Tire

Abstract

To provide a tire that improves snow traction, while maintaining steering stability on a dry road surface.SOLUTION: Provided is a tire having a tread part 2 with a designated rotation direction R. The tread part 2 includes a plurality of first inclined grooves 3, a plurality of second inclined grooves 4, and a plurality of first land parts 5. The plurality of first land parts 5 respectively includes a tread 5s, a first lateral wall 11, and a second lateral wall 12. At least one of the plurality of first land parts 5 is provided with at least one recess 15 being a first lateral wall 11 that has been locally recessed. The recess 15 is open at the tread 5s. In a plan view of the first land wall 5, a maximum recess amount in a direction crossing a longer direction of the first inclined groove 3 of the recess 15 is 10%-25% of a maximum length of the first land part 5 in the direction crossing the longer direction.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 as an all-season tire, in which a plurality of inclined lateral grooves and a plurality of connecting grooves are provided in the tread portion. The inclined lateral grooves extend from the outer side beyond the ground contact edge to the inner end near the tire equator, inclining toward one side in the tire circumferential direction toward the inside in the tire axial direction without crossing the tire equator. The connecting groove connects between the inclined lateral grooves adjacent in the tire circumferential direction. It is expected that this pneumatic tire will achieve high levels of both steering stability on dry roads and steering stability on snowy roads by the above-mentioned inclined lateral grooves and connecting grooves. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-052422 A Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, as vehicles have become more powerful, there has been a demand for improved tire performance on snow, particularly in terms of snow traction. At the same time, tires also need to be designed to provide driving stability on dry roads.

[0005] The present invention has been devised in view of the above circumstances, and has as its main object to provide a tire which improves snow traction while maintaining driving stability on dry road surfaces. [Means for solving the problem]

[0006] The present invention is a tire having a tread portion with a specified rotational direction, the tread portion including a first tread edge and a second tread edge, a plurality of first inclined grooves extending from at least the first tread edge toward the tire equator with an inclination toward the leading side in the rotational direction, a plurality of second inclined grooves extending from at least the second tread edge toward the tire equator with an inclination toward the leading side in the rotational direction, and a plurality of first land portions divided into the plurality of first inclined grooves, each of the plurality of first land portions including a tread surface, a first side wall on the leading side in the rotational direction, and a second side wall on the trailing side in the rotational direction, at least one of the plurality of first land portions is provided with at least one recessed portion formed by locally recessing the first side wall, the recessed portion being open at the tread surface, and a maximum recessed amount of the recessed portion in a direction perpendicular to the longitudinal direction of the first inclined groove in a plan view of the first land portion is 10% to 25% of a maximum length of the first land portion in a direction perpendicular to the longitudinal direction. Effect of the Invention

[0007] By adopting the above-mentioned configuration, the tire of the present invention can improve snow traction while maintaining steering stability on dry road surfaces. [Brief description of the drawings]

[0008] [Figure 1] 1 is a development view of a tread portion of a tire according to one embodiment of the present invention. [Diagram 2] 2 is an enlarged perspective view showing a first land portion and a first inclined groove in FIG. 1. [Diagram 3] 2 is an enlarged plan view of a first land portion and a first inclined groove in FIG. 1. [Figure 4] FIG. 4 is a cross-sectional view taken along line AA in FIG. [Diagram 5] FIG. 4 is an enlarged view of an edge of one recess in FIG. 3. [Figure 6] FIG. 4 is a cross-sectional view taken along line BB in FIG. [Figure 7] 4 is a cross-sectional view taken along line CC in FIG. [Figure 8] FIG. 2 is a development view of a tread portion of a tire of Comparative Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The drawings are described to include the features of the present invention, but may include exaggerated expressions or expressions different from the dimensional ratios of the actual structure in order to facilitate understanding of the present invention. In addition, the same or common elements are given the same reference numerals throughout the embodiments, and duplicated explanations are omitted. FIG. 1 is a development view of a tread portion 2 of a tire 1 of this embodiment (hereinafter, may be simply referred to as a "tire"). As shown in FIG. 1, the tire 1 of this embodiment is an all-season tire for passenger cars, which is designed to run on snowy roads in addition to running on dry roads. However, the tire 1 of the present invention is not limited to such an embodiment, and may be, for example, a heavy-duty tire.

[0010] The tire 1 of the present invention has a tread portion 2 with a specified rotational direction R. The rotational direction R is indicated, for example, by letters or symbols on a sidewall portion (not shown).

[0011] The tread portion 2 of the tire 1 of this embodiment includes a first tread edge T1 and a second tread edge T2. In each drawing of this specification, the tread edge on the left side of the tire equator C is the first tread edge T1, and the tread edge on the right side of the tire equator C is the second tread edge T2. The tread portion 2 includes a first tread portion 2A on the first tread edge T1 side of the tire equator C, and a second tread portion 2B on the second tread edge T2 side of the tire equator C. The first tread portion 2A and the second tread portion 2B are substantially configured to be line-symmetrical with respect to the tire equator C, except that they are misaligned in the tire circumferential direction. Therefore, each configuration of the first tread portion 2A can be applied to the second tread portion 2B.

[0012] The first tread edge T1 and the second tread edge T2 are the axially outermost contact points when the tire 1 in a normal state is loaded with 70% of a normal load and contacts a flat surface with a camber angle of 0°.

[0013] In the case of a pneumatic tire for which various standards are established, the "normal state" refers to a state in which the tire is mounted on a normal rim, inflated to a normal internal pressure, and no load is applied. In the case of a tire for which various standards are not established or a non-pneumatic tire, the normal state refers to a standard use state 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 state. In addition, in this specification, unless otherwise specified, the method of measuring the dimensions can be appropriately applied to known methods.

[0014] 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."

[0015] "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."

[0016] For pneumatic tires with various standards, the "normal load" is the load that each standard specifies for each tire in the standard system that includes 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". For tires without various standards, the "normal load" refers to the maximum load that can be applied when using the tire according to the above standards.

[0017] The tread portion 2 includes a plurality of first inclined grooves 3 and a plurality of second inclined grooves 4. In FIG. 1, these grooves and a through groove 30 described later are dotted. The first inclined grooves 3 extend from at least the first tread edge T1 toward the tire equator with an inclination toward the leading side in the rotation direction R. The second inclined grooves 4 extend from at least the second tread edge T2 toward the tire equator C with an inclination toward the leading side in the rotation direction R. The second inclined grooves 4 have substantially the same configuration as the first inclined grooves 3, and the configuration of the first inclined grooves 3 can be applied to the second inclined grooves 4.

[0018] From the viewpoint of ensuring wet performance, the groove width W1 of the first inclined groove 3 and the groove width W2 of the second inclined groove 4 are, for example, 3 mm or more, desirably 4.0 to 7.0 mm, and more desirably 4.5 to 6.0 mm. The depth of these inclined grooves is, for example, 4.0 to 8.5 mm, and desirably 5.0 to 8.0 mm.

[0019] The first inclined groove 3 in this embodiment extends from a position (omitted in FIG. 1) axially outward of the first tread edge T1. The first inclined groove 3 crosses the center position in the tire axial direction between the first tread edge T1 and the tire equator C, and extends to the vicinity of the tire equator C. The first inclined groove 3 includes, for example, a transverse first inclined groove 3A extending to a position beyond the tire equator C, and a non-transverse first inclined groove 3B that ends without crossing the tire equator C. In this embodiment, the transverse first inclined grooves 3A and the non-transverse first inclined grooves 3B are alternately provided in the tire circumferential direction.

[0020] The axial distance from the inner end of the first inclined groove 3 on the tire equator C side to the tire equator C is, for example, 15% or less of the tread half width TWh. However, the present invention is not limited to this embodiment. The tread half width TWh corresponds to the axial distance from the tire equator C to the first tread end T1 in the normal state.

[0021] The tread portion 2 of the present invention includes a plurality of first land portions 5 divided into a plurality of first inclined grooves 3. FIG. 2 shows an enlarged perspective view of the first land portion 5 and the first inclined groove 3. FIG. 3 shows an enlarged plan view of two first inclined grooves 3 and one first land portion 5. FIG. 4 shows a cross-sectional view of line AA in FIG. 3. As shown in FIGS. 2 to 4, each of the plurality of first land portions 5 includes a tread surface 5s, a first side wall 11 on the leading side in the rotation direction R, and a second side wall 12 on the trailing side in the rotation direction R.

[0022] At least one of the plurality of first land portions 5 is provided with at least one recess 15 that is formed by locally recessing the first side wall 11. This recess 15 is open at the tread surface 5s.

[0023] 3, in a plan view of the first land portion 5, the maximum recess amount da of the recess 15 in a direction perpendicular to the longitudinal direction of the first inclined groove 3 is 10% to 25% of the maximum length La of the first land portion 5 in the direction perpendicular to the longitudinal direction. As a result, the tire 1 of the present invention can improve snow traction while maintaining steering stability on dry road surfaces. The reason is as follows.

[0024] In the tire 1 of the present invention, the recesses 15 are provided on the first sidewall 11, which is the sidewall on the leading side in the rotational direction R, so that when traveling on snow, the recesses 15 can form hard snow pillars when the first land portion 5 touches the ground. Furthermore, the snow pillars are sheared, providing excellent snow traction.

[0025] Furthermore, in the present invention, the maximum recess amount da of the recess 15 is specified to be 10% to 25% of the maximum length La of the first land portion 5, so that the above-mentioned effects can be obtained while maintaining steering stability on dry road surfaces (hereinafter sometimes simply referred to as "steering stability").

[0026] The maximum depression amount da of the recess 15 is measured by the following procedure. FIG. 5 shows an enlarged view of an edge 15e of one recess 15 shown in FIG. 3. The recess 15 in FIG. 5 corresponds to the first recess 16 described later. As shown in FIG. 5, the intersections of the groove edge 3e of the first inclined groove 3 and the edge 15e of the recess 15 on the tread surface 5s are the first end 15a and the second end 15b of the recess 15. The distance from the imaginary straight line VL connecting the first end 15a and the second end 15b to the imaginary point VP of the edge 15e of the recess 15 that is the farthest from the imaginary straight line 20 (the distance in the direction perpendicular to the imaginary straight line) is the maximum depression amount da. When the edge 15e of the recess 15 includes a portion that includes the imaginary point VP and extends parallel to the imaginary straight line VL, the center position in the longitudinal direction of the portion extending parallel is recognized as the imaginary point VP.

[0027] As shown in Fig. 4, the maximum length La of the first land portion 5 corresponds to the distance from the end of the tread 5s of the first land portion 5 on the first side wall 11 side to the end on the second side wall 12 side in a state in which the recess 15 is completely filled, in a cross section (corresponding to Fig. 4) of the first land portion 5 that is perpendicular to the longitudinal direction of the first inclined groove 3 and passes through the imaginary point VP (shown in Fig. 5). Note that, in the case where a chamfered portion 23 (details of which will be described later) is provided on the second side wall 12 side as in this embodiment, the inner end of the chamfered portion 23 in the tire radial direction is defined as the end of the tread surface 5s on the second side wall 12 side.

[0028] In a more preferable embodiment, the maximum recess amount da of the recess 15 is 15% to 20% of the maximum length La of the first land portion 5. The maximum recess amount da is preferably 1.0 to 2.5 mm, and more preferably 1.5 to 2.0 mm. This ensures that the above-mentioned effects are achieved.

[0029] 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.

[0030] As shown in FIG. 3, the angle of the first inclined groove 3 with respect to the tire axial direction increases toward the tire equator C. As a result, the first inclined groove 3 includes an outer groove portion 3a, a central groove portion 3b, and an inner groove portion 3c, which have different angles with respect to the tire axial direction. The outer groove portion 3a extends linearly from at least the first tread edge T1 toward the inner side in the tire axial direction. The angle of the outer groove portion 3a with respect to the tire axial direction is, for example, 10° or less. The outer groove portion 3a of this embodiment extends parallel to the tire axial direction. The length of the outer groove portion 3a (so-called periphery length, the same applies below) is 10% to 25% of the total length of the first inclined groove 3.

[0031] The central groove portion 3b is inclined at a larger angle with respect to the tire axial direction than the outer groove portion 3a and extends linearly. The angle θ1 of the central groove portion 3b with respect to the tire axial direction is, for example, 25 to 35°. The length of the central groove portion 3b is 30% to 40% of the total length of the first inclined groove 3. The inner groove portion 3c is inclined at a larger angle with respect to the tire axial direction than the central groove portion 3b and extends linearly. The angle θ2 of the inner groove portion 3c with respect to the tire axial direction is, for example, 40 to 50°. The length of the inner groove portion 3c is 40% to 50% of the total length of the first inclined groove 3. The first inclined groove 3 having such outer groove portion 3a, central groove portion 3b and inner groove portion 3c is useful for improving wet performance.

[0032] It is preferable that a plurality of recesses 15 are provided in the first land portion 5. In this embodiment, the maximum recess amount da of each of the plurality of recesses 15 provided in one first land portion 5 is 10% to 25% of the maximum length La of the first land portion 5. This ensures that the above-mentioned effects are achieved.

[0033] In this embodiment, the multiple recesses 15 provided in one first land portion 5 are composed of a first recess 16, a second recess 17, and a third recess 18. The first recess 16 is provided closest to the first tread edge T1 among the multiple recesses 15, and in this embodiment, is in contact with the outer groove portion 3a of the first inclined groove 3. The second recess 17 is located closer to the tire equator C than the first recess 16. The third recess 18 is located closer to the tire equator C than the second recess 17. The second recess 17 and the third recess 18 are each in contact with the central groove portion 3b of the first inclined groove 3.

[0034] The first recess 16 is desirably, for example, 5.0 mm or more away from the first tread edge T1 and the through-groove 30 described below. The second recess 17 is desirably, for example, 5.0 mm or more away from the through-groove 30. The third recess 18 is desirably, for example, 5.0 mm or more away from the second recess 17. This suppresses uneven wear of the first land portion 5.

[0035] 1, the axial distance L6 from the tire equator C to the first recessed portion 16 is 75% to 85% of the tread half-width TWh. Similarly, the axial distance L7 from the tire equator C to the second recessed portion 17 is 50% to 60% of the tread half-width TWh. The axial distance L8 from the tire equator C to the third recessed portion 18 is 40% to 50% of the tread half-width TWh.

[0036] As shown in FIG. 3, among the plurality of recesses 15 provided in one first land portion 5, the maximum length in the longitudinal direction of the recess 15 (the first recess 16 in this embodiment) provided closest to the first tread edge T1 side is greater than the maximum length in the longitudinal direction of the other recesses 15 (the second recess 17 and the third recess 18 in this embodiment). Specifically, the maximum length L1 of the first recess 16 is 150% to 250% of the maximum length L2 of the second recess 17. In addition, the maximum length L2 of the second recess 17 is 80% to 120% of the maximum length L3 of the third recess 18, and these are the same in this embodiment. Such a plurality of recesses 15 is useful for improving steering stability and snow traction in a well-balanced manner.

[0037] The maximum length L1 of the first recess 16 is, for example, 3.0 to 12.0 mm, and preferably 5.0 to 10.0 mm. The maximum length L2 of the second recess 17 and the maximum length L3 of the third recess 18 are, for example, 3.0 to 8.0 mm, and preferably 4.0 to 7.0 mm.

[0038] 5, in a plan view of the first land portion 5, the recess 15 desirably includes a portion in which the length in the longitudinal direction continuously decreases from the first side wall 11 toward the second side wall 12 (shown in FIG. 3). This makes it easier for snow to be tightly packed in the recess 15, further improving snow traction.

[0039] The opening shape of the recess 15 in the tread surface of the first land portion 5 is, for example, trapezoidal. However, the present invention is not limited to such a shape, and the opening shape may be triangular or semicircular.

[0040] 2 and 5, the recess 15 of this embodiment includes three planar inner walls extending radially inward from each linearly extending edge. This allows the recess 15 to have a trapezoidal opening even when the tread portion 2 is worn.

[0041] In a plan view of the first land portion 5, the opening area of ​​one recess 15 is preferably 2.5% or more, more preferably 3.0% or more, and preferably 5.0% or less, more preferably 4.5% or less of the area of ​​the tread surface 5s (shown in FIG. 3) of one first land portion 5. This improves the driving stability and snow traction in a well-balanced manner.

[0042] From the same viewpoint, as shown in Fig. 4, the maximum depth d2 of the recess 15 from the tread surface 5s is 50% or more, more preferably 60% or more, and preferably 80% or less, more preferably 70% or less of the maximum depth d1 of the first inclined groove 3. The maximum depth d2 is 2.0 to 4.0 mm, and preferably 2.5 to 3.5 mm.

[0043] At least one first land portion 5 has a chamfered portion 23 formed at least partially between the second side wall 12 and the tread surface 5s. The chamfered portion 23 is configured as a minute inclined surface 23s arranged so as to remove an edge formed by the second side wall 12 and the tread surface 5s. In this embodiment, by forming such a chamfered portion 23 on the second side wall 12 side, distortion of the tread surface during braking on a dry road surface is suppressed, the effective contact area is increased, and the braking performance is improved.

[0044] The angle θ3 of the inclined surface 23s of the chamfered portion 23 with respect to the tire normal is, for example, 30 to 60°, and preferably 40 to 50°. The width W3 (shown in FIG. 3) of the inclined surface 23s in a plan view of the first land portion 5 is, for example, 0.5 to 2.0 mm, and preferably 1.0 to 1.5 mm. The depth d3 of the inclined surface 23s is, for example, 0.5 to 2.5 mm, and preferably 1.0 to 2.0 mm.

[0045] As shown in Fig. 3, in this embodiment, the above-mentioned chamfered portion 23 (shown in Fig. 4, and the same applies below) is configured in the portion of the first land portion 5 that contacts the outer groove portion 3a and the central groove portion 3b of the first inclined groove 3. As a result, the chamfered portion 23 is disposed in an area where the ground contact pressure increases during braking, so that the above-mentioned effect can be reliably obtained.

[0046] In a plan view of the first land portion 5, the area of ​​the chamfered portion 23 is 10% to 15% of the area of ​​the tread surface 5s of one first land portion 5. This improves the steering stability and the performance on snow in a well-balanced manner.

[0047] The second side wall 12 includes a non-chamfered portion 24 that is continuous with the tread surface 5s without a chamfered portion 23. The non-chamfered portion 24 is disposed in a portion of the second side wall 12 that contacts the inner groove portion 3c. This allows the non-chamfered portion 24 to be disposed in an area close to the tire equator C, and a high edge effect can be expected. Therefore, excellent snow traction can be expected.

[0048] At least one inclined sipe 25 extending along the longitudinal direction of the first inclined groove 3 is provided in the first land portion 5. In this embodiment, one inclined sipe 25 is provided in one first land portion 5. In this specification, the term "sipe" means a cut having a small width, and the width between two sipe walls in the sipe body is less than 1.5 mm. The sipe body means a portion in which two sipe walls extend substantially parallel to each other in the tire radial direction. "Substantially parallel" means an aspect in which the angle between the two sipe walls is 10° or less. As described later, the sipe may have a chamfered portion formed on its edge. The sipe may also have a so-called flask bottom whose width is expanded at its bottom.

[0049] Furthermore, by providing the sipe with the above-mentioned width, when ground pressure acts on the first land portion 5, the two sipe walls come into contact with each other, and the rigidity of the land portion can be maintained. Meanwhile, in this specification, the term "groove" refers to a groove having a width of at least 1.5 mm that can ensure a drainage path without the groove walls coming into contact with each other even when ground pressure acts on the land portion.

[0050] The inclined sipes 25 extend along the first inclined groove 3 from the first tread edge T1 to the end of the first land portion 5 on the tire equator C side. In a preferred embodiment, the inclined sipes 25 are provided in a central region when the first land portion 5 is divided into thirds in a direction perpendicular to the longitudinal direction by two imaginary lines extending along the longitudinal direction of the first inclined groove 3. Such inclined sipes 25 can enhance snow traction while suppressing uneven wear of the first land portion 5.

[0051] The inclined sipes 25 include an outer sipe portion 25a, a central sipe portion 25b, and an inner sipe portion 25c. The outer sipe portion 25a extends linearly from at least the first tread edge T1 toward the inner side in the tire axial direction. The outer sipe portion 25a of this embodiment extends along the outer groove portion 3a of the first inclined groove 3, and in a preferred embodiment, these are parallel to each other. The length of the outer sipe portion 25a is 80% to 120% of the length of the outer groove portion 3a.

[0052] The central sipe portion 25b extends linearly, continuing from the outer sipe portion 25a on the axially inner side of the tire. The central sipe portion 25b extends along the central groove portion 3b of the first inclined groove 3, and in a preferred embodiment, these are parallel to each other. The length of the central sipe portion 25b is 80% to 120% of the length of the central groove portion 3b.

[0053] The inner sipe portion 25c extends linearly, continuing from the central sipe portion 25b on the inner side in the tire axial direction. The inner sipe portion 25c extends along the inner groove portion 3c of the first inclined groove 3, and in a preferred embodiment, these are parallel to each other. The length of the inner sipe portion 25c is set to 80% to 120% of the length of the inner groove portion 3c. The inclined sipes 25 including such outer sipe portions 25a, central sipe portion 25b, and inner sipe portion 25c can reliably suppress uneven wear of the first land portion 5.

[0054] Fig. 6 shows a cross-sectional view of line BB in Fig. 3. As shown in Fig. 6, the inclined sipe 25 has a chamfered portion 28 on the edge on the leading side in the rotation direction R. The chamfered portion 28 is configured as a minute inclined surface arranged so as to remove the ridge angle formed by the tread surface 5s of the first land portion 5 and the sipe wall 25w. The angle of this inclined surface with respect to the tire normal is, for example, 40 to 50 degrees. Such a chamfered portion 28 can improve braking performance on dry road surfaces.

[0055] In a preferred embodiment, the inclined sipes 25 are not provided with a chamfered portion on the edge on the rear side in the rotational direction R. This allows the edge on the rear side of the inclined sipes 25 to generate a large frictional force when traveling on snow, improving snow traction.

[0056] As shown in Fig. 3, the outer sipe portion 25a and the central sipe portion 25b are provided with the above-mentioned chamfered portion 28 (shown in Fig. 6). On the other hand, the inner sipe portion 25c is not provided with a chamfered portion on either edge of either side. This improves the steering stability and snow traction on dry roads in a well-balanced manner.

[0057] In the present embodiment, at least one through-longitudinal groove 30 is provided in the first land portion 5, connecting two first inclined grooves 3 adjacent in the tire circumferential direction. In the present embodiment, one through-longitudinal groove 30 is provided in one first land portion 5. The through-longitudinal groove 30 in the present embodiment connects the central groove portions 3b of the first inclined grooves 3 adjacent in the tire circumferential direction. The communication position of the through-longitudinal groove 30 with the central groove portion 3b is on the first tread edge T1 side from the longitudinal center position of the central groove portion 3b. Such a through-longitudinal groove 30 makes the periphery thereof easily deformed to an appropriate degree, and can suppress snow from clogging the first inclined groove 3. This allows excellent on-snow performance to be continuously exhibited.

[0058] The through grooves 30 are inclined in the opposite direction to the central groove portion 3b with respect to the tire axial direction. The angle θ4 of the through grooves 30 with respect to the tire circumferential direction is, for example, 5 to 15°. Such through grooves 30 can exert a large snow column shear force in the tire axial direction when traveling on snow.

[0059] In the present embodiment, at least one through sipe 35 is provided in the first land portion 5, connecting two first inclined grooves 3 adjacent in the tire circumferential direction. In the present embodiment, one through sipe 35 is provided in one first land portion 5. The through sipe 35 in the present embodiment connects the inner groove portions 3c of the first inclined grooves 3 adjacent in the tire circumferential direction. The distance in the tire axial direction from the tire equator C to the through sipe 35 is preferably 10% to 30% of the tread half width TWh (shown in FIG. 1), more preferably 20% to 25%. The communication position of the through sipe 35 with the inner groove portion 3c is on the first tread end T1 side from the longitudinal center position of the inner groove portion 3c. Such a through sipe 35 is useful for improving the steering stability on dry road surfaces and the wet performance in a well-balanced manner.

[0060] 1, in this embodiment, first land portions 5 provided with through sipes 35 and first land portions 5 without through sipes 35 are alternately provided in the tire circumferential direction. In the first land portions 5 with the through sipes 35, the recesses 15 are directed only toward the first tread edge T1 side relative to the through sipes 35. This maintains rigidity near the tire equator C and improves steering stability on dry road surfaces.

[0061] FIG. 7 shows a cross-sectional view of line CC in FIG. 3. As shown in FIG. 7, the through sipe 35 includes a sipe body 36 and a widened portion 37. The sipe body 36 has a width W3 of less than 1.5 mm, and in this embodiment, extends from the tread surface 5s toward the inside in the tire radial direction. The width W4 of the sipe body 36 is preferably 0.4 to 0.8 mm, and more preferably 0.5 to 0.6 mm. In another embodiment, a chamfered portion may be provided between the tread surface 5s and the sipe body 36 (not shown). The widened portion 37 is continuous with the sipe body 36 toward the inside in the tire radial direction, and has a width W5 of 1.5 mm or more. The width W5 of the widened portion 37 is preferably 2.5 mm or less, and more preferably 2.0 mm or less. Such a through sipe 35 can suppress a decrease in wet performance due to wear.

[0062] From the viewpoint of preventing molding defects during vulcanization and reliably achieving the above-mentioned effects, the width W5 of the widened portion 37 of the through sipe is desirably 2.5 to 4.0 times the width W4 of the sipe body .

[0063] In this embodiment, the widened portion 37 is located radially inward of the bottom of the recess 15 (shown in FIG. 4). As a result, even if the volume of the recess 15 is reduced or disappears due to wear of the tread portion 2, the through sipe 35 including the widened portion 37 remains, and wet performance can be maintained. Specifically, the length L4 of the sipe body 36 in the radial direction of the tire is, for example, 3.5 to 5.5 mm, and preferably 4.0 to 5.5 mm. The length L5 of the widened portion 37 in the radial direction of the tire is, for example, 1.5 to 2.5 mm, and preferably 1.5 to 2.0 mm.

[0064] 1, the land ratio of the tread portion 2 of this embodiment is, for example, 50% to 65%, and preferably 55% to 60%, which improves steering stability and snow traction in a well-balanced manner. In this specification, the "land ratio" corresponds to the ratio of the actual contact area to the contact area when all the grooves and sipes of the tread portion 2 are filled.

[0065] In this embodiment, since each component has the above-mentioned characteristics, the land ratio of the tread portion 2 in a hypothetical 80% worn state in which the tread portion 2 is uniformly worn down to 80% of the maximum depth of the first inclined grooves 3 is 100% to 110% of the land ratio of the tread portion 2 in an unworn state. This makes it possible to maintain wet performance even when the tread portion 2 is worn down to a certain extent.

[0066] The number of pitches in the entire circumference of the tire (the number of units in the entire circumference of the tire that are each made up of the first land portion 5 and the first inclined groove 3) is, for example, 70 to 90, and preferably 75 to 85. This improves the driving stability on dry roads and snow traction in a well-balanced manner.

[0067] 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

[0068] As an example, a pneumatic tire having a size of 205 / 55R16 and the basic pattern of FIG. 1 was prototyped. In the example, the maximum recessed amount of the recessed portion is 10% to 25% of the maximum length of the first land portion. In addition, as Comparative Example 1, a tire having a pattern shown in FIG. 8 was prototyped. As shown in FIG. 8, the tire of Comparative Example 1 does not have the recessed portion of the present invention. In addition, as Comparative Examples 2 and 3, tires having the basic pattern of FIG. 1 and having a maximum recessed amount of the recessed portion outside the range of the present invention were prototyped. These test tires have substantially the same configuration except for the above-mentioned matters. Each test tire was tested for steering stability and snow traction on a dry road surface. The common specifications and test methods of each test tire are as follows. Rim: 16×6.5 Tire pressure: 250kPa for all wheels Test vehicle: 2000cc, front-wheel drive Tire mounting position: All wheels

[0069] <Steering stability on dry roads> The driving stability of the test vehicle when it was driven on a dry road surface was evaluated by the driver. The higher the score, the better the driving stability.

[0070] <Snow Traction> The traction of the test vehicle on a snowy road was evaluated by the driver. The higher the score, the better the snow traction. The test results are shown in Table 1.

[0071] [Table 1]

[0072] As shown in Table 1, the test results confirmed that the tires of the examples improved snow traction while maintaining driving stability on dry roads.

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

[0074] [Invention 1] A tire having a tread portion with a specified rotation direction, the tread portion includes a first tread edge and a second tread edge, a plurality of first inclined grooves extending from at least the first tread edge toward the tire equator with an inclination toward the leading side in the rotational direction, a plurality of second inclined grooves extending from at least the second tread edge toward the tire equator with an inclination toward the leading side in the rotational direction, and a plurality of first land portions divided into the plurality of first inclined grooves, Each of the plurality of first land portions includes a tread surface, a first side wall on a leading side in the rotation direction, and a second side wall on a trailing side in the rotation direction, At least one of the plurality of first land portions is provided with at least one recessed portion formed by locally recessing the first side wall, The recess is open at the tread surface, In a plan view of the first land portion, a maximum recess amount of the recess in a direction perpendicular to the longitudinal direction of the first inclined groove is 10% to 25% of a maximum length of the first land portion in a direction perpendicular to the longitudinal direction. tire. [Invention 2] The tire according to claim 1, wherein, in a plan view of the first land portion, the recess includes a portion whose length in the longitudinal direction continuously decreases from the first side wall toward the second side wall. [Invention 3] The tire according to the first or second aspect of the present invention, wherein a plurality of the recessed portions are provided in the first land portion. [Invention 4] The tire according to present invention 3, wherein the maximum length in the longitudinal direction of the recessed portion provided closest to the first tread end side among the plurality of recessed portions is greater than the maximum length in the longitudinal direction of the other recessed portions. [Invention 5] The tire according to invention 1 or 2, wherein a maximum depth of the recess from the tread surface is 50% to 80% of a maximum depth of the first inclined groove. [Invention 6] The tire according to invention 1 or 2, wherein, in a plan view of the first land portion, an opening area of ​​the recessed portion is 2.5% to 5.0% of an area of ​​the tread surface of one of the first land portions. [Invention 7] The tire according to the first or second aspect of the present invention, wherein a land ratio of the tread portion in a hypothetical 80% worn state in which the tread portion is uniformly worn down to 80% of the maximum depth of the first inclined groove is 100% to 110% of the land ratio of the tread portion in an unworn state. [Invention 8] The tire according to invention 1 or 2, wherein the at least one first land portion has a chamfered portion formed in at least a portion between the second side wall and the tread surface. [The present invention 9] The tire according to invention 8, wherein the second side wall includes a non-chamfered portion that is continuous with the tread surface without the chamfered portion therebetween. [The present invention 10] 9. The tire according to invention 8, wherein an area of ​​the chamfered portion in a plan view of the first land portion is 10% to 15% of an area of ​​the tread surface of one of the first land portions. [The present invention 11] At least one through sipe is provided in the first land portion to connect the first inclined grooves adjacent to each other in the tire circumferential direction, The tire according to claim 1 or 2, wherein the through sipe includes a sipe body having a width of less than 1.5 mm extending radially inward from the tread surface, and a widened portion having a width of 1.5 mm or more on the radially inward side of the sipe body. [The present invention 12] 12. The tire according to claim 11, wherein the width of the widened portion of the through sipe is 2.5 to 4.0 times the width of the sipe main body portion. [The present invention 13] 12. The tire according to claim 11, wherein the recess is provided only on the first tread edge side of the through sipe. [Invention 14] The first land portion is provided with at least one inclined sipe extending along the longitudinal direction, The tire according to the first or second aspect of the present invention, wherein the inclined sipe has a chamfered portion on an edge on a leading side in the rotational direction. [The present invention 15] 15. The tire according to claim 14, wherein the inclined sipe has no chamfered edge on the trailing edge in the rotational direction. [Explanation of symbols]

[0075] 2 Tread section 3 1st inclined groove 4 2nd inclined groove 5 1st Land Department 5s Tread 11 First side wall 12 Second side wall 15 Recess R Rotation direction T1 First tread edge T2 Second tread edge

Claims

1. A tire having a tread portion with a specified rotation direction, the tread portion includes a first tread edge and a second tread edge, a plurality of first inclined grooves extending from at least the first tread edge toward the tire equator with an inclination toward the leading side in the rotational direction, a plurality of second inclined grooves extending from at least the second tread edge toward the tire equator with an inclination toward the leading side in the rotational direction, and a plurality of first land portions divided into the plurality of first inclined grooves, Each of the plurality of first land portions includes a tread surface, a first side wall on a leading side in the rotation direction, and a second side wall on a trailing side in the rotation direction, At least one of the plurality of first land portions is provided with at least one recessed portion formed by locally recessing the first side wall, The recess is open at the tread surface, In a plan view of the first land portion, a maximum recess amount of the recess in a direction perpendicular to the longitudinal direction of the first inclined groove is 10% to 25% of a maximum length of the first land portion in a direction perpendicular to the longitudinal direction. tire.

2. The tire according to claim 1 , wherein, in a plan view of the first land portion, the recess includes a portion whose length in the longitudinal direction continuously decreases from the first side wall toward the second side wall.

3. The tire according to claim 1 , wherein a plurality of the recessed portions are provided in the first land portion.

4. The tire according to claim 3 , wherein a maximum length in the longitudinal direction of the recessed portion provided closest to the first tread end side among the plurality of recessed portions is greater than a maximum length in the longitudinal direction of the other recessed portions.

5. 3. The tire according to claim 1, wherein a maximum depth of the recess from the tread surface is 50% to 80% of a maximum depth of the first inclined groove.

6. 3. The tire according to claim 1, wherein an opening area of ​​the recessed portion in a plan view of the first land portion is 2.5% to 5.0% of an area of ​​the tread surface of one of the first land portions.

7. 3. The tire according to claim 1, wherein a land ratio of the tread portion in a hypothetical 80% worn state in which the tread portion is uniformly worn down to 80% of the maximum depth of the first inclined groove is 100% to 110% of a land ratio of the tread portion in an unworn state.

8. The tire according to claim 1 or 2, wherein the at least one first land portion has a chamfered portion formed in at least a portion between the second side wall and the tread surface.

9. The tire according to claim 8 , wherein the second sidewall includes a non-chamfered portion that is continuous with the tread surface without the chamfered portion therebetween.

10. The tire according to claim 8, wherein an area of ​​the chamfered portion in a plan view of the first land portion is 10% to 15% of an area of ​​the tread surface of one of the first land portions.

11. At least one through sipe is provided in the first land portion to connect the first inclined grooves adjacent to each other in the tire circumferential direction, 3. The tire according to claim 1, wherein the through sipe includes a sipe body having a width of less than 1.5 mm extending radially inward from the tread surface, and a widened portion having a width of 1.5 mm or more on the radially inward side of the sipe body.

12. The tire according to claim 11, wherein the width of the widened portion of the through sipe is 2.5 to 4.0 times the width of the sipe main body portion.

13. The tire according to claim 11 , wherein the recess is provided only on the first tread edge side relative to the through sipe.

14. The first land portion is provided with at least one inclined sipe extending along the longitudinal direction, The tire according to claim 1 or 2, wherein the inclined sipe has a chamfered portion on an edge on a leading side in the rotational direction.

15. The tire according to claim 14 , wherein the inclined sipe has no chamfered portion on an edge on a trailing side in the rotational direction.

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