Tire

Abstract

The present invention provides a tire capable of suppressing uneven wear such as heel-toe wear. A tire has a tread portion (2). The tread portion (2) includes: a first shoulder land portion (11) including a first tread end (T1) and a first shoulder circumferential groove (6) adjacent to the first shoulder land portion (11) on the axially inner side of the tire and extending continuously in the tire circumferential direction. A plurality of first shoulder transverse grooves (16) are provided on the first shoulder land portion (11), extending from the first shoulder circumferential grooves (6) and traversing the first tread end (T1). The first shoulder transverse grooves (16) have a pair of first groove walls (17). A pair of first chamfered portions (18) are provided on the pair of first groove walls (17), extending from the first shoulder circumferential grooves (6) to a position beyond the first tread end (T1).

Description

Technical Field

[0001] This invention relates to tires. Background Technology

[0002] Patent Document 1 discloses a pneumatic tire with outer and inner shoulder lateral grooves on the tread portion in a specified direction for vehicle mounting. In this pneumatic tire, the intersection of the edge of the outer shoulder lateral groove with the outer tread end and the intersection of the edge of the inner shoulder lateral groove with the inner tread end are located at different positions in the tire circumferential direction. Therefore, it is expected that the aforementioned pneumatic tire will maintain wet road performance and improve resistance to uneven wear.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2018-140745

[0004] The above-mentioned pneumatic tires have the following problems: when the vehicle is driving or braking, the edge of the tread block facing the shoulder groove is prone to slipping relative to the road surface, which in turn easily causes heel-toe wear (hereinafter sometimes referred to as "H&T wear"), which causes the edge of the tread block to wear prematurely. Summary of the Invention

[0005] The present invention was made in view of the above-mentioned actual situation, and the main objective is to provide a tire that can suppress uneven wear such as H&T wear.

[0006] The present invention is a tire having a tread portion comprising: a first tread end and a second tread end, which form the outermost contact point in the tire axial direction when the tire, in a standard condition mounted on a standard rim and filled with standard internal pressure, is loaded with 70% of a standard load; a first shoulder land portion including the first tread end; and a first shoulder circumferential groove adjacent to the inner side of the first shoulder land portion in the tire axial direction and extending continuously along the tire circumferential direction, wherein a plurality of first shoulder transverse grooves are provided in the first shoulder land portion extending from the first shoulder circumferential groove and traversing the first tread end, the first shoulder transverse grooves having a pair of first groove walls, wherein a pair of first chamfer portions are provided in the pair of first groove walls extending from the first shoulder circumferential groove to a position beyond the first tread end.

[0007] Preferably, in the tire of the present invention, the pair of first chamfered portions terminate at a first position in the tire axial direction, and the first shoulder lateral groove has a groove edge without chamfered portions at a position further outward in the tire axial direction than the first position of the pair of first groove walls.

[0008] In the tire of the present invention, the first position is preferably a position less than 5 mm from the end of the first tread.

[0009] Preferably, in the tire of the present invention, the chamfer width of the pair of first chamfer portions decreases toward the outer side of the tire axial direction.

[0010] Preferably, in the tire of the present invention, the tread portion includes: a second shoulder land portion including the second tread end, and a second shoulder circumferential groove adjacent to the inner side of the second shoulder land portion in the tire axial direction and extending continuously in the tire circumferential direction. A plurality of second shoulder transverse grooves extending from the second shoulder circumferential grooves and traversing the second tread end are provided in the second shoulder land portion. The second shoulder transverse grooves have a pair of second groove walls, and a pair of second chamfer portions extending from the second shoulder circumferential grooves to a position beyond the second tread end are provided in the pair of second groove walls.

[0011] Preferably, in the tire of the present invention, the tread portion is designated to be mounted on the vehicle with the first tread end located on the outside of the vehicle, the first shoulder land portion includes a plurality of first shoulder tread blocks divided by the first shoulder lateral groove, the second shoulder land portion includes a plurality of second shoulder tread blocks divided by the second shoulder lateral groove, and the contact area of ​​one first shoulder tread block is greater than the contact area of ​​one second shoulder tread block.

[0012] In the tire of the present invention, it is preferable that no grooves or sipes are provided on the land portion of the first shoulder except for the first shoulder transverse groove.

[0013] Preferably, in the tire of the present invention, a plurality of shoulder grooves extending along the second shoulder transverse groove are provided on the land portion of the second shoulder.

[0014] Preferably, in the tire of the present invention, the first shoulder lateral groove includes a first reinforcing rib with a partial bulge at the bottom of the groove, and the second shoulder lateral groove includes a second reinforcing rib with a partial bulge at the bottom of the groove, wherein the axial length of the first reinforcing rib is greater than the axial length of the second reinforcing rib.

[0015] Preferably, in the tire of the present invention, the depth of the first reinforcing bar is greater than the depth of the second reinforcing bar.

[0016] The tire of the present invention, by employing the above-described structure, is able to suppress uneven wear such as H&T wear. Attached Figure Description

[0017] Figure 1 This is a unfolded view of the tread section of a tire according to one embodiment of the present invention.

[0018] Figure 2 yes Figure 1 Enlarged 3D view of the first shoulder land area.

[0019] Figure 3 yes Figure 1Enlarged view of the first shoulder land area.

[0020] Figure 4 yes Figure 3 A sectional view along line AA.

[0021] Figure 5 yes Figure 3 BB line section view.

[0022] Figure 6 yes Figure 1 Enlarged view of the second fetal shoulder land area.

[0023] Figure 7 yes Figure 6 CC-line sectional view.

[0024] Figure 8 yes Figure 1 Enlarged view of the first intermediate landmass, the crown landmass, and the second intermediate landmass.

[0025] Figure 9 yes Figure 8 DD-line sectional view.

[0026] Figure 10 yes Figure 8 EE line section view.

[0027] Figure 11 This is a unfolded diagram of the tread of a comparative example tire.

[0028] Explanation of reference numerals in the attached figures: 2…tire tread; 6…first shoulder circumferential groove; 11…first shoulder land portion; 16…first shoulder transverse groove; 17…first groove wall; 18…first chamfer portion; T1…first tread end. Detailed Implementation

[0029] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Figure 1 This is a unfolded view of the tread portion 2 of the tire 1 in this embodiment. Figure 1 As shown, the tire 1 in this embodiment is, for example, a pneumatic tire for passenger cars, used as a so-called summer tire. However, the present invention is not limited to this method and can also be applied to all-season tires and heavy-duty tires.

[0030] The tire 1 in this embodiment, for example, has a tread portion 2 with a specified direction for mounting to a vehicle. Furthermore, the tread portion 2 is configured with an asymmetrical tread pattern (meaning the tread pattern is not linearly symmetrical with respect to the tire equator C). In this invention, the tire 1 may not specify a direction for mounting to a vehicle, and the tread portion 2 may also be configured with a symmetrical tread pattern. In this embodiment, the direction for mounting to a vehicle is indicated, for example, by text or markings on the sidewall portion (illustrations omitted).

[0031] The tread portion 2 includes a first tread end T1 and a second tread end T2 on both sides of the tire axial direction. In this embodiment, the tread portion 2 is designated to be installed in the vehicle direction such that the first tread end T1 is located on the outer side of the vehicle during vehicle installation, and the second tread end T2 is located on the inner side of the vehicle during vehicle installation. The first tread end T1 and the second tread end T2 are respectively equivalent to the outermost contact points of the tire axial direction when the tire 1 is loaded with 70% of the standard load in a standard state, with a 0° camber angle as the contact plane. The aforementioned first tread end T1 and second tread end T2 approximate the actual contact points of the tread portion 2 when the vehicle is stationary or traveling straight at a certain speed. Therefore, the area closer to the inner side of the tire axial direction than the first tread end T1 and the second tread end T2 is always in contact with the ground except when the contact pressure becomes excessively small. In addition, there is a tendency for significant changes in contact pressure around the first tread end T1 and the second tread end T2.

[0032] "Standard condition" refers to the condition where, for pneumatic tires of various specifications, the tire and rim are assembled on a standard rim and filled with standard internal pressure, and under no load. For tires without specified specifications or non-pneumatic tires, the above standard condition means the standard operating condition corresponding to the tire's intended use, and under no load. Unless otherwise specified in this manual, the dimensions of all parts of the tire are values ​​measured under the above standard condition.

[0033] "Standard rim" refers to a rim with a specified specification for each tire within a specification system that includes the specifications on which the tire is based. For example, if it is JATMA, it is a "standard rim"; if it is TRA, it is a "Design Rim"; and if it is ETRTO, it is a "Measuring Rim".

[0034] "Standard internal pressure" refers to the air pressure specified for each tire in the specification system, including the specifications on which the tire is based. If it is JATMA, it is the "maximum air pressure". If it is TRA, it is the maximum value recorded in the table "TIRE LOAD LIMITS ATVARIOUS COLD INFLATION PRESSURES". If it is ETRTO, it is "INFLATION PRESSURE".

[0035] "Standard load" refers to the load specified for each tire within a specification system, including the specifications the tire is based on, when various sizes of pneumatic tires are defined. For JATMA, it is the "maximum load capacity"; for TRA, it is the maximum value recorded in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES"; and for ETRTO, it is the "LOAD CAPACITY". Furthermore, in the case of tires without specified sizes or non-pneumatic tires, "standard load" refers to the load acting on a tire in its standard mounting condition. The aforementioned "standard mounting condition" refers to the tire being mounted on a standard vehicle corresponding to the tire's intended use, and the vehicle being stationary on a flat road surface in a drivable condition.

[0036] The tread portion 2 includes a plurality of circumferential grooves 3 extending continuously along the tire circumference between the first tread end T1 and the second tread end T2, and a plurality of land portions divided by the circumferential grooves 3. In this embodiment, the tire 1 is configured as a so-called five-strip tire with a tread portion 2 divided by four circumferential grooves 3, comprising five land portions. However, the invention is not limited to this configuration; for example, it could also be a so-called four-strip tire with a tread portion 2 consisting of three circumferential grooves 3 and four land portions.

[0037] The circumferential groove 3 includes, for example, a first crown circumferential groove 4 and a second crown circumferential groove 5, a first shoulder circumferential groove 6 and a second shoulder circumferential groove 7. The first crown circumferential groove 4 and the second crown circumferential groove 5 are positioned across the tire equator C. The first shoulder circumferential groove 6 is located between the first crown circumferential groove 4 and the first tread end T1. The second shoulder circumferential groove 7 is located between the second crown circumferential groove 5 and the second tread end T2.

[0038] The circumferential groove 3 can be formed in various ways, such as a groove extending in a straight line along the tire circumference or a groove extending in a serrated shape.

[0039] The distance L1 from the center line of the first circumferential groove 4 or the second circumferential groove 5 to the tire equator C is, for example, 5% to 15% of the tread width TW. The distance L2 from the center line of the first shoulder circumferential groove 6 or the second shoulder circumferential groove 7 to the tire equator C is, for example, 25% to 35% of the tread width TW. Furthermore, the tread width TW is the distance from the first tread end T1 to the second tread end T2 under the above standard conditions.

[0040] The groove width W1 of the circumferential groove 3 is preferably at least 3 mm. In a preferred embodiment, the groove width W1 of the circumferential groove 3 is 2.0% to 6.0% of the tread width TW.

[0041] The land portion includes at least a first shoulder land portion 11 including a first tread end T1. Additionally, the land portion in this embodiment includes a second shoulder land portion 12 including a second tread end T2.

[0042] Furthermore, the land portion of this embodiment includes a crown land portion 15, a first intermediate land portion 13, and a second intermediate land portion 14. The crown land portion 15 is divided between the first crown circumferential groove 4 and the second crown circumferential groove 5. The first intermediate land portion 13 is divided between the first crown circumferential groove 4 and the first shoulder circumferential groove 6. The second intermediate land portion 14 is divided between the second crown circumferential groove 5 and the second shoulder circumferential groove 7.

[0043] Figure 2 Show Figure 1 Enlarged three-dimensional view of the first shoulder land portion 11. Figure 3 Show Figure 1 An enlarged view of the first shoulder land portion 11. (See image below.) Figure 2 as well as Figure 3 As shown, a plurality of first shoulder transverse grooves 16 are provided on the first shoulder land portion 11, extending from the first shoulder periphery to the groove 6 and traversing the first tread end T1.

[0044] Figure 4 The middle shows Figure 3 A sectional view along line AA. (e.g.) Figure 4 As shown, the first shoulder transverse groove 16 has a pair of first groove walls 17. A pair of first chamfered portions 18 are provided on the pair of first groove walls 17, extending obliquely relative to the outer surface of the first shoulder land portion 11. Additionally, as... Figure 3 As shown, when viewed from above, a pair of first chamfered portions 18 extend from the first shoulder periphery toward the groove 6 to a position beyond the first tread end T1. The tire 1 of the present invention employs the above-described structure, thereby suppressing uneven wear such as H&T wear. The following mechanism is presumed to be the reason for this.

[0045] In this invention, the pair of first chamfered portions 18 facilitates the uniform application of ground pressure to the groove edges on both sides of the first shoulder transverse groove 16, thereby effectively suppressing H&T wear. In particular, the first chamfered portions 18 extend beyond the first tread end T1, thus effectively suppressing uneven wear near the first tread end T1 where the applied ground pressure varies significantly. This mechanism is presumed to effectively suppress uneven wear such as H&T wear in this invention.

[0046] Furthermore, in this invention, a pair of first chamfered portions 18 are used to uniformly distribute the ground pressure acting on the first tire shoulder land portion 11. Through this action, the first tire shoulder land portion 11 appropriately generates turning force, thereby improving the handling stability during lane changes and gentle turns.

[0047] The structure of this embodiment will be described in further detail below. Furthermore, each structure described below represents a specific embodiment. Therefore, it is self-evident that the present invention can achieve the above-described effects even without the structures described below. Furthermore, even when any one of the structures described below is applied individually in the tire of the present invention possessing the above-described features, an improvement in the performance corresponding to each structure can be expected. Additionally, when several of the structures described below are applied in combination, an improvement in the combined performance corresponding to each structure can be expected.

[0048] like Figure 4 As shown, the width W2 of the first chamfer (the width along the outer surface of the first shoulder land portion 11) is, for example, 1 to 3 mm. Furthermore, the width W2 of the first chamfer is preferably the width W3 of the contact surface of the first shoulder land portion 11. Figure 3 The content of (as shown) is 4.0% or more, more preferably 5.0% or more, and preferably 7.0% or less, more preferably 6.0% or less.

[0049] Furthermore, the depth d1 of the first chamfered portion 18 is, for example, 1 to 3 mm. Additionally, the angle θ1 of the inclined surface 18a of the first chamfered portion 18 relative to the tire normal is, for example, 40 to 60°. Furthermore, the aforementioned tire normal is an imaginary line that passes through the edge of the first shoulder lateral groove 16 and extends at a right angle relative to the outer surface of the first shoulder land portion 11.

[0050] like Figure 3 As shown, the pair of first chamfered portions 18 terminate at a first position in the tire axial direction beyond the first tread end T1. The aforementioned first position is a position less than 5 mm from the first tread end T1.

[0051] When viewed from above, the first chamfered portion 18 includes a constant-width portion 20 extending with a constant width, and a variable-width portion 21 whose chamfer width varies along the length direction of the first shoulder lateral groove 16. The constant-width portion 20 extends, for example, from the periphery of the first shoulder towards the groove 6 near the front of the first tread end T1. The variable-width portion 21 connects to the constant-width portion 20 and traverses the first tread end T1. Furthermore, the chamfer width of the variable-width portion 21 decreases towards the axially outward side of the tire. This effectively suppresses uneven wear at the outer periphery of the first chamfered portion 18.

[0052] In order to reliably achieve the above-mentioned effects, the tire axial length L3 of the variable width portion 21 is, for example, 30% to 45% of the tire axial width W3 of the contact surface of the first shoulder land portion 11.

[0053] The first shoulder lateral groove 16 has a groove edge 23 without a chamfer at a position axially outer of the tire than the first position of the first groove wall 17. The absence of a chamfer means that the first groove wall is directly connected to the outer surface of the first shoulder land portion 11, thereby forming an edge component that increases friction by scraping the road surface when in contact with the ground.

[0054] In this embodiment, for example, when braking, the ground pressure acting on the first tire shoulder land portion 11 increases, and the groove edge 23 contacts the ground in a region further outward from the first tread end T1 along the tire's axial direction, thereby increasing the tire's circumferential friction. Therefore, the groove edge 23 helps improve braking performance on both dry and wet road surfaces.

[0055] like Figure 3 As shown, in this embodiment, the aforementioned first position is a position 5 mm or less from the first tread end T1. In other words, the distance L4 from the first tread end T1 to the groove edge 23 excluding the chamfer is 5 mm or less. Therefore, the groove edge 23, which does not have a chamfer, can easily contact the ground during braking, thereby obtaining a larger friction force.

[0056] The length of the groove 23 (the outer circumference length when the tread is unfolded into a plane) is, for example, 40% to 70% of the tire axial width W3 of the contact patch of the first shoulder land portion 11. A groove 23 with such a sufficient length helps to reliably improve braking performance.

[0057] Figure 5 Show Figure 3 A BB-line sectional view. For example... Figure 5 As shown, the first shoulder lateral groove 16 includes a first reinforcing rib 26 with a partial bulge at the bottom of the groove. In this embodiment, the first reinforcing rib 26 is disposed at the inner end of the first shoulder lateral groove 16 in the tire axial direction. Such a first reinforcing rib 26 increases the rigidity of the first shoulder land portion 11, thereby improving handling stability.

[0058] The tire axial length L6 of the first brace 26 is, for example, the tire axial width W3 of the contact surface of the first shoulder land portion 11. Figure 3 The length L6 is 20% to 35% of the tire's radial length (as shown). When the axial length of the first reinforcing rib 26 changes due to the tire's radial position, the aforementioned length L6 is measured based on the radial center position of the first reinforcing rib 26. Furthermore, the minimum depth d3 of the first reinforcing rib 26 is, for example, 60% to 75% of the maximum depth d2 of the first shoulder groove 16. This first reinforcing rib 26 maintains the drainage performance of the first shoulder groove 16 and improves handling stability.

[0059] like Figure 3As shown, the circumferential spacing length P1 of the first shoulder lateral groove 16 is, for example, 100% to 130% of the axial width W3 of the contact patch of the first shoulder land portion 11. This improves handling stability on dry roads and wet road performance in a balanced manner. Furthermore, the circumferential spacing length of the lateral grooves arranged along the tire is, for example, equivalent to the circumferential distance from the inner end of the centerline of one lateral groove to the inner end of the centerline of the adjacent lateral groove in the tire circumferential direction.

[0060] In a further preferred embodiment, the first shoulder land portion 11 includes a plurality of first shoulder tread blocks 25 divided by a plurality of first shoulder transverse grooves 16. Furthermore, the first shoulder land portion 11 does not have grooves or sipes other than the first shoulder transverse grooves 16. This first shoulder land portion 11 has high rigidity, thereby further improving handling stability.

[0061] Figure 6 An enlarged view of the second shoulder land portion 12 is shown. (See attached image.) Figure 6 As shown, a plurality of second shoulder transverse grooves 31 are provided on the land portion 12 of the second shoulder. The second shoulder transverse grooves 31 extend from the periphery of the second shoulder toward the groove 7 and traverse the end T2 of the second tread.

[0062] The second shoulder lateral groove 31 has a pair of second groove walls (not shown). Furthermore, a pair of second chamfered portions 32 are provided on the pair of second groove walls, extending from the second shoulder circumference towards the groove 7 and beyond the second tread end T2. Thus, based on the same mechanism as described above, handling stability and resistance to uneven wear are further improved.

[0063] Furthermore, the second chamfered portion 32 has essentially the same structure as the first chamfered portion 18. Therefore, the structure of the first chamfered portion 18 described above can be applied to the second chamfered portion 32, and the description is omitted here. The pair of second chamfered portions 32 terminate at a second position in the tire axial direction (essentially the same as the first position described above). In addition, a groove edge 33 without chamfered portions is provided at a position further outward in the tire axial direction than the second position of the pair of second groove walls. This further improves braking performance.

[0064] The tire circumferential spacing length P2 of the second shoulder groove 31 is, for example, 80 to 120% of the tire circumferential spacing length P1 of the first shoulder groove 16.

[0065] Figure 7 Show Figure 6 A CC-line sectional view. For example... Figure 7 As shown, the second shoulder groove 31 includes a second reinforcing rib 34 with a partial bulge at the bottom of the groove. In this embodiment, the second reinforcing rib 34 is disposed at the inner end of the second shoulder groove 31 in the tire axial direction.

[0066] The tire axial length L7 of the second brace 34 is, for example, the tire axial width W4 of the contact surface of the second shoulder land portion 12. Figure 7 (as shown) 20% to 35%. In addition, the minimum depth d5 ​​of the second tie 34 is, for example, 60% to 75% of the maximum depth d4 of the second shoulder lateral groove 31. Such a second tie 34 improves handling stability on dry roads and wet road performance in a balanced way.

[0067] If the first tie 26 is set in the first shoulder transverse groove 16 ( Figure 5 As shown, when comparing the first rib 26 with the second rib 34 located in the second shoulder lateral groove 31, the tire axial length of the first rib 26 is preferably greater than that of the second rib 34. This rib configuration helps to relatively increase the rigidity of the first shoulder land portion 11, thereby achieving superior handling stability.

[0068] On the other hand, the depth of the first tie rod 26 is preferably greater than the depth of the second tie rod 34. This ensures the drainage of the first shoulder groove 16 and maintains wet road performance.

[0069] like Figure 6 As shown, the second shoulder land portion 12 includes a plurality of second shoulder tread blocks 35 divided by a plurality of second shoulder transverse grooves 31. In this embodiment, one first shoulder tread block 25 ( Figure 3 The contact area of ​​the first shoulder tread block 25 (as shown) is larger than the contact area of ​​the second shoulder tread block 35. Specifically, the area of ​​the first shoulder tread block 25 is 110% to 120% of the area of ​​the second shoulder tread block 35. This maintains resistance to uneven wear and provides superior handling stability.

[0070] A shoulder sipe 36 extending along the second shoulder transverse groove 31 is provided on the second shoulder tread block 35. In this embodiment, the second shoulder transverse groove 31 and the shoulder sipe 36 are alternately provided along the tire circumference. Furthermore, in this specification, a "sipe" is a groove element with a relatively small width, meaning the width between two opposing inner walls is 1.5 mm or less. The width of the sipe is preferably 0.3 to 1.0 mm. A chamfered portion with a width exceeding 1.5 mm may also be connected to the opening of the sipe. Additionally, a flask-shaped bottom with a width exceeding 1.5 mm may also be connected to the bottom of the sipe.

[0071] The shoulder groove 36 extends, for example, from the periphery of the second shoulder towards the groove 7 and traverses the second tread end T2. Such a shoulder groove 36 can suppress deformation of the contact surface of the land portion 12 of the second shoulder, thereby suppressing its uneven wear.

[0072] The shoulder sipe 36 preferably includes a shallow bottom (not shown) at the inner end of the tire axial direction. The depth of the shallow bottom is, for example, 35% to 45% of the maximum depth of the shoulder sipe 36.

[0073] Figure 8 Enlarged views of the first intermediate landmass 13, the crown landmass 15, and the second intermediate landmass 14 are shown. Figure 8 As shown, a plurality of first intermediate grooves 41 and a plurality of second intermediate grooves 42 are alternately provided along the tire circumference of the first intermediate land portion 13. The first intermediate grooves 41, for example, completely traverse the first intermediate land portion 13 along the tire axial direction. The second intermediate grooves 42, for example, extend from the first crown circumferential groove 4 and have an interrupted end 42a within the first intermediate land portion 13.

[0074] The first intermediate groove 41 is, for example, oriented in a first direction relative to the tire axial direction (in... Figure 8 The center groove (sloping upwards to the right) is inclined. The angle of the first intermediate groove 41 relative to the tire axial direction is greater than the angle of the first shoulder lateral groove 16 relative to the tire axial direction, for example, 20° to 40°. This first intermediate groove 41 can provide friction not only in the tire circumferential direction but also in the tire axial direction.

[0075] Figure 9 The middle shows Figure 8 A DD-line sectional view. For example... Figure 9 As shown, a chamfered portion 46 with a width larger than its main body 41a is connected to the first intermediate groove 41. The opening width W5 of the chamfered portion 46 is preferably greater than the width W2 of one of the first chamfered portions 18 of the first shoulder transverse groove 16. Figure 4 (As shown). As a result, the wear progression of the first shoulder land portion 11 and the first intermediate land portion 13 is easily uniformized, thereby improving the resistance to uneven wear.

[0076] like Figure 8 As shown, the circumferential spacing length P3 of the first intermediate groove 41 is preferably greater than the aforementioned spacing length P1 of the first shoulder transverse groove 16. Figure 3 (As shown). Specifically, the aforementioned spacing length P3 is 150% to 250% of the aforementioned spacing length P1. As a result, uneven wear of the first intermediate land portion 13 can be suppressed.

[0077] like Figure 1 As shown, the end of the first shoulder circumferential groove 6 of the first intermediate groove 41 preferably overlaps with the projected area of ​​the end of the first shoulder circumferential groove 6 of the first shoulder transverse groove 16 extended parallel to the tire axial direction. This allows the first shoulder transverse groove 16 to open easily upon contact with the ground, thereby improving wet road performance.

[0078] like Figure 8As shown, the second intermediate sipe 42 extends obliquely in the first direction. The second intermediate sipe 42 preferably extends along the first intermediate sipe 41, and in this embodiment, their angle difference is 5° or less. Furthermore, the tire axial length L8 of the second intermediate sipe 42 is 40% to 60% of the tire axial width W6 of the contact surface of the first intermediate land portion 13.

[0079] Figure 10 The middle shows Figure 8 A sectional view along the EE line. (e.g.) Figure 10 As shown, the second intermediate cutting groove 42, for example, has its inner wall connected to the contact surface of the first intermediate land portion 13 to form an edge component. The edge of such a second intermediate cutting groove 42 provides greater friction, thereby contributing to improved braking performance.

[0080] like Figure 8 As shown, a plurality of tread grooves 45 are provided in the land portion 15 of the tread. The tread grooves 45 extend, for example, from the second circumferential groove 5 of the tread and have an interrupted end 45a within the land portion 15 of the tread. The tread grooves 45 extend, for example, in a second direction opposite to the first direction relative to the tire axial direction (in... Figure 8 The center is inclined to the upper left. The angle of the tread groove 45 relative to the tire axis is, for example, 10 to 30°. The edge of such a tread groove 45 exerts friction in a direction different from that of the first intermediate sipe 41, thereby further improving braking performance.

[0081] The lateral groove 45 does not, for example, traverse the tire equator C, nor does it traverse the center position of the tire axial direction of the lateral land portion 15. The axial length L of the lateral groove 45 is preferably less than the axial length of the second intermediate sipe 42. Specifically, the aforementioned length L9 of the lateral groove 45 is 35% to 45% of the axial width W7 of the lateral land portion 15. Such a lateral groove 45 can maintain resistance to uneven wear and improve wet road performance.

[0082] A plurality of third intermediate grooves 43 and a plurality of fourth intermediate grooves 44 are alternately provided along the tire circumference of the second intermediate land portion 14. The third intermediate grooves 43 and the fourth intermediate grooves 44 completely traverse the second intermediate land portion 14 along the tire axial direction. The third intermediate grooves 43 and the fourth intermediate grooves 44 are inclined, for example, relative to the tire axial direction in the first direction described above. The angle of the third intermediate groove 43 relative to the tire axial direction and the angle of the fourth intermediate groove 44 relative to the tire axial direction are 10° to 30° respectively.

[0083] The third intermediate tool groove 43, for example, has a similar design to... Figure 9 The third intermediate groove 43 has the same cross-sectional shape as the first intermediate groove 41 shown. That is, the third intermediate groove 43 is connected to a chamfered portion with a width greater than its main body. Such a third intermediate groove 43 can suppress uneven wear of the second intermediate land portion 14.

[0084] The fourth intermediate tool groove 44, for example, has the same as... Figure 10 The second intermediate sipe 42 shown has the same cross-sectional shape. That is, the inner wall of the fourth intermediate sipe 44 is connected to the contact surface of the second intermediate land portion 14 to form an edge component. Such a fourth intermediate sipe 44 provides greater friction. In this embodiment, the aforementioned third intermediate sipe 43 and fourth intermediate sipe 44 are alternately arranged along the tire circumference, thereby evenly improving resistance to uneven wear and braking performance.

[0085] like Figure 1 As shown, the end of the second shoulder circumferential groove 7 of the third intermediate groove 43 preferably overlaps with the projected area of ​​the end of the second shoulder circumferential groove 7 of the second shoulder transverse groove 31 extended parallel to the tire axial direction. This allows the second shoulder transverse groove 31 to open easily upon contact with the ground, thereby improving wet road performance.

[0086] The tire according to one embodiment of the present invention has been described in detail above, but the present invention is not limited to the specific embodiment described above, but can be implemented in various ways.

[0087]

Example

[0088] Based on the specifications in Table 1, a prototype with... Figure 1 A tire with a tread pattern size of 235 / 50R18 was prototyped. As a comparative example, a tire with... Figure 11 The tire shown has a tread pattern. Figure 11 As shown, in the comparative example tire, no chamfered portions are provided in the first shoulder lateral groove a and the second shoulder lateral groove b. In addition to the above-described structure, the comparative example tire also has the same... Figure 1 The tread patterns shown are essentially the same. Uneven wear resistance, handling stability, and braking performance were tested on each test tire. Common specifications and test methods for all test tires are as follows.

[0089] Wheel rim installation: 18×7.5J

[0090] Tire internal pressure: 230 kPa for all tires

[0091] Test vehicle: 3000cc engine, four-wheel drive vehicle

[0092] Tire mounting location: All wheels

[0093] <Resistance to uneven wear>

[0094] After driving the test vehicle for a certain distance, the wear condition (degree of uneven wear such as H&T wear) of the first and second tire shoulder lateral grooves was visually observed. The results were scored with the wear condition of the comparative example as 100, and the higher the score, the better the resistance to uneven wear.

[0095] <Maneuverability>

[0096] The handling stability of the test vehicle on a dry road surface was evaluated by the driver's senses. The results were scored with the handling stability of the comparative example set at 100, and the higher the score, the better the handling stability.

[0097] <Braking performance>

[0098] The braking performance of the test vehicle on dry and wet roads was evaluated by the driver's senses. The results were scored with the braking performance of the comparative example as 100, and the higher the score, the better the braking performance.

[0099] The test results are shown in Table 1.

[0100] Table 1

[0101]

[0102] As shown in Table 1, the tires of the embodiments were confirmed to have excellent resistance to uneven wear, effectively suppressing uneven wear such as H&T wear. Furthermore, the tires of the embodiments were also confirmed to exhibit excellent handling stability. Additionally, the tires of the embodiments were confirmed to maintain braking performance.

Claims

1. A tire having a tread portion, characterized in that, the tread portion includes: a first tread end and a second tread end which become the tire axially outermost ground contact positions when a standard state of the tire mounted on a regular rim and filled with a standard internal pressure is loaded with 70% of a standard load; a first shoulder land portion including the first tread end; and a first shoulder circumferential groove adjacent to the tire axially inner side of the first shoulder land portion and extending continuously in the tire circumferential direction, a plurality of first shoulder transverse grooves are provided in the first shoulder land portion extending from the first shoulder circumferential groove and transversely across the first tread end, the first shoulder transverse grooves have a pair of first groove walls, a pair of first chamfer portions extending from the first shoulder circumferential groove to a position beyond the first tread end are provided in the pair of first groove walls, the pair of first chamfer portions terminate at a first position in the tire axial direction, the first shoulder transverse grooves have a groove edge without a chamfer portion at a position in the tire axial direction outside the first position of the pair of first groove walls, the first chamfer portion includes, when viewed in plan view of the tread, a constant width portion extending with a constant width, and a variable width portion in which the chamfer width varies in the length direction of the first shoulder transverse groove, the constant width portion extends from the first shoulder circumferential groove to near the first tread end, the variable width portion is connected to the constant width portion and transversely across the first tread end.

2. The tire according to claim 1, characterized in that, the first position is a position 5 mm or less from the first tread end.

3. The tire according to claim 1 or 2, characterized in that, the chamfer width of the variable width portion decreases toward the tire axial direction outside.

4. The tire according to claim 1 or 2, characterized in that, the tread portion includes a second shoulder land portion including the second tread end, and a second shoulder circumferential groove adjacent to the tire axially inner side of the second shoulder land portion and extending continuously in the tire circumferential direction, a plurality of second shoulder transverse grooves are provided in the second shoulder land portion extending from the second shoulder circumferential groove and transversely across the second tread end, the second shoulder transverse grooves have a pair of second groove walls, a pair of second chamfer portions extending from the second shoulder circumferential groove to a position beyond the second tread end are provided in the pair of second groove walls.

5. The tire according to claim 4, characterized in that, the tread portion is designated in a direction of mounting to a vehicle with the first tread end on the vehicle outer side, the first shoulder land portion includes a plurality of first shoulder blocks divided by the first shoulder transverse grooves, the second shoulder land portion includes a plurality of second shoulder blocks divided by the second shoulder transverse grooves, the area of the ground surface of one of the first shoulder blocks is larger than the area of the ground surface of one of the second shoulder blocks.

6. The tire according to claim 4, characterized in that, no groove and sipe other than the first shoulder transverse grooves are provided in the first shoulder land portion.

7. The tire according to claim 4, characterized in that, A plurality of shoulder notches extending along the second shoulder transverse groove are provided in the second shoulder land portion.

8. The tire according to claim 4, wherein The first shoulder transverse groove includes a first bead partially raised from a groove bottom, The second shoulder transverse groove includes a second bead partially raised from a groove bottom, The first bead has a length in the tire axial direction that is greater than a length in the tire axial direction of the second bead.

9. The tire according to claim 8, wherein The first bead has a depth that is greater than a depth of the second bead.

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