Tire

Abstract

To provide a tire which can improve noise performance without damaging performance of uneven wear resistance.SOLUTION: A tire 1 includes a tread part 2. The tread part 2 includes: a first tread ground contact end e1 which is at one side in a tire axial direction; a first shoulder peripheral direction groove 3A at or nearest to the first tread ground contact end e1; and a first shoulder land part 4A which is segmented at the outside of the first shoulder peripheral direction groove 3A in the tire axial direction. The first shoulder land part 4A includes a plurality of first shoulder groove-like parts 5 extending from the first shoulder peripheral direction groove 3A to the first tread ground contact end e1. A pair of adjacent first shoulder groove-like parts 5, 5 in the tire circumferential direction have different angles θ1 regarding the tire axial direction. The plurality of first shoulder groove-like parts 5 include plural kinds of grooves whose first pitch lengths L1 at the communication part 7 with the first shoulder peripheral direction groove 3A are different each other. The maximum value L1m of the first pitch lengths is 1.2 - 1.5 times as average value of the first pitch lengths L1.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a tire.

Background Art

[0002] Patent Document 1 below describes a tire having a tread portion. This tread portion is provided with a first tread end, a plurality of main grooves continuously extending in the circumferential direction of the tire between the first tread end and the second tread end, and a plurality of land portions divided by the main grooves.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above tire, although noise reduction is attempted, there is room for improvement in terms of uneven wear resistance.

[0005] The present disclosure has been devised in view of the above actual situation, and the main object is to provide a tire capable of improving noise performance without deteriorating uneven wear resistance.

Means for Solving the Problems

[0006] The present disclosure relates to a tire having a tread portion, wherein the tread portion includes a first tread grounding end on one side in the tire axial direction, a first shoulder circumferential groove closest to the first tread grounding end, and a first shoulder land portion defined outside the first shoulder circumferential groove in the tire axial direction. The first shoulder land portion is provided with a plurality of first shoulder groove-shaped portions extending from the first shoulder circumferential groove to the first tread grounding end. Among the plurality of first shoulder groove-shaped portions, an angle θ1 with respect to the tire axial direction of a pair of adjacent first shoulder groove-shaped portions in the tire circumferential direction is different from each other. The plurality of first shoulder groove-shaped portions include a plurality of types having different first pitch lengths, which are the pitch lengths in the tire circumferential direction at the communication portion with the first shoulder circumferential groove. The maximum value of the first pitch length is 1.2 to 1.5 times the average of the first pitch lengths.

Advantages of the Invention

[0007] By adopting the above configuration, the tire of the present disclosure can improve the noise performance without deteriorating the uneven wear resistance performance.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

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

[0010] [Tire (First Embodiment)] FIG. 1 shows a developed view of the tread part 2 of the tire 1 of this embodiment. For ease of understanding, in each figure of this specification, the circumferential grooves 3 and the like are colored. The tire 1 of this embodiment is preferably used, for example, as a pneumatic tire for a passenger car. However, the present disclosure is not limited to such a mode, and may be used, for example, for a pneumatic tire for heavy loads or a non-pneumatic tire (airless tire) in which the inside of the tire is not filled with pressurized air.

[0011] As shown in FIG. 1, the tire 1 of this embodiment has a tread part 2. The tread part 2 includes a first tread ground contact end e1 on one side in the tire axial direction and a second tread ground contact end e2 on the other side in the tire axial direction.

[0012] The first tread ground contact end e1 and the second tread ground contact end e2 are specified as the outermost ground contact positions in the tire axial direction when the tire 1 is a pneumatic tire and a normal load is applied to the normal state of the tire 1 and it is grounded on a plane at a camber angle of 0°.

[0013] The normal state means a no-load state where the tire 1 is mounted on a normal rim and filled with the normal internal pressure. In this specification, unless otherwise specified, the dimensions and the like of each part of the tire are indicated by the values measured in the normal state.

[0014] The "normal rim" is the rim defined for each tire in the standard system including the standards on which the tire 1 is based. Therefore, the normal rim is, for example, the "standard rim" in JATMA, the "Design Rim" in TRA, and the "Measuring Rim" in ETRTO.

[0015] The "normal internal pressure" is the air pressure defined for each tire in the standard system including the standards on which the tire 1 is based. Therefore, the normal internal pressure is, for example, the "maximum air pressure" in JATMA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in TRA, and the "INFLATION PRESSURE" in ETRTO.

[0016] The "normal load" is the load defined for each tire in the standard system including the standards on which the tire 1 is based. Therefore, the normal load is, for example, the "maximum load capacity" in JATMA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in TRA, and the "LOAD CAPACITY" in ETRTO.

[0017] [Circumferential groove] In the tread portion 2 of the present embodiment, a plurality of circumferential grooves 3 continuously extending in the tire circumferential direction are provided. By these circumferential grooves 3, when driving on a wet road surface, water on the road surface is smoothly discharged, and the hydroplaning resistance performance is improved. The groove width W1 and the groove depth (not shown) of the circumferential groove 3 can be set as appropriate. The groove width W1 can be set to 4.0% to 8.0% of the tread width TW. The groove depth is, for example, 5.0 to 10.0 mm.

[0018] In this embodiment, four circumferential grooves 3 are provided in the tread portion 2. As a result, the tread portion 2 is divided into five land portions 4. However, the present disclosure is not limited to such a mode, and the tread portion 2 may be composed of, for example, three land portions 4 divided by two circumferential grooves 3, or may be composed of four land portions 4 divided by three circumferential grooves 3.

[0019] The circumferential groove 3 of this embodiment includes a first shoulder circumferential groove 3A, a second shoulder circumferential groove 3B, a first center circumferential groove 3C, and a second center circumferential groove 3D.

[0020] The first shoulder circumferential groove 3A is the closest to the first tread grounding end e1 among the other circumferential grooves 3. The second shoulder circumferential groove 3B is the closest to the second tread grounding end e2 among the other circumferential grooves 3. The distance D1 from the tire equator C to the groove center line c1 of each of the first shoulder circumferential groove 3A and the second shoulder circumferential groove 3B is, for example, 20% to 25% of the tread width TW.

[0021] The first center circumferential groove 3C is provided between the first shoulder circumferential groove 3A and the tire equator C. The second center circumferential groove 3D is provided between the second shoulder circumferential groove 3B and the tire equator C. The distance D2 from the tire equator C to the groove center line c2 of each of the first center circumferential groove 3C and the second center circumferential groove 3D is, for example, 6% to 15% of the tread width TW.

[0022] [Land portion] The land portion 4 of this embodiment includes a first shoulder land portion 4A and a second shoulder land portion 4B. The first shoulder land portion 4A is divided on the outer side in the tire axial direction of the first shoulder circumferential groove 3A. On the other hand, the second shoulder land portion 4B is divided on the outer side in the tire axial direction of the second shoulder circumferential groove 3B.

[0023] The land portion 4 of the present embodiment includes a first middle land portion 4C, a second middle land portion 4D, and a center land portion 4E. The first middle land portion 4C is demarcated between the first shoulder circumferential groove 3A and the first center circumferential groove 3C. The second middle land portion 4D is demarcated between the second shoulder circumferential groove 3B and the second center circumferential groove 3D. The center land portion 4E is demarcated between the first center circumferential groove 3C and the second center circumferential groove 3D.

[0024] The first middle land portion 4C, the second middle land portion 4D, and the center land portion 4E of the present embodiment are formed as straight ribs extending linearly in the tire circumferential direction. In the first middle land portion 4C, the second middle land portion 4D, and the center land portion 4E of the present embodiment, no transverse grooves (not shown) or sipes (not shown) extending in a direction intersecting the circumferential groove 3 are provided, but transverse grooves and sipes may be provided as appropriate.

[0025] [First Shoulder Land Portion] FIG. 2 is a partially enlarged view of the first shoulder land portion 4A. The first shoulder land portion 4A of the present embodiment is formed as a straight rib extending linearly in the tire circumferential direction. A plurality of first shoulder groove-like portions 5 extending from the first shoulder circumferential groove 3A to the first tread ground contact end e1 are provided in the first shoulder land portion 4A. As a result, a plurality of first shoulder blocks 6 divided by the plurality of first shoulder groove-like portions 5 are provided in the first shoulder land portion 4A.

[0026] [First Shoulder Groove-Like Portion] The plurality of first shoulder groove-like portions 5 of the present embodiment are formed as sipes with a groove width W2 of 1.0 mm or less. As a result, in the tire 1 of the present embodiment during traveling, the wall surfaces on both sides of the first shoulder groove-like portion 5 support each other, suppressing the difference in front-back rigidity of the first shoulder land portion 4A. Thereby, the noise performance is improved without deteriorating the uneven wear resistance performance. The groove width W2 is preferably 0.8 mm or less, and more preferably 0.6 mm or less. Also, the depth (not shown) of the first shoulder groove-like portion 5 can be set, for example, to 5.0 to 7.0 mm.

[0027] The first shoulder groove portion 5 of the present embodiment extends linearly from the first shoulder circumferential groove 3A to the first tread grounding end e1. Note that the first shoulder groove portion 5 may be bent or curved.

[0028] Among the plurality of first shoulder groove portions 5, a pair of adjacent first shoulder groove portions 5, 5 in the tire circumferential direction have different angles θ1 with respect to the tire axial direction. In this specification, the angle θ1 is specified with the angle inclined toward one side S1 in the tire circumferential direction from the inner side to the outer side in the tire axial direction being positive.

[0029] The angle θ1 of the present embodiment is specified on a straight line (in this example, the groove center line c5) connecting the first intersection point P1 between the first shoulder groove portion 5 and the first shoulder circumferential groove 3A and the second intersection point P2 between the first shoulder groove portion 5 and the first tread grounding end e1. The first intersection point P1 is specified as the position where the groove center line c5 of the first shoulder groove portion 5 intersects the groove edge 3As of the first shoulder circumferential groove 3A. The second intersection point P2 is specified as the position where the groove center line c5 of the first shoulder groove portion 5 intersects the first tread grounding end e1.

[0030] The plurality of first shoulder groove portions 5 include a plurality of types having different first pitch lengths L1, which are the pitch lengths in the tire circumferential direction at the communication portion 7 with the first shoulder circumferential groove 3A. As a result, the first shoulder land portion 4A includes a plurality of types of first shoulder blocks 6 having different tire circumferential lengths on the side of the first shoulder circumferential groove 3A where the grounding pressure during running is relatively large. Note that the communication portion 7 is specified by the above-described first intersection point P1.

[0031] Thus, in the tire 1 of the present embodiment, the angles θ1 of a pair of adjacent first shoulder groove-like portions 5, 5 in the tire circumferential direction are different from each other, and moreover, the tire has a plurality of types of first shoulder groove-like portions 5 with different first pitch lengths L1 from each other. As a result, the angle θ1 of the first shoulder groove-like portion 5 and the ground contact end shapes on both sides in the tire circumferential direction of the first shoulder block 6 always change in the tire circumferential direction. For this reason, when the first shoulder land portion 4A (first shoulder block 6) comes into contact with the road surface during traveling, the impact sound generated when it contacts is given intensity variations. Thereby, the frequency of the pitch sound is dispersed, and ultimately, the noise performance is improved.

[0032] In the present embodiment, the maximum value L1m of the first pitch length L1 is set to be 1.2 to 1.5 times the average of the first pitch lengths L1. By setting the maximum value L1m to be 1.2 times or more the average of the first pitch lengths L1, the plurality of first shoulder groove-like portions 5 will include a first shoulder groove-like portion 5 with a large first pitch length L1. Thereby, the frequency of the pitch sound is effectively dispersed, and ultimately, the density of the power value of the sound can be reduced. Thereby, the noise performance is improved. On the other hand, by setting the maximum value L1m to be 1.5 times or less the average of the first pitch lengths L1, it is possible to prevent a first shoulder groove-like portion 5 with an overly large first pitch length L1 from being included in the plurality of first shoulder groove-like portions 5. Thereby, it is possible to prevent the difference in the front and rear rigidity of the first shoulder land portion 4A (first shoulder block 6) from becoming overly large, and ultimately, the resistance to uneven wear performance is maintained. From such a perspective, the maximum value L1m is preferably 1.3 times or more the average of the first pitch lengths L1, and preferably 1.4 times or less. Note that the average of the first pitch lengths L1 is obtained by dividing the sum of all types of first pitch lengths L1 by the number of those types.

[0033] On the one hand, it is desirable that the minimum value L1s of the first pitch length L1 be set to 0.5 to 0.8 times the average of the first pitch length L1. By setting the minimum value L1s to 0.8 times or less the average of the first pitch length L1, among the plurality of first shoulder groove portions 5, a first shoulder groove portion 5 having a small first pitch length L1 will be provided. Thereby, the frequency of the pitch sound is more effectively dispersed, and as a result, the density of the sound power value can be reduced. Thereby, the noise performance is improved. On the other hand, by setting the minimum value L1s to 0.5 times or more the average of the first pitch length L1, it is possible to prevent a first shoulder groove portion 5 having an unnecessarily small first pitch length L1 from being included in the plurality of first shoulder groove portions 5. Thereby, the difference in the front-rear rigidity of the first shoulder land portion 4A (first shoulder block 6) is suppressed to be small, and as a result, the anti-abrasion performance due to eccentricity is maintained. From such a viewpoint, the minimum value L1s is preferably 0.6 times or more the average of the first pitch length L1, and preferably 0.7 times or less.

[0034] Also, the angle θ1 of the plurality of first shoulder groove portions 5 is preferably set to -70 to 70°. Thereby, since the range of each angle θ1 that the first shoulder groove portion 5 can take is set wide, the frequency of the pitch sound can be effectively dispersed. Further, in the vicinity of the communication portion 7 between the first shoulder groove portion 5 and the first shoulder circumferential groove 3A, the formation of a portion that is too sharp on the first shoulder land portion 4A is suppressed, and the anti-abrasion performance due to eccentricity is maintained. From such a viewpoint, the angle θ1 is more preferably -65 to 65°. Note that, in the first shoulder land portion 4A, a chamfered portion 10 for suppressing eccentric wear may be formed at a portion that is sharply angled in the vicinity of the communication portion 7.

[0035] [First Unit] As shown in FIG. 1, in the first shoulder land portion 4A of the present embodiment, a first unit 8 composed of some of the plurality of first shoulder groove-shaped portions 5 is arranged in a plurality in the tire circumferential direction. As a result, a pattern in which a plurality of first shoulder groove-shaped portions 5 are spaced apart in the tire circumferential direction is formed in the first shoulder land portion 4A. The number, angle θ1 (shown in FIG. 2), and first pitch length L1 (shown in FIG. 2) of the first shoulder groove-shaped portions 5 of each first unit 8 may be unified or different.

[0036] As shown in FIGS. 1 and 2, the first unit 8 of the present embodiment includes a first portion 11 in which the first shoulder groove-shaped portions 5 with a positive angle θ1 (shown in FIG. 2) are continuous, and a second portion 12 in which the first shoulder groove-shaped portions with a negative angle θ1 are continuous.

[0037] In order to effectively exhibit such an action, the angle θ1 of the first shoulder groove-shaped portions 5 constituting the first portion 11 and the second portion 12 is desirably continuously changed in the tire circumferential direction between the maximum value and the minimum value of the angle (for example, -70 to 70°). As a result, in the first unit 8 (the first shoulder land portion 4A), pitch sounds of different frequencies are continuously generated, and thus the noise performance is improved. The first portion 11 of the present embodiment is arranged on one side S1 in the tire circumferential direction with respect to the second portion 12, but may be arranged on the other side S2.

[0038] [First portion] In the first portion 11, the first shoulder groove-shaped portions 5 with a positive angle θ1 (that is, inclined toward one side S1 in the tire circumferential direction from the inner side to the outer side in the tire axial direction) are spaced apart in the tire circumferential direction. As shown in FIG. 2, the first portion 11 of the present embodiment includes three types of first shoulder groove-shaped portions 5 (first groove-shaped portion 5A, second groove-shaped portion 5B, and third groove-shaped portion 5C) with different angles θ1 from each other, but is not limited to such a mode. For example, two types of first shoulder groove-shaped portions 5 may be included, or four or more types of first shoulder groove-shaped portions 5 may be included.

[0039] As shown in FIG. 2, the first groove-shaped portion 5A of the present embodiment is the first shoulder groove-shaped portion 5 having the smallest angle θ1 in the first portion 11. The third groove-shaped portion 5C is the first shoulder groove-shaped portion 5 having the largest angle θ1 in the first portion 11. The second groove-shaped portion 5B is the first shoulder groove-shaped portion 5 having an angle θ1 that is larger than the angle θ1 of the first groove-shaped portion 5A and smaller than the angle θ1 of the third groove-shaped portion 5C.

[0040] As shown in FIG. 1, in the first portion 11 of the present embodiment, the first groove-shaped portion 5A, the second groove-shaped portion 5B, and the third groove-shaped portion 5C are sequentially arranged from one side S1 to the other side S2 in the tire circumferential direction. Thereby, in the first portion 11, the angle θ1 (shown in FIG. 2) of the first shoulder groove-shaped portion 5 can be gradually increased from one side S1 to the other side S2 in the tire circumferential direction. In such a first portion 11, the frequency of the pitch sound is effectively dispersed, and the noise performance is improved. Further, the change in the front-rear rigidity of the first shoulder land portion 4A (the first shoulder block 6) becomes gentle, and the uneven wear resistance performance is maintained.

[0041] As shown in FIGS. 1 and 2, in the first portion 11 of the present embodiment, the first groove-shaped portion 5A, the second groove-shaped portion 5B, and the third groove-shaped portion 5C are sequentially arranged from the other side S2 to the one side S1 in the tire circumferential direction. Thereby, in the first portion 11, since the angle θ1 of the first shoulder groove-shaped portion 5 can be gradually increased from the other side S2 to the one side S1 in the tire circumferential direction, the noise performance is improved without deteriorating the uneven wear resistance performance.

[0042] As shown in FIG. 1, in the first portion 11, a second groove-shaped portion 5B is provided between a pair of adjacent third groove-shaped portions 5C, 5C in the tire circumferential direction. Thereby, in the first portion 11, the change in the front-rear rigidity becomes gentle, and the uneven wear resistance performance is maintained.

[0043] [Second portion] As shown in FIGS. 1 and 2, in the second portion 12, first shoulder groove-shaped portions 5 with a negative angle θ1 (i.e., inclined toward the other side S2 in the tire circumferential direction from the inner side to the outer side in the tire axial direction) are provided at intervals in the tire circumferential direction. The second portion 12 of the present embodiment includes three types of first shoulder groove-shaped portions 5 (fourth groove-shaped portion 5D, fifth groove-shaped portion 5E, and sixth groove-shaped portion 5F) with different angles θ1, but is not limited to such a mode. For example, two types of first shoulder groove-shaped portions 5 may be included, or four or more types of first shoulder groove-shaped portions 5 may be included.

[0044] As shown in FIG. 2, the fourth groove-shaped portion 5D of the present embodiment is the first shoulder groove-shaped portion 5 with the largest angle θ1 in the second portion 12 where the angle θ1 is negative. The sixth groove-shaped portion 5F is the first shoulder groove-shaped portion 5 with the smallest angle θ1 in the second portion 12. Fifth groove portion 5E is the first shoulder groove-shaped portion 5 having an angle θ1 that is smaller than the angle θ1 of the fourth groove-shaped portion 5D and larger than the angle θ1 of the sixth groove-shaped portion 5F.

[0045] As shown in FIG. 1, in the second portion 12 of the present embodiment, the fourth groove-shaped portion 5D, the fifth groove-shaped portion 5E, and the sixth groove-shaped portion 5F are sequentially arranged from one side S1 to the other side S2 in the tire circumferential direction. Thereby, in the second portion 12, the angle θ1 of the first shoulder groove-shaped portion 5 can be gradually decreased from one side S1 to the other side S2 in the tire circumferential direction. In such a second portion 12, the frequency of the pitch sound is effectively dispersed, and the noise performance is improved. Further, the change in the front and rear rigidity of the first shoulder land portion 4A (first shoulder block 6) becomes gentle, and the resistance to uneven wear performance is maintained.

[0046] As shown in FIGS. 1 and 2, in the second portion 12 of the present embodiment, a fourth groove portion 5D, a fifth groove portion 5E, and a sixth groove portion 5F are sequentially arranged from the other side S2 in the tire circumferential direction toward the one side S1. Thereby, in the second portion 12, since the angle θ1 of the first shoulder groove portion 5 can be gradually increased from the other side S2 in the tire circumferential direction toward the one side S1, the noise performance is improved without deteriorating the uneven wear resistance performance.

[0047] In FIG. 1, in the second portion 12, a fifth groove portion 5E is provided between a pair of adjacent sixth groove portions 5F, 5F in the tire circumferential direction. Thereby, in the second portion 12, the change in the front-rear rigidity becomes gentle, and the uneven wear resistance performance is maintained.

[0048] [Third portion] As shown in FIG. 2, the first unit 8 of the present embodiment further includes a third portion 13 including a first shoulder groove portion 5 having an angle θ1 of zero. In such a third portion 13, pitch sounds having frequencies different from those of the first portion 11 and the second portion 12 are generated, and thus the noise performance is improved. The third portion 13 of the present embodiment is composed of one first shoulder groove portion 5, but may be composed of two or more first shoulder groove portions 5.

[0049] The third portion 13 of the present embodiment is provided between the first portion 11 and the second portion 12. Thereby, in the first unit 8, a third groove portion 5C, a second groove portion 5B, a first groove portion 5A, the third portion 13, a fourth groove portion 5D, a fifth groove portion 5E, and a sixth groove portion 5F are sequentially arranged from the one side S1 in the tire circumferential direction toward the other side S2. Thereby, in the present embodiment, the angle θ1 (shown in FIG. 2) of the first shoulder groove portion 5 continuously changes (gradually decreases) from the one side S1 in the tire circumferential direction toward the other side S2, the frequencies of the pitch sounds are effectively dispersed, and the noise performance is improved. Further, the change in the front-rear rigidity of the first shoulder land portion 4A (first shoulder block 6) becomes gentle, and the uneven wear resistance performance is maintained.

[0050] As shown in FIG. 1, the third part 13 (the first shoulder groove portion 5 where the angle θ1 is zero) of the present embodiment is arranged on one side S1 in the tire circumferential direction with respect to the first groove portion 5A (the first shoulder groove portion 5 where the angle θ1 is the smallest) of the first part 11. Thereby, in the first unit 8, the change in the front-rear rigidity of the first shoulder land portion 4A (the first shoulder block 6) becomes gentle, and the uneven wear resistance performance is maintained.

[0051] [Overhang portion] As shown in FIG. 2, the plurality of first shoulder groove portions 5 of the present embodiment each include an overhang portion 17 that extends outward in the tire axial direction from the first tread ground contact end e1. The overhang portion 17 of the present embodiment is also formed as a sipe with a maximum groove width W3 of 1.0 mm or less. Thereby, in the buttress portion 9 that comes into contact with the ground during turning travel, the tire 1 of the present embodiment maintains the rigidity in the tire circumferential direction, and the deterioration of the steering noise is suppressed. Thereby, the tire 1 of the present embodiment improves the noise performance (steering noise performance).

[0052] [First shoulder block] The first shoulder block 6 of the present embodiment has a trapezoidal tread surface 6t by being divided by the first shoulder circumferential groove 3A, the first tread ground contact end e1, and the plurality of first shoulder groove portions 5.

[0053] At the center position t1 in the tire axial direction of the first shoulder land portion 4A, the second pitch length L2, which is the pitch length in the tire circumferential direction of the plurality of first shoulder groove portions 5, is substantially constant. Here, "substantially constant" is considered in view of molding errors and the like due to vulcanization molding of the tire 1 in a mold. Therefore, when the ratio of the minimum second pitch length L2 divided by the maximum second pitch length L2 is within the range of 0.95 to 1.00, it is considered to be substantially constant. Further, the second pitch length L2 is specified at the intersection of the groove center line c5 of the first shoulder groove portion 5 and the center position t1.

[0054] Thus, in the present embodiment, by setting the second pitch length L2 to be substantially constant, while varying the first pitch length L1, the difference in the front-back rigidity of each of the first shoulder blocks 6 can be suppressed. As a result, the resistance to uneven wear performance is maintained.

[0055] In order to effectively exhibit such an effect, it is desirable that the areas of the tread surfaces 6t of the plurality of first shoulder blocks 6 are each set to be substantially the same. As a result, the rubber volume of each of the first shoulder blocks 6 approaches uniformity, the difference in the front-back rigidity of the first shoulder land portion 4A is suppressed, and thus, the resistance to uneven wear performance is maintained. Here, "substantially the same" takes into account molding errors and the like due to vulcanization molding of the tire 1 in a mold. For this reason, among the tread surfaces 6t of all the first shoulder blocks 6, if the ratio of the minimum value of the area of the tread surface 6t to the maximum value of the area of the tread surface 6t is within the range of 0.95 to 1.00, it is considered to be substantially the same.

[0056] [Second Shoulder Land Portion] FIG. 3 is a partially enlarged view of the second shoulder land portion 4B of FIG. 1. The second shoulder land portion 4B of the present embodiment is formed as a straight rib extending linearly in the tire circumferential direction. A plurality of second shoulder groove-like portions 18 extending from the second shoulder circumferential groove 3B to the second tread ground end e2 are provided in the second shoulder land portion 4B. As a result, a plurality of second shoulder blocks 19 divided by the plurality of second shoulder groove-like portions 18 are provided in the second shoulder land portion 4B.

[0057] [Second Shoulder Groove-Like Portion] The plurality of second shoulder groove-like portions 18 of the present embodiment are formed as sipes with a groove width W4 of 1.0 mm or less, similar to the first shoulder groove-like portion 5. As a result, the resistance to uneven wear performance is maintained. The second shoulder groove-like portion 18 of the present embodiment extends linearly from the second shoulder circumferential groove 3B to the second tread ground end e2, but it may be bent or curved.

[0058] Of the plurality of second shoulder groove portions 18, a pair of second shoulder groove portions 18, 18 adjacent to each other in the tire circumferential direction have different angles θ2 with respect to the tire axial direction. In this specification, the angle θ2 is specified such that the angle inclined toward one side S1 in the tire circumferential direction from the inner side to the outer side in the tire axial direction is positive.

[0059] The angle θ2 of the present embodiment is specified on a straight line (in this example, the groove center line c6) connecting a third intersection point P3 between the second shoulder groove portion 18 and the second shoulder circumferential groove 3B and a fourth intersection point P4 between the second shoulder groove portion 18 and the second tread grounding end e2. The third intersection point P3 is specified as an intersection point between the groove center line c6 of the second shoulder groove portion 18 and the groove edge 3Bs of the second shoulder circumferential groove 3B. The fourth intersection point P4 is specified as an intersection point between the groove center line c6 of the second shoulder groove portion 18 and the second tread grounding end e2.

[0060] The plurality of second shoulder groove portions 18 include a plurality of types having different third pitch lengths L3, which are the pitch lengths in the tire circumferential direction at the communication portion 22 with the second shoulder circumferential groove 3B. As a result, the second shoulder land portion 4B includes a plurality of types of second shoulder blocks 19 having different tire circumferential lengths on the side of the second shoulder circumferential groove 3B where the contact pressure during running is relatively large. The communication portion 22 is specified by the above-described third intersection point P3.

[0061] Thus, in the tire 1 of the present embodiment, the angles θ2 of a pair of second shoulder groove portions 18, 18 adjacent to each other in the tire circumferential direction are different from each other, and moreover, the second shoulder groove portions 18 include a plurality of types having different third pitch lengths L3. As a result, when the second shoulder land portion 4B (the second shoulder block 19) contacts the road surface during running, the impact sound generated is given intensity variations, so that the frequencies of the pitch sounds are dispersed, and thus the noise performance is improved.

[0062] In the present embodiment, from the same perspective as the above-described first pitch length L1 (shown in FIG. 2), it is desirable that the maximum value L3m of the third pitch length L3 be set to 1.2 to 1.5 times (more preferably, 1.3 to 1.4 times) the average of the third pitch length L3. Further, it is desirable that the minimum value L3s of the third pitch length L3 be set to 0.5 to 0.8 times (more preferably, 0.6 to 0.7 times) the average of the third pitch length L3.

[0063] The angles θ2 of the plurality of second shoulder groove portions 18 are preferably set to -70 to 70° (more preferably, -65 to 65°) from the same perspective as the angle θ1 of the above-described first shoulder groove portion 5 (shown in FIG. 2).

[0064] As shown in FIG. 1, the second shoulder groove portion 18 of the present embodiment is inclined in the same direction as the first shoulder groove portion 5 that is most adjacent in the tire circumferential direction. In the present specification, "most adjacent in the tire circumferential direction" means that the separation distance in the tire circumferential direction at the first intersection point P1 (shown in FIG. 2) and the third intersection point P3 (shown in FIG. 3) is the smallest.

[0065] In the present embodiment, all of the second shoulder groove portions 18 are inclined in the same direction as the adjacent first shoulder groove portions 5, but the present invention is not limited to such a mode. For example, some of the second shoulder groove portions 18 may be inclined in the same direction as the adjacent first shoulder groove portions 5.

[0066] In this embodiment, a second shoulder groove portion 18 (e.g., the seventh groove portion 18A) in which the angle θ2 (shown in FIG. 3) is positive and a first shoulder groove portion 5 (e.g., the first groove portion 5A) in which the angle θ1 (shown in FIG. 2) is positive are closest to each other in the tire circumferential direction. Similarly, a second shoulder groove portion 18 (e.g., the tenth groove portion 18D) in which the angle θ2 is negative and a first shoulder groove portion 5 (e.g., the fourth groove portion 5D) in which the angle θ1 is negative are closest to each other in the tire circumferential direction. In this embodiment, a second shoulder groove portion 18 in which the angle θ2 is zero and a first shoulder groove portion 5 in which the angle θ1 is zero are closest to each other in the tire circumferential direction.

[0067] As described above, in this embodiment, since the first shoulder groove portion 5 and the second shoulder groove portion 18 that are closest to each other in the tire circumferential direction are inclined in the same direction, the difference between the front-rear rigidity of the first shoulder land portion 4A and the front-rear rigidity of the second shoulder land portion 4B can be suppressed to be small. Thereby, the uneven wear resistance performance is maintained.

[0068] In order to effectively maintain the uneven wear resistance performance, for the first shoulder groove portion 5 and the second shoulder groove portion 18 that are closest to each other, their angles θ1 (shown in FIG. 2) and angle θ2 (shown in FIG. 3) may be set to be substantially the same. Thereby, the difference between the front-rear rigidity of the first shoulder land portion 4A and the front-rear rigidity of the second shoulder land portion 4B is suppressed to be smaller, and the uneven wear resistance performance is maintained. Note that "substantially the same" is considered in view of the above-mentioned molding errors, etc., and if the ratio of the angles θ1 / θ2 is in the range of 0.95 to 1.05, it is included in being substantially the same.

[0069] Furthermore, for the most adjacent first shoulder groove portion 5 and second shoulder groove portion 18, their first pitch length L1 (shown in FIG. 2) and third pitch length L3 (shown in FIG. 3) may be set to be substantially the same. Thereby, for the first shoulder block 6 and the second shoulder block 19 adjacent in the tire axial direction, the tread areas thereof can be made closer to the same. Therefore, the difference between the front - rear rigidity of the first shoulder land portion 4A and the front - rear rigidity of the second shoulder land portion 4B is suppressed to be smaller, and the uneven wear resistance performance is maintained. Note that "substantially the same" shall include those that are substantially the same if the ratio L1 / L3 of the pitch lengths is within the range of 0.95 to 1.05.

[0070] [Second Unit] As shown in FIG. 1, in the second shoulder land portion 4B of the present embodiment, a plurality of second units 20 each composed of a part of the plurality of second shoulder groove portions 18 are arranged in the tire circumferential direction. Thereby, a pattern in which a plurality of second shoulder groove portions 18 are spaced apart in the tire circumferential direction is formed in the second shoulder land portion 4B. Each second unit 20 may have the same number of second shoulder groove portions 18, angle θ2 (shown in FIG. 3), and third pitch length L3 (shown in FIG. 3), or they may be different.

[0071] As shown in FIGS. 1 and 3, the second unit 20 includes a fourth portion 14 in which the second shoulder groove portions 18 with a positive angle θ2 (shown in FIG. 3) are continuous, and a fifth portion 15 in which the second shoulder groove portions with a negative angle θ2 are continuous. Thereby, in the second unit 20, the pitch sound frequencies are different from each other between the fourth portion 14 and the fifth portion 15, and the noise performance is improved. In order to effectively exhibit such an effect, the angle θ2 of the second shoulder groove portions 18 constituting the fourth portion 14 and the fifth portion 15 desirably changes continuously between the maximum value and the minimum value of the angle (for example, - 70 to 70°).

[0072] [Fourth Portion] In the fourth part 14, second shoulder groove-like portions 18 where the angle θ2 is positive (i.e., inclined toward one side S1 in the tire circumferential direction from the inner side to the outer side in the tire axial direction) are provided at intervals in the tire circumferential direction. As shown in FIG. 3, the fourth part 14 of the present embodiment includes three types of second shoulder groove-like portions 18 (seventh groove-like portion 18A, eighth groove-like portion 18B, and ninth groove-like portion 18C) having different angles θ2 from each other, but the present invention is not limited to such an aspect.

[0073] As shown in FIG. 3, the seventh groove-like portion 18A of the present embodiment is the second shoulder groove-like portion 18 having the smallest angle θ2 in the fourth part 14. The ninth groove-like portion 18C is the second shoulder groove-like portion 18 having the largest angle θ2 in the fourth part 14. The eighth groove-like portion 18B has an angle θ2 that is larger than the angle θ2 of the seventh groove-like portion 18A and smaller than the angle θ2 of the ninth groove-like portion 18C. Second shoulder groove portion 18 That is.

[0074] As shown in FIG. 1, in the fourth part 14 of the present embodiment, the seventh groove-like portion 18A, the eighth groove-like portion 18B, and the ninth groove-like portion 18C are sequentially arranged from one side S1 to the other side S2 in the tire circumferential direction. Further, in the fourth part 14, the seventh groove-like portion 18A, the eighth groove-like portion 18B, and the ninth groove-like portion 18C are sequentially arranged from the other side S2 to one side S1 in the tire circumferential direction. Thereby, in the fourth part 14, the angle θ2 of the second shoulder groove-like portion 18 can be gradually increased from one side S1 to the other side S2 in the tire circumferential direction, and the angle θ2 can be gradually increased from the other side S2 to one side S1. Therefore, in the present embodiment, the noise performance is improved without deteriorating the uneven wear resistance performance. In the fourth part 14, since the eighth groove-like portion 18B is provided between a pair of adjacent ninth groove-like portions 18C, 18C in the tire circumferential direction, the change in front-rear rigidity becomes gentle and the uneven wear resistance performance is maintained.

[0075] [Fifth part] As shown in FIGS. 1 and 3, in the fifth portion 15, second shoulder groove-shaped portions 18 in which the angle θ2 is negative (that is, inclined toward the other side S2 in the tire circumferential direction from the inner side to the outer side in the tire axial direction) are provided at intervals in the tire circumferential direction. The fifth portion 15 of the present embodiment includes three types of second shoulder groove-shaped portions 18 (the tenth groove-shaped portion 18D, the eleventh groove-shaped portion 18E, and the twelfth groove-shaped portion 18F) having different angles θ2 from each other, but the present invention is not limited to such an aspect.

[0076] As shown in FIG. 3, the tenth groove-shaped portion 18D of the present embodiment is the second shoulder groove-shaped portion 18 having the largest angle θ2 in the fifth portion 15. The twelfth groove-shaped portion 18F is the second shoulder groove-shaped portion 18 having the smallest angle θ2 in the fifth portion 15. The eleventh groove-shaped portion 18E has an angle θ2 that is smaller than the angle θ2 of the tenth groove-shaped portion 18D and larger than the angle θ2 of the twelfth groove-shaped portion 18F. Second shoulder groove portion 18 is.

[0077] As shown in FIG. 1, in the fifth portion 15 of the present embodiment, the tenth groove-shaped portion 18D, the eleventh groove-shaped portion 18E, and the twelfth groove-shaped portion 18F are sequentially arranged from one side S1 to the other side S2 in the tire circumferential direction. Further, in the fifth portion 15, the tenth groove-shaped portion 18D, the eleventh groove-shaped portion 18E, and the twelfth groove-shaped portion 18F are sequentially arranged from the other side S2 to the one side S1 in the tire circumferential direction. Thereby, in the fifth portion 15, the angle θ2 of the second shoulder groove-shaped portion 18 can be gradually decreased from one side S1 to the other side S2 in the tire circumferential direction, and the angle θ2 can be gradually decreased from the other side S2 to the one side S1. Therefore, in the present embodiment, the noise performance is improved without deteriorating the uneven wear resistance performance. In the fifth portion 15, since the eleventh groove-shaped portion 18E is provided between a pair of adjacent twelfth groove-shaped portions 18F, 18F in the tire circumferential direction, the change in the front-rear rigidity becomes gentle, and the uneven wear resistance performance is maintained.

[0078] [Sixth portion] As shown in FIG. 3, since the second unit 20 of the present embodiment further includes a sixth portion 16 including a second shoulder groove portion 18 where the angle θ2 is zero, pitch sounds of frequencies different from those of the fourth portion 14 and the fifth portion 15 are generated, and thus the noise performance is improved. The sixth portion 16 of the present embodiment is composed of one Second shoulder groove portion 18 , but may be composed of two or more Second shoulder groove portion 18 .

[0079] The sixth portion 16 of the present embodiment is provided between the fourth portion 14 and the fifth portion 15. Thereby, the ninth groove portion 18C, the eighth groove portion 18B, the seventh groove portion 18A, the sixth portion 16, the tenth groove portion 18D, the eleventh groove portion 18E, and the twelfth groove portion 18F are sequentially arranged from one side S1 to the other side S2 in the tire circumferential direction. Thereby, in the present embodiment, from one side S1 to the other side S2 in the tire circumferential direction, the Angle θ2 of the second shoulder groove portion 18 continuously changes (gradually decreases), and the frequencies of the pitch sounds are effectively dispersed. Therefore, the noise performance is improved. Further, the change in the front-rear rigidity of the second shoulder land portion 4B (second shoulder block 19) becomes gentle, and the uneven wear resistance performance is maintained.

[0080] As shown in FIG. 1, the sixth portion 16 (second shoulder groove portion 18 where the angle θ2 is zero) of the present embodiment is arranged on one side S1 in the tire circumferential direction with respect to the seventh groove portion 18A (second shoulder groove portion 18 where the angle θ2 is the smallest) of the fourth portion 14. Thereby, in the second unit 20, the change in the front-rear rigidity of the second shoulder land portion 4B (second shoulder block 19) becomes gentle, and the uneven wear resistance performance is maintained.

[0081] [Overhang portion] As shown in FIG. 3, each of the plurality of second shoulder groove portions 18 of the present embodiment includes an overhang portion 21 extending outward in the tire axial direction from the second tread grounding end e2. Since the overhang portion 21 of the present embodiment is also formed as a sipe having a maximum groove width W5 of 1.0 mm or less, an increase in the steering noise is suppressed and the noise performance is improved.

[0082] [Second Shoulder Block] The second shoulder block 19 of the present embodiment has a trapezoidal tread surface 19t, which is demarcated by a second shoulder circumferential groove 3B, a second tread ground contact end e2, and a plurality of second shoulder groove portions 18.

[0083] At the center position t2 in the tire axial direction of the second shoulder land portion 4B, a fourth pitch length L4, which is the pitch length in the tire circumferential direction of the plurality of second shoulder groove portions 18, is substantially constant. Thereby, while making the third pitch length L3 different, the difference in the front and rear stiffness of the second shoulder land portion 4B (second shoulder block 19) is suppressed, and thus the uneven wear resistance performance is maintained. Note that, Fourth pitch length L4 is specified at the intersection of the groove center line c6 of the second shoulder groove portion 18 and the center position t2.

[0084] The areas of the tread surfaces 19t of the plurality of second shoulder blocks 19 are desirably set to be substantially the same. Thereby, since the stiffness of each second shoulder block 19 can be made closer to being uniform, the difference in the front and rear stiffness of the second shoulder land portion 4B is suppressed, and thus the uneven wear resistance performance is maintained.

[0085] [Tire (Second Embodiment)] FIG. 4 shows a developed view of the tread portion 2 of a tire 1 according to another embodiment of the present disclosure. In this embodiment, for the same configurations as those in the previous embodiments, the same reference numerals may be given and the description may be omitted.

[0086] The second shoulder groove portion 18 of this embodiment is inclined in a direction opposite to that of the first shoulder groove portion 5 that is closest in the tire circumferential direction. In this embodiment, among all the second shoulder groove portions 18, some of the second shoulder groove portions 18 are inclined in a direction opposite to that of the adjacent first shoulder groove portion 5, but the present invention is not limited to such a mode. For example, all the second shoulder groove portions 18 may be inclined in a direction opposite to that of the adjacent first shoulder groove portion 5.

[0087] In this embodiment, the second shoulder groove portion 18 (for example, the seventh groove portion 18A) in which the angle θ2 (shown in FIG. 3) is positive and the first shoulder groove portion 5 (for example, the fourth groove portion 5D) in which the angle θ1 (shown in FIG. 2) is negative are closest to each other in the tire circumferential direction. Similarly, the second shoulder groove portion 18 (for example, the twelfth groove portion 18F) in which the angle θ2 is negative and the first shoulder groove portion 5 (for example, the first groove portion 5A) in which the angle θ1 is positive are closest to each other in the tire circumferential direction.

[0088] Thus, in this embodiment Second shoulder groove portion 18 is inclined in a direction opposite to that of the first shoulder groove portion 5 that is closest in the tire circumferential direction, so pitch sounds with different frequencies are generated in the first shoulder land portion 4A and the second shoulder land portion 4B. Thereby, the noise performance is improved.

[0089] [Tire (Third Embodiment)] FIG. 5 shows a developed view of the tread portion 2 of the tire 1 according to still another embodiment of the present disclosure. FIG. 6 is a partially enlarged view of the first shoulder land portion 4A of FIG. 5. In this embodiment, the same components as those in the previous embodiments may be denoted by the same reference numerals and the description thereof may be omitted.

[0090] [First Shoulder Groove Portion (Third Embodiment)] The plurality of first shoulder groove portions 5 of this embodiment are configured as transverse grooves in which the groove width W2 (maximum groove width W2m) shown in FIG. 6 is greater than 1.0 mm. Such a first shoulder groove portion 5 can discharge water on the road surface during wet running at the first shoulder land portion 4A, improving the hydroplaning resistance performance. In order to effectively exhibit such an effect, the maximum value of the groove width W2 (maximum groove width W2m) can be set to 2.0% to 5.0% of the tread width TW (shown in FIG. 5).

[0091] The groove width W2 of this embodiment gradually increases from the first shoulder circumferential groove 3A toward the first tread ground contact end e1. As a result, the first shoulder groove portion 5 is formed in a wedge shape that protrudes inward in the tire axial direction. Such a first shoulder groove portion 5 has a relatively high contact pressure at the first shoulder land portion 4A and a relatively large air inflow and outflow during grounding in the inner side in the tire axial direction where the groove volume is relatively small. Thereby, the air pumping sound in the first shoulder groove portion 5 becomes small, improving the noise performance. Therefore, in this embodiment, the noise performance is effectively improved by the dispersion effect of the pitch sound frequency and the reduction effect of the air pumping sound. On the other hand, on the outer side in the tire axial direction (the first tread ground contact end e1 side) where the influence of the air pumping sound is low, since the groove volume is set relatively large, the hydroplaning resistance performance is improved.

[0092] By the way, the first shoulder groove portion 5 with a large angle θ1 has a greater length along the groove center line c5 than the first shoulder groove portion 5 with a small angle θ1. For example, when the groove volumes of these first shoulder groove portions 5 are set to be the same, the groove width W2 of the first shoulder groove portion 5 with a large angle θ1 (for example, the second groove portion 5B) is smaller than the groove width W2 of the first shoulder groove portion 5 with a small angle θ1 (for example, the first groove portion 5A). For this reason, there is a possibility that the drainage efficiency cannot be maintained.

[0093] In order to improve the drainage efficiency, it is desirable that the groove volumes of the plurality of first shoulder groove portions 5 of this embodiment are set to be larger in proportion to the angle θ1. When, as in this embodiment, the first shoulder groove portion 5 with a positive angle θ1 and the first shoulder groove portion 5 with a negative angle θ1 are included, the groove volume is set to be larger in proportion to the absolute value of the angle θ1. In this embodiment, the groove volume of the first shoulder groove portion 5 of the third portion 13 where the angle θ1 is zero is set to be the smallest. On the other hand, the groove volumes of the third groove portion 5C and the sixth groove portion 5F with the largest absolute value of the angle θ1 are set to be the largest.

[0094] Thereby, in this embodiment, it is suppressed that the groove width W2 of the first shoulder groove portion 5 with a large angle θ1 (in this example, the absolute value of the angle θ1) becomes small, and the hydroplaning resistance performance is maintained. In this embodiment, the maximum groove width W2m is set to be larger in proportion to the absolute value of the angle θ1.

[0095] The maximum groove width W3 of the protruding portion 17 can be appropriately set. In each first shoulder groove portion 5, if the maximum groove width W3 and the groove width W2 (maximum groove width W2m) at the first tread ground contact end e1 are set to be the same, in the first shoulder groove portion 5 with a large angle θ1 (absolute value of the angle θ1), the maximum groove width W3 becomes larger than necessary. Thereby, there is a possibility that the steering noise during turning deteriorates. For this reason, the maximum groove width W3 of the protruding portion 17 may be made smaller than the maximum groove width W2m. Thereby, without reducing the groove volume from the first shoulder circumferential groove 3A to the first tread ground contact end e1 in the first shoulder groove portion 5, the deterioration of the steering noise during turning can be suppressed.

[0096] In order to effectively suppress the deterioration of the steering noise, it is desirable that the maximum groove width W3 of the protruding portion 17 is set to 7.0 mm or less. Thereby, it is suppressed that the maximum groove width W3 becomes larger than necessary, and the steering noise during turning is suppressed. In order to effectively exhibit such an effect, more preferably, the maximum groove width W3 is set to 6.4 mm or less.

[0097] The first shoulder land portion 4A may include a plurality of types of protruding portions 17 having different maximum groove widths W3 from each other. However, in order to prevent the deterioration of the steering noise, it is desirable that the maximum groove widths W3 of all the protruding portions 17 are substantially constant. Thereby, the deterioration of the steering noise during turning can be effectively suppressed. Note that "substantially constant" is as described above, taking into account molding errors and the like. The maximum groove width W3 of this embodiment is adjusted according to the smallest maximum groove width W2m among all the maximum groove widths W2m of the first shoulder groove-shaped portions 5 (in this example, the first shoulder groove-shaped portion 5 of the third portion 13 where the angle θ1 is zero).

[0098] The angle θ3 formed by the pair of groove walls 5w, 5w of the first shoulder groove-shaped portion 5 can be set as appropriate. Note that if the angle θ3 is small, there is a risk that the drainage efficiency on the communication portion 7 side (inner side in the tire axial direction) cannot be maintained. On the other hand, if the angle θ3 is large, the maximum groove width W2m of the first shoulder groove-shaped portion 5 becomes larger than necessary. As a result, the deviation between the maximum groove width W2m and the maximum groove width W3 of the protruding portion 17 becomes large, and ultimately, the risk of deterioration of the steering noise increases. From such a viewpoint, the angle θ3 is preferably 2 to 15°, more preferably 3 to 11°.

[0099] [Second Shoulder Groove-Shaped Portion (Third Embodiment)] FIG. 7 is a partially enlarged view of the second shoulder land portion 4B in FIG. 5. The plurality of second shoulder groove-shaped portions 18 of this embodiment are configured as transverse grooves having a groove width W4 (maximum groove width W4m) greater than 1.0 mm. In this embodiment, the groove width W4 is specified as the average groove width from the second shoulder circumferential groove 3B (third intersection point P3) to the second tread ground contact end e2 (fourth intersection point P4). Such second shoulder groove-shaped portions 18 can discharge water on the road surface during wet running in the second shoulder land portion 4B, improving the hydroplaning resistance performance.

[0100] The groove width W4 of this embodiment gradually increases from the second shoulder circumferential groove 3B toward the second tread grounding end e2. As a result, the second shoulder groove portion 18 is formed in a wedge shape that bulges inward in the tire axial direction, similar to the first shoulder groove portion 5, so that the noise performance and the hydroplaning resistance performance are improved.

[0101] The groove volumes of the plurality of second shoulder groove portions 18 of this embodiment are set to be large in proportion to the angle θ2, similar to the first shoulder groove portion 5 (shown in FIG. 6). As a result, in this embodiment, it is suppressed that the groove width W4 of the second shoulder groove portion 18 with a large angle θ2 (in this example, the absolute value of the angle θ2) becomes small, and the hydroplaning resistance performance is maintained.

[0102] It is desirable that the maximum groove width W5 of the protruding portion 21 is smaller than the maximum groove width W4m of the second shoulder groove portion 18. Thereby, in the second shoulder groove portion 18, the deterioration of the steering noise during turning can be suppressed without reducing the groove volume from the second shoulder circumferential groove 3B to the second tread grounding end e2. Note that it is desirable that the maximum groove width W5 of the protruding portion 21 is set within the same range as the maximum groove width W3 (shown in FIG. 6) of the protruding portion 17 of the first shoulder land portion 4A described above. Further, in order to prevent the deterioration of the steering noise, it is desirable that the maximum groove widths W5 of all the protruding portions 21 are substantially constant.

[0103] It is desirable that the angle θ4 formed by the pair of groove walls 18w, 18w of the second shoulder groove portion 18 is set within the same range as the angle θ3 of the first shoulder groove portion 5 described above. Thereby, while suppressing the deterioration of the steering noise, the hydroplaning resistance performance is maintained.

[0104] As described above, the particularly preferred embodiments of the present disclosure have been described in detail. However, the present disclosure is not limited to the illustrated embodiments and can be implemented in various forms.

Example

[0105] [Example A] The tires shown in Fig. 1 were prototype-produced based on the specifications in Tables 1 and 2 (Examples 1 to 7, Comparative Examples 1 to 2). For comparison, as shown in Fig. 8, a tire (Conventional Example 1) was prototype-produced in which the angle θ1 of the first shoulder groove portion and the angle θ2 of the second shoulder groove portion were set to be the same. Then, for each prototype tire, the noise performance and the resistance to uneven wear performance were evaluated. The specifications of each tire are the same except for the configurations described in Tables 1 and 2, and the tire size and the like are as follows. Also, the test method is as follows. The test results are shown in Tables 1 and 2. Tire size: 205 / 55R16 Rim size: 16×6.5J Internal pressure: 230 kPa Vehicle: Domestic electric vehicle Tire mounting position: All wheels

[0106] <Noise performance> The test driver drove the above vehicle on the test course on a dry road, and the noise generated from the tire at this time was evaluated by sensory evaluation. The result is a score with Conventional Example 1 being 100. The larger the numerical value, the better.

[0107] <Resistance to uneven wear performance> After driving a certain distance with the above vehicle, the degree of uneven wear of the first shoulder land portion and the second shoulder land portion was visually evaluated. The result is a score with Conventional Example 1 being 100, and the larger the numerical value, the better.

[0108]

Table 1

[0109]

Table 2

[0110] As a result of the test, the tires of the examples improved the noise performance without sacrificing the resistance to uneven wear performance as compared with the tires of the conventional examples and the comparative examples.

[0111] [Example B] The tires shown in Fig. 5 were prototype-produced based on the specifications in Table 3 (Examples 8 to 13, Comparative Examples 3 to 4). For comparison, as shown in Fig. 9, a tire (Conventional Example 2) in which the angle θ1 of the first shoulder groove portion and the angle θ2 of the second shoulder groove portion were set to be the same was prototype-produced. Then, for each prototype tire, the noise performance and the resistance to uneven wear performance were evaluated.

[0112] The specifications of each tire are the same except for the configuration described in Table 3, and the tire size and the like are as described in Example A. Also, the test method is the same as that of Example A except for the following. Note that the test results are scores with Conventional Example 2 being 100. The test results are shown in Table 3.

[0113] <Resistance to hydroplaning performance> The driving performance when the vehicle travels on a wet road surface was evaluated by the sensory evaluation of the test driver. The results are scores with Conventional Example 2 being 100, and the larger the numerical value, the better the resistance to hydroplaning performance (wet performance).

[0114] <Steering noise performance> The steering noise generated when the vehicle makes a turning run on a dry road test course was evaluated by the sensory evaluation of the test driver. The results are scores with Conventional Example 2 being 100. The larger the numerical value, the better.

[0115]

Table 3

[0116] As a result of the test, the tires of the examples improved the noise performance without sacrificing the resistance to uneven wear performance as compared with the tires of the conventional examples and the comparative examples. Also, in the examples in which the maximum groove width of the protruding portion was set in a preferable range, the deterioration of the steering noise was suppressed. Furthermore, in the examples in which the groove volume of the first shoulder groove portion and the second shoulder groove portion increased in proportion to the angles θ1 and θ2, the resistance to hydroplaning performance was improved.

[0117] [Supplementary Note] The present disclosure includes the following aspects.

[0118] [Disclosure 1] A tire having a tread portion, wherein the tread portion includes a first tread contact end on one side in the tire axial direction, a first shoulder circumferential groove closest to the first tread contact end, and a first shoulder land portion defined outside the first shoulder circumferential groove in the tire axial direction; the first shoulder land portion is provided with a plurality of first shoulder groove-like portions extending from the first shoulder circumferential groove to the first tread contact end; among the plurality of first shoulder groove-like portions, an angle θ1 with respect to the tire axial direction is different between a pair of adjacent first shoulder groove-like portions in the tire circumferential direction; the plurality of first shoulder groove-like portions include a plurality of types having different first pitch lengths, which are the pitch lengths in the tire circumferential direction at the communication portions with the first shoulder circumferential groove; a maximum value of the first pitch length is 1.2 to 1.5 times an average of the first pitch lengths; a tire. [Disclosure 2] a minimum value of the first pitch length is 0.5 to 0.8 times an average of the first pitch lengths, the tire according to Disclosure 1. [Disclosure 3] the angle θ1 is -70 to 70° when an angle inclined to one side in the tire circumferential direction is defined as positive, the tire according to Disclosure 1 or 2. [Disclosure 4] in the first shoulder land portion, a plurality of first units each composed of some of the plurality of first shoulder groove-like portions are arranged in the tire circumferential direction; the first unit includes a first portion in which the first shoulder groove-like portions having a positive angle θ1 are continuous when an angle inclined to one side in the tire circumferential direction is defined as positive, and a second portion in which the first shoulder groove-like portions having a negative angle θ1 are continuous, the tire according to any one of Disclosures 1 to 3. [Disclosure 5] The tire according to Disclosure 4, wherein the first unit further includes a third portion including the first shoulder groove-shaped portion where the angle θ1 is zero. [Disclosure 6] The tire according to Disclosure 4 or 5, wherein the angle θ1 of the first shoulder groove-shaped portion constituting the first portion and the second portion continuously changes between the maximum value and the minimum value of the angle. [Disclosure 7] The tire according to any one of Disclosures 1 to 6, wherein at the center position in the tire axial direction of the first shoulder land portion, a second pitch length, which is the pitch length in the tire circumferential direction of the plurality of first shoulder groove-shaped portions, is substantially constant. [Disclosure 8] The first shoulder land portion includes a plurality of first shoulder blocks divided by the plurality of first shoulder groove-shaped portions, The tire according to any one of Disclosures 1 to 7, wherein the tread surface areas of the plurality of first shoulder blocks are substantially the same. [Disclosure 9] The tire according to any one of Disclosures 1 to 8, wherein the plurality of first shoulder groove-shaped portions are sipes having a groove width of 1.0 mm or less. [Disclosure 10] The tire according to any one of Disclosures 1 to 8, wherein the plurality of first shoulder groove-shaped portions are lateral grooves having a groove width greater than 1.0 mm. [Disclosure 11] The tire according to Disclosure 10, wherein the groove width gradually increases from the first shoulder circumferential groove toward the first tread grounding end. [Disclosure 12] The tire according to Disclosure 10 or 11, wherein the groove volume of the plurality of first shoulder groove-shaped portions increases in proportion to the angle θ1. [Disclosure 13] The plurality of first shoulder groove-shaped portions each include an overhanging portion extending from the first tread grounding end toward the outer side in the tire axial direction, The tire according to any one of Disclosures 10 to 12, wherein the maximum groove width of the overhanging portion is 7.0 mm or less. [Disclosure 14] The tread portion includes a second tread grounding end on the other side in the tire axial direction, a second shoulder circumferential groove closest to the second tread grounding end, and a second shoulder land portion divided on the outer side in the tire axial direction of the second shoulder circumferential groove. The second shoulder land portion is provided with a plurality of second shoulder groove-shaped portions extending from the second shoulder circumferential groove to the second tread grounding end. Among the plurality of second shoulder groove-shaped portions, a pair of second shoulder groove-shaped portions adjacent to each other in the tire circumferential direction have different angles θ2 with respect to the tire axial direction. The plurality of second shoulder groove-shaped portions include a plurality of types having different third pitch lengths, which are the pitch lengths in the tire circumferential direction at the communication portions with the second shoulder circumferential groove, of the tire according to any one of Disclosures 1 to 13. [Disclosure 15] The second shoulder groove-shaped portion is the tire according to Disclosure 14, which is inclined in the same direction as the first shoulder groove-shaped portion closest to it in the tire circumferential direction. [Disclosure 16] The second shoulder groove-shaped portion is the tire according to Disclosure 14, which is inclined in the opposite direction to the first shoulder groove-shaped portion closest to it in the tire circumferential direction.

Explanation of Signs

[0119] 1 Tire 2 Tread portion 3A First shoulder circumferential groove 4A First shoulder land portion 5 First shoulder groove-shaped portion 7 Communication portion

Claims

1. A tire having a tread portion, The tread portion includes a first tread contact end on one side in the tire axial direction, a first shoulder circumferential groove closest to the first tread contact end, and a first shoulder land portion defined outside the first shoulder circumferential groove in the tire axial direction, The first shoulder land portion is provided with a plurality of first shoulder groove-like portions extending from the first shoulder circumferential groove to the first tread contact end, Among the plurality of first shoulder groove-like portions, an angle θ1 with respect to the tire axial direction of a pair of adjacent first shoulder groove-like portions in the tire circumferential direction is different from each other, The plurality of first shoulder groove-like portions include a plurality of types having different first pitch lengths, which are the pitch lengths in the tire circumferential direction at the communication portion with the first shoulder circumferential groove, The maximum value of the first pitch length is 1.2 to 1.5 times the average of the first pitch lengths, The first shoulder land portion includes a plurality of first units formed by some of the plurality of first shoulder groove-like portions arranged in the tire circumferential direction, The first unit is, When the angle inclined to one side in the tire circumferential direction is defined as positive, a first portion in which the first shoulder groove-like portions with the angle θ1 being positive are continuous, and A second portion in which the first shoulder groove-like portions with the angle θ1 being negative are continuous, Tire.

2. The tire according to claim 1, wherein the first unit further includes a third portion including the first shoulder groove-like portion where the angle θ1 is zero.

3. The tire according to claim 1 or 2, wherein the angle θ1 of the first shoulder groove-like portions constituting the first portion and the second portion continuously changes between the maximum value and the minimum value of the angle.

4. A tire having a tread portion, The tread portion includes a first tread grounding end on one side in the tire axial direction, a first shoulder circumferential groove closest to the first tread grounding end, and a first shoulder land portion defined outside the first shoulder circumferential groove in the tire axial direction. The first shoulder land portion is provided with a plurality of first shoulder groove-shaped portions extending from the first shoulder circumferential groove to the first tread grounding end. Among the plurality of first shoulder groove-shaped portions, a pair of adjacent first shoulder groove-shaped portions in the tire circumferential direction have different angles θ1 with respect to the tire axial direction. The plurality of first shoulder groove-shaped portions include a plurality of types having different first pitch lengths, which are the pitch lengths in the tire circumferential direction at the communication portion with the first shoulder circumferential groove. The maximum value of the first pitch length is 1.2 to 1.5 times the average of the first pitch lengths. At the center position of the first shoulder land portion in the tire axial direction, the second pitch length, which is the pitch length in the tire circumferential direction of the plurality of first shoulder groove-shaped portions, is substantially constant. Tire.

5. A tire having a tread portion, The tread portion includes a first tread grounding end on one side in the tire axial direction, a first shoulder circumferential groove closest to the first tread grounding end, and a first shoulder land portion defined outside the first shoulder circumferential groove in the tire axial direction. The first shoulder land portion is provided with a plurality of first shoulder groove-shaped portions extending from the first shoulder circumferential groove to the first tread grounding end. Among the plurality of first shoulder groove-shaped portions, a pair of adjacent first shoulder groove-shaped portions in the tire circumferential direction have different angles θ1 with respect to the tire axial direction. The plurality of first shoulder groove-shaped portions include a plurality of types having different first pitch lengths, which are the pitch lengths in the tire circumferential direction at the communication portion with the first shoulder circumferential groove. The maximum value of the first pitch length is 1.2 to 1.5 times the average of the first pitch lengths. The first shoulder land portion includes a plurality of first shoulder blocks divided by the plurality of first shoulder groove-like portions, The areas of the tread surfaces of the plurality of first shoulder blocks are substantially the same, respectively. Tire.

6. The tire according to any one of claims 1 to 5, wherein the plurality of first shoulder groove-like portions are sipes having a groove width of 1.0 mm or less.

7. The tire according to any one of claims 1 to 5, wherein the plurality of first shoulder groove-like portions are transverse grooves having a groove width greater than 1.0 mm.

8. The tire according to claim 7, wherein the groove width gradually increases from the first shoulder circumferential groove toward the first tread grounding end.

9. A tire having a tread portion, The tread portion includes a first tread grounding end on one side in the tire axial direction, a first shoulder circumferential groove closest to the first tread grounding end, and a first shoulder land portion defined outside the first shoulder circumferential groove in the tire axial direction. The first shoulder land portion is provided with a plurality of first shoulder groove-like portions extending from the first shoulder circumferential groove to the first tread grounding end. Among the plurality of first shoulder groove-like portions, a pair of adjacent first shoulder groove-like portions in the tire circumferential direction have different angles θ1 with respect to the tire axial direction. The plurality of first shoulder groove-like portions include a plurality of types having different first pitch lengths, which are the pitch lengths in the tire circumferential direction at the communication portions with the first shoulder circumferential groove. The maximum value of the first pitch length is 1.2 to 1.5 times the average of the first pitch lengths. The plurality of first shoulder groove-like portions are transverse grooves having a groove width greater than 1.0 mm. The plurality of first shoulder groove-like portions have a larger groove volume in proportion to the angle θ1. Tire.

10. The tire according to claim 9, wherein the groove width gradually increases from the first shoulder circumferential groove toward the first tread grounding end.

11. The plurality of first shoulder groove portions each include an overhanging portion extending outward in the tire axial direction from the first tread grounding end, and the maximum groove width of the overhanging portion is 7.0 mm or less. The tire according to claim 9 or 10.

12. The tire according to any one of claims 1 to 11, wherein the minimum value of the first pitch length is 0.5 to 0.8 times the average of the first pitch lengths.

13. The tire according to any one of claims 1 to 12, wherein the angle θ1 is -70 to 70° when the angle inclined to one side in the tire circumferential direction is defined as positive.

14. The tread portion includes a second tread grounding end on the other side in the tire axial direction, a second shoulder circumferential groove closest to the second tread grounding end, and a second shoulder land portion defined outside the second shoulder circumferential groove in the tire axial direction, the second shoulder land portion is provided with a plurality of second shoulder groove portions extending from the second shoulder circumferential groove toward the second tread grounding end, among the plurality of second shoulder groove portions, a pair of adjacent second shoulder groove portions in the tire circumferential direction have different angles θ2 with respect to the tire axial direction, and the plurality of second shoulder groove portions include a plurality of types having different third pitch lengths, which are the pitch lengths in the tire circumferential direction at the communication portion with the second shoulder circumferential groove. The tire according to any one of claims 1 to 13.

15. The second shoulder groove portion is inclined in the same direction as the first shoulder groove portion closest to it in the tire circumferential direction. The tire according to claim 14.

16. The second shoulder groove portion is inclined in the opposite direction to the first shoulder groove portion closest to it in the tire circumferential direction. The tire according to claim 14.

Images