tire

Abstract

To provide a tire that has improved wet performance and on-snow performance while maintaining traction performance on a dry road surface.SOLUTION: A tire has a tread part 2 having a designated installation direction to a vehicle. The tread part 2 includes an outside tread part To, an inside tread part Ti, four circumferential grooves 3 and five land parts 4. The four circumferential grooves 3 include an inside shoulder circumferential groove 5, an inside crown circumferential groove 6 and an outside crown circumferential groove 7. The five land parts 4 include an inside shoulder land part 10, an inside middle land part 11 and a crown land part 12. A plurality of axial grooves 15 are arranged in the tread part 2. At least one crown sipe 20 extending in the tire axial direction from the inside crown circumferential groove 6 or the outside crown circumferential groove 7 and ending in the crown land part 12 is arranged in the crown land part 12. The crown sipe 20 crosses a central position in the tire axial direction of the crown land part 12.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] The following Patent Document 1 proposes a pneumatic tire with an asymmetric tread pattern whose mounting direction on a vehicle is specified. The tread portion of the pneumatic tire is provided with inner lateral grooves that extend from the inner side of the vehicle to the tire equator from the inner side of the ground contact edge on the vehicle inner side. The pneumatic tire is expected to discharge a water film between the crown land portion and the road surface to the inner side of the vehicle by the inner lateral grooves. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-100020 A Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a demand for tires that can be used on various road surfaces. Although the pneumatic tire of Patent Document 1 provides high wet performance, there is room for improvement in terms of performance on snow.

[0005] On the other hand, tires with improved wet or snow performance have the problem that they are prone to losing traction performance on dry roads.

[0006] The present invention has been devised in view of the above-mentioned circumstances, and has as its main object to provide a tire which maintains traction performance on dry roads while improving wet performance and performance on snow. [Means for solving the problem]

[0007] The present invention relates to a tire having a tread portion whose orientation when mounted on a vehicle is specified, the tread portion including an outer tread edge that is on the outer side of the vehicle when mounted on the vehicle, an inner tread edge that is on the inner side of the vehicle when mounted on the vehicle, four circumferential grooves extending continuously in the tire circumferential direction between the outer tread edge and the inner tread edge, and five land portions divided into the four circumferential grooves, the four circumferential grooves including an inner shoulder circumferential groove disposed closest to the inner tread edge, an inner crown circumferential groove disposed between the inner shoulder circumferential groove and the tire equator, and an outer crown circumferential groove adjacent to the inner crown circumferential groove across the tire equator, the five land portions being arranged in a front The tread portion includes an inner shoulder land portion including the inner tread end, an inner middle land portion between the inner shoulder circumferential groove and the inner crown circumferential groove, and a crown land portion between the inner crown circumferential groove and the outer crown circumferential groove, the tread portion being provided with a plurality of axial grooves extending at least from the inner tread end to the crown land portion and terminated within the crown land portion, the crown land portion being provided with at least one crown sipe extending in the tire axial direction from the inner crown circumferential groove or the outer crown circumferential groove and terminated within the crown land portion, and the crown sipe crosses a center position of the crown land portion in the tire axial direction.

[0008] In the tire of the present invention, it is preferable that the axial groove includes a crown groove portion arranged in the crown land portion, the crown sipes include a plurality of first crown sipes extending from the inner crown circumferential groove, and the axial length of the first crown sipes is smaller than the axial length of the crown groove portion.

[0009] In the tire of the present invention, it is desirable that the crown sipes include a plurality of second crown sipes extending from the outer crown circumferential groove, and that the axial length of the first crown sipes is equal to or greater than the axial length of the second crown sipes.

[0010] In the tire of the present invention, it is preferable that the first crown sipes and the second crown sipes are provided alternately in the tire circumferential direction.

[0011] In the tire of the present invention, it is desirable that the total number of the second crown sipes be equal to or less than the total number of the first crown sipes.

[0012] In the tire of the present invention, it is preferable that the axial groove includes a crown groove portion arranged in the crown land portion, and the crown groove portion includes an outer portion opening with a width greater than 1.5 mm on the tread surface of the crown land portion, and a sipe portion extending in the tire radial direction with a width of 1.5 mm or less from the bottom of the outer portion.

[0013] In the tire of the present invention, the depth of the outer portion is preferably 2.5 mm or less.

[0014] In the tire of the present invention, it is preferable that a one-pitch length of the plurality of axial grooves in the tire circumferential direction is smaller than an axial width of the inner shoulder land portion in the tire circumferential direction.

[0015] In the tire of the present invention, it is preferable that the axial grooves include a middle groove portion disposed in the inner middle land portion, and the middle groove portion includes a tie bar having a locally raised bottom portion.

[0016] In the tire of the present invention, the inner middle land portion is provided with a plurality of first middle sipes extending axially from the inner shoulder circumferential groove and terminated within the inner middle land portion, and a plurality of second middle sipes extending axially from the inner crown circumferential groove and terminated within the inner middle land portion, and it is desirable that the total number of the second middle sipes be greater than the total number of the first middle sipes. Effect of the Invention

[0017] By adopting the above-mentioned configuration, the tire of the present invention can exhibit excellent wet performance and performance on snow while maintaining traction performance on dry road surfaces. [Brief description of the drawings]

[0018] [Figure 1] 1 is a development view of a tread portion of a tire according to one embodiment of the present invention. [Diagram 2] 2 is an enlarged view of an inner shoulder land portion, an inner middle land portion, and a crown land portion in FIG. 1. [Diagram 3] 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 4] FIG. 3 is a cross-sectional view taken along line BB in FIG. [Diagram 5] 3 is a cross-sectional view taken along line CC in FIG. 2. [Figure 6] FIG. 3 is a cross-sectional view taken along line DD in FIG. [Figure 7] 3 is a cross-sectional view taken along line EE in FIG. 2. [Figure 8] FIG. 2 is an enlarged view of an outer middle land portion and an outer shoulder land portion of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a development view of a tread portion 2 of a tire 1 of this embodiment. As shown in Fig. 1, the tire 1 of this embodiment is used, for example, as a pneumatic tire for passenger cars for all seasons, including driving on snowy roads. However, the tire 1 of the present invention is not limited to such an embodiment.

[0020] The tire 1 of the present invention has a tread portion 2 whose mounting direction on a vehicle is specified. The mounting direction on a vehicle is indicated, for example, by characters or marks on the sidewall portion (not shown). The tread portion 2 is configured, for example, in an asymmetric pattern (meaning that the tread pattern is not line-symmetric with respect to the tire equator C).

[0021] The tread portion 2 includes an outer tread edge To that is on the inside of the vehicle when mounted on the vehicle, and an inner tread edge Ti that is on the outside of the vehicle when mounted on the vehicle. The outer tread edge To and the inner tread edge Ti each correspond to the axially outermost contact positions when the tire 1 in a normal state is loaded with a normal load and contacts a flat surface with a camber angle of 0°.

[0022] "Normal condition" means, in the case of a pneumatic tire for which various standards are established, that the tire is mounted on a normal rim, inflated to the normal internal pressure, and no load is applied. In the case of a tire for which various standards are not established or a non-pneumatic tire, the normal condition means a standard use condition according to the intended use of the tire, and a state in which no load is applied. In this specification, unless otherwise specified, the dimensions of each part of the tire are values ​​measured in the normal condition.

[0023] A "genuine rim" is a rim that is defined for each tire by the standard system that includes the standard on which the tire is based. For example, in the case of JATMA, it is called a "standard rim," in the case of TRA, it is called a "Design Rim," and in the case of ETRTO, it is called a "Measuring Rim."

[0024] "Normal internal pressure" is the air pressure set for each tire by each standard in the standard system on which the tire is based. In the case of JATMA, it is the "maximum air pressure." In the case of TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." In the case of ETRTO, it is the "INFLATION PRESSURE."

[0025] In the case of a pneumatic tire for which various standards are established, the "normal load" is the load that each standard specifies for each tire in the standard system including the standard on which the tire is based. For JATMA, it is the "maximum load capacity", for TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", and for ETRTO, it is the "LOAD CAPACITY". In addition, in the case of a tire for which various standards are not established or a non-pneumatic tire, the "normal load" refers to the load acting on one tire in the standard mounting state of the tire. The "standard mounting state" refers to a state in which the tire is mounted on a standard vehicle according to the intended use of the tire, and the vehicle is stationary on a flat road surface in a drivable state.

[0026] The tread portion 2 includes four circumferential grooves 3 extending continuously in the tire circumferential direction between an outer tread end To and an inner tread end Ti, and five land portions 4 divided by the four circumferential grooves 3.

[0027] The four circumferential grooves 3 include an inner shoulder circumferential groove 5 arranged on the innermost tread end Ti side, an inner crown circumferential groove 6 arranged between the inner shoulder circumferential groove 5 and the tire equator C, and an outer crown circumferential groove 7 adjacent to the inner crown circumferential groove 6 across the tire equator C. Furthermore, in this embodiment, an outer shoulder circumferential groove 8 is provided between the outer tread end To and the outer crown circumferential groove 7. The outer shoulder circumferential groove 8 is arranged on the outermost tread end To side.

[0028] The circumferential grooves 3 may have various configurations, such as extending linearly in the tire circumferential direction or extending in a zigzag pattern.

[0029] The axial distance L1 from the groove centerline of the outer crown circumferential groove 7 or the inner crown circumferential groove 6 to the tire equator C is, for example, 5% to 15% of the tread width TW. The axial distance L2 from the groove centerline of the outer shoulder circumferential groove 8 or the inner shoulder circumferential groove 5 to the tire equator C is, for example, 25% to 35% of the tread width TW. The tread width TW is the axial distance from the outer tread end To to the inner tread end Ti in the normal state.

[0030] The groove width W1 of the circumferential groove 3 is preferably at least 3 mm or more. More preferably, the groove width W1 of the circumferential groove 3 is 3.0% to 7.0% of the tread width TW.

[0031] The five land portions 4 include at least an inner shoulder land portion 10 including the inner tread edge Ti, an inner middle land portion 11 between the inner shoulder circumferential groove 5 and the inner crown circumferential groove 6, and a crown land portion 12 between the inner crown circumferential groove 6 and the outer crown circumferential groove 7. The five land portions 4 in this embodiment further include an outer shoulder land portion 14 including the outer tread edge To, and an outer middle land portion 13 between the outer shoulder circumferential groove 8 and the outer crown circumferential groove 7.

[0032] 2 shows an enlarged view of the inner shoulder land portion 10, the inner middle land portion 11, and the crown land portion 12. As shown in FIG. 2, the tread portion 2 is provided with a plurality of axial grooves 15. The axial grooves 15 extend from at least the inner tread edge Ti toward the axially inner side of the tire. The axial grooves 15 cross the inner shoulder land portion 10, the inner shoulder circumferential groove 5, the inner middle land portion 11, and the inner crown circumferential groove 6, respectively, and extend to the crown land portion 12, and are interrupted within the crown land portion 12. The axial grooves 15 form a drainage path extending from the crown land portion 12 to the inner tread edge Ti.

[0033] At least one crown sipe 20 is provided in the crown land portion 12. The crown sipe 20 extends in the tire axial direction from the inner crown circumferential groove 6 or the outer crown circumferential groove 7 and terminates within the crown land portion 12.

[0034] In this specification, the term "sipe" refers to a cut element having a small width, and the width between two inner walls facing each other is 1.5 mm or less. The width of the sipe is preferably 0.3 to 1.0 mm. Each sipe in this embodiment opens within the above-mentioned width range on the tread surface of the land portion. The bottom of the sipe may be connected to a flask bottom having a width exceeding 1.5 mm, for example.

[0035] In the present invention, the crown sipe 20 crosses the axial center position of the crown land portion 12. By adopting the above-mentioned configuration, the present invention can exhibit excellent wet performance and performance on snow while maintaining traction performance on dry roads. The following mechanism is presumed to be the reason for this.

[0036] The above-mentioned axial grooves 15 can exhibit high drainage and are useful for improving wet performance. In addition, the axial grooves 15 form horizontally elongated snow columns during driving on snow, providing large snow column shear force and improving performance on snow. In addition, the crown sipes 20 are interrupted within the crown land portion 12, so that the rigidity of the crown land portion 12 can be maintained, which in turn helps to maintain traction performance on dry road surfaces. Furthermore, the crown sipes 20 that cross the center position of the crown land portion 12 exhibit a large edge effect and can improve wet performance and performance on snow. It is presumed that the tire 1 of the present invention can exhibit excellent wet performance and performance on snow while maintaining traction performance on dry road surfaces due to such a mechanism.

[0037] A more detailed configuration of this embodiment will be described below. Each configuration described below shows a specific aspect of this embodiment. Therefore, it goes without saying that the present invention can achieve the above-mentioned effects even if it does not have the configuration described below. In addition, even if any one of the configurations described below is applied alone to the tire of the present invention having the above-mentioned characteristics, an improvement in performance according to each configuration can be expected. Furthermore, when some of the configurations described below are applied in combination, a composite improvement in performance according to each configuration can be expected.

[0038] The axial groove 15 crosses the inner shoulder land portion 10, for example, axially outward of the inner tread edge Ti. As a result, the inner shoulder land portion 10 is divided into a plurality of blocks. Such an axial groove 15 can exhibit excellent drainage. The axial groove 15 includes a shoulder groove portion 16 arranged in the inner shoulder land portion 10, a middle groove portion 17 arranged in the inner middle land portion 11, and a crown groove portion 18 arranged in the crown land portion 12. The axial groove 15 substantially forms one drainage path by the shoulder groove portion 16, the middle groove portion 17, and the crown groove portion 18. Therefore, a virtual area obtained by extending the shoulder groove portion 16 toward the tire equator C along its length direction overlaps with an end portion of the middle groove portion 17 on the inner tread edge Ti side. Also, a virtual area obtained by extending the middle groove portion 17 toward the tire equator C along its length direction overlaps with an end portion of the crown groove portion 18 on the inner tread edge Ti side.

[0039] The virtual area of ​​the shoulder groove portion 16 overlaps with preferably 50% or more, more preferably 80% of the groove width of the end of the middle groove portion 17. Similarly, the virtual area of ​​the middle groove portion 17 overlaps with preferably 50% or more, more preferably 80% of the groove width of the end of the crown groove portion 18. As a more preferable aspect, in this embodiment, the virtual area of ​​the shoulder groove portion 16 overlaps with 100% of the groove width of the end of the middle groove portion 17, and the virtual area of ​​the middle groove portion 17 overlaps with 100% of the groove width of the end of the crown groove portion 18. This more reliably improves wet performance.

[0040] The groove width of the axial groove 15 is preferably smaller toward the outer tread end To (shown in FIG. 1, and the same applies below). In other words, the groove width of the middle groove portion 17 is smaller than the groove width of the shoulder groove portion 16, and the groove width of the crown groove portion 18 is smaller than the groove width of the middle groove portion 17. The groove width of the shoulder groove portion 16 is, for example, 4.4 to 5.0 mm. The groove width of the middle groove portion 17 is, for example, 3.3 to 4.4 mm. The groove width of the crown groove portion 18 is, for example, 3.3 mm or less. Such an axial groove 15 can improve the steering stability on dry roads (hereinafter sometimes simply referred to as "steering stability"), wet performance, and snow performance in a well-balanced manner.

[0041] The axial grooves 15 are, for example, inclined with respect to the tire axial direction. The angle of the axial grooves 15 with respect to the tire axial direction is, for example, 5 to 25°. In a more preferable embodiment, the angle of the axial grooves 15 of this embodiment with respect to the tire axial direction increases toward the outer tread end To side. Such axial grooves 15 can provide snow column shear force also in the tire axial direction when traveling on snow.

[0042] The circumferential pitch length P1 of the axial grooves 15 is preferably smaller than the axial width W2 of the inner shoulder land portion 10. Specifically, the pitch length P1 is 70% to 95% of the width W2 of the inner shoulder land portion 10. As a more preferable embodiment, the pitch length P1 of the axial grooves 15 is smaller than the axial width W3 of the inner middle land portion 11 and smaller than the axial width W4 of the crown land portion 12. Such an arrangement of the axial grooves 15 is useful for reliably improving wet performance and on-snow performance. In this specification, the pitch length means the distance between the groove center lines of two adjacent grooves.

[0043] The crown groove portion 18 crosses, for example, the axial center position of the crown land portion 12. The axial length L3 of the crown groove portion 18 is, for example, 60% to 90% of the axial width W4 of the crown land portion 12. This improves the traction performance on dry roads and the performance on wet roads and on snow in a well-balanced manner.

[0044] 3 shows a cross-sectional view of line AA in FIG. 2. As shown in FIG. 3, the crown groove portion 18 includes an outer portion 23 that opens with a width greater than 1.5 mm on the tread surface of the crown land portion 12, and a sipe portion 24 that extends in the tire radial direction with a width of 1.5 mm or less from the bottom of the outer portion 23. The depth d1 of the outer portion 23 is, for example, 2.5 mm or less, and preferably 1.0 to 2.0 mm. The depth d1 of the outer portion 23 is 15% to 30% of the total depth dt of the crown groove portion 18. Such a crown groove portion 18 can smoothly guide water inside the crown groove portion 18 toward the middle groove portion 17 (shown in FIG. 2) in accordance with changes in ground pressure during wet driving, while maintaining the rigidity of the crown land portion 12.

[0045] Fig. 4 shows a cross section of line BB in Fig. 2. As shown in Fig. 4, the middle groove portion 17 preferably includes a tie bar 25 whose bottom is locally raised. In this embodiment, the tie bar 25 is provided in a central region when the middle groove portion 17 is divided into three equal parts in the length direction in a plan view of the tread. Such a tie bar 25 helps to maintain the rigidity of the inner middle land portion 11 and improve the traction performance on dry roads.

[0046] In order to ensure wet performance while achieving the above-mentioned effects, the axial length L9 of the tie bar 25 is preferably 25% to 40% of the axial width W3 (shown in FIG. 2) of the inner middle land portion 11. If the length of the tie bar 25 varies in the radial direction of the tire, the length is measured at the radial center position of the tire. The minimum depth d3 of the portion where the tie bar 25 is provided is, for example, 30% to 50% of the maximum depth d2 of the middle groove portion 17.

[0047] 5 shows a cross-sectional view of the tie bar 25 taken along line CC in FIG. 2. As shown in FIG. 5, the tie bar 25 is desirably provided with a groove bottom sipe 26 that opens on its outer surface. The groove bottom sipe 26 is provided, for example, so as to completely cross the tie bar 25 in the longitudinal direction of the middle groove portion 17. Such a groove bottom sipe 26 helps to maintain the drainage of the middle groove portion 17.

[0048] Fig. 6 shows a cross section taken along line DD in Fig. 2. As shown in Fig. 6, the shoulder groove portion 16 includes a minimum portion 27 where the groove width of the shoulder groove portion 16 is minimum, between the contact surface 10s of the inner shoulder land portion 10 and the groove bottom of the shoulder groove portion 16. This makes it possible to mitigate the deterioration of wet performance due to wear of the tread portion 2.

[0049] The maximum depth d4 of the shoulder groove portion 16 is, for example, 70% to 90% of the maximum depth of the inner shoulder circumferential groove 5. The depth d5 ​​from the ground contact surface 10s to the minimum portion 27 is, for example, less than 50% of the maximum depth d4 of the shoulder groove portion 16. The depth d5 ​​of the minimum portion 27 is preferably 10% to 40% of the depth d1. This allows the minimum portion 27 to be exposed to the ground contact surface 10s at a stage when the wear of the tread portion 2 has progressed moderately, and the deterioration of wet performance due to the subsequent wear of the tread portion can be suppressed.

[0050] The groove width W6 of the minimum portion 27 is, for example, 30% to 60%, and preferably 40% to 50%, of the groove width W5 at the contact surface 10s of the shoulder groove portion 16. Such a minimum portion 27 helps to maintain a balance between dry performance and wet performance.

[0051] In the region from the contact surface 10s to the minimum portion 27, the angle θ1 of the groove wall of the shoulder groove portion 16 with respect to the tire normal is, for example, 40 to 60°. As a result, when the tire starts to be used, the groove wall radially outward of the minimum portion 27 contacts the ground appropriately in response to an increase in ground contact pressure. In other words, the groove wall radially outward of the minimum portion 27 can function as a chamfer, which is expected to improve traction performance and braking performance.

[0052] The shoulder groove portion 16 includes a main body portion 28 located radially inward of the minimum portion 27. The maximum groove width W7 of the main body portion 28 is equal to or smaller than the groove width W5 of the shoulder groove portion 16 at the contact surface 10s. The maximum groove width W7 of the main body portion 28 is, for example, 50% to 100% of the groove width W5 of the shoulder groove portion 16 at the contact surface 10s, and preferably 70% to 100%. As a result, sufficient wet performance is exhibited when the tread portion 2 is worn to such an extent that the vicinity of the maximum groove width W7 is exposed.

[0053] The main body portion 28 includes a region in which the groove width increases toward the inside in the tire radial direction. The angle θ2 of the groove wall in this region with respect to the tire normal is smaller than the angle θ1, and is, for example, 15 to 25°.

[0054] As shown in FIG. 2, the crown sipes 20 include a plurality of first crown sipes 21 and a plurality of second crown sipes 22. The first crown sipes 21 extend from the inner crown circumferential groove 6 in the tire axial direction and are terminated in the crown land portion 12. The second crown sipes 22 extend from the outer crown circumferential groove 7 in the tire axial direction and are terminated in the crown land portion 12. The first crown sipes 21 and the second crown sipes 22 are, for example, alternately provided in the tire circumferential direction. As a more preferable aspect, in this embodiment, one first crown sipe 21 and one second crown sipe 22 are provided between two crown groove portions 18. However, the present invention is not limited to such an aspect.

[0055] The total number of the second crown sipes 22 in the entire crown land portion 12 is, for example, equal to or less than the total number of the first crown sipes 21. As a desirable aspect, in this embodiment, the total number of the first crown sipes 21 and the total number of the second crown sipes are set to be the same. This suppresses uneven wear of the crown land portion 12.

[0056] In order to improve steering stability on dry roads and wet performance in a well-balanced manner, the length L4 of the crown sipes 20 in the tire axial direction is smaller than the length L3 of the crown groove portion 18 in the tire axial direction. Specifically, the length L4 of the crown sipes 20 is 55% to 80% of the width W4 of the crown land portion 12 in the tire axial direction.

[0057] The axial length of the first crown sipes 21 is smaller than the axial length L3 of the crown groove portion 18. In addition, the axial length of the first crown sipes 21 is preferably equal to or greater than the axial length of the second crown sipes 22.

[0058] The first crown sipes 21 and the second crown sipes 22 are inclined, for example, in the same direction as the crown groove portion 18, and in a desirable embodiment, the difference in angle therebetween is 5° or less. The angles of the first crown sipes 21 and the second crown sipes 22 with respect to the tire axial direction are, for example, 15 to 25°. As a more desirable embodiment, in this embodiment, the first crown sipes 21, the second crown sipes 22, and the crown groove portion 18 extend parallel to each other. This suppresses uneven wear of the crown land portion 12.

[0059] The inner middle land portion 11 is provided with a plurality of first middle sipes 31 and a plurality of second middle sipes 32. The first middle sipes 31 extend in the tire axial direction from the inner shoulder circumferential groove 5 and terminate within the inner middle land portion 11. The second middle sipes 32 extend in the tire axial direction from the inner crown circumferential groove 6 and terminate within the inner middle land portion 11. Such first middle sipes 31 and second middle sipes 32 can exhibit an edge effect while maintaining the rigidity of the inner middle land portion 11.

[0060] In a preferred embodiment, the total number of the second middle sipes 32 is greater than the total number of the first middle sipes 31. Specifically, the total number of the second middle sipes 32 is 1.5 to 2.5 times the total number of the first middle sipes 31. This makes the end of the middle groove portion 17 on the tire equator C side more easily deformable than the end on the inner tread end Ti side. Therefore, the middle groove portion 17 is more easily deformed during wet driving so as to guide water therein toward the inner tread end Ti, further improving wet performance.

[0061] The axial length L5 of the first middle sipe 31 is, for example, 40% to 60% of the axial width W3 of the inner middle land portion 11. The same is true for the second middle sipe 32. This makes it easier to achieve the above-mentioned effects.

[0062] The first middle sipes 31 and the second middle sipes 32 are inclined in the same direction as the middle groove portion 17, for example, and in a desirable embodiment, the difference in angle between them is 5° or less. The angles of the first middle sipes 31 and the second middle sipes 32 with respect to the tire axial direction are, for example, 10 to 20°. As a more desirable embodiment, in this embodiment, the first middle sipes 31, the second middle sipes 32, and the middle groove portion 17 extend parallel to each other. This suppresses uneven wear of the inner middle land portion 11.

[0063] The inner shoulder land portion 10 is provided with a plurality of inner shoulder sipes 33. The inner shoulder sipes 33 extend axially outward from the inner shoulder circumferential groove 5 and cross at least the inner tread edge Ti.

[0064] The inner shoulder sipes 33 are inclined, for example, in the same direction as the shoulder groove portion 16, and in a desirable embodiment, the difference in angle therebetween is 5° or less. The angle of the inner shoulder sipes 33 with respect to the tire axial direction is, for example, 5 to 15°. More preferably, in this embodiment, the inner shoulder sipes 33 and the shoulder groove portion 16 extend parallel to each other. This suppresses uneven wear of the inner shoulder land portion 10.

[0065] 7 shows a cross-sectional view of line EE in FIG. 2. As shown in FIG. 7, the inner shoulder sipe 33 extends in the tire radial direction from the ground contact surface 10s of the inner shoulder land portion 10 with a width W8 of 1.5 mm or less. In addition, an inner groove 34 having a groove width larger than the width of the inner shoulder sipe 33 communicates with the inner side of the inner shoulder sipe 33 in the tire radial direction. The maximum groove width W9 of the inner groove 34 is 2.0 to 4.0 times the width W8 of the inner shoulder sipe 33. Such an inner groove 34 helps maintain wet performance even when the tread portion 2 is worn.

[0066] Fig. 8 shows an enlarged view of the outer middle land portion 13 and the outer shoulder land portion 14. As shown in Fig. 8, the outer middle land portion 13 is provided with a first middle interrupted groove 36, a second middle interrupted groove 37, and a decorative sipe 38.

[0067] The first interrupted middle groove 36 extends from the outer crown circumferential groove 7 and terminates within the outer middle land portion 13. The first interrupted middle groove 36 terminates, for example, without crossing the axial center position of the outer middle land portion 13. The axial length L6 of the first interrupted middle groove 36 is, for example, 15% to 25% of the axial width W10 of the outer middle land portion 13. Such a first interrupted middle groove 36 improves driving stability and wet performance in a well-balanced manner.

[0068] The first middle interrupted grooves 36 are inclined, for example, in the same direction as the axial grooves 15 with respect to the tire axial direction. The angle of the first middle interrupted grooves 36 with respect to the tire axial direction is desirably larger than the maximum angle of the axial grooves 15 with respect to the tire axial direction. The angle of the first middle interrupted grooves 36 with respect to the tire axial direction is, for example, 70 to 80°.

[0069] From a similar viewpoint, the second middle discontinuous groove 37 extends from the outer shoulder circumferential groove 8 and is discontinued within the outer middle land portion 13. The second middle discontinuous groove 37 is discontinued, for example, without crossing the axial center position of the outer middle land portion 13. The axial length L7 of the second middle discontinuous groove 37 is, for example, 30% to 45% of the axial width W10 of the outer middle land portion 13.

[0070] The second middle discontinuous grooves 37 are, for example, inclined in the opposite direction to the axial grooves 15 with respect to the tire axial direction. The angle of the second middle discontinuous grooves 37 with respect to the tire axial direction is smaller than the angle of the first middle discontinuous grooves 36 with respect to the tire axial direction. The angle of the second middle discontinuous grooves 37 with respect to the tire axial direction is, for example, 5 to 15°.

[0071] The decorative sipes 38 have an opening width of 1.5 mm or less at the contact surface of the land portion and a depth of 0.5 to 1.5 mm. Such decorative sipes 38 exhibit a high edge effect at the beginning of use of the tire, and can improve performance on snow.

[0072] For example, both ends of the decorative sipe 38 are interrupted within the outer middle land portion 13. The decorative sipe 38 is inclined with respect to the tire axial direction in the same direction as the first middle interrupted groove 36. The angle of the decorative sipe 38 with respect to the tire axial direction is, for example, 60 to 80 degrees.

[0073] For example, the decorative sipe 38 crosses the axial center position of the outer middle land portion 13. The circumferential length L8 of the decorative sipe 38 is, for example, 1.3 to 2.0 times the circumferential pitch length P2 of the second middle discontinuous groove 37. Such decorative sipes 38 can exert a large axial friction force on snowy roads.

[0074] The outer shoulder land portion 14 is provided with a plurality of outer shoulder lateral grooves 41 and a plurality of outer shoulder sipes 42. The outer shoulder lateral grooves 41 have substantially the same configuration as the shoulder groove portion 16 (shown in FIG. 2). Therefore, the configuration of the shoulder groove portion 16 described above can be applied to the outer shoulder lateral grooves 41. The outer shoulder sipes 42 have substantially the same configuration as the inner shoulder sipes 33 (shown in FIG. 2). Therefore, the configuration of the inner shoulder sipes 33 described above can be applied to the outer shoulder sipes 42.

[0075] Although the tire according to one embodiment of the present invention has been described in detail above, the present invention is not limited to the above specific embodiment and can be modified and carried out in various aspects. EXAMPLES

[0076] A tire having the pattern shown in FIG. 1 and a size of 275 / 40ZR20 was prototyped based on the specifications in Table 1. As a comparative example, a tire in which the first crown sipe and the second crown sipe do not cross the center position in the tire axial direction of the crown land portion was prototyped. The comparative tire has substantially the same configuration as the tire shown in FIG. 1 except for the above-mentioned points. Each test tire was tested for traction performance on dry roads, wet performance, and performance on snow. The common specifications and test methods of each test tire are as follows. Rim: 20×9.5J Tire pressure: 250kPa for all wheels Test vehicle: 3500cc, rear-wheel drive Tire mounting position: All wheels

[0077] <Traction performance on dry roads> The traction performance of the test vehicle when it was driven on a dry road surface was evaluated by the driver. The results are rated based on the traction performance of the comparative example being 100, with a higher value indicating better dry or wet performance.

[0078] <Wet performance> The wet performance of the test vehicle when it was driven on a wet road surface was evaluated by the driver. The results are rated based on the wet performance of the comparative example being 100, with the higher the value, the better the wet performance.

[0079] <Snow performance> The snow performance of the test vehicle was evaluated by the driver. The results are given as a score based on the snow performance of the comparative example being 100, with the higher the score, the better the snow performance. The test results are shown in Table 1.

[0080] [Table 1]

[0081] As shown in Table 1, the tires of the examples maintain the traction performance on dry roads at 98 to 102 points, while showing excellent values ​​of wet performance at 104 to 108 points and snow performance at 104 to 109 points. In other words, it was confirmed that the tires of the present invention exhibit excellent wet performance and snow performance while maintaining the traction performance on dry roads. [Explanation of symbols]

[0082] 2 Tread section 3 Circumferential groove 4 Land 5 Inner shoulder circumferential groove 6 Inner crown circumferential groove 7 Outer crown circumferential groove 10 Inner shoulder land area 11 Inner Middle Land Section 12 Crown Land Division 15 Axial groove 20 Crown sipes To outer tread edge Ti inner tread edge

Claims

1. A tire having a tread portion with a specified mounting direction on a vehicle, the tread portion includes an outer tread end that is on the outer side of the vehicle when the tire is mounted on the vehicle, an inner tread end that is on the inner side of the vehicle when the tire is mounted on the vehicle, four circumferential grooves that extend continuously in the tire circumferential direction between the outer tread end and the inner tread end, and five land portions that are divided into the four circumferential grooves, the four circumferential grooves include an inner shoulder circumferential groove disposed closest to the inner tread end, an inner crown circumferential groove disposed between the inner shoulder circumferential groove and a tire equator, and an outer crown circumferential groove adjacent to the inner crown circumferential groove across the tire equator, the five land portions include an inner shoulder land portion including the inner tread edge, an inner middle land portion between the inner shoulder circumferential groove and the inner crown circumferential groove, and a crown land portion between the inner crown circumferential groove and the outer crown circumferential groove, The tread portion is provided with a plurality of axial grooves extending from at least the inner tread end to the crown land portion and terminated within the crown land portion, At least one crown sipe is provided in the crown land portion, the crown sipe extending in the tire axial direction from the inner crown circumferential groove or the outer crown circumferential groove and terminated within the crown land portion, The crown sipe crosses a center position of the crown land portion in the tire axial direction, a circumferential pitch length of the plurality of axial grooves is smaller than an axial width of the inner shoulder land portion; tire.

2. the axial groove includes a crown groove portion disposed in the crown land portion, the crown sipes include a plurality of first crown sipes extending from the inner crown circumferential groove, The tire according to claim 1 , wherein an axial length of the first crown sipe is smaller than an axial length of the crown groove portion.

3. the crown sipes include a plurality of second crown sipes extending from the outer crown circumferential groove, The tire according to claim 2 , wherein an axial length of the first crown sipe is equal to or greater than an axial length of the second crown sipe.

4. The tire according to claim 3 , wherein the first crown sipes and the second crown sipes are alternately provided in a tire circumferential direction.

5. The tire according to claim 3 or 4, wherein a total number of the second crown sipes is equal to or less than a total number of the first crown sipes.

6. the axial groove includes a crown groove portion disposed in the crown land portion, 6. The tire according to claim 1, wherein the crown groove portion includes an outer portion that opens with a width greater than 1.5 mm on a tread surface of the crown land portion, and a sipe portion that extends in the tire radial direction with a width of 1.5 mm or less from a bottom of the outer portion.

7. 7. The tire of claim 6, wherein the depth of said outer portion is less than or equal to 2.5 mm.

8. The axial groove includes a middle groove portion disposed in the inner middle land portion, 8. The tire according to claim 1, wherein the middle groove portion includes a tie bar having a locally raised bottom.

9. the inner middle land portion is provided with a plurality of first middle sipes extending in the tire axial direction from the inner shoulder circumferential groove and terminated within the inner middle land portion, and a plurality of second middle sipes extending in the tire axial direction from the inner crown circumferential groove and terminated within the inner middle land portion, The tire according to claim 1 , wherein a total number of the second middle sipes is greater than a total number of the first middle sipes.

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