectively exhibit such an effect, the distance R3 in the tire axial direction between the width center L3 of the center land portion 4C and the tire equator C (shown in FIG. 3) is 5% to 8% of the tread contact width TW (shown in FIG. 1).

[0030] As shown in FIG. 3, the central land portion 4C of the present embodiment has a width W3 in the tire axial direction that is 30% to 45% of the tread contact width TW (shown in FIG. 1). By setting the width W3 to be 30% or more of the tread contact width TW, for the central land portion 4C where a large contact pressure acts during straight running, initial turning, and turning, while enhancing its lateral rigidity, it is possible to make contact over a wide range in the tire axial direction. Therefore, the grip performance during straight running, initial turning, and turning can be enhanced, and the handling stability on a dry road surface is improved. On the other hand, by setting the width W3 to be 45% or less of the tread contact width TW, the outer circumferential groove 3A and the inner circumferential groove 3B arranged on both sides of the central land portion 4C can be arranged within the contact surface A1 (shown in FIGS. 6 to 8) during straight running, initial turning, and turning, and the wet performance is improved. From such a viewpoint, the width W3 is preferably 35% or more of the tread contact width TW, and preferably 40% or less.

[0031] [First Central Transverse Groove] As shown in FIGS. 1 and 3, a plurality of first central transverse grooves 5 are provided in the central land portion 4C. Each of the first central transverse grooves 5 extends from the inner circumferential groove 3B toward the tire equator C side and terminates without reaching the tire equator C. By such first central transverse grooves 5, the rigidity of the central land portion 4C where a large contact pressure acts during straight running, initial turning, and turning is maintained high. Therefore, the handling stability on a dry road surface is improved.

[0032] Since the plurality of first central transverse grooves 5 extend from the inner circumferential groove 3B toward the tire equator C side, during wet running, the water on the road surface can be discharged into the inner circumferential groove 3B. Therefore, the wet performance is improved. Furthermore, since the plurality of first central transverse grooves 5 of the present embodiment can be located within the contact surface A1 (shown in FIGS. 6 to 8) during straight running, initial turning, and turning, the water on the road surface can be smoothly discharged during their running. As shown in FIG. 3, in order to further improve the wet performance, it is desirable that the groove center line L4 of the first central transverse groove 5 be linear.

[0033] Each of the first central transverse grooves 5 of the present embodiment is inclined with respect to the tire axial direction and has an angle θ1 of 5 to 35 degrees with respect to the tire axial direction. By setting the angle θ1 to 5 degrees or more, simultaneous grounding of the first central transverse grooves 5 is avoided, and thus generation of a circumferential rigidity step in the contact surface is suppressed. Furthermore, since the discharge of water on the road surface can be promoted, the grip performance during wet running is improved. On the other hand, since the angle θ1 is set to 35 degrees or less, a decrease in the lateral rigidity of the central land portion 4C can be prevented, and thus the responsiveness at the initial stage of turning and during turning is improved on both dry and wet road surfaces. Therefore, the handling stability on a dry road surface and the wet performance are improved. From such a viewpoint, the angle θ1 is preferably 10 degrees or more and preferably 30 degrees or less.

[0034] The groove width W4 of each of the first central transverse grooves 5 of the present embodiment continuously decreases from the inner circumferential groove 3B toward the inner side in the tire axial direction (toward the tire equator C side). Such first central transverse grooves 5 can prevent a decrease in the rigidity of the central land portion 4C where a large contact pressure acts during straight running, at the initial stage of turning, and during turning, and thus the handling stability on a dry road surface is improved. Also, during wet running, since the water pressure in the first central transverse groove 5 decreases from the inner end 5i in the tire axial direction toward the inner circumferential groove 3B, the water in the first central transverse groove 5 can be smoothly discharged toward the inner circumferential groove 3B. Therefore, the wet performance is improved. Note that the maximum value of the groove width W4 of the first central transverse groove 5 (the groove width on the inner circumferential groove 3B side) is preferably 3% to 6% of the tread contact width TW (shown in FIG. 1).

[0035] Each groove width W4 of the first central transverse groove 5 may continuously decrease from the inner circumferential groove 3B to the inner end 5i in the tire axial direction. As a result, the first central transverse groove 5 is formed in a triangular shape that is convex at the inner end 5i in plan view. Such a first central transverse groove 5 can prevent a decrease in the rigidity of the central land portion 4C on the tire equator C side (the central portion in the tire axial direction) where the contact pressure at the central land portion 4C becomes relatively large. Further, since the water pressure in the first central transverse groove 5 can be gradually decreased from the inner end 5i toward the inner circumferential groove 3B, drainage can be performed more smoothly toward the inner circumferential groove 3B. Therefore, the handling stability on a dry road surface and the wet performance are improved.

[0036] The length R5 in the tire axial direction of each of the first central transverse grooves 5 is preferably set to 60% to 75% of the width W3 of the central land portion 4C. By setting the length R5 to 60% or more of the width W3, the first central transverse groove 5 can be arranged over a wide range in the tire axial direction of the central land portion 4C, so that the wet performance is improved. On the other hand, by setting the length R5 to 75% or less of the width W3, a decrease in the rigidity of the central land portion 4C can be prevented, so that the handling stability on a dry road surface is improved.

[0037] As shown in FIG. 2, the groove depth D4 of each of the first central transverse grooves 5 can be appropriately set. In order to achieve both the handling stability on a dry road surface and the wet performance, the groove depth D4 is set to 60% to 80% of the groove depth D2 of the inner circumferential groove 3B.

[0038] [Second Central Transverse Groove] As shown in FIG. 3, a plurality of second central transverse grooves 6 are provided in the central land portion 4C of the present embodiment. Each of the second central transverse grooves 6 extends from the outer circumferential groove 3A toward the tire equator C side and terminates without reaching the tire equator C. By such second central transverse grooves 6, the rigidity of the central land portion 4C where a large contact pressure acts during straight running, at the initial stage of turning, and during turning is maintained high, and the handling stability performance on a dry road surface is improved.

[0039] Since the plurality of second central transverse grooves 6 extend from the outer circumferential groove 3A toward the tire equator C, water on the road surface can be discharged into the outer circumferential groove 3A during wet driving. Further, since the plurality of second central transverse grooves 6 of the present embodiment can be located within the ground contact surface A1 (shown in FIGS. 6 to 8) during straight driving, initial turning, and turning together with the first central transverse groove 5, water on the road surface can be efficiently discharged. Therefore, wet performance is improved. In order to further improve the wet performance, it is desirable that the groove center line L5 of the second central transverse groove 6 be linear.

[0040] Each of the second central transverse grooves 6 of the present embodiment is inclined with respect to the tire axial direction and has an angle θ2 of 5 to 25 degrees with respect to the tire axial direction. Since the angle θ2 is 5 degrees or more, simultaneous ground contact of the second central transverse groove 6 is avoided, and thus generation of a circumferential rigidity step within the ground contact surface A1 can be suppressed. Further, since discharge of water on the road surface can be promoted, grip performance during wet driving is improved. On the other hand, since the angle θ2 is 25 degrees or less, a decrease in the lateral rigidity of the central land portion 4C can be prevented, and responsiveness during initial turning is improved on both dry and wet road surfaces. Therefore, handling stability on dry road surfaces and wet performance are improved. From such a viewpoint, the angle θ2 is preferably 10 degrees or more and preferably 20 degrees or less.

[0041] Each of the second central transverse grooves 6 of the present embodiment is inclined in the same direction as the first central transverse groove 5 with respect to the tire axial direction. Thereby, the second central transverse groove 6 can act on the central land portion 4C with edge components in the same direction together with the first central transverse groove 5. Therefore, handling stability on dry road surfaces and wet performance are improved.

[0042] In the present embodiment, each groove width W5 of the second central transverse groove 6 continuously decreases from the outer circumferential groove 3A toward the inner side in the tire axial direction (toward the tire equator C side). Such a second central transverse groove 6, similar to the first central transverse groove 5, can prevent a reduction in the rigidity of the central land portion 4C. Further, during wet running, since the water pressure in the second central transverse groove 6 decreases toward the outer circumferential groove 3A, the water in the second central transverse groove 6 can be smoothly discharged toward the outer circumferential groove 3A. Therefore, the handling stability on a dry road surface and the wet performance are improved.

[0043] Each groove width W5 of the second central transverse groove 6 may continuously decrease from the outer circumferential groove 3A to the inner end 6i in the tire axial direction. Thereby, the second central transverse groove 6 is formed in a triangular shape that protrudes at the inner end 6i in plan view. Such a second central transverse groove 6, similar to the first central transverse groove 5, can prevent a reduction in the rigidity of the central land portion 4C on the tire equator C side (the central portion in the tire axial direction) where the contact pressure at the central land portion 4C becomes relatively large. Further, since the water pressure in the second central transverse groove 6 can be gradually decreased from the inner end 6i toward the outer circumferential groove 3A, drainage can be performed more smoothly toward the outer circumferential groove 3A. Therefore, the handling stability on a dry road surface and the wet performance are improved.

[0044] It is desirable that the maximum value of each groove width W5 of the second central transverse groove 6 (the groove width on the outer circumferential groove 3A side) is set smaller than the maximum value of each groove width W4 of the first central transverse groove 5 (the groove width on the inner circumferential groove 3B side). Thereby, the rigidity of the outer side S1 (the outer tread end T1 side) of the vehicle where a large contact pressure acts during turning in the central land portion 4C is maintained high, and the handling stability on a dry road surface is improved. From such a viewpoint, the maximum value of the groove width W5 of the second central transverse groove 6 is preferably 50% to 70% of the maximum value of the groove width W4 of the first central transverse groove 5.

[0045] The tire axial length R6 of each of the second central grooves 6 is preferably set shorter than the tire axial length R5 of each of the first central grooves 5. Thereby, in the central land portion 4C, the rigidity of the outer side S1 (outer tread edge T1 side) of the vehicle where a large ground pressure acts during turning is maintained high, so that the handling stability on a dry road surface is improved. From such a viewpoint, the length R6 of the second central groove 6 is preferably 25% to 40% of the length R5 of the first central groove 5.

[0046] From the same viewpoint as the length R6 of the second central groove 6 described above, the pitch length P2 in the tire circumferential direction of the second central groove 6 is preferably set larger than the pitch length P1 in the tire circumferential direction of the first central groove 5. Note that the pitch length P2 of the second central groove 6 is preferably 1.5 to 2.5 times the pitch length P1 of the first central groove 5.

[0047] As shown in FIG. 2, the groove depth D6 of each of the second central grooves 6 can be set as appropriate. In order to improve the handling stability and wet performance on a dry road surface, the groove depth D6 is set to 60% to 80% of the groove depth D1 of the outer circumferential groove 3A.

[0048] [Central sipes] As shown in FIG. 3, a plurality of central sipes 7 are provided in the central land portion 4C of the present embodiment. Each of the central sipes 7 extends from the outer circumferential groove 3A toward the tire equator C side and terminates without reaching the tire equator C. Such central sipes 7 can promote the deformation of the central land portion 4C and improve the grip performance during wet running. On the other hand, at the initial stage of turning on a dry road surface, the wall surfaces on both sides of the central sipes 7 support each other, and the rigidity of the central land portion 4C is ensured. Therefore, the wet performance and the handling stability on a dry road surface are improved. In order to effectively exhibit such an effect, the width W7 of the central sipes 7 is preferably set to 0.5 to 1.0 mm.

[0049] Each of the central sipes 7 of the present embodiment is inclined with respect to the tire axial direction and has an angle θ3 of 5 to 30 degrees with respect to the tire axial direction. By setting the angle θ3 to 30 degrees or less, the deformation of the central land portion 4C can be efficiently promoted during wet running, and the grip performance can be improved. On the other hand, by setting the angle θ3 to 5 degrees or more, the wall surfaces on both sides of the central sipes 7 can effectively support each other, and a decrease in the lateral rigidity of the central land portion 4C can be prevented. From such a viewpoint, the angle θ3 is preferably 25 degrees or less, and preferably 10 degrees or more.

[0050] Each of the central sipes 7 of the present embodiment is inclined in the same direction as the first central transverse groove 5 and the second central transverse groove 6 with respect to the tire axial direction. Thereby, the second central transverse groove 6, together with the first central transverse groove 5 and the second central transverse groove 6, can act an edge component in the same direction on the central land portion 4C, so that the handling stability and wet performance on a dry road surface are improved.

[0051] It is desirable that the length R7 in the tire axial direction of each of the central sipes 7 is 30% to 40% of the width W3 of the central land portion 4C. By setting the length R7 to 30% or more of the width W3, the deformation of the central land portion 4C can be efficiently promoted during wet running, and the grip performance can be improved. On the other hand, by setting the length R7 to 40% or less of the width W3, it is possible to prevent the rigidity of the central land portion 4C from decreasing more than necessary, so that the handling stability on a dry road surface is maintained. In order to effectively exhibit such an action, the length R7 is preferably 32% or more of the width W3, and preferably 38% or less.

[0052] Each of the central sipes 7 of the present embodiment is arranged between adjacent second central transverse grooves 6, 6 in the tire circumferential direction. Thereby, in the central land portion 4C, the rigidity of the outer side S1 (outer tread end T1 side) of the vehicle where a large ground pressure acts during turning is maintained high, so that the handling stability on a dry road surface is improved. Note that the pitch length P3 in the tire circumferential direction of the central sipes 7 is preferably set within the same range as the pitch length P2 of the second central transverse groove 6.

[0053] [Inner land portion] As shown in FIG. 1, the inner land portion 4B of the present embodiment is partitioned to the inner side S2 of the vehicle with respect to the inner circumferential groove 3B and includes the inner tread edge T2. As shown in FIG. 4, the inner land portion 4B of the present embodiment has a width W8 in the tire axial direction that is 12% to 18% of the tread contact width TW (shown in FIG. 1). By setting the width W8 to be 12% or more of the tread contact width TW, the lateral rigidity of the inner land portion 4B where a large contact pressure acts from straight-ahead travel to the initial stage of turning can be increased. On the other hand, by setting the width W8 to be 18% or less of the tread contact width TW, as shown in FIGS. 6 to 8, the central land portion 4C arranged on the outer side S1 of the vehicle with respect to the inner land portion 4B can be brought into contact with a wide range in the tire axial direction during straight-ahead travel, the initial stage of turning, and turning. Therefore, the handling stability on a dry road surface is improved. From such a viewpoint, the width W8 is preferably 14% or more of the tread contact width TW, and preferably 16% or less.

[0054] [Inner lateral groove] As shown in FIG. 4, a plurality of inner lateral grooves 8 are provided in the inner land portion 4B of the present embodiment. Each of the inner lateral grooves 8 extends inward in the tire axial direction so as to cross the inner tread edge T2 and terminates without reaching the inner circumferential groove 3B. By such inner lateral grooves 8, the rigidity of the inner land portion 4B where a large contact pressure acts during straight-ahead travel and the initial stage of turning is maintained high. Therefore, the handling stability on a dry road surface is improved.

[0055] Since each of the inner lateral grooves 8 of the present embodiment is arranged so as to cross the inner tread edge T2, during wet running, the water on the road surface can be discharged from the inner tread edge T2 to the outside of the tire (inner side S2 of the vehicle). Therefore, the wet performance is improved.

[0056] Each of the inner lateral grooves 8 of the present embodiment has an angle θ4 of 0 to 40 degrees with respect to the tire axial direction. By setting the angle θ4 to 40 degrees or less, it is possible to prevent a decrease in the lateral rigidity of the inner land portion 4B where a large contact pressure acts during straight running and at the initial stage of turning. Thereby, the responsiveness at the initial stage of turning can be improved, and the handling stability on a dry road surface is improved. From such a viewpoint, the angle θ4 is preferably 30 degrees or less. Further, in the inner land portion 4B, in order to suppress the generation of a circumferential rigidity step in the contact surface A1, the angle θ4 is preferably greater than 0 degrees, and more preferably 10 degrees or more.

[0057] As shown in FIG. 1, each of the inner lateral grooves 8 of the present embodiment is inclined in a direction opposite to (a direction intersecting with each other) the first central groove 5 and the second central groove 6 with respect to the tire axial direction. Thereby, the inner lateral groove 8 can act on edge components different from those of the first central groove 5 and the second central groove 6. Therefore, the handling stability and wet performance on a dry road surface are improved.

[0058] As shown in FIG. 4, the groove width W9 of each of the inner lateral grooves 8 of the present embodiment continuously decreases from the vicinity of the inner tread edge T2 toward the inner side in the tire axial direction (toward the tire equator C side). Such an inner lateral groove 8 can prevent a decrease in the rigidity of the inner land portion 4B where a large contact pressure acts during straight running and at the initial stage of turning, so that the handling stability on a dry road surface is improved. Further, during wet running, since the water pressure in the inner lateral groove 8 decreases toward the inner tread edge T2, it is possible to smoothly drain water from the inner tread edge T2 to the outside of the tire, and thus the wet performance is improved. The “vicinity of the inner tread edge T2” means a range where the distance in the tire axial direction from the inner tread edge T2 is 5 mm or less. Further, the maximum value of the groove width W9 of the inner lateral groove 8 (the groove width on the inner tread edge T2 side) is preferably 2% to 5% of the tread contact width TW (shown in FIG. 1).

[0059] In the present embodiment, the groove width W9 of the inner lateral groove 8 continuously decreases from the inner tread edge T2 to the inner end 8i in the tire axial direction. As a result, the inner lateral groove 8 is formed in a triangular shape that protrudes at the inner end 8i in plan view. Such an inner lateral groove 8 can prevent a decrease in the rigidity of the inner land portion 4B at the central portion of the inner land portion 4B in the tire axial direction. Furthermore, since the water pressure in the inner lateral groove 8 can be gradually decreased from the inner end 8i toward the inner tread edge T2, drainage can be smoothly performed from the inner tread edge T2 to the outside of the tire. Therefore, the handling stability on a dry road surface and the wet performance are improved.

[0060] Each of the inner lateral grooves 8 of the present embodiment is configured to include a first portion 8A having a constant groove width W9 and a second portion 8B in which the groove width W9 continuously decreases toward the inner end 8i in the tire axial direction.

[0061] The first portion 8A of the present embodiment extends from the vicinity of the inner tread edge T2 toward the outside in the tire axial direction (the inner side S2 of the vehicle). This first portion 8A is connected to the second portion 8B in the vicinity of the inner tread edge T2.

[0062] In the inner lateral groove 8 of the present embodiment, since the water pressure in the second portion 8B can be gradually decreased from the inner end 8i toward the inner tread edge T2, drainage can be smoothly performed to the first portion 8A. On the other hand, in the first portion 8A, since the groove width W9 is constant, drainage can be smoothly performed to the outside of the tire (the inner side S2 of the vehicle). Therefore, the wet performance is improved.

[0063] The angle θ4a of the first portion 8A of the present embodiment with respect to the tire axis direction is smaller than the angle θ4b of the second portion 8B with respect to the tire axis direction. Thereby, the first portion 8A can smoothly discharge the water guided to the inner tread end T2 side by the second portion 8B toward the outer side in the tire axis direction (the inner side S2 of the vehicle). Therefore, the wet performance is improved. In order to effectively exhibit such an effect, it is desirable that the angle θ4a of the first portion 8A of the present embodiment be set to 60% to 80% of the angle θ4b of the second portion 8B. Note that the angle θ4a of the first portion 8A and the angle θ4b of the second portion 8B can be appropriately set as long as they are within the range of the angle θ4 of the inner lateral groove 8 described above.

[0064] As shown in FIG. 6, at the ground contact surface A1 with a negative camber angle of 3 degrees, it is desirable that the length (maximum length) R8a of the first portion 8A in the tire axis direction be larger than the length (maximum length) R8b of the second portion 8B in the tire axis direction. Thereby, for example, when going straight in a racing vehicle or the like, water can be smoothly drained from the inner tread end T2 to the outside of the tire, and thus the wet performance is improved. In order to effectively exhibit such an effect, the length R8a of the first portion 8A is preferably 1.3 to 1.8 times the length R8b of the second portion 8B.

[0065] On the other hand, as shown in FIG. 7, at the ground contact surface A1 with a camber angle of 0 degrees, it is desirable that the length (maximum length) R9a of the first portion 8A in the tire axis direction be smaller than the length (maximum length) R9b of the second portion 8B in the tire axis direction. As described above, since the camber angle of 0 degrees corresponds to the alignment of the tire 1 at the initial stage of turning, it is possible to make the ground contact area of the tread portion 2 at the initial stage of turning larger than the ground contact area when going straight (shown in FIG. 6). Therefore, the responsiveness at the initial stage of turning can be improved, and the handling stability on a dry road surface is improved. In order to effectively exhibit such an effect, the length R9a of the first portion 8A is preferably 0.3 to 0.7 times the length R9b of the second portion 8B.

[0066] As shown in FIG. 4, the pitch length P4 in the tire circumferential direction of the inner lateral groove 8 can be set as appropriate. The pitch length P4 is preferably set within the same range as the pitch length P1 (shown in FIG. 3) in the tire circumferential direction of the first central groove 5. Thereby, while preventing a decrease in the rigidity of the inner land portion 4B, the inner lateral groove 8 can effectively discharge water on the road surface.

[0067] As shown in FIG. 2, each groove depth D7 of the inner lateral groove 8 can be set as appropriate. In order to improve the handling stability on a dry road surface and wet performance, the groove depth D7 is set to 60% to 80% of the groove depth D2 of the inner circumferential groove 3B.

[0068] [Outer land portion] As shown in FIG. 1, the outer land portion 4A of the present embodiment is divided into the outer side S1 of the vehicle with respect to the outer circumferential groove 3A and includes the outer tread edge T1. As shown in FIG. 5, the outer land portion 4A of the present embodiment has a width W10 in the tire axial direction that is 25% to 35% of the tread contact width TW (shown in FIG. 1). By setting the width W10 to be 25% or more of the tread contact width TW, the lateral rigidity of the outer land portion 4A where a large contact pressure acts from the initial stage of turning to during turning can be increased. On the other hand, by setting the width W10 to be 35% or less of the tread contact width TW, the central land portion 4C arranged on the inner side S2 of the vehicle with respect to the outer land portion 4A can be brought into contact with a wide range in the tire axial direction during straight running, the initial stage of turning, and turning as shown in FIGS. 6 to 8. Therefore, the handling stability on a dry road surface is improved. From such a viewpoint, the width W10 is preferably 28% or more of the tread contact width TW, and preferably 32% or less.

[0069] [First outer lateral groove] As shown in FIG. 5, a plurality of first outer lateral grooves 10 are provided in the outer land portion 4A of the present embodiment. Each of the first outer lateral grooves 10 extends in the tire axial direction so as to cross the outer tread edge T1 and terminates without reaching the outer circumferential groove 3A. By such first outer lateral grooves 10, the rigidity of the outer land portion 4A where a large contact pressure acts from the initial stage of turning to during turning is maintained high. Therefore, the handling stability on a dry road surface is improved.

[0070] Since each of the first outer lateral grooves 10 of the present embodiment is arranged so as to cross the outer tread edge T1, during wet running, water on the road surface can be discharged from the outer tread edge T1 to the outside of the tire (the outside S1 of the vehicle). Therefore, the wet performance is improved.

[0071] Each of the first outer lateral grooves 10 of the present embodiment is inclined with respect to the tire axial direction and has an angle θ5 of 5 to 30 degrees with respect to the tire axial direction. By setting the angle θ5 to 5 degrees or more, simultaneous grounding of the first outer lateral grooves 10 is avoided, and thus generation of a circumferential rigidity step in the contact surface A1 can be suppressed. Furthermore, since the discharge of water on the road surface can be promoted, the grip performance during wet running is improved. On the other hand, since the angle θ5 is set to 30 degrees or less, a decrease in the lateral rigidity of the outer land portion 4A can be prevented. Thereby, the responsiveness during turning is improved on both dry and wet road surfaces. Therefore, the handling stability and wet performance on a dry road surface are improved. From such a viewpoint, the angle θ5 is preferably 10 degrees or more and preferably 25 degrees or less.

[0072] As shown in FIG. 1, each of the first outer lateral grooves 10 of the present embodiment is inclined in a direction opposite to (a direction intersecting with each other) the first central groove 5 and the second central groove 6 with respect to the tire axial direction. Thereby, the first outer lateral groove 10 can act different edge components from the first central groove 5 and the second central groove 6, for example, at the initial stage and during turning (shown in FIGS. 7 and 8) of a racing vehicle or the like. Therefore, the handling stability on a dry road surface and the wet performance are improved.

[0073] As shown in FIG. 5, the groove width W11 of each of the first outer lateral grooves 10 of the present embodiment continuously decreases from the vicinity of the outer tread end T1 toward the inner side in the tire axial direction (tire equator C). Such a first outer lateral groove 10 can prevent a decrease in the rigidity of the outer land portion 4A where a large ground pressure acts at the initial stage of turning and during turning. Further, during wet running, since the water pressure in the first outer lateral groove 10 decreases toward the outer tread end T1, water can be smoothly drained from the outer tread end T1 to the outside of the tire. Therefore, the handling stability on a dry road surface and the wet performance are improved. Note that the "vicinity of the outer tread end T1" means a range where the distance in the tire axial direction from the outer tread end T1 is 5 mm or less. Further, the maximum value of the groove width W11 of the first outer lateral groove 10 (the groove width on the outer tread end T1 side) is preferably 2% to 5% of the tread contact width TW.

[0074] The groove width W11 of the first outer lateral groove 10 of the present embodiment continuously decreases from the outer tread end T1 to the inner end 10i in the tire axial direction. As a result, the first outer lateral groove 10 is formed in a triangular shape that bulges at the inner end 10i in plan view. Such a first outer lateral groove 10 can prevent a decrease in the rigidity of the outer land portion 4A at the central portion of the outer land portion 4A in the tire axial direction. Further, since the water pressure in the first outer lateral groove 10 can be gradually decreased from the inner end 10i toward the outer tread end T1, water can be smoothly drained from the inner tread end T2 to the outside of the tire. Therefore, the handling stability on a dry road surface and the wet performance are improved.

[0075] Each of the first outer lateral grooves 10 of the present embodiment includes an outer portion 10A and an inner portion 10B. The outer portion 10A is a portion on the outer side in the tire axial direction (outer side S1 of the vehicle) than the outer tread end T1. On the other hand, the inner portion 10B is a portion on the inner side in the tire axial direction (toward the tire equator C side) than the outer tread end T1. The outer portion 10A is connected to the inner portion 10B in the vicinity of the outer tread end T1.

[0076] Regarding the angle θ5 of the first outer lateral groove 10 of the present embodiment, the outer portion 10A is smaller than the inner portion 10B. Thereby, by utilizing the large lateral force during turning, the water in the first outer lateral groove 10 can be smoothly discharged from the inner portion 10B to the outer portion 10A, improving the wet performance. In order to effectively exert such an effect, it is desirable that the angle θ5a of the outer portion 10A is set to 0.85 to 0.95 times the angle θ5b of the inner portion 10B. Note that the angle θ5a of the outer portion 10A and the angle θ5b of the inner portion 10B can be appropriately set as long as they are within the range of the angle θ5 of the first outer lateral groove 10 described above.

[0077] In the first outer lateral groove 10 of the present embodiment, the groove width W11a of the outer portion 10A is set to be constant, and the groove width W11b of the inner portion 10B continuously decreases toward the inner end 10i in the tire axial direction. Such a first outer lateral groove 10 can gradually reduce the water pressure in the inner portion 10B from the inner end 10i toward the outer tread end T1, so that it can drain smoothly to the outer portion 10A. On the other hand, in the outer portion 10A, since the groove width W11a is set to be constant, it can drain smoothly to the outside of the tire (the outside S1 of the vehicle) by utilizing the large lateral force during turning. Therefore, the wet performance is improved.

[0078] It is desirable that the length R10 of each of the first outer lateral grooves 10 in the tire axial direction of the present embodiment is 60% or more of the width W10 of the outer land portion 4A in the tire axial direction. By setting the length R10 to 60% or more of the width W10, the first outer lateral groove 10 can be arranged over a wide range in the tire axial direction of the outer land portion 4A, so that the water on the road surface can be drained smoothly. On the other hand, if the length R10 becomes larger than necessary, there is a possibility that the rigidity of the outer land portion 4A cannot be sufficiently maintained. For this reason, it is desirable that the length R10 is set to 80% or less of the width W10.

[0079] As shown in FIG. 6, on the ground contact surface A1 at a negative camber angle of 3 degrees, while the outer circumferential groove 3A is located within the ground contact surface A1, it is desirable that the first outer lateral groove 10 be located outside the ground contact surface A1. Thereby, when going straight in the above-mentioned racing vehicle or the like, the outer circumferential groove 3A, together with the inner circumferential groove 3B, can efficiently drain the water on the road surface, improving the wet performance. On the other hand, since the first outer lateral groove 10 is located outside the ground contact surface A1, the ground contact area during straight running can be ensured, improving the grip performance during straight running.

[0080] As shown in FIG. 7, on the ground contact surface A1 at a camber angle of 0 degrees, the outer circumferential groove 3A and the first outer lateral groove 10 are located within the ground contact surface A1. Thereby, at the initial stage of turning in the above-mentioned racing vehicle or the like, the outer circumferential groove 3A and the first outer lateral groove 10 can efficiently drain the water on the road surface, improving the wet performance.

[0081] Furthermore, as shown in FIG. 8, on the ground contact surface A1 during turning, the outer circumferential groove 3A and the first outer lateral groove 10 are located within the ground contact surface A1. For this reason, during turning, the water on the road surface can be efficiently drained, improving the wet performance. Furthermore, on the ground contact surface A1 during turning, compared with the ground contact surface A1 at the initial stage of turning shown in FIG. 7, the ratio of the outer portion 10A of the first outer lateral groove 10 can be increased, ensuring the groove volume during turning and effectively improving the wet performance.

[0082] As shown in FIG. 5, the pitch length P5 in the tire circumferential direction of the first outer lateral groove 10 can be appropriately set. The pitch length P5 of the present embodiment is set to be larger than the pitch length P1 (shown in FIG. 3) in the tire circumferential direction of the first central lateral groove 5. Thereby, the first outer lateral groove 10 can effectively drain the water on the road surface while preventing a decrease in the rigidity of the outer land portion 4A. Note that the pitch length P4 of the first outer lateral groove 10 is preferably 1.5 to 2.5 times the pitch length P1 of the first central lateral groove 5.

[0083] As shown in FIG. 2, the groove depth D8 of each of the first outer lateral grooves 10 can be appropriately set. In order to improve the handling stability on dry road surfaces and wet performance, the groove depth D8 is set to 60% to 80% of the groove depth D1 of the outer circumferential groove 3A.

[0084] [Patch sipe] As shown in FIG. 5, on the outer land portion 4A of the present embodiment, a patch sipe 11 that connects the inner end 10i in the tire axial direction of the first outer lateral groove 10 and the outer circumferential groove 3A is provided. Such a patch sipe 11 can cooperate with the first outer lateral groove 10 during wet running to promote the deformation of the outer land portion 4A and improve the grip performance. On the other hand, during turning on a dry road surface, the wall surfaces on both sides of the patch sipe 11 support each other, so that the lateral rigidity of the outer land portion 4A is ensured, and the handling stability on the dry road surface is maintained. In order to effectively exhibit such an action, it is desirable that the width W12 of the patch sipe 11 is 0.5 to 1.0 mm.

[0085] Each of the patch sipes 11 preferably has an angle θ6 of 5 to 30 degrees with respect to the tire axial direction. By setting the angle θ6 to 30 degrees or less, the deformation of the outer land portion 4A can be efficiently promoted during wet running, and the grip performance can be improved. On the other hand, by setting the angle θ6 to 5 degrees or more, the wall surfaces on both sides of the patch sipe 11 effectively support each other, and a decrease in the lateral rigidity of the outer land portion 4A can be prevented. From this point of view, the angle θ6 is preferably 25 degrees or less and preferably 10 degrees or more.

[0086] [Second outer lateral groove] A plurality of second outer lateral grooves 12 are provided in the outer land portion 4A of the present embodiment. Each of the second outer lateral grooves 12 extends inward in the tire axial direction so as to cross the outer tread edge T1 and terminates without reaching the outer circumferential groove 3A.

[0087] Since each of the second outer lateral grooves 12 is arranged to cross the outer tread edge T1, when driving on a wet road surface, together with the first outer lateral groove 10, water on the road surface can be discharged from the outer tread edge T1 to the outside of the tire (the outside S1 of the vehicle). Therefore, the wet performance is improved.

[0088] Since each of the second outer lateral grooves 12 terminates without reaching the outer circumferential groove 3A, the rigidity of the outer land portion 4A where a large ground pressure acts during turning is maintained high. Therefore, the handling stability on a dry road surface is improved.

[0089] The length R11 in the tire axial direction of each of the second outer lateral grooves 12 of the present embodiment is smaller than the length R10 in the tire axial direction of each of the first outer lateral grooves 10. Thereby, a decrease in the rigidity of the outer land portion 4A is suppressed, so that the wet performance is improved while maintaining the handling stability on a dry road surface. In order to effectively exhibit such an effect, the length R11 of the second outer lateral groove 12 is preferably 70% to 85% of the length R10 of the first outer lateral groove 10.

[0090] Each of the second outer lateral grooves 12 preferably has an angle θ7 of 5 to 30 degrees with respect to the tire axial direction. When the angle θ7 is 5 degrees or more, simultaneous grounding of the second outer lateral grooves 12 is avoided, and thus generation of a circumferential rigidity step in the contact surface A1 can be suppressed. On the other hand, since the angle θ7 is 30 degrees or less, a decrease in the lateral rigidity of the outer land portion 4A can be prevented, and the handling stability on a dry road surface is improved. From such a viewpoint, the angle θ7 is preferably 10 degrees or more and preferably 25 degrees or less.

[0091] As shown in FIG. 1, each of the second outer lateral grooves 12 of the present embodiment is inclined in a direction opposite to (a direction intersecting with each other) the first central lateral groove 5 and the second central lateral groove 6 with respect to the tire axial direction. Thereby, as shown in FIGS. 7 and 8, the second outer lateral groove 12 can act on edge components different from those of the first central lateral groove 5 and the second central lateral groove 6 at the initial stage of turning and during turning in the above-mentioned racing vehicle or the like. Further, since the second outer lateral groove 12 is inclined in the same direction as the first outer lateral groove 10 with respect to the tire axial direction, in the outer land portion 4A, together with the first outer lateral groove 10, edge components in the same direction can be made to act. Therefore, the handling stability on a dry road surface and the wet performance are improved.

[0092] Each of the second outer lateral grooves 12 of the present embodiment is configured to include a first portion 12A and a second portion 12B. In the first portion 12A, the groove width W13 of the second outer lateral groove 12 continuously decreases toward the inner end 12i in the tire axial direction. On the other hand, in the second portion 12B, the groove width W13 of the second outer lateral groove 12 continuously decreases from the first portion 12A toward the outer end 12o in the tire axial direction. By these first portion 12A and second portion 12B, the second outer lateral groove 12 is formed in a rhombus shape in plan view.

[0093] Such a second outer lateral groove 12 can prevent a decrease in the rigidity of the outer land portion 4A where a large contact pressure acts at the initial stage of turning and during turning. Also, during wet running, since the water pressure of the first portion 12A decreases from the inner end 12i toward the second portion 12B, the water in the first portion 12A can be smoothly guided to the second portion 12B. On the other hand, since the second portion 12B crosses the outer tread edge T1, the water in the second portion 12B can be discharged to the outer tread edge T1 side. Therefore, the handling stability on a dry road surface and the wet performance are improved. Note that the maximum value of the groove width W13 of the second outer lateral groove 12 is preferably 2% to 4% of the tread contact width TW (shown in FIG. 1).

[0094] In the second outer lateral groove 12 of the present embodiment, on the outer land portion 4A, it is alternately arranged with the first outer lateral groove 10 in the tire circumferential direction. Thereby, the second outer lateral groove 12, together with the first outer lateral groove 10, suppresses a decrease in the lateral rigidity of the outer land portion 4A where a large ground pressure acts during turning, and can discharge water on the road surface from the outer tread edge T1 to the outside of the tire (the outside S1 of the vehicle) during wet running. Therefore, the handling stability on a dry road surface and the wet performance are improved.

[0095] As described above, the particularly preferred embodiments of the present disclosure have been described in detail. However, the present disclosure is not limited to the illustrated embodiments and can be implemented in various forms by deformation.

Example

[0096] [Example A] The pneumatic tire shown in FIG. 1 was prototyped based on the specifications in Tables 1 and 2 (Examples 1 to 6, Comparative Examples 3 to 7). For comparison, the pneumatic tire described in Patent Document 1 shown in FIG. 9 (Comparative Example 1) and the pneumatic tire in which the width center of the central land portion is located on the tire equator shown in FIG. 10 (Comparative Example 2) were prototyped. Then, for each prototyped tire, the handling stability on a dry road surface and the wet performance were evaluated. The common specifications are as follows except for the configurations described in Tables 1 and 2. Also, the test method is as follows. The test results are shown in Tables 1 and 2. Tire size: 215 / 45R17 Rim size: 17×7.5J Internal pressure: 200 kPa Vehicle: Sports car (FR vehicle with a displacement of 2000 cc) Tread contact width TW: 160.0 mm Outer circumferential groove: Groove width W1: 12.0 mm Distance between groove center lines R1: 26.0 mm Inner circumferential groove: Groove width W2: 15.0 mm Distance between groove center lines R2: 47.5 mm Width of central land portion W3 / TW: 37.5% First outer lateral groove: Groove width (maximum width) W11: 5.0 mm Second outer transverse groove: Groove width (maximum width) W13: 6.0 mm Angle θ7: 20 degrees Length R11 in the tire axial direction: 31.0 mm Joint sipe: Angle θ6: 20 degrees First central transverse groove: Groove width (maximum width) W4: 7.0 mm Second central transverse groove: Groove width (maximum width) W5: 4.0 mm Angle θ2: 10 degrees Central sipe: Angle θ3: 20 degrees Inner transverse groove: Groove width (maximum width) W9: 5.0 mm

[0097] <Handling stability and dry grip performance on dry road surface> Each prototype tire was rim-mounted on the above rim, filled with the above internal pressure, and mounted on all wheels of the above vehicle. Then, the handling stability and dry grip performance when driving on the test course of the dry road surface were evaluated by the sensory evaluation of the test driver. The results are shown in a score with Example 1 set to 100. The results indicate that the larger the numerical value, the better.

[0098] <Wet performance and wet grip performance> Each prototype tire was rim-mounted on the above rim, filled with the above internal pressure, and mounted on all wheels of the above vehicle. Then, the handling stability (wet performance) and wet grip performance when driving on the test course of the wet road with a water depth of 1 mm were evaluated by the sensory evaluation of the test driver. The results are shown in a score with Example 1 set to 100. The results indicate that the larger the numerical value, the better.

[0099]

Table 1

[0100]

Table 2

[0101] As a result of the tests, the pneumatic tire of the example was able to improve the handling stability (including dry grip performance) and wet performance (including wet grip performance) on a dry road surface as compared with the pneumatic tire of the comparative example.

[0102] [Example B] The pneumatic tire shown in FIG. 1 was prototyped based on the specifications in Tables 3 and 4 (Examples 1, 7 to 18). And for each prototyped tire, the handling stability and wet performance on a dry road surface were evaluated. The common specifications are as described in Example A except for the configurations described in Tables 3 and 4. The test method is as described in Example A. The test results are shown in Tables 3 and 4.

[0103] [Table 3]

[0104] [Table 4]

[0105] As a result of the tests, the examples in which the width W3 of the central land portion, the angle θ2 of the second central transverse groove, and the angle θ3 of the central sipe were within the preferable ranges were able to improve the handling stability and wet performance on a dry road surface as compared with the other examples.

[0106] [Appendix] This disclosure includes the following aspects.

[0107] [This Disclosure 1] A pneumatic tire having a tread portion, the tread portion has a direction of attachment to a vehicle specified, whereby an outer tread end and an inner tread end facing the outside and inside of the vehicle when mounted on the vehicle are provided, The tread portion is divided into three land portions by two circumferential grooves. The two circumferential grooves are an outer circumferential groove that continuously extends in the tire circumferential direction on the side of the outer tread end and an inner circumferential groove that continuously extends in the tire circumferential direction on the side of the inner tread end. The three land portions include an outer land portion including the outer tread end, an inner land portion including the inner tread end, and a central land portion between the outer land portion and the inner land portion. The width center of the central land portion in the tire axial direction is located on the side of the inner tread end with respect to the tire equator. A plurality of first outer lateral grooves are provided in the outer land portion. Each of the first outer lateral grooves extends in the tire axial direction so as to cross the outer tread end and terminates without reaching the outer circumferential groove. Each of the first outer lateral grooves has an angle of 5 to 30 degrees with respect to the tire axial direction. A plurality of inner lateral grooves are provided in the inner land portion. Each of the inner lateral grooves extends inward in the tire axial direction so as to cross the inner tread end and terminates without reaching the inner circumferential groove. Each of the inner lateral grooves has an angle of 0 to 40 degrees with respect to the tire axial direction. A plurality of first central lateral grooves are provided in the central land portion. Each of the first central lateral grooves extends from the inner circumferential groove toward the tire equator side and terminates without reaching the tire equator. Each of the first central lateral grooves has an angle of 5 to 35 degrees with respect to the tire axial direction. Pneumatic tire. [Disclosure 2] The pneumatic tire according to Disclosure 1, wherein the central land portion has a width in the tire axial direction of 30% to 45% of the tread contact width. [Disclosure 3] The pneumatic tire according to Disclosure 1 or 2, wherein a splicing sipe is provided in the outer land portion to connect the inner end in the tire axial direction of the first outer lateral groove and the outer circumferential groove. [Disclosure 4] The groove width of the first outer transverse groove continuously decreases from the vicinity of the outer tread edge toward the inner side in the tire axial direction, for the pneumatic tire according to any one of Disclosures 1 to 3. [Disclosure 5] Regarding the angle of the first outer transverse groove, the outer portion of the first outer transverse groove outside the outer tread edge is smaller than the inner portion of the first outer transverse groove inside the outer tread edge, for the pneumatic tire according to any one of Disclosures 1 to 4. [Disclosure 6] The axial length in the tire axial direction of each of the first outer transverse grooves is 60% or more of the axial width of the outer land portion, for the pneumatic tire according to any one of Disclosures 1 to 4. [Disclosure 7] A plurality of second outer transverse grooves are provided in the outer land portion. Each of the second outer transverse grooves extends inward in the tire axial direction so as to cross the outer tread edge and terminates without reaching the outer circumferential groove. The axial length in the tire axial direction of each of the second outer transverse grooves is smaller than the axial length in the tire axial direction of each of the first outer transverse grooves, for the pneumatic tire according to any one of Disclosures 1 to 6. [Disclosure 8] The groove width of the inner transverse groove continuously decreases from the vicinity of the inner tread edge toward the inner side in the tire axial direction, for the pneumatic tire according to any one of Disclosures 1 to 7. [Disclosure 9] The groove width of the first central transverse groove continuously decreases from the inner circumferential groove toward the inner side in the tire axial direction, for the pneumatic tire according to any one of Disclosures 1 to 8. [Disclosure 10] A plurality of second central transverse grooves are provided in the central land portion. Each of the second central transverse grooves extends from the outer circumferential groove toward the tire equator side and terminates without reaching the tire equator, for the pneumatic tire according to any one of Disclosures 1 to 9. [Disclosure 11] Each of the second central transverse grooves has an angle of 5 to 25 degrees with respect to the tire axial direction, for the pneumatic tire according to Disclosure 10. [Disclosure 12] The pneumatic tire according to Disclosure 10 or 11, wherein the tire axial length of each of the second central transverse grooves is shorter than the tire axial length of each of the first central transverse grooves. [Disclosure 13] The pneumatic tire according to any one of Disclosures 1 to 12, wherein a plurality of central sipes are provided in the central land portion, and each of the central sipes extends from the outer circumferential groove toward the tire equator side and terminates without reaching the tire equator. [Disclosure 14] The pneumatic tire according to Disclosure 13, wherein each of the central sipes has an angle of 5 to 30 degrees with respect to the tire axial direction. [Disclosure 15] The pneumatic tire according to any one of Disclosures 1 to 14, wherein, on the ground contact surface where the tire is mounted on a standard rim at a standard internal pressure and a standard load is applied to give a negative camber angle of 3 degrees, the outer circumferential groove is located within the ground contact surface, while the first outer transverse groove is located outside the ground contact surface. [Disclosure 16] Each of the inner transverse grooves includes a first portion having a constant groove width and a second portion having a groove width that continuously decreases toward the inner end in the tire axial direction. The pneumatic tire according to any one of Disclosures 1 to 15, wherein, on the ground contact surface where the tire is mounted on a standard rim at a standard internal pressure and a standard load is applied to give a negative camber angle of 3 degrees, the tire axial length of the first portion is greater than the tire axial length of the second portion. The pneumatic tire according to any one of Disclosures 1 to 15, wherein, on the ground contact surface where the tire is mounted on a standard rim at a standard internal pressure and a standard load is applied to give a camber angle of 0 degrees, the tire axial length of the first portion is smaller than the tire axial length of the second portion.

Description of Reference Numerals

[0108] 1 Pneumatic tire 3A Outer circumferential groove 3B Inner circumferential groove 4C Central land portion 5 First central transverse groove 8 Inner horizontal groove 10 First outer horizontal groove

Claims

1. A pneumatic tire having a tread portion, wherein the tread portion has a specified mounting direction on the vehicle, and thereby includes an outer tread end and an inner tread end that face the outside and the inside of the vehicle when mounted on the vehicle, the tread portion is divided into three land portions by two circumferential grooves, the two circumferential grooves are an outer circumferential groove that continuously extends in the tire circumferential direction on the side of the outer tread end and an inner circumferential groove that continuously extends in the tire circumferential direction on the side of the inner tread end, the three land portions include an outer land portion including the outer tread end, an inner land portion including the inner tread end, and a central land portion between the outer land portion and the inner land portion, the width center of the central land portion in the tire axial direction is located on the side of the inner tread end rather than the tire equator, a plurality of first outer lateral grooves are provided in the outer land portion, and each of the first outer lateral grooves extends in the tire axial direction so as to cross the outer tread end and terminates without reaching the outer circumferential groove, each of the first outer lateral grooves has an angle of 5 to 30 degrees with respect to the tire axial direction, a plurality of inner lateral grooves are provided in the inner land portion, and each of the inner lateral grooves extends inward in the tire axial direction so as to cross the inner tread end and terminates without reaching the inner circumferential groove, each of the inner lateral grooves has an angle of 0 to 40 degrees with respect to the tire axial direction, a plurality of first central lateral grooves are provided in the central land portion, and each of the first central lateral grooves extends from the inner circumferential groove toward the tire equator side and terminates without reaching the tire equator, each of the first central lateral grooves has an angle of 5 to 35 degrees with respect to the tire axial direction, a plurality of second outer lateral grooves are provided in the outer land portion, and each of the second outer lateral grooves extends inward in the tire axial direction so as to cross the outer tread end and terminates without reaching the outer circumferential groove, the tire axial direction length of each of the second outer lateral grooves is smaller than the tire axial direction length of each of the first outer lateral grooves, A pneumatic tire.

2. The pneumatic tire according to claim 1, wherein a plurality of second central lateral grooves are provided in the central land portion, and each of the second central lateral grooves extends from the outer circumferential groove toward the tire equator side and terminates without reaching the tire equator. **Claim 3**: A pneumatic tire having a tread portion, wherein the tread portion has a specified mounting direction on the vehicle, and thereby includes an outer tread edge and an inner tread edge facing the outside and inside of the vehicle when mounted on the vehicle, the tread portion is divided into three land portions by two circumferential grooves, the two circumferential grooves are an outer circumferential groove continuously extending in the tire circumferential direction on the side of the outer tread edge and an inner circumferential groove continuously extending in the tire circumferential direction on the side of the inner tread edge, the three land portions include an outer land portion including the outer tread edge, an inner land portion including the inner tread edge, and a central land portion between the outer land portion and the inner land portion, the width center of the central land portion in the tire axial direction is located on the side of the inner tread edge with respect to the tire equator, a plurality of first outer transverse grooves are provided in the outer land portion, and each of the first outer transverse grooves extends in the tire axial direction so as to cross the outer tread edge and terminates without reaching the outer circumferential groove, each of the first outer transverse grooves has an angle of 5 to 30 degrees with respect to the tire axial direction, a plurality of inner transverse grooves are provided in the inner land portion, and each of the inner transverse grooves extends inward in the tire axial direction so as to cross the inner tread edge and terminates without reaching the inner circumferential groove, each of the inner transverse grooves has an angle of 0 to 40 degrees with respect to the tire axial direction, a plurality of first central transverse grooves are provided in the central land portion, and each of the first central transverse grooves extends from the inner circumferential groove toward the tire equator side and terminates without reaching the tire equator, each of the first central transverse grooves has an angle of 5 to 35 degrees with respect to the tire axial direction, a plurality of second central transverse grooves are provided in the central land portion, and each of the second central transverse grooves extends from the outer circumferential groove toward the tire equator side and terminates without reaching the tire equator, the tire axial length of each of the second central transverse grooves is shorter than the tire axial length of each of the first central transverse grooves, A pneumatic tire. **Claim 4**: The pneumatic tire according to claim 2 or 3, wherein each of the second central transverse grooves has an angle of 5 to 25 degrees with respect to the tire axial direction. **Claim 5**: A pneumatic tire having a tread portion, The tread portion has a specified mounting direction on the vehicle, and thereby includes an outer tread edge and an inner tread edge facing the outside and the inside of the vehicle when mounted on the vehicle. The tread portion is divided into three land portions by two circumferential grooves. The two circumferential grooves are an outer circumferential groove continuously extending in the tire circumferential direction on the side of the outer tread edge and an inner circumferential groove continuously extending in the tire circumferential direction on the side of the inner tread edge. The three land portions include an outer land portion including the outer tread edge, an inner land portion including the inner tread edge, and a central land portion between the outer land portion and the inner land portion. The width center of the central land portion in the tire axial direction is located on the side of the inner tread edge rather than the tire equator. A plurality of first outer transverse grooves are provided in the outer land portion, and each of the first outer transverse grooves extends in the tire axial direction so as to cross the outer tread edge and terminates without reaching the outer circumferential groove. Each of the first outer transverse grooves has an angle of 5 to 30 degrees with respect to the tire axial direction. A plurality of inner transverse grooves are provided in the inner land portion, and each of the inner transverse grooves extends inward in the tire axial direction so as to cross the inner tread edge and terminates without reaching the inner circumferential groove. Each of the inner transverse grooves has an angle of 0 to 40 degrees with respect to the tire axial direction. A plurality of first central transverse grooves are provided in the central land portion, and each of the first central transverse grooves extends from the inner circumferential groove toward the tire equator side and terminates without reaching the tire equator. Each of the first central transverse grooves has an angle of 5 to 35 degrees with respect to the tire axial direction. A plurality of central sipes are provided in the central land portion, and each of the central sipes extends from the outer circumferential groove toward the tire equator side and terminates without reaching the tire equator. Pneumatic tire.

6. The pneumatic tire according to claim 5, wherein each of the central sipes has an angle of 5 to 30 degrees with respect to the tire axial direction.

7. A pneumatic tire having a tread portion, The tread portion has a specified mounting direction on the vehicle, and thereby includes an outer tread edge and an inner tread edge facing the outside and the inside of the vehicle when mounted on the vehicle. The tread portion is divided into three land portions by two circumferential grooves. The two circumferential grooves are an outer circumferential groove that extends continuously in the tire circumferential direction on the side of the outer tread end and an inner circumferential groove that extends continuously in the tire circumferential direction on the side of the inner tread end. The three land portions include an outer land portion including the outer tread end, an inner land portion including the inner tread end, and a central land portion between the outer land portion and the inner land portion. The width center of the central land portion in the tire axial direction is located on the side of the inner tread end with respect to the tire equator. A plurality of first outer lateral grooves are provided in the outer land portion. Each of the first outer lateral grooves extends in the tire axial direction so as to cross the outer tread end and terminates without reaching the outer circumferential groove. Each of the first outer lateral grooves has an angle of 5 to 30 degrees with respect to the tire axial direction. A plurality of inner lateral grooves are provided in the inner land portion. Each of the inner lateral grooves extends inward in the tire axial direction so as to cross the inner tread end and terminates without reaching the inner circumferential groove. Each of the inner lateral grooves has an angle of 0 to 40 degrees with respect to the tire axial direction. A plurality of first central lateral grooves are provided in the central land portion. Each of the first central lateral grooves extends from the inner circumferential groove toward the tire equator side and terminates without reaching the tire equator. Each of the first central lateral grooves has an angle of 5 to 35 degrees with respect to the tire axial direction. On the ground contact surface where the tire is mounted on a standard rim at a standard internal pressure and a standard load is applied and a negative camber angle of 3 degrees is given, the outer circumferential groove is located within the ground contact surface, while the first outer lateral groove is located outside the ground contact surface. Pneumatic tire. A pneumatic tire having a tread portion, wherein the tread portion has a specified mounting direction on the vehicle, and thereby includes an outer tread end and an inner tread end that face the outside and inside of the vehicle when mounted on the vehicle. The tread portion is divided into three land portions by two circumferential grooves. The two circumferential grooves are an outer circumferential groove that extends continuously in the tire circumferential direction on the side of the outer tread end and an inner circumferential groove that extends continuously in the tire circumferential direction on the side of the inner tread end. The three land portions include an outer land portion including the outer tread end, an inner land portion including the inner tread end, and a central land portion between the outer land portion and the inner land portion. The width center of the central land portion in the tire axial direction is located on the side of the inner tread end with respect to the tire equator. A plurality of first outer lateral grooves are provided in the outer land portion. Each of the first outer lateral grooves extends in the tire axial direction so as to cross the outer tread end and terminates without reaching the outer circumferential groove. Each of the first outer lateral grooves has an angle of 5 to 30 degrees with respect to the tire axial direction. A plurality of inner lateral grooves are provided in the inner land portion. Each of the inner lateral grooves extends inward in the tire axial direction so as to cross the inner tread end and terminates without reaching the inner circumferential groove. Each of the inner lateral grooves has an angle of 0 to 40 degrees with respect to the tire axial direction. A plurality of first central lateral grooves are provided in the central land portion. Each of the first central lateral grooves extends from the inner circumferential groove toward the tire equator side and terminates without reaching the tire equator. Each of the first central lateral grooves has an angle of 5 to 35 degrees with respect to the tire axial direction. Each of the inner lateral grooves includes a first portion with a constant groove width and a second portion whose groove width continuously decreases toward the inner end in the tire axial direction. On the contact surface where the tire is mounted on a standard rim at a standard internal pressure and a standard load is applied with a negative camber angle of 3 degrees, the length of the first portion in the tire axial direction is greater than the length of the second portion in the tire axial direction. On the contact surface where the tire is mounted on a standard rim at a standard internal pressure and a standard load is applied with a camber angle of 0 degrees, the length of the first portion in the tire axial direction is smaller than the length of the second portion in the tire axial direction. Pneumatic tire.

9. The central land portion has a width in the tire axial direction of 30% to 45% of the tread contact width. The pneumatic tire according to any one of Claims 1 to 8.

10. A splicing sipe connecting the inner end in the tire axial direction of the first outer lateral groove and the outer circumferential groove is provided in the outer land portion. The pneumatic tire according to any one of Claims 1 to 9.

11. The groove width of the first outer lateral groove continuously decreases from near the outer tread end toward the inner side in the tire axial direction. The pneumatic tire according to any one of Claims 1 to 10.

12. The pneumatic tire according to any one of claims 1 to 11, wherein, with respect to the angle of the first outer lateral groove, an outer portion of the first outer lateral groove that is outside the outer tread edge is smaller than an inner portion of the first outer lateral groove that is inside the outer tread edge.

13. The pneumatic tire according to any one of claims 1 to 12, wherein a tire axial direction length of each of the first outer lateral grooves is 60% or more of a tire axial direction width of the outer land portion.

14. The pneumatic tire according to any one of claims 1 to 13, wherein a groove width of the inner lateral groove continuously decreases from near the inner tread edge toward the inner side in the tire axial direction.

15. The pneumatic tire according to any one of claims 1 to 14, wherein a groove width of the first central lateral groove continuously decreases from the inner circumferential groove toward the inner side in the tire axial direction.

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