tire

Abstract

To provide a tire improved in traction performance and brake performance.SOLUTION: The tire has a tread part 2 whose rotation direction R is designated. The tread part 2 includes a plurality of first inclined grooves 5 and a plurality of first inclined land parts 7. At least one of the first inclined land parts 7 includes an outside part 9 and an inside part 10. The outside part 9 includes a first wall surface 11 and a second wall surface 12. The inside part 10 includes a third wall surface 13 and a fourth wall surface 14. An angle θ1 of the first wall surface 11 with respect to a tire normal line and an angle θ2 of the second wall surface 12 with respect to the tire normal line satisfy the following formula (1) and an angle θ3 of the third wall surface 13 with respect to the tire normal line and an angle θ4 of the fourth wall surface 14 with respect to the tire normal line satisfy the following formula (2): θ1<θ2 (1) and θ3>θ4 (2).SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] For example, Patent Document 1 below proposes a tire having a tread portion provided with a plurality of inclined grooves extending obliquely from a first tread edge on one side in the tire axial direction toward the tire equator, a plurality of central lateral grooves that cross the tire equator and communicate with the inclined grooves, and a plurality of inclined land portions separated by the inclined grooves. Furthermore, the inclined land portions are provided with connecting grooves that communicate between the inclined grooves. The tire of Patent Document 1 is expected to improve snow and ice performance and handling stability on dry roads by improving the inclined grooves, central lateral grooves, and connecting grooves. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-156025 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, as vehicle performance has improved, there has been a demand for tires to have even greater improvements in traction performance and braking performance.

[0005] The present disclosure has been devised in view of the above circumstances, and has as its main object to provide a tire with improved traction performance and braking performance. [Means for solving the problem]

[0006] The present disclosure relates to a tire having a tread portion with a designated rotation direction, the tread portion including a first tread edge, a plurality of first inclined grooves extending from the first tread edge toward the tire equator at an incline toward a leading side in the rotation direction, and a plurality of first inclined land portions divided by the plurality of first inclined grooves, at least one of the first inclined land portions including an outer portion on the first tread edge side and an inner portion on the tire equator side, the outer portion including a first wall surface defined by the first inclined groove on the leading side and a second wall surface on the leading side. and a second wall surface defined by the pair of first inclined grooves on the rear-arrival side, the inner side portion includes a third wall surface defined by the first inclined grooves on the front-arrival side and a fourth wall surface defined by the first inclined grooves on the rear-arrival side, wherein an angle θ1 of the first wall surface with respect to the tire normal and an angle θ2 of the second wall surface with respect to the tire normal satisfy the following formula (1), and an angle θ3 of the third wall surface with respect to the tire normal and an angle θ4 of the fourth wall surface with respect to the tire normal satisfy the following formula (2): θ1<θ2...(1) θ3>θ4...(2) [Effects of the Invention]

[0007] By adopting the above-described configuration, the tire of the present disclosure can improve traction performance and braking performance. [Brief explanation 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 disclosure. [Figure 2] FIG. 2 is an enlarged view of the first inclined land portion of FIG. [Figure 3] FIG. 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. 2. [Figure 5] 2 is an enlarged view of the contour of the first inclined groove of FIG. 1; DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is a development view of a tread portion 2 of a tire 1 according to this embodiment (hereinafter, sometimes simply referred to as "tire"). As shown in FIG. 1, the tire 1 according to this embodiment is, for example, a pneumatic tire for winter use, and is preferably for use on passenger cars. However, the tire 1 according to the present disclosure is not limited to this embodiment.

[0010] A tire 1 of the present disclosure has a tread portion 2 in which a rotation direction R is specified. The rotation 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 in this specification, the tread edge on the left side of the tire equator C is referred to as the first tread edge T1, and the tread edge on the right side of the tire equator C is referred to as the second tread edge T2. The tread portion 2 includes a first tread portion 2A between the tire equator C and the first tread edge T1, and a second tread portion 2B between the tire equator C and the second tread edge T2. The first tread portion 2A and the second tread portion 2B are configured to be substantially line-symmetrical about 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 a normal load and contacts the ground on a flat surface with a camber angle of 0°.

[0013] "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.

[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 specified for each tire by each standard in the standard system, including the standard on which the tire is based. For JATMA, it is the "maximum air pressure," 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 "INFLATION PRESSURE."

[0016] For pneumatic tires for which various standards are established, "normal load" refers to the load specified for each tire in the standard system including the standard on which the tire is based. For JATMA, this is "maximum load capacity," for TRA, this is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and for ETRTO, this is "LOAD CAPACITY." For tires for which various standards are not established, "normal load" refers to the maximum load that can be applied when using the tire in accordance with the above standards.

[0017] The tread portion 2 is provided with a plurality of first inclined grooves 5 and a plurality of second inclined grooves 6. The first inclined grooves 5 extend from the first tread edge T1 toward the tire equator C, inclining toward the leading side in the rotational direction R (downward in each drawing in this specification). Similarly, the second inclined grooves 6 extend from the second tread edge T2 toward the tire equator C, inclining toward the leading side. In this embodiment, the end of the first inclined groove 5 on the tire equator C side communicates with the second inclined groove 6 to form a three-way intersection. Furthermore, the end of the second inclined groove 6 on the tire equator C side communicates with the second inclined groove 6 to form a three-way intersection. However, the tire 1 of the present disclosure is not limited to this embodiment.

[0018] In this embodiment, first inclined grooves 5 crossing the tire equator C and first inclined grooves 5 that terminate just before the tire equator C are alternately provided in the tire circumferential direction. Similarly, second inclined grooves 6 crossing the tire equator C and second inclined grooves 6 that terminate just before the tire equator C are alternately provided in the tire circumferential direction. The groove widths of the first inclined grooves 5 and second inclined grooves 6 are, for example, 2 to 12 mm. The depths of the first inclined grooves 5 and second inclined grooves 6 are, for example, 5 to 15 mm.

[0019] The tread portion 2 includes a plurality of first inclined land portions 7 divided into a plurality of first inclined grooves 5, and a plurality of second inclined land portions 8 divided into a plurality of second inclined grooves 6. In this embodiment, the first inclined land portions 7 and the second inclined land portions 8 have substantially the same configuration.

[0020] FIG. 2 shows an enlarged view of two first inclined land portions 7. As shown in FIG. 2, at least one of the first inclined land portions 7 includes an outer portion 9 on the first tread edge T1 side and an inner portion 10 on the tire equator C side. The outer portion 9 includes a first wall surface 11 defined by the first inclined grooves 5 on the leading side in the rotational direction R, and a second wall surface 12 defined by the first inclined grooves 5 on the trailing side (the upper side in each drawing of this specification) opposite the leading side. The inner portion 10 includes a third wall surface 13 defined by the first inclined grooves 5 on the leading side, and a fourth wall surface 14 defined by the first inclined grooves 5 on the trailing side.

[0021] FIG. 3 shows a cross-sectional view taken along line AA in FIG. 2, and FIG. 4 shows a cross-sectional view taken along line BB in FIG. 2. As shown in FIGS. 3 and 4, in the present disclosure, the angle θ1 of the first wall surface 11 relative to the tire normal and the angle θ2 of the second wall surface 12 relative to the tire normal satisfy the following formula (1). The angle θ3 of the third wall surface 13 relative to the tire normal and the angle θ4 of the fourth wall surface 14 relative to the tire normal satisfy the following formula (2). The tire normal is a reference line when indicating the angle of the wall surface of the land portion, and refers to a line perpendicular to the contact surface of the tread portion 2 or a virtual contact surface when each groove of the tread portion 2 is filled. The virtual contact surface refers to a virtual surface that smoothly connects to the actual contact surface of the tread portion 2 when each groove of the tread portion 2 is filled. In addition, in Figs. 3 and 4, the angles θ1, θ2, θ3, and θ4 are shown larger than they actually are in order to facilitate understanding of the contents of the present disclosure. θ1<θ2…(1) θ3>θ4…(2)

[0022] The tire 1 of the present disclosure employs the above-described configuration, thereby enabling improved traction performance and braking performance, the reason for which is presumed to be the following mechanism.

[0023] As a result of various studies, the developers have reached the following findings: In the tire 1 having the above-described first inclined land portion 7, during traction, a large contact pressure acts on the tire equator C side, and suppressing deformation of the land portion on the tire equator C side is important for improving traction performance. Furthermore, during braking, a large contact pressure also acts on the land portion on the first tread edge T1 side, and suppressing deformation of the land portion on the first tread edge T1 side is important for improving braking performance.

[0024] Based on this knowledge, in the present disclosure, in the inner portion 10 on the tire equator C side, the angle θ3 of the third wall surface is larger than the angle θ4 of the fourth wall surface, so that the inner portion 10 exerts a larger driving force and improves traction performance. On the other hand, in the outer portion 9 on the first tread edge T1 side, the angle θ2 of the second wall surface 12 is larger than the angle θ1 of the first wall surface 11, so that the outer portion 9 exerts a larger braking force and improves braking performance. In the present disclosure, it is believed that such a mechanism improves traction performance and braking performance.

[0025] Furthermore, while conventional methods have involved reducing the volume of the grooves and increasing the volume of the land areas to improve traction and braking performance, the present disclosure does not rely on such methods, and is therefore expected to maintain hydroplaning resistance (the ability to suppress hydroplaning).

[0026] The following describes the configuration of this embodiment in more detail. Note that each configuration described below represents a specific aspect of this embodiment. Therefore, it goes without saying that the present disclosure can achieve the above-described effects even if it does not include the configurations described below. Furthermore, even if any one of the configurations described below is applied alone to a tire of the present disclosure having the above-described characteristics, performance improvement corresponding to each configuration can be expected. Furthermore, when several of the configurations described below are applied in combination, combined performance improvement corresponding to each configuration can be expected.

[0027] As shown in FIG. 2, the outer portion 9 is disposed closer to the first tread edge T1 than a circumferential imaginary line 20 extending parallel to the tire circumferential direction between the tire equator C and the first tread edge T1. The inner portion 10 is disposed closer to the tire equator C than the circumferential imaginary line 20. The axial distance L1 from the tire equator C to the circumferential imaginary line 20 is 20% to 60%, and more preferably 30% to 50%, of the tread half width TWh from the tire equator C to the first tread edge T1. Such an arrangement of the outer portion 9 and the inner portion 10 ensures the above-mentioned effects. The tread half width TWh is the axial distance from the tire equator C to the first tread edge T1 in the normal state.

[0028] As shown in Figures 3 and 4, from the viewpoint of improving traction performance and braking performance in a balanced manner, angle θ1 is, for example, 0 to 2.0°, and preferably 0 to 1.5°. More preferably, angle θ1 in this embodiment is set to 0°. Furthermore, angle θ2 is, for example, 6.0 to 8.0°, and preferably 6.5 to 7.5°. Furthermore, the difference between angle θ1 and angle θ2 is preferably 5.0 to 7.0°.

[0029] From the same viewpoint, the angle θ3 is, for example, 4.0 to 6.0°, and preferably 4.5 to 5.5°. The angle θ4 is, for example, 0 to 3.0°, and preferably 0 to 2.5°. As a more preferable aspect, the angle θ4 in this embodiment is 0°. The difference between the angle θ3 and the angle θ4 is preferably 2.0 to 4.0°.

[0030] It is desirable that angles θ1 and θ4 satisfy the following formula (3). Furthermore, it is desirable that the difference between angles θ1 and θ4 be 3.0° or less. This makes the progress of wear uniform near the first wall surface 11 and near the fourth wall surface 14, thereby suppressing uneven wear. θ1≦θ4…(3)

[0031] The angles θ2 and θ3 preferably satisfy the following formula (4): The difference between the angles θ2 and θ3 is, for example, 3.0° or less, and preferably 2.5° or less. This allows wear to progress uniformly near the second wall surface 12 and the third wall surface 13, thereby suppressing uneven wear. θ2 ≥ θ3…(4)

[0032] As shown in FIG. 3, in the region where the first wall surface 11 is formed, the first inclined groove 5 has a groove width W1 and a depth D1. In the region where the second wall surface 12 is formed, the first inclined groove 5 has a groove width W2 and a depth D2. Also, as shown in FIG. 4, in the region where the third wall surface 13 is formed, the first inclined groove 5 has a groove width W3 and a depth D3. In the region where the fourth wall surface 14 is formed, the first inclined groove 5 has a groove width W4 and a depth D4. Furthermore, it is desirable that the angle θn (which is any one of θ1 to θ4) of any one of the wall surfaces of the first wall surface 11, the second wall surface 12, the third wall surface 13, and the fourth wall surface 14 with respect to the tire normal, and the groove width Wn (which is any one of W1 to W4 corresponding to the θ1 to θ4) and depth Dn (which is any one of D1 to D4 corresponding to the θ1 to θ4) of the first inclined groove 5 formed by the wall surfaces satisfy the following formula (5): As a more preferable aspect, in this embodiment, each wall surface satisfies formula (5), which optimizes the width of each wall surface in a tread plan view (the width of the first inclined grooves 5 in the groove width direction), thereby improving traction performance and braking performance while maintaining hydroplaning resistance. 0≦(Dn×tanθn) / Wn≦0.2…(5)

[0033] Furthermore, as a more desirable aspect, in this embodiment, the above-mentioned formulas (1) to (4) are simultaneously satisfied. In other words, this embodiment satisfies the following formula (6). This further improves traction performance and braking performance while maintaining hydroplaning resistance. θ1≦θ4<θ3≦θ2…(6)

[0034] 2, one first longitudinal groove 23 is provided in the first inclined land portion 7. As a result, the first inclined land portion 7 includes an outer land portion 26 defined between the first tread edge T1 and the first longitudinal groove 23, and a central land portion 27 defined on the tire equator C side of the first longitudinal groove 23. In this embodiment, the first inclined land portions 7 whose central land portions 27 straddle the tire equator C and the first inclined land portions 7 whose central land portions 27 do not straddle the tire equator C are alternately provided in the tire circumferential direction.

[0035] As shown in Fig. 1, the axial distance L2 from the tire equator C to the first longitudinal groove 23 is, for example, 40% to 60% of the tread half width TWh (shown in Fig. 2). It is also desirable that the groove width of the first longitudinal groove 23 increases toward the leading side in the rotation direction R. Such first longitudinal grooves 23 can use the rotation of the tire to strongly compact snow within the groove, improving on-snow performance.

[0036] In a more preferable aspect, the first longitudinal grooves 23 of this embodiment are inclined toward the first tread edge T1 toward the leading side. The angle of the first longitudinal grooves 23 with respect to the tire circumferential direction is, for example, 5 to 15 degrees. This makes it easier for snow to be discharged from the first longitudinal grooves 23 when driving on snow, thereby continuously demonstrating excellent on-snow performance.

[0037] In this embodiment, a plurality of first longitudinal grooves 23 are aligned in the tire circumferential direction, but it is desirable that these first longitudinal grooves 23 are arranged so as not to form a see-through region that extends continuously in parallel to the tire circumferential direction due to the inclination described above. In other words, it is desirable that the tread portion 2 does not have a circumferential groove that extends continuously in the tire circumferential direction. This improves the rigidity of the tread portion 2 in the tire axial direction.

[0038] As shown in Fig. 2, the first inclined land portion 7 is provided with a plurality of longitudinal shallow grooves 30. The longitudinal shallow grooves 30 are connected to the first inclined grooves 5 on both sides in the tire circumferential direction, and completely traverse the first inclined land portion 7. The depth of the longitudinal shallow grooves 30 is 25% to 50% of the depth of the first longitudinal groove 23. The longitudinal shallow grooves 30 include one outer longitudinal shallow groove 30a provided in the outer land portion 26 and one or two inner longitudinal shallow grooves 30b provided in the central land portion 27.

[0039] In this embodiment, the longitudinal shallow groove 30 has a groove width that increases toward the rearward arrival side in the rotational direction R. The longitudinal shallow groove 30 includes a first portion 31 having a constant groove width and a second portion 32 whose groove width increases toward the rearward arrival side. The second portion 32 is continuous with the rearward arrival side of the first portion 31. Such a longitudinal shallow groove 30 allows snow to be easily discharged from the second portion 32 side, and prevents snow from clogging inside.

[0040] The central land portion 27 includes a plurality of block pieces separated by the inner longitudinal shallow groove 30b. The central land portion 27 having only one inner longitudinal shallow groove 30b includes a crown block piece 35 closest to the tire equator C and a first middle block piece 36 separated between the inner longitudinal shallow groove 30b and the first longitudinal groove 23. The central land portion 27 having two inner longitudinal shallow grooves 30b includes a crown block piece 35 closest to the tire equator C, a first middle block piece 36 separated between the inner longitudinal shallow groove 30b and the first longitudinal groove 23, and a second middle block piece 37 separated by the two inner longitudinal shallow grooves 30b.

[0041] In this embodiment, the first middle block piece 36 is disposed on the circumferential virtual line 20. As a result, at least the outer land portion 26 is configured as the outer portion 9 and includes the first wall surface 11 and the second wall surface 12. In a more preferred embodiment, the first wall surface 11 and the second wall surface 12 having the above-mentioned relationship are disposed over the entire outer land portion 26. Furthermore, within the central land portion 27, at least the crown block piece 35 and the second middle block piece 37 are configured as the inner portion 10 and include the third wall surface 13 and the fourth wall surface 14. In a more preferred embodiment, the third wall surface 13 and the fourth wall surface 14 having the above-mentioned relationship are disposed over the entire crown block piece 35 and the second middle block piece 37.

[0042] The angle of each wall surface of the first middle block piece 36 is not particularly limited. In this embodiment, the angle of each wall surface of the first middle block piece 36 changes in the length direction of the first inclined groove 5, thereby forming a boundary between the outer portion 9 and the inner portion 10.

[0043] It is desirable that a plurality of sipes 40 be provided in the first inclined land portion 7. The sipes 40 in this embodiment extend, for example, in a zigzag pattern. However, the sipes 40 are not limited to this form and may extend linearly. In this specification, the term "sipe" refers to a small cut, with a width between two inner walls of 1.5 mm or less. The width of the sipe 40 is preferably 0.2 to 1.2 mm, and more preferably 0.2 to 1.0 mm. The sipe 40 in this embodiment has a width within the above range throughout its entire depth direction. The sipe 40 may be connected to a chamfered opening or flask bottom whose width is greater than the above range.

[0044] The sipes 40 include, for example, crown sipes 41, middle sipes 42, and outer sipes 43. The crown sipes 41 are provided in the crown block piece 35. The middle sipes 42 are provided in the first middle block piece 36 or the second middle block piece 37. The outer sipes 43 are provided in the outer land portion 26. The crown sipes 41 preferably extend along the tire axial direction, for example. The middle sipes 42 preferably incline in the opposite direction to the first inclined grooves 5 with respect to the tire axial direction, for example. The outer sipes 43 preferably extend along the first inclined grooves 5, for example. Note that when the sipes 40 extend in a zigzag pattern, it is desirable that the center line of the amplitude of the zigzag-extending sipes has the above-described configuration.

[0045] Figure 5 shows an enlarged view of the contours of the first inclined grooves 5 in Figure 1. Note that sipes arranged in the land portions are omitted in Figure 5. As shown in Figure 5, the angle of the first inclined grooves 5 relative to the tire axial direction increases from the first tread edge T1 side toward the tire equator C side. Such first inclined grooves 5 provide snow column shear force in multiple directions, which helps to improve traction and cornering performance on snow.

[0046] The first inclined groove 5 preferably includes a plurality of linear groove portions 45 that extend linearly and inclined with respect to the tire axial direction. In a more preferred embodiment, the first inclined groove 5 of this embodiment is composed of a plurality of linear groove portions 45 and does not include curved groove edges. Compared to inclined grooves composed of curved groove edges, such first inclined grooves 5 can increase the area of ​​the land portion while maintaining the friction force generated by the groove edges.

[0047] The first oblique groove 5 includes, for example, a first linear groove portion 46, a second linear groove portion 47, a third linear groove portion 48, and a fourth linear groove portion 49. The first linear groove portion 46 extends linearly at an angle relative to the tire axial direction from at least the first tread edge T1. The second linear groove portion 47 continues to the first linear groove portion 46 and extends linearly at a larger angle relative to the tire axial direction than the first linear groove portion 46. The third linear groove portion 48 continues to the second linear groove portion 47 and extends linearly at a larger angle relative to the tire axial direction than the second linear groove portion 47. The fourth linear groove portion 49 continues to the third linear groove portion 48 and extends linearly at a larger angle relative to the tire axial direction than the third linear groove portion 48.

[0048] The angle of the first straight groove portion 46 with respect to the tire axial direction is, for example, 5 to 15 degrees. The length of the first straight groove portion 46 (the so-called periphery length along the length direction of the groove) is 25% to 40% of the total length of the first oblique groove 5 from the first tread edge T1 to the end on the tire equator C side (also the periphery length). Hereinafter, in this specification, unless otherwise specified, the length of a groove or groove portion refers to the so-called periphery length along the length direction.

[0049] The angle of the second straight groove portions 47 with respect to the tire axial direction is, for example, 30 to 40°. The length of the second straight groove portions 47 is shorter than the length of the first straight groove portions 46, and is, for example, 15% to 30% of the total length of the first inclined grooves 5.

[0050] The angle of the third straight groove portions 48 with respect to the tire axial direction is, for example, 50 to 60°. The length of the third straight groove portions 48 is greater than the length of the second straight groove portions 47, and is, for example, 25% to 40% of the total length of the first inclined grooves 5.

[0051] The angle of the fourth straight groove portions 49 with respect to the tire axial direction is, for example, 55 to 65 degrees. The length of the fourth straight groove portions 49 is shorter than the length of the third straight groove portions 48, and is, for example, 5% to 15% of the total length of the first inclined grooves 5.

[0052] The traction performance and cornering performance on snow can be improved in a well-balanced manner by arranging the linear groove portions 45 as described above. However, the first oblique grooves 5 are not limited to the arrangement of the linear groove portions 45 as described above.

[0053] In order to achieve a good balance between dry performance and on-snow performance, the land ratio Lr of the tread portion 2 of this embodiment is desirably, for example, 55% to 70%, as shown in Figure 1. In this specification, the "land ratio" refers to the ratio Sb / Sa of the actual total contact area Sb to the total area Sa of the virtual contact area in which all grooves and sipes are filled.

[0054] From the same viewpoint, it is desirable that the rubber hardness Ht of the tread rubber forming the tread portion 2 is, for example, 55 to 70°. In this specification, the "rubber hardness" is a hardness measured by a durometer type A in accordance with JIS-K6253 under an environment of 23°C.

[0055] Although a tire according to one embodiment of the present disclosure has been described in detail above, the present disclosure is not limited to the above-described specific embodiment and can be modified and implemented in various aspects. [Example]

[0056] Pneumatic tires of size 205 / 55R16 having the basic tread pattern of Figure 1 were prototyped based on the specifications in Tables 1 and 2. As a comparative example, a tire in which the angle of each wall surface of the first inclined land portion was constant was prototyped. The comparative tire was substantially the same as the tire shown in Figure 1 except for the above-mentioned points. The traction performance, braking performance, and hydroplaning resistance of each test tire were tested. The common specifications and test methods for each test tire are as follows: Test vehicle: 2000cc, front-wheel drive Test tire mounting position: All wheels Rim: 16x6.5 Tire pressure: 230kPa on all wheels

[0057] <Traction performance> The traction performance of the test vehicle when driven on a dry road surface was evaluated by the driver. The results are expressed as a score with the comparative example being 100, with a higher score indicating better traction performance.

[0058] <Braking performance> The braking performance of the test vehicle when it was driven on a dry road was evaluated by the driver. The results are expressed as a score with the comparative example being 100, with a higher score indicating better braking performance.

[0059] <Hydroplaning resistance> The test vehicle was driven on a wet road and the speed at which hydroplaning occurred was measured. The results are expressed as an index, with the speed of the comparative example being 100, and the higher the index, the better the hydroplaning resistance. The test results are shown in Tables 1-2.

[0060] [Table 1]

[0061] [Table 2]

[0062] As shown in Table 1, the test results confirmed that the tires of the examples had improved traction performance and braking performance. It was also confirmed that the tires of the examples maintained resistance to hydroplaning.

[0063] In Tables 1 and 2, the sum of the evaluation scores for the traction performance, braking performance, and hydroplaning resistance may be used as an index of the overall performance of the tire. As shown in Tables 1 and 2, it can be seen that the tires of the examples exhibit excellent overall performance.

[0064] [Note] The present disclosure includes the following aspects.

[0065] [Disclosure 1] A tire having a tread portion with a designated rotation direction, the tread portion includes a first tread edge, a plurality of first inclined grooves extending from the first tread edge toward the tire equator at an incline toward the leading side in the rotational direction, and a plurality of first inclined land portions separated by the plurality of first inclined grooves, At least one of the first inclined land portions includes an outer portion on the first tread edge side and an inner portion on the tire equator side, the outer portion includes a first wall surface defined by the first inclined groove on the leading side and a second wall surface defined by the first inclined groove on the trailing side opposite to the leading side, the inner portion includes a third wall surface defined by the first inclined groove on the leading side and a fourth wall surface defined by the first inclined groove on the trailing side, An angle θ1 of the first wall surface with respect to the tire normal line and an angle θ2 of the second wall surface with respect to the tire normal line satisfy the following formula (1), An angle θ3 of the third wall surface with respect to the tire normal line and an angle θ4 of the fourth wall surface with respect to the tire normal line satisfy the following formula (2): tire. θ1<θ2…(1) θ3>θ4…(2) [Disclosure 2] The tire according to Disclosure 1, wherein the angle θ1 and the angle θ4 satisfy the following formula (3). θ1≦θ4…(3) [Disclosure 3] The tire according to Disclosure 1 or 2, wherein the angle θ2 and the angle θ3 satisfy the following formula (4): θ2 ≥ θ3…(4) [Disclosure 4] A tire described in any one of Disclosures 1 to 3, wherein an angle θn of any one of the first wall surface, the second wall surface, the third wall surface, and the fourth wall surface with respect to the tire normal, and a groove width Wn and a depth Dn of a first inclined groove formed by the wall surfaces satisfy the following formula (5): 0≦(Dn×tanθn) / Wn≦0.2…(5) [Disclosure 5] The tire according to any one of Disclosures 1 to 4, wherein the tread portion is not provided with a circumferential groove that extends continuously in the tire circumferential direction. [Disclosure 6] The tire according to any one of Present Disclosures 1 to 5, wherein an angle of the first inclined groove with respect to the tire axial direction increases from the first tread end side toward the tire equator side. [Disclosure 7] the tread portion includes a second tread edge opposite to the first tread edge, and a plurality of second inclined grooves extending from the second tread edge toward the tire equator at an incline toward the leading side in the rotational direction, The tire according to any one of the first to sixth disclosures, wherein an end portion of the first inclined groove on the tire equator side is connected to the second inclined groove to form a three-way intersection. [Disclosure 8] the outer portion is disposed on the first tread edge side of a circumferential imaginary line extending parallel to the tire circumferential direction between the tire equator and the first tread edge, The tire according to any one of Present Disclosures 1 to 7, wherein the inner portion is disposed closer to the tire equator than the circumferential virtual line. [Disclosure 9] The tire according to Disclosure 8, wherein the distance in the tire axial direction from the tire equator to the circumferential virtual line is 20% to 60% of the tread half width from the tire equator to the first tread edge. [Explanation of symbols]

[0066] 2 Tread section 5 1st inclined groove 7 First slope land area 9 Outer part 10 Inner part 11 First wall 12 Second wall 13 Third wall 14 Fourth Wall R Rotation direction T1 First tread edge θ1 Angle of the first wall surface relative to the tire normal θ2 Angle of the second wall surface relative to the tire normal θ3 Angle of the third wall surface relative to the tire normal θ4 Angle of the fourth wall surface relative to the tire normal

Claims

1. A tire having a tread portion with a designated rotation direction, the tread portion includes a first tread edge, a plurality of first inclined grooves extending from the first tread edge toward the tire equator at an incline toward the leading side in the rotational direction, and a plurality of first inclined land portions separated by the plurality of first inclined grooves, At least one of the first inclined land portions includes an outer portion on the first tread edge side and an inner portion on the tire equator side, the outer portion includes a first wall surface defined by the first inclined groove on the leading side and a second wall surface defined by the first inclined groove on the trailing side opposite to the leading side, the inner portion includes a third wall surface defined by the first inclined groove on the leading side and a fourth wall surface defined by the first inclined groove on the trailing side, An angle θ1 of the first wall surface with respect to a tire normal line and an angle θ2 of the second wall surface with respect to a tire normal line satisfy the following formula (1), An angle θ3 of the third wall surface with respect to the tire normal line and an angle θ4 of the fourth wall surface with respect to the tire normal line satisfy the following formula (2): tire. θ1<θ2 (1) θ3>θ4...(2)

2. The tire according to claim 1 , wherein the angle θ1 and the angle θ4 satisfy the following formula (3): θ1≦θ4 (3)

3. The tire according to claim 1 or 2, wherein the angle θ2 and the angle θ3 satisfy the following formula (4): θ2 ≧ θ3 (4)

4. 4. The tire according to claim 1, wherein an angle θn of any one of the first wall surface, the second wall surface, the third wall surface, and the fourth wall surface with respect to a tire normal, and a groove width Wn and a depth Dn of a first inclined groove formed by the wall surfaces satisfy the following formula (5): 0≦(Dn×tan θn) / Wn≦0.2 (5)

5. The tire according to claim 1 , wherein the tread portion is not provided with a circumferential groove that extends continuously in the tire circumferential direction.

6. The tire according to claim 1 , wherein an angle of the first inclined groove with respect to the tire axial direction increases from the first tread end side toward the tire equator side.

7. the tread portion includes a second tread edge opposite to the first tread edge, and a plurality of second inclined grooves extending from the second tread edge toward the tire equator at an incline toward the leading side in the rotational direction, The tire according to claim 1 , wherein an end portion of the first inclined groove on the tire equator side is connected to the second inclined groove to form a three-way intersection.

8. the outer portion is disposed on the first tread edge side of a circumferential imaginary line extending parallel to the tire circumferential direction between the tire equator and the first tread edge, The tire according to claim 1 , wherein the inner portion is disposed closer to the tire equator than the circumferential imaginary line.

9. The tire according to claim 8, wherein the distance in the tire axial direction from the tire equator to the circumferential virtual line is 20% to 60% of the tread half width from the tire equator to the first tread edge.

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