tire
The tire design addresses uneven wear and wet performance issues by using specific groove and sipe configurations, enhancing rigidity and drainage to improve both rolling resistance and wet performance.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-08-27
- Publication Date
- 2026-03-11
AI Technical Summary
Tires with shoulder blocks divided by shoulder lateral grooves experience uneven wear when used as steering wheels, particularly affecting rolling resistance and wet performance.
A tire design featuring circumferential grooves with shoulder blocks having a specific groove depth ratio, lateral grooves with narrower sipes, and a reinforcing layer to enhance rigidity and drainage, ensuring the shoulder blocks maintain high rigidity and improve wet performance.
The tire achieves both improved wet performance and resistance to uneven shoulder wear by maintaining block rigidity and effective drainage through the designed groove and sipe configurations.
Smart Images
Figure 2026042590000001_ABST
Abstract
Description
[Technical Field]
[0001] The present invention relates to a tire having a tread portion. [Background technology]
[0002] Conventionally, tires having a tread portion that can achieve both rolling resistance performance and wet performance have been known. For example, Patent Document 1 below proposes a tire in which the positional relationship between shoulder circumferential grooves and a band layer is specified. [Prior art documents] [Patent documents]
[0003] [Patent Document 1] Japanese Patent Publication No. 2023-180553 Summary of the Invention [Problem to be solved by the invention]
[0004] However, when the tire is used as a steering wheel, uneven wear is likely to occur in the shoulder region, and this tendency is particularly pronounced in tires divided into shoulder blocks by shoulder lateral grooves such as those in Patent Document 1.
[0005] The present invention has been devised in view of the above circumstances, and has as its main object to provide a tire that can achieve both wet performance and resistance to uneven shoulder wear. [Means for solving the problem]
[0006] The present invention provides a tire having a tread portion, the tread portion having a plurality of circumferential grooves extending in the tire circumferential direction and a plurality of land portions divided by the circumferential grooves, the circumferential grooves including a shoulder circumferential groove located closest to the tread edge, the land portion including a shoulder land portion divided between the shoulder circumferential groove and the tread edge, the shoulder land portion having a plurality of shoulder lateral grooves crossing the shoulder land portion and shoulder blocks divided by the shoulder lateral grooves, and a groove depth in the tire radial direction of the shoulder lateral groove a width of each shoulder block in the tire radial direction is smaller than the radial depth of the shoulder circumferential groove, a first shoulder sipe is provided at the groove bottom of the shoulder lateral groove, extending from the shoulder circumferential groove to the tread edge, the first shoulder sipe includes a first narrow width portion that is on the radially outer side of the tire and has a smaller width in a direction perpendicular to the sipe longitudinal direction, and a first wide width portion that is on the radially inner side of the tire than the first narrow width portion and has a larger width in the direction perpendicular to the sipe longitudinal direction, and the shoulder blocks have a maximum circumferential length that is greater than their maximum axial width. [Effects of the Invention]
[0007] The tire of the present invention has the above-described configuration, and thus can achieve both wet performance and resistance to uneven shoulder wear. [Brief explanation of the drawings]
[0008] [Figure 1] 1 is a development view showing an embodiment of a tread portion of a tire of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along the line AA in FIG. [Figure 3] FIG. 2 is a tire meridian cross-sectional view of the tire. [Figure 4] FIG. 10 is a cross-sectional view of a first shoulder sipe of another embodiment. [Figure 5] FIG. 10 is a cross-sectional view of a first shoulder sipe of still another embodiment. [Figure 6] FIG. 10 is a cross-sectional view of a first shoulder sipe of still another embodiment. [Figure 7]FIG. 4 is a partial development view showing a tread portion of a tire according to a second embodiment. [Figure 8] FIG. 8 is a cross-sectional view taken along the line BB in FIG. 7. DETAILED DESCRIPTION OF THE INVENTION
[0009] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a tread development view showing a tread portion 2 of a tire 1 of this embodiment. As shown in Fig. 1, the tire 1 of this embodiment has a tread portion 2. A suitable example of the tire 1 is a pneumatic tire for heavy loads.
[0010] The tire 1 is not limited to such an embodiment, and can be applied to various types of tires 1, such as pneumatic tires and airless tires for passenger cars, tires for industrial machinery, etc. The tire 1 of this embodiment is suitably used, for example, as an all-season tire with an aspect ratio of 70% or less.
[0011] The tread portion 2 of this embodiment has a plurality of circumferential grooves 3 extending in the tire circumferential direction and a plurality of land portions 4 separated by the plurality of circumferential grooves 3. Such a tread portion 2 can suppress deformation of the land portions 4 when the tire comes into contact with the ground, and is useful for improving the tire 1's resistance to uneven shoulder wear.
[0012] The plurality of circumferential grooves 3 in this embodiment include a pair of shoulder circumferential grooves 3A located closest to the tread end Te. The pair of shoulder circumferential grooves 3A are preferably located on both sides in the tire axial direction across the tire equator C.
[0013] Here, in the case where the tire 1 is a heavy-duty pneumatic tire, the "tread edge Te" refers to the axially outermost contact point when the tire 1 is in a normal state and is subjected to a normal load and is in contact with a flat surface with a camber angle of 0°. Also, the "tire equator C" refers to the axial center position between the pair of tread edges Te on the contact surface 2a.
[0014] In the case where the tire 1 is a pneumatic tire, the "normal state" refers to a state in which the tire 1 is mounted on a normal rim, adjusted to a normal internal pressure, and no load is applied. Unless otherwise specified below, the dimensions of each part of the tire 1 are values measured in this normal state.
[0015] A "genuine rim" is a rim that is defined for each tire by a standard system that includes the standard on which tire 1 is based, such as a "standard rim" for JATMA, a "design rim" for TRA, or a "measuring rim" for ETRTO. If there is no standard system that includes the standard on which tire 1 is based, a "genuine rim" is a rim that can be mounted on a rim and does not cause air leakage, and that has the smallest rim diameter and narrowest rim width among such rims.
[0016] "Normal internal pressure" is the air pressure set for each tire by a standard set by each standard, if there is one that includes the standard on which tire 1 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." If there is no standard set that includes the standard on which tire 1 is based, "normal internal pressure" is the air pressure set for each tire by the manufacturer, etc.
[0017] "Normal load" is the load specified for each tire by a standard system that includes the standard on which tire 1 is based, if such a system exists; for JATMA, it is "Maximum Load Capacity," for TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and for ETRTO, it is "LOAD CAPACITY." If there is no standard system that includes the standard on which tire 1 is based, "Normal load" is the load specified for each tire by the manufacturer, etc., as the maximum load that can be applied when using tire 1.
[0018] The plurality of circumferential grooves 3 may include, for example, a middle circumferential groove 3B located axially inward of the shoulder circumferential grooves 3A, and a crown circumferential groove 3C located axially inward of the middle circumferential groove 3B. Such circumferential grooves 3 are useful for improving the wet performance of the tire 1.
[0019] The plurality of land portions 4 in this embodiment includes a shoulder land portion 4A that is partitioned between the shoulder circumferential groove 3A and the tread edge Te. The shoulder land portion 4A in this embodiment has a plurality of shoulder lateral grooves 5A that cross the shoulder land portion 4A and a plurality of shoulder blocks 6A that are partitioned by the plurality of shoulder lateral grooves 5A. The tire 1 having such a land portion 4 can improve grip when traveling on snowy roads due to the edge effect of the shoulder blocks 6A, thereby improving the snow performance of the tire 1.
[0020] Fig. 2 is a cross-sectional view taken along line AA in Fig. 1, and Fig. 3 is a tire meridian cross-sectional view of the tire 1 in a normal state. As shown in Fig. 2 and Fig. 3, the radial groove depth d1 of the shoulder lateral grooves 5A of this embodiment is smaller than the radial groove depth d2 of the shoulder circumferential grooves 3A. Such shoulder lateral grooves 5A can improve drainage while maintaining the rigidity of the shoulder land portion 4A, and can also exert high snow column shear force.
[0021] As shown in Figures 1 and 2, it is desirable to provide a first shoulder sipe 7A at the groove bottom 5a of the shoulder lateral groove 5A, extending from the shoulder circumferential groove 3A to the tread edge Te. Here, a sipe is a cut having a width of less than 1.0 mm in a direction perpendicular to the sipe longitudinal direction, and is clearly distinguished from grooves having a groove width of 1.0 mm or more. Such first shoulder sipe 7A can maintain high rigidity of the shoulder land portion 4A and improve the shoulder uneven wear resistance of the tire 1.
[0022] The first shoulder sipes 7A preferably include a first narrow portion 7a located radially outward and narrower in the direction perpendicular to the sipe longitudinal direction, and a first wide portion 7b located radially inward of the first narrow portion 7a and wider in the direction perpendicular to the sipe longitudinal direction. In this embodiment, the minimum width wg1 of the first narrow portion 7a in the direction perpendicular to the sipe longitudinal direction is less than 1.0 mm. At least the first wide portion 7b—in this embodiment, the first narrow portion 7a and the first wide portion 7b—open at the shoulder circumferential groove 3A and the tread edge Te. Such first shoulder sipes 7A can drain water even when the shoulder lateral grooves 5A are lost due to wear, improving the wet performance of the tire 1 in the later stages of wear.
[0023] 1, the shoulder blocks 6A of this embodiment have a maximum circumferential length L1 that is greater than their axial maximum width W1. Such shoulder blocks 6A can maintain high rigidity and improve the uneven shoulder wear resistance of the tire 1. As a result, the tire 1 of this embodiment can achieve both wet performance and uneven shoulder wear resistance.
[0024] In a more preferred embodiment, each of the multiple circumferential grooves 3 extends in a zigzag pattern around the tire circumferential direction. Such circumferential grooves 3 can provide high traction on snowy road surfaces and improve the on-snow performance of the tire 1. The multiple circumferential grooves 3 are not limited to this embodiment, and for example, each may extend linearly around the tire circumferential direction, or a mixture of linear and zigzag extending grooves may be present.
[0025] The shoulder lateral grooves 5A have, for example, shoulder widened portions 5b in which the groove width gradually increases toward the tread end Te side. Such shoulder lateral grooves 5A can smoothly drain water to the outside of the tread end Te, thereby improving drainage performance.
[0026] The shoulder blocks 6A have a polygonal shape, and in this embodiment, an octagonal shape, in plan view due to the zigzag circumferential grooves 3 and the shoulder widened portions 5b. Such shoulder blocks 6A can exert an edge effect in multiple directions, improving the on-snow performance of the tire 1. However, the shape of the shoulder blocks 6A in plan view is not limited to this, and may be, for example, a tetragonal to heptagonal shape or a shape including a curve.
[0027] The maximum circumferential length L1 of the shoulder block 6A is preferably at least 1.2 times the axial maximum width W1 of the shoulder block 6A. By making the maximum length L1 of the shoulder block 6A at least 1.2 times the axial maximum width W1, the shoulder block 6A can reliably maintain high rigidity and improve uneven shoulder wear resistance of the tire 1. From this perspective, the maximum length L1 of the shoulder block 6A is more preferably at least 1.3 times the axial maximum width W1 of the shoulder block 6A.
[0028] The maximum circumferential length L1 of the shoulder block 6A is preferably 1.6 times or less the maximum axial width W1 of the shoulder block 6A. By making the maximum length L1 of the shoulder block 6A 1.6 times or less the maximum width W1, the volume of the shoulder lateral grooves 5A can be secured, thereby improving the wet performance of the tire 1. From this perspective, the maximum length L1 of the shoulder block 6A is more preferably 1.5 times or less the maximum width W1 of the shoulder block 6A.
[0029] For these reasons, the maximum circumferential length L1 of the shoulder block 6A is preferably 1.2 to 1.6 times, and more preferably 1.3 to 1.5 times, the maximum axial width W1 of the shoulder block 6A. The combination of the upper and lower limits of these numerical ranges can be selected arbitrarily.
[0030] As shown in Fig. 3, the tread portion 2 includes, for example, a cap rubber layer 2A and a base rubber layer 2B. In such a tread portion 2, the cap rubber layer 2A is formed from a high-rigidity rubber, which helps to improve the shoulder uneven wear resistance of the tire 1. In addition, the tread portion 2 can improve the rolling resistance performance of the tire 1 by forming the base rubber layer 2B from a low-heat-generation rubber.
[0031] The circumferential grooves 3 are preferably provided in the cap rubber layer 2A. Such a tread portion 2 prevents the base rubber layer 2B from being exposed to the contact surface 2a even in the later stage of wear, and helps maintain the uneven shoulder wear resistance of the tire 1 in the later stage of wear.
[0032] The tread portion 2 preferably includes a reinforcing layer 8 disposed radially inward of the land portion 4. The reinforcing layer 8 is disposed, for example, radially inward of the base rubber layer 2B. Such a reinforcing layer 8 helps to increase the rigidity of the tread portion 2 by its hoop effect.
[0033] The reinforcing layer 8 of this embodiment includes a band layer 9 in which steel cords are wound spirally at an angle of 5° or less with respect to the tire circumferential direction. That is, the band layer 9 is formed as a so-called jointless band ply. Such a band layer 9 can effectively suppress deformation during running, even in a tire 1 with an aspect ratio of 70% or less and a large amount of deformation during running in the shoulder land portion 4A, and can improve the shoulder uneven wear resistance of the tire 1.
[0034] The axial end 9a of the band layer 9 is preferably positioned axially outward of the axially outermost end 3a of the shoulder circumferential groove 3A. Such a band layer 9 can increase the rigidity of the shoulder land portion 4A, and can improve the shoulder uneven wear resistance of the tire 1 even in a tire 1 with an aspect ratio of 70% or less and in which the shoulder land portion 4A deforms significantly during running.
[0035] The reinforcing layer 8 includes a plurality of belt plies 10 each having steel cords arranged at an angle of 10 to 50° with respect to the tire circumferential direction, that is, a first belt ply 10A, a second belt ply 10B, and a third belt ply 10C in this embodiment. The plurality of belt plies preferably include belt plies whose inclination directions with respect to the tire circumferential direction are different from each other. Such a belt layer 10 can increase the rigidity of the tread portion 2 by its hoop effect.
[0036] The first belt ply 10A is disposed, for example, at the innermost position in the tire radial direction. The second belt ply 10B is disposed, for example, between the first belt ply 10A and the third belt ply 10C in the tire radial direction. The third belt ply 10C is disposed, for example, at the outermost position in the tire radial direction. The number of belt plies is not limited to three, and may be, for example, two, four or more.
[0037] At least one belt ply of the belt layer 10, the first belt ply 10A in this embodiment, is located radially inward of the band layer 9. Such a belt layer 10 can suppress the tension acting on the band layer 9, and can improve the durability performance of the tire 1.
[0038] 2 and 3, the groove depth d1 of the shoulder lateral grooves 5A in the tire radial direction is preferably at least 0.15 times the groove depth d2 of the shoulder circumferential grooves 3A in the tire radial direction. By making the groove depth d1 of the shoulder lateral grooves 5A at least 0.15 times the groove depth d2 of the shoulder circumferential grooves 3A, a sufficient groove volume can be ensured, ensuring drainage in the initial stage of wear and improving the wet performance of the tire 1. From this perspective, the groove depth d1 of the shoulder lateral grooves 5A is more preferably at least 0.2 times the groove depth d2 of the shoulder circumferential grooves 3A.
[0039] The groove depth d1 of the shoulder lateral grooves 5A in the tire radial direction is preferably 0.45 or less times the groove depth d2 of the shoulder circumferential grooves 3A in the tire radial direction. By making the groove depth d1 of the shoulder lateral grooves 5A 0.45 or less times the groove depth d2 of the shoulder circumferential grooves 3A, it is possible to maintain high rigidity of the shoulder land portion 4A and improve the shoulder uneven wear resistance of the tire 1. From this perspective, the groove depth d1 of the shoulder lateral grooves 5A is more preferably 0.4 or less times the groove depth d2 of the shoulder circumferential grooves 3A.
[0040] For these reasons, the radial groove depth d1 of the shoulder lateral grooves 5A is preferably 0.15 to 0.45 times, and more preferably 0.2 to 0.4 times, the radial groove depth d2 of the shoulder circumferential grooves 3A. The combination of the upper and lower limits of these numerical ranges can be selected arbitrarily.
[0041] 2, the radial depth d3 of the first shoulder sipes 7A is preferably greater than the radial depth d1 of the shoulder lateral grooves 5A. Such first shoulder sipes 7A can reliably ensure drainage in the later stages of wear, and are useful for improving the wet performance of the tire 1 in the later stages of wear.
[0042] The radial depth d3 of the first shoulder sipes 7A is preferably at least 1.1 times the radial depth d1 of the shoulder lateral grooves 5A. By making the depth d3 of the first shoulder sipes 7A at least 1.1 times the radial depth d1 of the shoulder lateral grooves 5A, it is possible to reliably ensure drainage in the later stages of wear and improve the wet performance of the tire 1. From this perspective, the depth d3 of the first shoulder sipes 7A is more preferably at least 1.2 times the radial depth d1 of the shoulder lateral grooves 5A.
[0043] The radial depth d3 of the first shoulder sipes 7A is preferably 5.5 times or less the radial depth d1 of the shoulder lateral grooves 5A. By making the depth d3 of the first shoulder sipes 7A 5.5 times or less the groove depth d1 of the shoulder lateral grooves 5A, the rigidity of the shoulder land portion 4A can be maintained and the shoulder uneven wear resistance of the tire 1 can be improved. From this perspective, the depth d3 of the first shoulder sipes 7A is more preferably 4.5 times or less the groove depth d1 of the shoulder lateral grooves 5A.
[0044] For these reasons, the radial depth d3 of the first shoulder sipes 7A is preferably 1.1 to 5.5 times, and more preferably 1.2 to 4.5 times, the radial depth d1 of the shoulder lateral grooves 5A. The combination of the upper and lower limits of these numerical ranges can be selected arbitrarily.
[0045] The radial depth d4 of the first narrow width portion 7a of the first shoulder sipe 7A is preferably at least 0.3 times the radial depth d3 of the first shoulder sipe 7A. By making the depth d4 of the first narrow width portion 7a at least 0.3 times the radial depth d3 of the first shoulder sipe 7A, the rigidity of the shoulder land portion 4A can be maintained and the shoulder uneven wear resistance of the tire 1 can be improved. From this perspective, the depth d4 of the first narrow width portion 7a is more preferably at least 0.4 times the radial depth d3 of the first shoulder sipe 7A.
[0046] The depth d4 in the tire radial direction of the first narrow width portion 7a of the first shoulder sipe 7A is preferably 0.8 times or less the depth d3 in the tire radial direction of the first shoulder sipe 7A. By making the depth d4 of the first narrow width portion 7a 0.8 times or less the depth d3 of the first shoulder sipe 7A, a sufficient volume of the first wide width portion 7b can be ensured, and the wet performance of the tire 1 can be improved. From this perspective, the depth d4 of the first narrow width portion 7a is more preferably 0.7 times or less the depth d3 of the first shoulder sipe 7A.
[0047] For these reasons, the radial depth d4 of the first narrow width portion 7a of the first shoulder sipe 7A is preferably 0.3 to 0.8 times, and more preferably 0.4 to 0.7 times, the radial depth d3 of the first shoulder sipe 7A. Note that the combination of the upper and lower limits of these numerical ranges can be selected arbitrarily.
[0048] In this embodiment, the maximum width wg2 of the first widened portion 7b in the direction perpendicular to the sipe longitudinal direction is smaller than the minimum groove width wg3 of the shoulder lateral groove 5A at the contact patch 2a. Such first widened portion 7b helps to maintain high rigidity of the shoulder land portion 4A.
[0049] The maximum width wg2 of the first widened portion 7b is preferably 0.30 or more times the minimum groove width wg3 of the shoulder lateral groove 5A. By making the maximum width wg2 of the first widened portion 7b 0.30 or more times the minimum groove width wg3 of the shoulder lateral groove 5A, a sufficient volume of the first widened portion 7b can be ensured, thereby improving the wet performance of the tire 1. From this perspective, the maximum width wg2 of the first widened portion 7b is more preferably 0.35 or more times the minimum groove width wg3 of the shoulder lateral groove 5A.
[0050] The maximum width wg2 of the first widened portion 7b is preferably 0.85 times or less the minimum groove width wg3 of the shoulder lateral groove 5A. By setting the maximum width wg2 of the first widened portion 7b to 0.85 times or less the minimum groove width wg3 of the shoulder lateral groove 5A, it is possible to maintain high rigidity of the shoulder land portion 4A and improve the shoulder uneven wear resistance of the tire 1. From this perspective, the maximum width wg2 of the first widened portion 7b is more preferably 0.80 times or less the minimum groove width wg3 of the shoulder lateral groove 5A.
[0051] For these reasons, the maximum width wg2 of the first widened portion 7b is preferably 0.30 to 0.85 times, and more preferably 0.35 to 0.80 times, the minimum groove width wg3 of the shoulder lateral groove 5A. The combination of the upper and lower limits of these numerical ranges can be selected arbitrarily.
[0052] The bottom 7c of the first widened portion 7b, which is the innermost in the tire radial direction, preferably has an arcuate portion with a curvature radius r1 greater than 1 mm. Such a first widened portion 7b serves to suppress the occurrence of cracks due to strain concentration and improve the durability of the tire 1. From this perspective, the curvature radius r1 of the bottom 7c of the first widened portion 7b is more preferably greater than 1.3 mm.
[0053] Figure 4 is a cross-sectional view of a first shoulder sipe 7A according to another embodiment. As shown in Figure 4, the first narrow portion 7a of the first shoulder sipe 7A may extend in a zigzag pattern in the sipe depth direction, for example. This type of first shoulder sipe 7A allows the wall surfaces to effectively support each other under load, improving the rigidity of the shoulder land portion 4A when in contact with the ground, thereby improving the shoulder uneven wear resistance of the tire 1.
[0054] Although not shown, the first narrow width portion 7a of the first shoulder sipe 7A may extend in a zigzag pattern in the sipe longitudinal direction, or may be a 3D sipe extending in a zigzag pattern in the sipe longitudinal direction and the sipe depth direction. Such first shoulder sipes 7A allow the wall surfaces to more effectively support each other under load, further improving the shoulder uneven wear resistance of the tire 1.
[0055] When the zigzag amplitude of the first narrow width portion 7a in the sipe longitudinal direction is smaller than the maximum width wg2 of the first wide width portion 7b, it is desirable that the first wide width portion 7b of the first shoulder sipe 7A extend linearly in the sipe longitudinal direction. When the zigzag amplitude of the first narrow width portion 7a in the sipe longitudinal direction is larger than the maximum width wg2 of the first wide width portion 7b, for example, the first wide width portion 7b of the first shoulder sipe 7A may also extend zigzag in the sipe longitudinal direction.
[0056] Fig. 5 is a cross-sectional view of a first shoulder sipe 7A according to yet another embodiment. As shown in Fig. 5, the radially innermost bottom portion 7c of the first widened portion 7b of the first shoulder sipe 7A may be formed, for example, in a straight line. This type of first shoulder sipe 7A can increase the volume of the first widened portion 7b, thereby further improving the wet performance of the tire 1 in the later stages of wear.
[0057] Fig. 6 is a cross-sectional view of a first shoulder sipe 7A according to yet another embodiment. As shown in Fig. 6, the first widened portion 7b of the first shoulder sipe 7A may have, for example, an oval or elliptical shape that is elongated in the tire radial direction. This type of first shoulder sipe 7A can increase the volume of the first widened portion 7b, thereby further improving the wet performance of the tire 1 in the later stages of wear.
[0058] 1, the plurality of land portions 4 include, for example, a middle land portion 4B defined between the shoulder circumferential groove 3A and the middle circumferential groove 3B, and a crown land portion 4C defined between the middle circumferential groove 3B and the crown circumferential groove 3C. Like the shoulder land portion 4A, the middle land portion 4B and the crown land portion 4C of this embodiment have a polygonal shape in a plan view.
[0059] The middle land portion 4B has, for example, a plurality of middle lateral grooves 5B crossing the middle land portion 4B and a plurality of middle blocks 6B divided by the plurality of middle lateral grooves 5B. The crown land portion 4C has, for example, a plurality of crown lateral grooves 5C crossing the crown land portion 4C and a plurality of crown blocks 6C divided by the plurality of crown lateral grooves 5C. The tire 1 having such land portion 4 can improve grip when traveling on snowy roads and performance on snow by the edge effect of the middle blocks 6B and crown blocks 6C.
[0060] The radial groove depth d5 of the middle lateral grooves 5B is preferably greater than the radial groove depth d1 of the shoulder lateral grooves 5A. Such middle lateral grooves 5B improve drainage on the axially inner side of the tire, thereby improving the wet performance of the tire 1.
[0061] The radial groove depth d5 of the middle lateral grooves 5B is preferably smaller than the radial groove depth d2 of the shoulder circumferential grooves 3A. Such middle lateral grooves 5B suppress excessive deformation of the middle blocks 6B when the tire comes into contact with the ground, and are useful for improving the uneven wear resistance of the tire 1.
[0062] The middle block 6B has, for example, a middle slot 6a at a portion facing the crown lateral groove 5C. The crown block 6C has, for example, a crown slot 6b at a portion facing the middle lateral groove 5B. The middle slot 6a and the crown slot 6b cooperate with the crown lateral groove 5C and the middle lateral groove 5B to improve drainage, thereby improving the wet performance of the tire 1.
[0063] Fig. 7 is a partial development view showing the tread portion 12 of a tire 11 of the second embodiment. The same elements as those in the above-described embodiment are given the same reference numerals, and their description will be omitted. As shown in Fig. 7, the tire 11 of the second embodiment has a tread portion 12, similar to the tire 1 described above.
[0064] Similar to the above-described tread portion 2, the tread portion 12 of the second embodiment has a plurality of circumferential grooves 3 extending in the tire circumferential direction and a plurality of land portions 14 separated by the plurality of circumferential grooves 3. Similar to the above-described land portion 4, the plurality of land portions 14 of the second embodiment include shoulder land portions 14A separated between the shoulder circumferential grooves 3A and the tread end Te. Similar to the above-described tread portion 2, such a tread portion 12 can suppress deformation of the land portions 14 during contact with the ground, and is useful for improving the shoulder uneven wear resistance of the tire 11.
[0065] The shoulder land portion 14A of the second embodiment has, like the above-described shoulder land portion 4A, a plurality of shoulder lateral grooves 5A crossing the shoulder land portion 14A and a plurality of shoulder blocks 16A separated by the plurality of shoulder lateral grooves 5A. A tire 11 having such a land portion 14 is suitable for exhibiting the performance required of an all-season tire, like the above-described tire 1.
[0066] Figure 8 is a cross-sectional view taken along line BB in Figure 7. As shown in Figures 7 and 8, the shoulder block 16A of the second embodiment has a second shoulder sipe 7B that crosses the shoulder block 16A. Such a second shoulder sipe 7B can improve drainage while maintaining high rigidity of the shoulder block 16A.
[0067] Like the first shoulder sipes 7A described above, the second shoulder sipes 7B preferably include a second narrow portion 7d and a second wide portion 7e. The second narrow portion 7d in the second embodiment is a portion that is radially outwardly spaced and narrower in width in a direction perpendicular to the sipe longitudinal direction. The second wide portion 7e in the second embodiment is a portion that is radially inwardly spaced from the second narrow portion 7d and wider in a direction perpendicular to the sipe longitudinal direction. This second shoulder sipe 7B can promote drainage by exposing the second wide portion 7e during the intermediate wear stage, thereby improving the wet performance of the tire 1 during the intermediate wear stage.
[0068] 8, the radially innermost bottom portion 7f of the second widened portion 7e of the second embodiment is located radially outward of the radially outer end 7g of the first widened portion 7b. In this shoulder land portion 14A, the second widened portion 7e ensures drainage in the middle stage of wear, and the first widened portion 7b ensures drainage in the later stage of wear.
[0069] The distance L2 in the tire radial direction between the bottom 7f of the second widened portion 7e and the outer end 7g of the first widened portion 7b is preferably 2.0 mm or less. By making the distance L2 between the bottom 7f of the second widened portion 7e and the outer end 7g of the first widened portion 7b 2.0 mm or less, it is possible to ensure continuous drainage from the middle to the later stages of wear, thereby improving the wet performance of the tire 1. From this perspective, the distance L2 between the bottom 7f of the second widened portion 7e and the outer end 7g of the first widened portion 7b is more preferably 1.0 mm or less.
[0070] In the second embodiment, the radially outer ends 7h of the second widened portions 7e are located radially inward of the groove bottoms 5a of the shoulder lateral grooves 5A. In such a shoulder land portion 14A, the shoulder lateral grooves 5A ensure drainage in the early stages of wear, and the second widened portions 7e ensure drainage in the middle stages of wear.
[0071] The distance L3 in the tire radial direction between the outer ends 7h of the second widened portions 7e and the groove bottoms 5a of the shoulder lateral grooves 5A is preferably 2.0 mm or less. By making the distance L3 between the outer ends 7h of the second widened portions 7e and the groove bottoms 5a of the shoulder lateral grooves 5A 2.0 mm or less, drainage can be continuously ensured from the initial to intermediate wear stages, improving the wet performance of the tire 1. From this perspective, the distance L3 between the outer ends 7h of the second widened portions 7e and the groove bottoms 5a of the shoulder lateral grooves 5A is more preferably 1.0 mm or less.
[0072] Although a particularly preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment and can be modified and practiced in various ways.
[0073] [Note] The present invention is as follows.
[0074] [Invention 1] A tire having a tread portion, The tread portion has a plurality of circumferential grooves extending in the tire circumferential direction and a plurality of land portions separated by the circumferential grooves, the circumferential grooves include a shoulder circumferential groove located closest to a tread end, the land portion includes a shoulder land portion partitioned between the shoulder circumferential groove and the tread edge, The shoulder land portion has a plurality of shoulder lateral grooves crossing the shoulder land portion and shoulder blocks separated by the shoulder lateral grooves, a groove depth in the tire radial direction of the shoulder lateral groove is smaller than a groove depth in the tire radial direction of the shoulder circumferential groove, a first shoulder sipe extending from the shoulder circumferential groove to the tread edge is provided at the groove bottom of the shoulder lateral groove, The first shoulder sipe includes a first narrow width portion that is located on the outer side in the tire radial direction and has a small width in a direction perpendicular to the sipe longitudinal direction, and a first wide width portion that is located on the inner side in the tire radial direction than the first narrow width portion and has a large width in the direction perpendicular to the sipe longitudinal direction, The shoulder blocks have a maximum circumferential length greater than a maximum axial width of the tire. tire.
[0075] [Invention 2] The tire according to invention 1, wherein the groove depth in the tire radial direction of the shoulder lateral grooves is 0.15 to 0.45 times the groove depth in the tire radial direction of the shoulder circumferential grooves.
[0076] [Invention 3] 3. The tire according to claim 1 or 2, wherein the maximum length of the shoulder block in the tire circumferential direction is 1.2 to 1.6 times the maximum width of the shoulder block in the tire axial direction.
[0077] [Invention 4] the tread portion includes a reinforcing layer disposed radially inward of the land portion, 4. The tire according to any one of claims 1 to 3, wherein the reinforcing layer includes a band layer in which a steel cord is wound spirally at an angle of 5° or less with respect to the tire circumferential direction.
[0078] [Invention 5] the reinforcing layer includes a belt layer having a plurality of belt plies in which steel cords are arranged at an angle of 10 to 50 degrees with respect to the tire circumferential direction, The tire according to invention 4, wherein at least one of the belt plies of the belt layers is located radially inward of the band layer.
[0079] [Invention 6] The tire according to invention 4 or 5, wherein an end portion of the band layer in the tire axial direction is positioned outside the shoulder circumferential groove in the tire axial direction.
[0080] [Invention 7] The tire according to any one of claims 1 to 6, wherein the maximum width of the first widened portion in a direction perpendicular to the sipe longitudinal direction is smaller than the minimum groove width of the shoulder lateral groove at the contact patch.
[0081] [Invention 8] 8. The tire according to claim 7, wherein the maximum width of the first widened portion is 0.30 to 0.85 times the minimum groove width of the shoulder lateral groove.
[0082] [Invention 9] The tire according to any one of claims 1 to 8, wherein the first narrow portion of the first shoulder sipe extends in a zigzag pattern in the sipe longitudinal direction and the sipe depth direction.
[0083] [Invention 10] The shoulder block has a second shoulder sipe that crosses the shoulder block, A tire according to any one of claims 1 to 9, wherein the second shoulder sipe includes a second narrow width portion on the radially outer side of the tire and having a smaller width in a direction perpendicular to the sipe longitudinal direction, and a second wide width portion on the radially inner side of the tire than the second narrow width portion and having a larger width in a direction perpendicular to the sipe longitudinal direction.
[0084] [Invention 11] The tire according to invention 10, wherein the innermost bottom portion in the tire radial direction of the second widened portion is positioned radially outward of the outermost end in the tire radial direction of the first widened portion.
[0085] [Invention 12] 12. The tire according to claim 10 or 11, wherein the radially outer ends of the second widened portions are located radially inward of the groove bottoms of the shoulder lateral grooves. [Explanation of symbols]
[0086] 1 tire 2 Tread section 3 Circumferential groove 3A Shoulder circumferential groove 4 Land 4A Shoulder Land Section 5A Shoulder groove 5a groove bottom 6A Shoulder Block 7A First shoulder sipe 7a 1st narrow part 7b First widening section
Claims
1. A tire having a tread portion, The tread portion has a plurality of circumferential grooves extending in the tire circumferential direction and a plurality of land portions separated by the circumferential grooves, the circumferential grooves include a shoulder circumferential groove located closest to a tread end, the land portion includes a shoulder land portion partitioned between the shoulder circumferential groove and the tread edge, The shoulder land portion has a plurality of shoulder lateral grooves crossing the shoulder land portion and shoulder blocks separated by the shoulder lateral grooves, a groove depth in the tire radial direction of the shoulder lateral groove is smaller than a groove depth in the tire radial direction of the shoulder circumferential groove, a first shoulder sipe extending from the shoulder circumferential groove to the tread edge is provided at a groove bottom of the shoulder lateral groove, The first shoulder sipe includes a first narrow width portion that is located on the outer side in the tire radial direction and has a small width in a direction perpendicular to the sipe longitudinal direction, and a first wide width portion that is located on the inner side in the tire radial direction than the first narrow width portion and has a large width in the direction perpendicular to the sipe longitudinal direction, The shoulder blocks have a maximum circumferential length greater than a maximum axial width of the tire. tire.
2. 2. The tire according to claim 1, wherein the groove depth in the tire radial direction of the shoulder lateral grooves is 0.15 to 0.45 times the groove depth in the tire radial direction of the shoulder circumferential grooves.
3. 3. The tire according to claim 1, wherein the maximum length of the shoulder block in the tire circumferential direction is 1.2 to 1.6 times the maximum width of the shoulder block in the tire axial direction.
4. the tread portion includes a reinforcing layer disposed radially inward of the land portion, The tire according to claim 1 or 2, wherein the reinforcing layer includes a band layer in which a steel cord is wound spirally at an angle of 5° or less with respect to the tire circumferential direction.
5. the reinforcing layer includes a belt layer having a plurality of belt plies in which steel cords are arranged at an angle of 10 to 50 degrees with respect to the tire circumferential direction, The tire according to claim 4 , wherein at least one of the belt plies of the belt layers is located radially inward of the band layer.
6. The tire according to claim 4 , wherein an end portion of the band layer in the tire axial direction is located axially outward of the shoulder circumferential groove.
7. The tire according to claim 1 or 2, wherein a maximum width of the first widened portion in a direction perpendicular to the sipe longitudinal direction is smaller than a minimum groove width of the shoulder lateral groove at the contact patch.
8. The tire according to claim 7, wherein the maximum width of the first widened portion is 0.30 to 0.85 times the minimum groove width of the shoulder lateral groove.
9. The tire according to claim 1 or 2, wherein the first narrow width portion of the first shoulder sipe extends in a zigzag pattern in the sipe longitudinal direction and the sipe depth direction.
10. The shoulder block has a second shoulder sipe that crosses the shoulder block, 3. The tire according to claim 1, wherein the second shoulder sipe includes a second narrow width portion on the outer side in the tire radial direction and having a smaller width in a direction perpendicular to the sipe longitudinal direction, and a second wide width portion on the inner side in the tire radial direction than the second narrow width portion and having a larger width in the direction perpendicular to the sipe longitudinal direction.
11. The tire according to claim 10 , wherein a bottom portion at an innermost position in the tire radial direction of the second widened portion is located radially outward of an outer end in the tire radial direction of the first widened portion.
12. The tire according to claim 11 , wherein an outer end in the tire radial direction of the second widened portion is located radially inward of a groove bottom of the shoulder lateral groove.
Citation Information
Patent Citations
Tire
JP2023180553A