Tire

Abstract

The present application provides a tire capable of exhibiting superior cornering performance on snow. The tire has a tread portion (2) toward which a vehicle is mounted. A plurality of outer shoulder sipes (50) are provided in an outer shoulder land portion (11). A plurality of inner shoulder sipes (55) are provided in an inner shoulder land portion (15). Each outer shoulder sipe (50) includes an inner sipe portion (50i) and an outer sipe portion (50o), thereby being bent convexly toward one side in the tire circumferential direction. Each inner shoulder sipe (55) includes an inner sipe portion (55i) and an outer sipe portion (55o), thereby being bent convexly toward the other side in the tire circumferential direction. The angle θ2i of the inner sipe portion (55i) of the inner shoulder sipe (55) is larger than the angle θ1i of the inner sipe portion (50i) of the outer shoulder sipe (50). The angle θ2o of the outer sipe portion (55o) of the inner shoulder sipe (55) is smaller than the angle θ1o of the outer sipe portion (50o) of the outer shoulder sipe (50).

Description

Technical Field

[0001] This invention relates to tires. Background Technology

[0002] Patent document 1 discloses a tire with multiple shoulder grooves on the land surface of the shoulder. These shoulder grooves are intended to improve snow performance.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2018-134960

[0004] In recent years, there has been a demand for further improvements in snow performance, especially in snow cornering performance. Summary of the Invention

[0005] The present invention was proposed in view of the above-mentioned actual situation, and the main objective is to provide a tire that can perform well in snow cornering.

[0006] The present invention provides a tire having a tread portion facing a designated direction for mounting on a vehicle. The tread portion includes: a first tread end that becomes the outer side of the vehicle when mounted on the vehicle; a second tread end that becomes the inner side of the vehicle when mounted on the vehicle; a plurality of circumferential grooves extending continuously in the tire circumferential direction between the first tread end and the second tread end; and a plurality of land portions separated by the plurality of circumferential grooves. The plurality of circumferential grooves includes: an outer shoulder circumferential groove disposed closest to the first tread end; and an inner shoulder circumferential groove disposed closest to the second tread end. The sidewall shoulder circumferential groove includes a plurality of land portions comprising: an outer shoulder land portion disposed on the axially outer side of the outer shoulder circumferential groove and including the first tread end; and an inner shoulder land portion disposed on the axially outer side of the inner shoulder circumferential groove and including the second tread end. The outer shoulder land portion has a plurality of outer shoulder lateral grooves extending from the outer shoulder circumferential groove beyond the first tread end. The inner shoulder land portion has a plurality of lateral grooves extending from the inner shoulder circumferential groove beyond the second tread end. The tire has multiple inner shoulder transverse grooves. Each of the aforementioned outer shoulder transverse grooves, located between the outer shoulder circumferential groove and the first tread end, includes an inner groove portion inclined in a first direction relative to the tire axial direction, and an outer groove portion disposed outside the inner groove portion and inclined in a second direction opposite to the first direction relative to the tire axial direction. Thus, it bends protruding to one side in the tire circumferential direction. Each of the aforementioned inner shoulder transverse grooves, located between the inner shoulder circumferential groove and the second tread end, includes an inner groove portion inclined in the first direction relative to the tire axial direction. The inner shoulder groove and the outer groove, which are located on the outer side of the tire axial direction and inclined in the second direction relative to the tire axial direction, bend outwards to the other side of the tire circumferential direction. The angle θ2i of the inner shoulder groove relative to the tire axial direction is greater than the angle θ1i of the inner shoulder groove relative to the tire axial direction, and the angle θ2o of the outer shoulder groove relative to the tire axial direction is less than the angle θ1o of the outer shoulder groove relative to the tire axial direction.

[0007] In the tire of the present invention, it is preferable that the difference between the angle θ2i of the inner groove portion of the inner shoulder transverse groove and the angle θ1i of the inner groove portion of the outer shoulder transverse groove is 5 to 20°.

[0008] In the tire of the present invention, it is preferable that the difference between the angle θ2o of the outer groove portion of the inner shoulder transverse groove and the angle θ1o of the outer groove portion of the outer shoulder transverse groove is 10° or less.

[0009] In the tire of the present invention, it is preferable that the axial length of the outer groove portion of the outer shoulder groove is greater than the axial length of the outer groove portion of the inner shoulder groove.

[0010] In the tire of the present invention, it is preferable that the maximum width of the plurality of outer shoulder transverse grooves is greater than the maximum width of the plurality of inner shoulder transverse grooves.

[0011] In the tire of the present invention, it is preferable that a plurality of inner shoulder interruption grooves are provided on the land portion of the inner shoulder, extending from the inner shoulder circumferential groove and interrupted instead of reaching the second tread end.

[0012] In the tire of the present invention, it is preferable that the maximum width of the plurality of inner shoulder interruption grooves is smaller than the maximum width of the plurality of inner shoulder transverse grooves.

[0013] In the tire of the present invention, it is preferable that the maximum depth of the plurality of inner shoulder interruption grooves is less than the maximum depth of the plurality of inner shoulder transverse grooves.

[0014] In the tire of the present invention, preferably, the plurality of inner shoulder interruption grooves are located between the inner shoulder circumferential groove and the second tread end, including an inner groove portion that is inclined toward the first direction relative to the tire axial direction, and an outer groove portion disposed on the outer side of the inner groove portion and inclined toward the second direction relative to the tire axial direction, thereby bending in the same direction as the inner shoulder transverse groove.

[0015] In the tire of the present invention, preferably the inner shoulder transverse groove includes the bend apex between the inner groove and the outer groove, the inner shoulder break groove includes the bend apex between the inner groove and the outer groove, and the bend apex of the inner shoulder break groove is located axially inside the tire than the bend apex of the inner shoulder transverse groove.

[0016] The tire of the present invention, by adopting the above-described structure, is able to achieve superior cornering performance on snow. 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 views of the outer and inner shoulder land areas of the tire.

[0019] Figure 3 yes Figure 1 Enlarged view of the outer shoulder land area and the outer middle land area.

[0020] Figure 4 yes Figure 1 Enlarged view of the inner shoulder land area and the inner middle land area.

[0021] Figure 5 yes Figure 1 Enlarged view of the land portion of the calf's crown.

[0022] Figure 6 This is a unfolded diagram of the tread of a reference tire.

[0023] Explanation of reference numerals in the attached figures

[0024] 2…tread portion; 3…circumferential groove; 4…outer shoulder circumferential groove; 7…inner shoulder circumferential groove; 10…land portion; 11…outer shoulder land portion; 15…inner shoulder land portion; 50…outer shoulder transverse groove; 50i…inner groove; 50o…outer groove; 55…inner shoulder transverse groove; 55i…inner groove; 55o…outer groove; θ1i…angle of the inner groove of the outer shoulder transverse groove relative to the tire axis; θ2i…angle of the inner groove of the inner shoulder transverse groove relative to the tire axis; θ1o…angle of the outer groove of the outer shoulder transverse groove relative to the tire axis; θ2o…angle of the outer groove of the inner shoulder transverse groove relative to the tire axis; T1…first tread end; T2…second tread end. Detailed Implementation

[0025] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0026] 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 of this embodiment is used, for example, as a pneumatic tire for passenger cars intended for use in winter. However, the tire 1 of the present invention is not limited to this form.

[0027] The tire 1 in this embodiment has, for example, a tread portion 2 with a vehicle-mounting orientation specified. This vehicle-mounting orientation is indicated, for example, by text or markings on the tire sidewall (illustrations omitted). 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).

[0028] The tread portion 2 includes a first tread end T1 that becomes the outer side of the vehicle when mounted on the vehicle, and a second tread end T2 that becomes the inner side of the vehicle when mounted on the vehicle. The first tread end T1 and the second tread end T2 respectively correspond to the outermost contact position of the tire axially when the tire 1 is loaded with 70% of the normal load and touches the ground at a camber angle of 0°.

[0029] "Standard condition" in the context of specified pneumatic tire sizes refers to the condition where the tire is assembled on a standard rim, inflated to the standard internal pressure, and unloaded. For tires without specified sizes or non-pneumatic tires, the above-mentioned standard condition means the standard operating condition corresponding to the tire's intended use and unloaded. In this manual, unless otherwise specified, the dimensions of various parts of the tire are values ​​measured under the above-mentioned standard condition.

[0030] "Standard rim" refers to a rim with a specific specification for each tire within a specification system that includes the specifications on which the tire is based. For example, JATMA is "standard rim", TRA is "Design Rim", and ETRTO is "Measuring Rim".

[0031] "Standard tire pressure" refers to the tire 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 tire 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 the "INFLATION PRESSURE".

[0032] When various sizes of pneumatic tires are specified, "standard load" refers to the load capacity specified for each tire within a specification system, including the specifications the tire is based on. For JATMA, it is "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 "LOAD CAPACITY". Furthermore, when tire sizes are not specified, "standard load" refers to the maximum load that can be applied when using the tire according to the aforementioned specifications.

[0033] 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 10 separated by the circumferential grooves 3. In this embodiment, the tire 1 is configured as a so-called 5-rib tire, where the tread portion 2 includes 5 land portions 10 separated by 4 circumferential grooves 3. However, the present invention is not limited to this configuration; for example, it may also be a so-called 4-rib tire, where the tread portion 2 consists of 3 circumferential grooves 3 and 4 land portions 10.

[0034] The circumferential groove 3 includes the outer shoulder circumferential groove 4 and the inner shoulder circumferential groove 7. The outer shoulder circumferential groove 4 is located on the side closest to the first tread end T1 among the multiple circumferential grooves 3. The inner shoulder circumferential groove 7 is located on the side closest to the second tread end T2 among the multiple circumferential grooves 3.

[0035] In this embodiment, the circumferential groove 3 includes, in addition to the outer shoulder circumferential groove 4 and the inner shoulder circumferential groove 7, an outer crown circumferential groove 5 and an inner crown circumferential groove 6. The outer crown circumferential groove 5 is located between the outer shoulder circumferential groove 4 and the tire equator C. The inner crown circumferential groove 6 is located between the inner shoulder circumferential groove 7 and the tire equator C.

[0036] The circumferential groove 3 can take various forms, such as a groove extending in a straight line along the tire circumference or a groove extending in a serrated shape. The specific form of this embodiment will be described later.

[0037] The distance L1 from the center line of the outer shoulder circumferential groove 4 or the inner shoulder circumferential groove 7 to the tire equator C is, for example, 20% to 35% of the tread width TW. The distance L2 from the center line of the outer crown circumferential groove 5 or the inner crown circumferential groove 6 to the tire equator C is, for example, 3% to 15% of the tread width TW. Here, the tread width TW is the distance from the first tread end T1 to the second tread end T2 under the above-described normal condition.

[0038] 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. In this embodiment, the inner crown circumferential groove 6 among the four circumferential grooves 3 has the largest groove width.

[0039] The plurality of land portions 10 include an outer shoulder land portion 11 and an inner shoulder land portion 15. The outer shoulder land portion 11 is disposed on the axially outer side of the outer shoulder circumferential groove 4 and includes a first tread end T1. The inner shoulder land portion 15 is disposed on the axially outer side of the inner shoulder circumferential groove 7 and includes a second tread end T2.

[0040] In addition to the outer shoulder land portion 11 and the inner shoulder land portion 15 described above, the plurality of land portions 10 in this embodiment also include an outer intermediate land portion 12, an inner intermediate land portion 14, and a crown land portion 13. The outer intermediate land portion 12 is located between the outer shoulder circumferential groove 4 and the outer crown circumferential groove 5. That is, the outer intermediate land portion 12 is adjacent to the outer shoulder land portion 11 across the outer shoulder circumferential groove 4. The inner intermediate land portion 14 is located between the inner shoulder circumferential groove 7 and the inner crown circumferential groove 6. That is, the inner intermediate land portion 14 is adjacent to the inner shoulder land portion 15 across the inner shoulder circumferential groove 7. The crown land portion 13 is located between the outer crown circumferential groove 5 and the inner crown circumferential groove 6.

[0041] Figure 2 Enlarged views of the outer shoulder land portion 11 and the inner shoulder land portion 15 are shown. For ease of understanding of the invention, in... Figure 2 In this context, the outer middle land portion 12, the inner middle land portion 14, and the crown land portion 13 are omitted, which is self-evident.

[0042] like Figure 2 As shown, a plurality of outer shoulder transverse grooves 50 are provided on the outer shoulder land portion 11. The outer shoulder transverse grooves 50 extend from the outer shoulder circumference toward groove 4 to a position beyond the first tread end. Furthermore, in the figures of this specification, areas axially outer of the tire beyond the first tread end T1 and the second tread end T2 are omitted. Additionally, a plurality of inner shoulder transverse grooves 55 are provided on the inner shoulder land portion 15. The inner shoulder transverse grooves 55 extend from the inner shoulder circumference toward groove 7 to a position beyond the second tread end T2.

[0043] Each outer shoulder lateral groove 50, located between the outer shoulder circumferential groove 4 and the first tread end T1, includes an inner groove portion 50i and an outer groove portion 50o disposed on the outer side of the tire axial direction of the inner groove portion 50i. The inner groove portion 50i is inclined relative to the tire axial direction in a first direction (upper right in the figures of this specification). The outer groove portion 50o is inclined relative to the tire axial direction in a second direction opposite to the first direction (lower right in the figures of this specification). Thus, each outer shoulder lateral groove 50 bends protruding to one side of the tire circumferential direction.

[0044] Each inner shoulder lateral groove 55, located between the inner shoulder circumferential groove 7 and the second tread end T2, includes an inner groove portion 55i and an outer groove portion 55o disposed on the outer side of the tire axial direction relative to the inner groove portion 55i. The inner groove portion 55i is inclined in the first direction relative to the tire axial direction. The outer groove portion 55o is inclined in the second direction relative to the tire axial direction. As a result, each inner shoulder lateral groove 55 bends protruding to the other side of the tire circumferential direction.

[0045] Furthermore, in this specification, "the lateral groove bends circumferentially towards the tire" means that by making the lateral groove locally curved, the curved area of ​​at least the center line of the lateral groove converges to less than 10% of the total length of the lateral groove. As a preferred embodiment, the curved areas of the center lines of the outer shoulder lateral groove 50 and the inner shoulder lateral groove 55 in this embodiment converge to less than 5% of the total length of the groove. In a more preferred embodiment, the radius of curvature of the curved area of ​​the center lines of these lateral grooves is formed to be less than 1.0 mm.

[0046] In this invention, the angle θ2i of the inner groove portion 55i of the inner shoulder lateral groove 55 relative to the tire axial direction is greater than the angle θ1i of the inner groove portion 50i of the outer shoulder lateral groove 50 relative to the tire axial direction. Furthermore, the angle θ2o of the outer groove portion 55o of the inner shoulder lateral groove 55 relative to the tire axial direction is smaller than the angle θ1o of the outer groove portion 55o of the outer shoulder lateral groove 50 relative to the tire axial direction. By employing the above-described structure, the tire 1 of this invention can achieve superior cornering performance on snow. The following mechanism can be deduced as a reason for this.

[0047] In this invention, the outer shoulder lateral groove 50 and the inner shoulder lateral groove 55 are bent, thereby providing a large snow column shearing force and edge friction during cornering at a relatively small slip angle. Conversely, the outer shoulder lateral groove 50 provides a large snow column shearing force and edge friction during cornering at a relatively large slip angle. Therefore, cornering performance on snow can be improved over a wide range of slip angles.

[0048] In addition, the outer shoulder groove 50 and the inner shoulder groove 55 are bent in opposite directions, so that even in various turning conditions, greater snow shearing force and edge friction can be expected.

[0049] Furthermore, the angle θ2i of the inner groove portion 55i of the inner shoulder lateral groove 55 is greater than the angle θ1i of the inner groove portion 50i of the outer shoulder lateral groove 50. This increases the tread rigidity of the inner shoulder land portion 15 in the tire axial direction, thereby improving handling stability during cornering on snow and ice. On the other hand, the angle θ2o of the outer groove portion 55o of the inner shoulder lateral groove 55 is smaller than the angle θ1o of the outer groove portion 50o of the outer shoulder lateral groove 50. Therefore, the edge of the outer groove portion 50o of the outer shoulder lateral groove 50 can provide greater friction in the tire axial direction. Additionally, this angular distribution appropriately reduces the rigidity of the outer shoulder land portion 11, resulting in a linear transition characteristic of grip relative to ground contact pressure on snow and ice. Consequently, the driver can more easily control the tire's maximum grip when cornering on snow and ice. In this invention, it is believed that superior cornering performance on snow can be achieved through this mechanism.

[0050] The structure of this embodiment will now be described in more detail. Furthermore, each structure described below represents a specific form of this embodiment. Therefore, it is self-evident that the present invention can achieve the aforementioned effects even without the structures described below. Additionally, even when any one of the structures described below is applied individually to the tire of the present invention possessing the above features, an improvement in the performance corresponding to each structure can be expected. Furthermore, when several of the structures described below are applied in combination, an improvement in the combined performance corresponding to each structure can be expected.

[0051] like Figure 1 As shown, the outer shoulder circumferential groove 4 extends in a straight line with a constant groove width. On the other hand, the inner crown circumferential groove 6 includes multiple widening portions 6a in the tire circumferential direction, whose groove width gradually decreases towards one side of the tire circumferential direction (the direction in which the outer shoulder transverse groove 50 protrudes). Similarly, the inner shoulder circumferential groove 7 also includes multiple widening portions 7a in the tire circumferential direction, whose groove width gradually decreases towards one side of the tire circumferential direction. The outer crown circumferential groove 5 includes multiple widening portions 5a in the tire circumferential direction, whose groove width gradually decreases towards the other side of the tire circumferential direction (the direction in which the inner shoulder transverse groove 55 protrudes). The circumferential grooves 3 including these widening portions can strongly compact snow internally, thereby helping to improve snow cornering performance. Furthermore, by specifying the direction of the widening portions 5a as described above, a large snow column shearing force can be exerted during both acceleration and deceleration.

[0052] like Figure 2 As shown, in this embodiment, the axial width W3 of the inner shoulder land portion 15 at its contact surface is preferably smaller than the axial width W2 of the outer shoulder land portion 11 at its contact surface. Specifically, the width W3 of the inner shoulder land portion 15 is 75% to 95%, preferably 80% to 90%, of the width W2 of the outer shoulder land portion 11. Therefore, the inner shoulder land portion 15 can easily deform appropriately, thereby achieving superior snow performance.

[0053] The angle θ1i of the inner groove 50i of the outer shoulder transverse groove 50 is, for example, 5 to 15°. The angle θ2i of the inner groove 55i of the inner shoulder transverse groove 55 is, for example, 20 to 35°. Furthermore, the difference between the angles θ1i and θ2i is, for example, 5 to 20°. By making the difference between the angles θ1i and θ2i relatively large, the difference between the air velocity flowing from the outer shoulder circumference into the outer shoulder transverse groove 50 and the air velocity flowing from the inner shoulder circumference into the inner shoulder transverse groove 55 can be increased, thereby effectively whitening the noise generated by each transverse groove.

[0054] The angle θ1o of the outer groove portion 50o of the outer shoulder lateral groove 50 is, for example, 5 to 10°. The angle θ2o of the outer groove portion 55o of the inner shoulder lateral groove 55 is, for example, 3 to 7°. Furthermore, the difference between the angles θ1o and θ2o is, for example, less than 10°. This reduces the stiffness difference in the land portion near the first tread end T1 and near the second tread end T2. Consequently, the steering feel becomes linear, resulting in superior snow cornering performance.

[0055] In a more preferred configuration, the difference between angles θ1o and θ2o is less than the difference between angles θ1i and θ2i. This allows for a balanced improvement in both noise performance and snow cornering performance.

[0056] In this embodiment, the bending angle θ1b between the inner groove portion 50i and the outer groove portion 50o of the outer shoulder lateral groove 50 is greater than the bending angle θ2b between the inner groove portion 55i and the outer groove portion 55o of the inner shoulder lateral groove 55. This disperses the frequency bands of various noises generated by these grooves, thereby improving noise performance. Furthermore, since the bending angle θ1b of the outer shoulder lateral groove 50 is relatively large, the reduction in tire axial stiffness of the outer shoulder land portion 11 caused by the outer shoulder lateral groove 50 can be suppressed, thereby maintaining cornering performance on snow.

[0057] like Figure 2 As shown, the bending angle θ1b of the outer shoulder transverse groove 50 and the bending angle θ2b of the inner shoulder transverse groove 55 are, for example, 135 to 170°. More preferably, the bending angle θ1b of the outer shoulder transverse groove 50 is 150 to 170°. More preferably, the bending angle θ2b of the inner shoulder transverse groove 55 is 140 to 160°. In a further preferred embodiment, the bending angle θ1b is 101% to 120% of the bending angle θ2b, and in an even more preferred embodiment, it is 105% to 115%. With this angle configuration, noise performance and snow cornering performance are improved in a balanced manner.

[0058] In this embodiment, the angle difference θ1b-θ2b between the bending angle θ1b and the bending angle θ2b is preferably 3° or more, more preferably 8° or more, more preferably 28° or less, and more preferably 18° or less. This improves noise performance and allows for optimal snow cornering performance.

[0059] The outer shoulder lateral groove 50 includes a bend apex 50t between the inner groove portion 50i and the outer groove portion 50o. The bend apex 50t of the outer shoulder lateral groove 50 is located axially inward of the tire's center position 11c of the contact patch of the outer shoulder land portion 11. The tire axial distance L3 from the center position 11c to the bend apex 50t is, for example, 15% to 25% of the tire axial width W2 of the contact patch of the outer shoulder land portion 11. This outer shoulder lateral groove 50 can suppress uneven wear of the outer shoulder land portion 11 and provides superior noise performance.

[0060] From the same viewpoint, the inner shoulder lateral groove 55 includes a bend apex 55t between the inner groove portion 55i and the outer groove portion 55o. The bend apex 55t of the inner shoulder lateral groove 55 is located axially inward of the tire's center position 15c of the contact patch of the inner shoulder land portion 15. The tire axial distance L4 from the center position 15c to the bend apex 55t is, for example, 15% to 25% of the tire axial width W3 of the contact patch of the inner shoulder land portion 15.

[0061] In a further preferred embodiment, the distance L4 is preferably smaller than the distance L3. This makes it easier to convert the noise generated by each transverse groove into white noise.

[0062] The tire axial length L5 of the outer groove portion 50o of the outer shoulder lateral groove 50 is, for example, 60% to 80% of the tire axial width W2 of the contact surface of the outer shoulder land portion 11, preferably 65% ​​to 75%. Similarly, the tire axial length L6 of the outer groove portion 55o of the inner shoulder lateral groove 55 is, for example, 60% to 75% of the tire axial width W3 of the contact surface of the inner shoulder land portion 15, preferably 65% ​​to 70%.

[0063] The tire axial length L5 of the outer groove portion 50o of the outer shoulder lateral groove 50 is preferably greater than the tire axial length L6 of the outer groove portion 55o of the inner shoulder lateral groove 55. Specifically, the aforementioned length L5 of the outer groove portion 50o of the outer shoulder lateral groove 50 is 105% to 130% of the aforementioned length L6 of the outer groove portion 55o of the inner shoulder lateral groove 55. This ensures the rigidity near the first tread end T1 of the land portion 11 of the outer shoulder, thereby achieving superior cornering performance on snow.

[0064] The inner ends of each of the multiple inner shoulder lateral grooves 55 are preferably offset in the tire circumferential direction relative to the inner ends of the outer shoulder lateral grooves 50. This configuration at least means that the inner ends of the groove centerlines of the inner shoulder lateral grooves 55 and the outer shoulder lateral grooves 50 are offset in the tire circumferential direction. The tire circumferential distance L7 between the inner ends of the inner shoulder lateral grooves 55 and the inner ends of the outer shoulder lateral grooves 50 is, for example, 3 to 15 mm, preferably 5 to 10 mm. This arrangement of the grooves disperses the air input from the circumferential groove side, thereby contributing to improved noise performance.

[0065] The circumferential pitch length P1 of the outer shoulder lateral groove 50 is, for example, 65% to 75% of the axial width W2 of the contact surface of the outer shoulder land portion 11. The circumferential pitch length P2 of the inner shoulder lateral groove 55 is, for example, 75% to 90% of the axial width W3 of the contact surface of the inner shoulder land portion 15. However, the present invention is not limited to this configuration.

[0066] The maximum width of the outer shoulder lateral groove 50 and the maximum width of the inner shoulder lateral groove 55 are preferably 3.0–8.0 mm, more preferably 4.0–7.0 mm. In a further preferred embodiment, the maximum width of the plurality of outer shoulder lateral grooves 50 is greater than the maximum width of the plurality of inner shoulder lateral grooves 55. Therefore, the outer shoulder lateral grooves 50 provide greater snow column shearing force, thereby improving snow cornering performance.

[0067] The maximum depth of the outer shoulder lateral groove 50 and the maximum depth of the inner shoulder lateral groove 55 are preferably 8.0–10.0 mm, and more preferably 8.0–9.0 mm. Such outer shoulder lateral grooves 50 and inner shoulder lateral grooves 55 improve noise performance and snow cornering performance in a balanced way.

[0068] The outer shoulder land portion 11 includes, for example, a plurality of outer shoulder tread blocks 51, which are separated by a plurality of outer shoulder transverse grooves 50. The outer shoulder tread blocks 51 do not have grooves, but are provided with a plurality of sipes. In this embodiment, the outer shoulder tread blocks 51 are provided with, for example, a plurality of first outer shoulder sipes 53 and a plurality of second outer shoulder sipes 54.

[0069] In this specification, a "groove" is a grooving element with a small width, meaning an element whose width between two inner walls extending towards each other and substantially parallel is 1.5 mm or less. Furthermore, "substantially parallel" means a shape where the angle between the two inner walls is 10° or less. The width of the groove is preferably 0.5 to 1.5 mm, more preferably 0.4 to 1.0 mm. Each groove in the embodiment is configured as a so-called 3D groove, extending in a serrated shape when viewed from above on the tread, and also extending in a serrated shape in the depth direction of the groove.

[0070] The structure of the cutting groove is not particularly limited; in other configurations, at least one of the edges of the cutting groove on both sides can be formed by a chamfer. Additionally, a flask bottom with a width exceeding 1.5 mm can be connected to the bottom of the cutting groove.

[0071] The first outer shoulder sipe 53 extends axially outward from the outer shoulder circumferential groove 4 and is interrupted within the outer shoulder tread block 51. In this embodiment, the first outer shoulder sipe 53 extends, for example, along the inner groove 50i of the outer shoulder transverse groove 50. Such a first outer shoulder sipe 53 can suppress uneven wear of the outer shoulder land portion 11 and improve snow performance.

[0072] The second outer shoulder sipe 54 is provided, for example, on the outer side of the tire axial direction of the first outer shoulder sipe 53, and its two ends are interrupted within the outer shoulder tread block 51. In this embodiment, the second outer shoulder sipe 54 extends, for example, along the outer groove 50o of the outer shoulder transverse groove 50.

[0073] In a more preferred configuration, within an outer shoulder tread block 51, the number of the second outer shoulder sipes 54 is preferably less than the number of the first outer shoulder sipes 53. This sipe configuration can suppress uneven wear near the first tread end T1 and make the steering feel linear even when cornering with a large slip angle.

[0074] Multiple inner shoulder interruption grooves 56 are provided on the inner shoulder land portion 15. The inner shoulder interruption grooves 56 extend from the inner shoulder circumference toward the groove 7 and are interrupted instead of reaching the second tread end T2. Such inner shoulder interruption grooves 56 help to improve noise performance and snow cornering performance in a balanced way.

[0075] Multiple inner shoulder interruption grooves 56 are located between the inner shoulder circumferential groove 7 and the second tread end T2, including an inner groove portion 56i and an outer groove portion 56o disposed on the outer side of the tire axial direction relative to the inner groove portion 56i. The inner groove portion 56i is inclined in the first direction relative to the tire axial direction. The outer groove portion 56o is inclined in the second direction. As a result, the inner shoulder interruption grooves 56 bend protrudingly in the same direction as the inner shoulder transverse groove 55. Such inner shoulder interruption grooves 56 can suppress uneven wear of the inner shoulder land portion 15 and achieve the above-mentioned effect.

[0076] The bending angle between the inner groove portion 56i and the outer groove portion 56o of the inner shoulder break groove 56 can be applied using the bending angle θ2b of the inner shoulder transverse groove 55 described above. Furthermore, the angle of the inner groove portion 56i of the inner shoulder break groove 56 relative to the tire axial direction can be applied using the aforementioned angle θ2i of the inner groove portion 55i of the inner shoulder transverse groove 55. Similarly, the angle of the outer groove portion 56o of the inner shoulder break groove 56 relative to the tire axial direction can be applied using the aforementioned angle θ2o of the outer groove portion 55o of the inner shoulder transverse groove 55.

[0077] The axial length of the outer groove 56o of the inner shoulder groove 56 is preferably less than the axial length of the inner groove 56i of the inner shoulder groove 56. This ensures a sufficient distance between the inner shoulder groove 56 and the second tread end T2, thereby suppressing the reduction in rigidity near the second tread end T2 and thus achieving superior cornering performance on snow.

[0078] The maximum width of the plurality of inner shoulder grooves 56 is less than the maximum width of the plurality of inner shoulder transverse grooves 55. The maximum width of the inner shoulder groove 56 is, for example, 3.0 mm or less, more preferably 2.5 mm or less. Furthermore, the maximum depth of the plurality of inner shoulder grooves 56 is less than the maximum depth of the plurality of inner shoulder transverse grooves 55. The maximum depth of the inner shoulder groove 56 is, for example, 3.0 to 7.0 mm, preferably 4.0 to 6.0 mm.

[0079] The inner shoulder groove 56 includes a bend apex 56t between the inner groove portion 56i and the outer groove portion 56o. The distance between the bend apex 56t of the inner shoulder groove 56 and the bend apex 55t of the inner shoulder lateral groove 55 along the tire axial direction is, for example, less than 10 mm. Thus, the inner shoulder groove 56 and the inner shoulder lateral groove 55 work together to improve cornering performance on snow.

[0080] In other embodiments, the apex 56t of the inner shoulder break groove 56 may also be located axially inside the tire than the apex 55t of the inner shoulder transverse groove 55. This can suppress uneven wear on the inner shoulder land portion 15.

[0081] The inner shoulder land portion 15 includes, for example, a plurality of inner shoulder tread blocks 57, which are separated by a plurality of inner shoulder transverse grooves 55. In this embodiment, the inner shoulder tread blocks 57 are provided with a plurality of first inner shoulder sipes 58 and a plurality of second inner shoulder sipes 59.

[0082] The first inner shoulder sipe 58 extends, for example, from the inner shoulder circumferential groove 7 outward toward the tire axial direction and is interrupted within the inner shoulder tread block 57. In this embodiment, the first inner shoulder sipe 58 extends, for example, along the inner groove portion 55i of the inner shoulder transverse groove 55. Such a first inner shoulder sipe 58 evenly improves handling stability on dry roads and snow performance.

[0083] The second inner shoulder sipe 59 is provided, for example, on the outer side of the tire axial direction of the first inner shoulder sipe 58, and its two ends are interrupted within the inner shoulder tread blocks 57. In this embodiment, the second inner shoulder sipe 59 extends, for example, along the outer groove 55o of the inner shoulder transverse groove 55. Such a second inner shoulder sipe 59 evenly improves handling stability on dry roads and snow performance.

[0084] Figure 3 Enlarged views of the outer shoulder land portion 11 and the outer middle land portion 12 are shown. Figure 3 As shown, the outer intermediate land portion 12 includes a plurality of outer intermediate tread blocks 24, which are distinguished by a plurality of outer intermediate transverse grooves 20 that traverse the outer intermediate land portion 12 along the tire axis.

[0085] The outer intermediate transverse groove 20 includes a first groove 21 extending axially along the tire at the first tread end T1 and a second groove 22 extending axially along the tire at the second tread end T2. Furthermore, the second groove 22 is offset relative to the first groove 21 in the tire circumferential direction, thereby the outer intermediate transverse groove 20 includes two longitudinal edges 25 extending circumferentially between the edges of the first groove 21 and the second groove 22. These longitudinal edges 25 of the outer intermediate transverse groove 20 provide high friction in the tire axial direction, thereby contributing to improved cornering performance on snow.

[0086] The outer center transverse groove 20 is inclined in the first direction relative to the tire axis. The angle of the outer center transverse groove 20 relative to the tire axis (the angle between the first groove 21 and the second groove 22) is, for example, 45° or less, preferably 15 to 25°. Such an outer center transverse groove 20 helps to improve cornering performance on snow.

[0087] The two longitudinal edges 25 are preferably included, for example, in the central portion where the outer middle tread block 24 is divided into three equal parts in the tire axial direction by an imaginary surface extending parallel to the tire circumference. The angle of the longitudinal edges 25 relative to the tire circumference is, for example, 10° or less, preferably 5° or less. As a further preferred embodiment, the longitudinal edges 25 of this embodiment are arranged parallel to the tire circumference. Such longitudinal edges 25 provide a large reaction force in the tire axial direction when driving on snow, thereby reliably improving cornering performance on snow.

[0088] A plurality of interrupted grooves 26 are preferably provided in the outer middle land portion 12. The interrupted grooves 26 extend from the outer shoulder periphery toward the groove 4 and are interrupted within the outer middle land portion 12. In a preferred configuration, the interrupted grooves 26 are interrupted at a position closer to the first tread end T1 than the longitudinal edge 25 of the outer middle transverse groove 20. In addition, the tire axial length of the interrupted grooves 26 is less than the tire axial length of the inner groove portion 50i of the outer shoulder transverse groove 50. Such interrupted grooves 26 can improve snow cornering performance without compromising noise performance.

[0089] The width of the interrupted groove 26 gradually decreases from the outer shoulder circumference towards the groove 4 toward its interrupted end 26a. Furthermore, the interrupted groove 26 is inclined relative to the tire axial direction in the first direction described above. The angle of the interrupted groove 26 relative to the tire axial direction is, for example, 45° or less, preferably 10 to 25°.

[0090] In a further preferred embodiment, the outer ends of each of the plurality of interrupted grooves 26 in the tire axial direction face the inner ends of the outer shoulder transverse groove 50 in the tire axial direction. This structure means that at least the area of ​​the interrupted groove 26 extending parallel to the tire axial direction while maintaining its width at least at the opening of the outer shoulder circumferential groove 4 (hereinafter referred to as the interrupted groove extension area) overlaps with at least a portion of the opening of the outer shoulder circumferential groove 50. In a preferred embodiment, more than 50% of the tire circumferential width of the interrupted groove extension area overlaps with the opening of the outer shoulder transverse groove 50. Thus, the outer shoulder transverse groove 50 and the interrupted grooves 26 cooperate to form large snow columns, thereby further improving snow cornering performance.

[0091] Multiple outer intermediate sipes 30 are provided on the outer intermediate tread block 24. The outer intermediate sipes 30 are inclined, for example, in the first direction described above. The angle of the outer intermediate sipes 30 relative to the tire axial direction is, for example, 15 to 25°. When the sipes extend in a wavy shape, the above angle is measured at the center line of the amplitude of the sipe.

[0092] At least one of the outer center sipes 30 extends from the outer shoulder circumference to the groove 4 or the outer crown circumference to the groove 5, and has an interrupted end within the outer center tread block 24. Such outer center sipes 30 can maintain the rigidity of the outer center tread block 24 and improve braking performance on snow.

[0093] In this embodiment, the outer intermediate tread block 24 has a recess 34 between the first groove 21 and the interrupted groove 26. This recess 34 is formed by recessing the area surrounded by an elliptical edge that extends longitudinally in the tire circumferential direction. Such a recess 34 appropriately mitigates the rigidity of the outer intermediate tread block 24, thereby helping to prevent snow from clogging the outer intermediate transverse groove 20 and the interrupted groove 26.

[0094] Figure 4 An enlarged view of the inner central land area 14 and the inner shoulder land area 15 is shown. Figure 4 As shown, the inner middle land portion 14 includes a plurality of inner middle patterned blocks 36, which are separated by a plurality of inner middle transverse grooves 35.

[0095] The inner intermediate transverse groove 35, for example, completely traverses the inner intermediate land portion 14 along the tire axial direction. The inner intermediate transverse groove 35, for example, is inclined in the first direction mentioned above relative to the tire axial direction. The angle of the inner intermediate transverse groove 35 relative to the tire axial direction is, for example, 15 to 25°.

[0096] In a preferred embodiment, the outer ends of each of the plurality of inner intermediate transverse grooves 35 in the tire axial direction face the inner ends of the inner shoulder interruption groove 56 in the tire axial direction. This structure means that at least for the opening of the inner intermediate transverse groove 35 at the inner shoulder circumferential groove 7, the region extending parallel to the tire axial direction while maintaining its width (hereinafter referred to as the inner intermediate transverse groove extension region) overlaps with at least a portion of the opening of the inner shoulder interruption groove 56 at the inner shoulder circumferential groove 7. In a preferred embodiment, a portion of more than 50% of the tire circumferential width of the inner intermediate transverse groove extension region overlaps with the aforementioned opening of the outer shoulder transverse groove 50. Thus, the inner intermediate transverse grooves 35 and the inner shoulder interruption groove 56 cooperate to form a large snow column, thereby further improving snow cornering performance.

[0097] From the viewpoint of further improving the above effect, it is preferable that the area obtained by extending the inner intermediate transverse groove 35 parallel to its length direction toward the second tread end T2 side overlaps with more than 50% of the opening area of ​​the inner groove 56i of the inner shoulder interruption groove 56 when the tread is viewed from above.

[0098] A plurality of lateral grooves 38 are provided on the inner intermediate land portion 14. The lateral grooves 38 completely traverse the inner intermediate land portion 14 along the tire axis. The lateral grooves 38 are inclined in the first direction relative to the tire axis. In addition, the width and depth of the lateral grooves 38 are smaller than the width and depth of the inner intermediate lateral grooves 35. Such lateral grooves 38 can maintain the rigidity of the inner intermediate land portion 14 and increase the edge composition.

[0099] In a preferred embodiment, the outer ends of each of the plurality of lateral grooves 38 in the tire axial direction face the inner ends of the inner shoulder lateral grooves 55 in the tire axial direction. This structure means that at least for the opening of the lateral groove 38 at the inner shoulder circumferential groove 7, the area extending parallel to the tire axial direction while maintaining its width (hereinafter referred to as the lateral groove extension region) overlaps with at least a portion of the opening of the inner shoulder lateral groove 55 at the inner shoulder circumferential groove 7. In a preferred embodiment, more than 50% of the tire circumferential width of the lateral groove extension region overlaps with the aforementioned opening of the outer shoulder lateral groove 50. Therefore, the lateral grooves 38 open easily upon contact with the ground, increasing the frictional force provided by the edges. Consequently, snow performance is improved.

[0100] From the viewpoint of further enhancing the above-mentioned effects, it is preferable that the area obtained by extending the inner groove portion 55i of the inner shoulder transverse groove 55 parallel to its length direction toward the tire equator C side overlaps with more than 50% of the opening area of ​​the transverse groove 38 when the tread is viewed from above.

[0101] Multiple inner center sipes 40 are provided on the inner center tread block 36. These inner center sipes 40 include, for example, fully open sipes 41 that completely traverse the inner center tread block 36 along the tire axial direction, and semi-open sipes 42 that extend from the inner tread circumferential groove 6 and are interrupted within the inner center tread block 36. Such inner center sipes 40 help to evenly improve handling stability on dry roads and snow performance.

[0102] In this embodiment, a recess 48 is provided between the semi-open sipe 42 of the inner intermediate tread block 36 and the inner shoulder circumferential groove 7. This recess 48 is formed by recessing the area surrounded by an elliptical edge that extends longitudinally in the tire circumferential direction. Such a recess 48 can appropriately alleviate the rigidity of the inner intermediate tread block 36, thereby preventing snow from clogging the grooves around it.

[0103] Figure 5 An enlarged view of the land portion 13 of the tire crown is shown. (See attached image.) Figure 5 As shown, the land portion 13 of the tread includes multiple tread pattern blocks 61 that are separated by multiple tread grooves 60.

[0104] The lateral groove 60 completely traverses the land portion 13 of the tire crown along the tire axial direction. In this embodiment, the lateral groove 60 includes, for example, a first lateral groove 60a and a second lateral groove 60b. The first lateral groove 60a communicates, for example, with the outer circumferential groove 5 of the tire crown and is inclined in the first direction relative to the tire axial direction. The second lateral groove 60b communicates, for example, with the inner circumferential groove 6 of the tire crown and is inclined in the second direction relative to the tire axial direction. Such a lateral groove 60 can strongly compact snow internally, thereby further improving snow performance.

[0105] The outer end of the first tread end T1 side of the first crown groove 60a overlaps, for example, with the area obtained by extending the second groove 22 of the outer intermediate transverse groove 20 along its length direction. The outer end of the second tread end T2 side of the second crown groove 60b overlaps, for example, with the area obtained by extending the end of the inner crown circumferential groove 6 side of the inner intermediate transverse groove 35 parallel to the tire axial direction.

[0106] The tread block 61 is provided with a first tread interruption groove 62 and a second tread interruption groove 63. The first tread interruption groove 62 extends, for example, from the transverse tread groove 60 and interrupts within the tread block 61. The second tread interruption groove 63 extends from the inner circumferential tread groove 6 and interrupts within the tread block 61. Such a first tread interruption groove 62 and a second tread interruption groove 63 can appropriately alleviate the rigidity of the tread block 61, thereby preventing snow from clogging the transverse tread groove 60 and the inner circumferential tread groove 6.

[0107] The tread pattern block 61 is provided with a plurality of tread grooves 65. The tread grooves 65 are inclined, for example, in the second direction mentioned above.

[0108] 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 and can be implemented in various ways.

[0109]

Example

[0110] Based on the specifications in Tables 1 and 2, a prototype with [specifications] was manufactured. Figure 1 The basic tread pattern size is 195 / 65R15. As a comparative example, a prototype tire with... Figure 1 The tire has a basic tread pattern, and the angle relationship between the inner and outer grooves of the outer shoulder lateral groove and the inner shoulder lateral groove does not satisfy the specific aspects of the invention. Additionally, a tire used as a benchmark for comparing noise performance (a benchmark tire), such as... Figure 6 As shown, a tire with the outer shoulder lateral groove a and the inner shoulder lateral groove b not bent was prototyped. The comparative example tire and the reference tire, in addition to the above-described structure, have the same characteristics as... Figure 1 The tread pattern shown is the same in practice. Noise performance and snow cornering performance were tested for each test tire. Common specifications and testing methods for all test tires are as follows.

[0111] Wheel rim: 15×6.0JJ

[0112] Tire internal pressure: 200 kPa for front tires, 200 kPa for rear tires

[0113] Test vehicle: 1500cc engine, front-wheel drive

[0114] Tire mounting location: All wheels

[0115] <Snow Cornering Performance>

[0116] The cornering performance of the test vehicle on snow was evaluated by the driver's senses. The results were used as a comparison example with a score of 100, where a higher score indicates better cornering performance on snow.

[0117] <Noise Performance>

[0118] The maximum sound pressure level of the exterior noise was measured when the test vehicle was traveling at 70 km / h on a dry road surface. The result was expressed as the difference between the sound pressure level of the test vehicle and that of the reference tire, i.e., the sound pressure reduction, with the sound pressure reduction of the comparative example as an exponent of 100. The larger the exponent, the lower the maximum sound pressure level of the noise, and the better the noise performance.

[0119] The test results are shown in Tables 1 and 2.

[0120] Table 1

[0121]

[0122] Table 2

[0123]

[0124] As shown in Tables 1 and 2, it can be confirmed that the tires of the embodiments exhibit superior snow cornering performance. Furthermore, it can be confirmed that the tires of the embodiments demonstrate improved noise performance.

Claims

1. A tire having a tread portion facing a designated direction for mounting on a vehicle, characterized in that, The tread portion includes: a first tread end that becomes the outer side of the vehicle when mounted on the vehicle; a second tread end that becomes the inner side of the vehicle when mounted on the vehicle; a plurality of circumferential grooves that extend continuously along the tire circumference between the first tread end and the second tread end; and a plurality of land portions that are separated by the plurality of circumferential grooves. The plurality of circumferential grooves include: an outer shoulder circumferential groove located closest to the first tread end, and an inner shoulder circumferential groove located closest to the second tread end. The plurality of land portions include: an outer shoulder land portion disposed on the axially outer side of the tire in the outer shoulder circumferential groove and including the first tread end, and an inner shoulder land portion disposed on the axially outer side of the tire in the inner shoulder circumferential groove and including the second tread end. The outer shoulder land portion is provided with a plurality of outer shoulder transverse grooves extending from the outer shoulder circumferential groove to a position beyond the first tread end. Multiple inner shoulder transverse grooves are provided on the inner shoulder land portion, extending from the inner shoulder circumferential groove to a position beyond the end of the second tread. Each of the aforementioned outer shoulder transverse grooves, between the outer shoulder circumferential groove and the first tread end, includes an inner groove portion inclined in a first direction relative to the tire axial direction, and an outer groove portion disposed on the outer side of the inner groove portion and inclined in a second direction opposite to the first direction relative to the tire axial direction, thereby bulging outward to one side of the tire circumferential direction. Each of the inner shoulder transverse grooves, located between the inner shoulder circumferential groove and the second tread end, includes an inner groove portion inclined in the first direction relative to the tire axial direction, and an outer groove portion disposed on the outer side of the inner groove portion and inclined in the second direction relative to the tire axial direction, thereby bulging outward to the other side of the tire circumferential direction. The angle θ2i of the inner groove portion of the inner shoulder transverse groove relative to the tire axial direction is greater than the angle θ1i of the inner groove portion of the outer shoulder transverse groove relative to the tire axial direction. The angle θ2o of the outer groove of the inner shoulder transverse groove relative to the tire axis is smaller than the angle θ1o of the outer groove of the outer shoulder transverse groove relative to the tire axis.

2. The tire according to claim 1, characterized in that, The difference between the angle θ2i of the inner groove of the inner shoulder transverse groove and the angle θ1i of the inner groove of the outer shoulder transverse groove is 5 to 20°.

3. The tire according to claim 1 or 2, characterized in that, The difference between the angle θ2o of the outer groove of the inner shoulder transverse groove and the angle θ1o of the outer groove of the outer shoulder transverse groove is less than 10°.

4. The tire according to any one of claims 1 to 3, characterized in that, The axial length of the outer groove portion of the outer shoulder groove is greater than the axial length of the outer groove portion of the inner shoulder groove.

5. The tire according to any one of claims 1 to 4, characterized in that, The maximum width of the plurality of outer shoulder transverse grooves is greater than the maximum width of the plurality of inner shoulder transverse grooves.

6. The tire according to any one of claims 1 to 5, characterized in that, The inner shoulder land portion is provided with a plurality of inner shoulder interruption grooves that extend from the inner shoulder circumferential groove and are interrupted instead of reaching the second tread end.

7. The tire according to claim 6, characterized in that, The maximum width of the plurality of inner shoulder break grooves is less than the maximum width of the plurality of inner shoulder transverse grooves.

8. The tire according to claim 6 or 7, characterized in that, The maximum depth of the plurality of inner shoulder break grooves is less than the maximum depth of the plurality of inner shoulder transverse grooves.

9. The tire according to any one of claims 6 to 8, characterized in that, The plurality of inner shoulder interruption grooves are located between the inner shoulder circumferential groove and the second tread end, including an inner groove portion that is inclined toward the first direction relative to the tire axial direction, and an outer groove portion that is disposed on the outer side of the inner groove portion and inclined toward the second direction relative to the tire axial direction, thereby bending in the same direction as the inner shoulder transverse groove.

10. The tire according to claim 9, characterized in that, The inner shoulder transverse groove includes the apex of the bend between the inner groove and the outer groove. The inner shoulder break groove includes the bend apex between the inner groove and the outer groove. The apex of the bend in the inner shoulder groove is located axially inside the tire than the apex of the bend in the inner shoulder transverse groove.

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