JP7494592B2 - tire - Google Patents

Description

The present invention relates to a tire.

The following Patent Document 1 proposes a pneumatic tire that improves the balance between turning performance and limit behavior when turning on snowy and icy roads by defining the pattern elements of the tread portion.

JP 2013-237360 A

In recent years, as vehicles have become more powerful, there is a demand for tires designed for use in winter that offer improved braking and cornering performance on ice.

The present invention was devised in light of the above-mentioned circumstances, and its main objective is to provide a tire with improved braking and cornering performance on ice.

The present invention is a tire having a tread portion with a specified orientation when mounted on a vehicle, the tread portion including an outer tread edge located on the outer side of the vehicle when mounted on the vehicle, an inner tread edge located on the inner side of the vehicle when mounted on the vehicle, a plurality of circumferential grooves extending continuously in a tire circumferential direction, and a plurality of land portions divided by the plurality of circumferential grooves, the plurality of land portions including an outer shoulder land portion including the outer tread edge, the outer shoulder land portion being divided into a plurality of outer shoulder blocks by a plurality of outer shoulder lateral grooves extending in the tire axial direction, at least one of the outer shoulder blocks being divided into a first block piece on the outer tread edge side and a second block piece on the inner tread edge side by a first longitudinal narrow groove extending in the tire circumferential direction, the first block piece being provided with a plurality of first sipes, and the second block piece being provided with a plurality of second sipes, the total number of the second sipes of the second block piece being greater than the total number of the first sipes of the first block piece.

In the tire of the present invention, it is desirable that the first sipes 23 and the second sipes 24 are each arranged at an angle of 10° or less with respect to the tire axial direction.

In the tire of the present invention, it is preferable that the first longitudinal narrow groove is arranged in the central region when the outer shoulder block is divided into three equal parts in the axial direction of the tire.

In the tire of the present invention, it is desirable that the first longitudinal narrow groove is curved in at least one place.

In the tire of the present invention, it is desirable that the depth of the first sipe and the depth of the second sipe are greater than the depth of the first longitudinal narrow groove.

In the tire of the present invention, it is desirable that the maximum axial width of the second block piece is 40% to 60% of the maximum axial width of the outer shoulder block.

In the tire of the present invention, it is preferable that the first sipe and the second sipe each have a tie bar with a raised bottom.

In the tire of the present invention, it is desirable that the depth of the portion where the tie bar is provided is greater than the depth of the first longitudinal narrow groove.

In the tire of the present invention, the multiple land portions include an inner shoulder land portion that includes the inner tread edge, and the inner shoulder land portion is divided into multiple inner shoulder blocks by multiple inner shoulder lateral grooves extending in the tire axial direction, and it is preferable that the maximum axial width of the inner shoulder block is smaller than the maximum axial width of the outer shoulder block.

In the tire of the present invention, the multiple land portions include an inner shoulder land portion including the inner tread edge, the inner shoulder land portion is divided into multiple inner shoulder blocks by multiple inner shoulder lateral grooves extending in the tire axial direction, at least one of the inner shoulder blocks is provided with a second longitudinal narrow groove extending in the tire circumferential direction, and it is desirable that the depth of the second longitudinal narrow groove is greater than the depth of the first longitudinal narrow groove.

In the tire of the present invention, the multiple land portions include an inner shoulder land portion including the inner tread edge, the inner shoulder land portion is divided into multiple inner shoulder blocks by multiple inner shoulder lateral grooves extending in the tire axial direction, at least one of the inner shoulder blocks is divided into a third block piece on the inner tread edge side and a fourth block piece on the outer tread edge side by a second longitudinal narrow groove extending in the tire circumferential direction, the third block piece is provided with multiple third sipes, the fourth block piece is provided with multiple fourth sipes, and it is preferable that the total number of the fourth sipes in the fourth block piece is the same as the total number of the third sipes in the third block piece.

In the tire of the present invention, the plurality of circumferential grooves includes an outer shoulder circumferential groove disposed closest to the outer tread end, and it is preferable that the outer shoulder circumferential groove has the smallest groove width among the plurality of circumferential grooves.

In the tire of the present invention, it is desirable that the maximum groove width of the portion of the outer shoulder lateral groove facing the first block piece is greater than the maximum groove width of the portion of the outer shoulder lateral groove facing the second block piece.

By adopting the above-mentioned configuration, the pneumatic tire of the present invention can improve braking performance and cornering performance on ice.

1 is a development view of a tread portion of a tire according to one embodiment of the present invention. FIG. 2 is an enlarged view of an outer shoulder land portion and an outer middle land portion of FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. FIG. 2 is an enlarged view of the inner shoulder land portion of FIG. 1 . FIG. 2 is an enlarged view of an inner middle land portion and a crown land portion of FIG. FIG. 4 is an enlarged view of an outer shoulder land portion of a comparative tire.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
Fig. 1 is a development view of a tread portion 2 of a tire 1 according to the present embodiment. As shown in Fig. 1, the tire 1 according to the present 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 such an embodiment.

The tire 1 of this embodiment has a tread portion 2 in which the orientation for mounting on a vehicle is specified. The orientation for mounting on a vehicle is indicated, for example, by letters or marks on the sidewall portion (not shown).

The tread portion 2 is composed of four circumferential grooves 3 that extend continuously in the tire circumferential direction between the outer tread end To and the inner tread end Ti, and five land portions 4 that are divided into the circumferential grooves 3. In other words, the tire 1 of the present invention is configured as a so-called five-rib tire. However, the tire 1 of the present invention is not limited to this embodiment, and may be, for example, a so-called four-rib tire composed of three circumferential grooves 3 and four land portions 4.

The outer tread edge To is the tread edge intended to be located on the outer side of the vehicle when mounted on the vehicle, and the inner tread edge Ti is the tread edge intended to be located on the inner side of the vehicle when mounted on the vehicle. The outer tread edge To and the inner tread edge Ti each correspond to the axially outermost contact positions of the tire when the tire 1 in a normal state is loaded with a normal load and touches the ground on a flat surface with a camber angle of 0°.

In the case of pneumatic tires for which various standards are established, the "normal state" refers to a state in which the tire is mounted on a normal rim, inflated to the normal internal pressure, and unloaded. In the case of tires for which various standards are not established or non-pneumatic tires, the normal state refers to a standard usage state according to the intended use of the tire, in which the tire is not mounted on a vehicle and is unloaded. In this specification, unless otherwise specified, the dimensions of each part of the tire are values measured in the normal state. Note that each configuration described in this specification is assumed to allow for normal errors that are included in rubber molded products.

A "genuine rim" is a rim that is specified for each tire by the standard system that includes the standard on which the tire is based. For example, in the case of JATMA, it is called a "standard rim," in the case of TRA, it is called a "design rim," and in the case of ETRTO, it is called a "measuring rim."

"Normal internal pressure" is the air pressure set for each tire by each standard in the standard system on which the tire is based. For JATMA, it is the "maximum air pressure." For TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." For ETRTO, it is the "INFLATION PRESSURE."

In the case of pneumatic tires for which various standards are established, the "normal load" is the load that each standard specifies for each tire in the standard system that includes the standards on which the tire is based. For JATMA, it is the "maximum load capacity", for TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", and for ETRTO, it is the "LOAD CAPACITY". For tires for which various standards are not established or non-pneumatic tires, the "normal load" refers to the load acting on a single tire in the standard mounting state of the tire. The "standard mounting state" refers to the state in which the tire is mounted on a standard vehicle corresponding to the intended use of the tire, and the vehicle is stationary on a flat road surface in a drivable state.

The circumferential grooves 3 include, for example, an outer shoulder circumferential groove 5, an outer crown circumferential groove 6, an inner crown circumferential groove 7, and an inner shoulder circumferential groove 8. The outer shoulder circumferential groove 5 is provided on the outermost tread edge To side among the multiple circumferential grooves 3. The outer crown circumferential groove 6 is adjacent to the inner tread edge Ti side of the outer shoulder circumferential groove 5 and is provided between the outer shoulder circumferential groove 5 and the tire equator C. The inner crown circumferential groove 7 is provided between the tire equator C and the inner tread edge Ti. The inner shoulder circumferential groove 8 is provided between the inner crown circumferential groove 7 and the inner tread edge Ti.

The circumferential grooves 3 may be of various configurations, such as extending linearly in the tire circumferential direction or extending in a zigzag pattern. In this embodiment, the outer shoulder circumferential groove 5, the inner crown circumferential groove 7, and the inner shoulder circumferential groove 8 extend linearly parallel to the tire circumferential direction. On the other hand, the outer crown circumferential groove 6 extends in a zigzag pattern. However, the tire 1 of the present invention is not limited to such a configuration.

The axial distance L1 from the groove centerline of the outer shoulder circumferential groove 5 or the inner shoulder circumferential groove 8 to the tire equator C is, for example, 20% to 35% of the tread width TW. The axial distance L2 from the groove centerline of the outer crown circumferential groove 6 or the inner crown circumferential groove 7 to the tire equator C is, for example, 3% to 15% of the tread width TW. In a desirable embodiment, the axial distance from the groove centerline of the inner crown circumferential groove 7 to the tire equator C is greater than the axial distance from the groove centerline of the outer crown circumferential groove 6 to the tire equator C. The tread width TW is the axial distance from the outer tread edge To to the inner tread edge Ti in the normal state.

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 5.0% of the tread width TW. In this embodiment, of the four circumferential grooves 3, the outer shoulder circumferential groove 5 has the smallest groove width.

The land portion 4 includes an outer shoulder land portion 11, an outer middle land portion 12, a crown land portion 15, an inner middle land portion 14, and an inner shoulder land portion 13. The outer shoulder land portion 11 includes the outer tread edge To. The outer middle land portion 12 is divided between the outer shoulder circumferential groove 5 and the outer crown circumferential groove 6. The crown land portion 15 is divided between the outer crown circumferential groove 6 and the inner crown circumferential groove 7. The inner middle land portion 14 is divided between the inner shoulder circumferential groove 8 and the inner crown circumferential groove 7. The inner shoulder land portion 13 includes the inner tread edge Ti.

Figure 2 shows an enlarged view of the outer shoulder land portion 11 and the outer middle land portion 12. As shown in Figure 2, the outer shoulder land portion 11 is divided into multiple outer shoulder blocks 20 by multiple outer shoulder lateral grooves 18 that extend in the tire axial direction.

At least one of the outer shoulder blocks 20 is divided into a first block piece 21 on the outer tread edge To side and a second block piece 22 on the inner tread edge Ti side by a first longitudinal narrow groove 19 extending in the tire circumferential direction.

The first block piece 21 is provided with a plurality of first sipes 23. The second block piece 22 is provided with a plurality of second sipes 24.

In this specification, a "sipe" refers to a cut element having a minute width, with the width between two opposing sipe walls being 0.6 mm or less. The width of the sipe is preferably 0.1 to 0.5 mm, and more preferably 0.2 to 0.4 mm. The sipe of this embodiment has the width in the above range throughout its entire depth. In this specification, a cut element that includes a region with a width of 0.6 mm or less that accounts for 50% or more of its entire depth in cross section is treated as a sipe (a sipe including a groove element), even if it includes a region with a width greater than 0.6 mm in part. In addition, a cut element that includes a region with a width greater than 0.6 mm that accounts for 50% or more of its entire depth in cross section is treated as a groove (a groove including a sipe element), even if it includes a region with a width of 0.6 mm or less in part.

In the present invention, the total number N2 of second sipes 24 arranged on one second block piece 22 is greater than the total number N1 of first sipes 23 arranged on one first block piece 21. By adopting the above configuration, the pneumatic tire of the present invention can improve braking performance and cornering performance on ice. The following mechanism is presumed to be the reason for this.

When braking on ice, it is desirable to have fewer sipes on the outer tread edge To side of the outer shoulder block 20 in order to prevent the blocks from collapsing. On the other hand, when turning on ice at a normal speed, the lateral G is smaller than when driving on a dry road surface, and the maximum length of the contact patch tends to be formed in a region of the tread of the outer shoulder land portion 11 that is relatively axially inward of the tire. In the present invention, by making the total number N2 of the second sipes 24 larger than the total number N1 of the first sipes 23, it is possible to place more sipes in the above-mentioned region while preventing the blocks from collapsing as described above, which is presumably to improve braking performance and cornering performance on ice.

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

The axial width W2 of the outer shoulder block 20 is, for example, 15% to 30% of the tread width TW (shown in FIG. 1, and the same applies below). However, the present invention is not limited to this embodiment.

The outer shoulder lateral groove 18 extends at an angle θ1 of, for example, 10° or less with respect to the tire axial direction. The outer shoulder lateral groove 18 includes a main body portion 18a that communicates with the outer shoulder circumferential groove 5 and a widened portion 18b that communicates with the outer tread edge To side of the main body portion 18a. The main body portion 18a has a length of, for example, 50% or more of the entire length of the outer shoulder lateral groove 18. In addition, the groove width W3 of the main body portion 18a is larger than the groove width W4 of the outer shoulder circumferential groove 5. The widened portion 18b has a groove width W5 that is larger than that of the main body portion 18a. The groove width W5 of the widened portion 18b is 103% to 110% of the groove width W3 of the main body portion 18a. As a result, the maximum groove width of the portion of the outer shoulder lateral groove 18 facing the first block piece 21 is larger than the maximum groove width of the portion of the outer shoulder lateral groove 18 facing the second block piece 22. Such outer shoulder grooves 18 help provide excellent on-snow performance.

The first longitudinal narrow groove 19 is arranged, for example, in the central region when the outer shoulder block 20 is divided into three equal parts in the axial direction. The axial distance between the groove centerline of the first longitudinal narrow groove 19 and the axial center position of the outer shoulder block 20 is 10% or less of the axial width W2 of the outer shoulder block 20. The first longitudinal narrow groove 19 also communicates with the main body portion 18a of the outer shoulder lateral groove 18. As a result, the maximum axial width of the second block piece 22 is 40% to 60% of the maximum axial width of the outer shoulder block 20.

The first longitudinal groove 19 is bent in at least one place. In this embodiment, the first longitudinal groove 19 is bent at two places at obtuse angles. Such a first longitudinal groove 19 provides frictional forces in multiple directions on ice. In this specification, "the groove is bent" includes at least a case where the length of the bent area of the groove center line is 3 mm or less.

The groove width W6 of the first longitudinal groove 19 is greater than 0.6 mm. The groove width W6 is, for example, 0.8 to 2.0 mm, and preferably 1.0 to 1.5 mm. The depth of the first longitudinal groove 19 is, for example, 1.5 to 3.0 mm. Such a first longitudinal groove 19 improves turning performance on ice while maintaining the rigidity of the outer shoulder block 20.

In this embodiment, the total number N1 of the first sipes 23 is, for example, 3 to 5. The total number N2 of the second sipes 24 is, for example, 4 to 6. From the viewpoint of suppressing uneven wear of the first block piece 21 and the second block piece 22, it is desirable that the total number N2 is 1.10 to 2.50 times the total number N1. However, the present invention is not limited to such an embodiment.

The first sipe 23 and the second sipe 24 have a tire axial component larger than the tire circumferential component. It is preferable that the first sipe 23 and the second sipe 24 cross each block piece in the tire axial direction. In this embodiment, the first sipe 23 and the second sipe 24 are arranged at an angle of 10° or less with respect to the tire axial direction. When each sipe extends in a zigzag shape, the angle is measured on a virtual line connecting both ends of the sipe. The first sipe 23 and the second sipe 24 are arranged approximately parallel to the outer shoulder lateral groove 18. Here, approximately parallel includes a case where the angle difference between the sipe and the lateral groove is 5° or less. Furthermore, the first block piece 21 and the second block piece 22 do not have sipes with a tire circumferential component larger than the tire axial component. This further improves traction performance and braking performance on ice.

At least one of the first sipes 23 and the second sipes 24 extends in a zigzag pattern in the length direction. In a preferred embodiment, at least one of the first sipes 23 and the second sipes 24 is configured as a so-called 3D sipe that also extends in a zigzag pattern in the depth direction. Such first sipes 23 and second sipes 24 suppress excessive collapse of the blocks when the opposing sipe walls come into contact with each other, improving braking performance on ice.

Of the multiple first sipes 23 aligned in the tire circumferential direction and the multiple second sipes 24 aligned in the tire circumferential direction, at least the sipes adjacent to the outer shoulder lateral groove 18 are preferably configured as 3D sipes. As a more preferable aspect, in this embodiment, all sipes provided in the outer shoulder block 20 are configured as 3D sipes. This ensures that the above-mentioned effects are achieved.

Figure 3 shows a cross-sectional view of the first sipe 23 of Figure 2 taken along line A-A, as a diagram for explaining the configuration of the first sipe 23 and the second sipe 24. The configuration of the first sipe 23 described below can also be applied to the second sipe 24. In addition, in Figure 3, the bent portion of the first sipe 23 configured as a 3D sipe is shown by a two-dot chain line. As shown in Figure 3, it is desirable that the maximum depth d1 of the first sipe 23 is greater than the maximum depth of the first longitudinal fine groove 19. The depth d1 of the first sipe 23 is 2.50 to 4.00 times the depth of the first longitudinal fine groove 19. Such a first sipe 23 can exhibit excellent water absorption.

The first sipe 23 of this embodiment has a tie bar 25 with a raised bottom. The tie bar 25 includes, for example, an end tie bar 26 provided at the end of the first sipe 23 opposite the first longitudinal narrow groove 19, and a central tie bar 27 provided in the center of the first sipe 23 in the longitudinal direction. The central tie bar 27 is provided, for example, in the central region when the first sipe 23 is divided into three equal parts in the longitudinal direction. In a more desirable embodiment, at least a portion of the central tie bar 27 overlaps with the center position of the first sipe 23 in the longitudinal direction. Such end tie bars 26 and central tie bar 27 can prevent the first sipe 23 from opening excessively, improving braking performance on ice.

The height h1 of the central tie bar 27 is, for example, smaller than the height of the end tie bar 26. The height h1 of the central tie bar 27 is 40% to 60% of the maximum depth d1 of the first sipe 23. The width W7 of the central tie bar 27 is smaller than the width of the end tie bar 26. The width W7 of the central tie bar 27 is, for example, 80% to 120% of the groove width W6 of the first longitudinal narrow groove 19. Such a central tie bar 27 can suppress excessive opening of the first sipe 23 while maintaining the water absorption of the first sipe 23. The width W7 is, for example, measured at a height that is 50% of the maximum height of the central tie bar 27.

From the same viewpoint, it is desirable that the depth of each of the portions in which the tie bars 25 are provided is greater than the depth of the first longitudinal grooves 19.

As shown in FIG. 2, the outer middle land portion 12 is provided with a plurality of outer middle lateral grooves 29 extending in the tire axial direction. The outer middle lateral grooves 29 cross the outer middle land portion 12. As a result, the outer middle land portion 12 is divided into a plurality of outer middle blocks 30.

The outer middle lateral grooves 29 are inclined, for example, in a first direction (slanting downward to the right in each figure of this specification) with respect to the tire axial direction. The angle θ2 of the outer middle lateral grooves 29 with respect to the tire axial direction is, for example, 45° or less, and preferably 15 to 25°. Such outer middle lateral grooves 29 improve braking performance and cornering performance on ice in a well-balanced manner.

The end of the outer middle lateral groove 29 on the outer tread edge To side should preferably overlap with the region of the end of the outer shoulder lateral groove 18 on the inner tread edge Ti side extended parallel to the tire axial direction. This allows solid snow pillars to be generated at the intersections of the outer shoulder circumferential groove 5 with the outer shoulder lateral groove 18 and the outer middle lateral groove 29 when driving on snow, and these are sheared to generate a large reaction force. This improves on-snow performance.

In this embodiment, the outer crown circumferential groove 6 extends in a zigzag shape including a long inclined portion 6a and a short inclined portion 6b having a shorter length, and at least one of the outer middle lateral grooves 29 is connected to the short inclined portion 6b. In a more desirable embodiment, the outer middle lateral grooves 29 connected to the short inclined portion 6b and the outer middle lateral grooves 29 connected to the long inclined portion 6a are alternately arranged in the tire circumferential direction. Such outer middle lateral grooves 29 can generate solid snow columns at the intersections with the short inclined portions 6b.

The outer middle block 30 is provided with a middle-discontinuous groove 32. The middle-discontinuous groove 32 extends from the outer crown circumferential groove 6 and terminates within the outer middle block 30. The groove width W8 of the middle-discontinuous groove 32 is smaller than the groove width of the outer shoulder lateral groove 18 and the groove width of the outer middle lateral groove 29. Such a middle-discontinuous groove 32 can improve braking performance on ice while maintaining the rigidity of the outer middle block 30.

The middle-disconnected grooves 32 are, for example, inclined in a first direction relative to the tire axial direction. In a preferred embodiment, the angle difference between the middle-disconnected grooves 32 and the outer middle lateral grooves 29 is 5° or less. Such middle-disconnected grooves 32 are useful for suppressing uneven wear of the outer middle blocks 30.

The outer middle block 30 is provided with a number of outer middle sipes 33. The outer middle sipes 33 are inclined, for example, in a second direction (upward to the right in each figure in this specification) that is opposite to the first direction with respect to the tire axial direction. The angle of the outer middle sipes 33 with respect to the tire axial direction is, for example, 15 to 25 degrees. Note that when the sipes extend in a zigzag shape, the direction and angle of inclination are measured on an imaginary straight line connecting both ends of the sipe.

Figure 4 shows an enlarged view of the inner shoulder land portion 13. As shown in Figure 4, the inner shoulder land portion 13 is divided into multiple inner shoulder blocks 35 by multiple inner shoulder lateral grooves 34 that extend in the tire axial direction.

The inner shoulder lateral groove 34 is inclined, for example, in the second direction with respect to the tire axial direction. In this embodiment, the angle θ3 of the inner shoulder lateral groove 34 with respect to the tire axial direction is larger than the angle of the outer shoulder lateral groove 18 with respect to the tire axial direction. Specifically, the angle θ3 of the inner shoulder lateral groove 34 with respect to the tire axial direction is 5 to 15°. Such an inner shoulder lateral groove 34 improves braking performance and cornering performance on ice in a well-balanced manner.

The maximum axial width W9 of the inner shoulder block 35 is, for example, 15% to 25% of the tread width TW. In a more desirable embodiment, the maximum axial width W9 of the inner shoulder block 35 is smaller than the maximum axial width W2 of the outer shoulder block 20. This makes the steering response during cornering more linear, improving handling stability.

At least one of the inner shoulder blocks 35 is divided into a third block piece 41 on the inner tread edge Ti side and a fourth block piece 42 on the outer tread edge To side by a second longitudinal narrow groove 38 extending in the tire circumferential direction.

The second longitudinal narrow groove 38 is disposed, for example, in a central region when the inner shoulder block 35 is divided into thirds in the axial direction. The axial distance between the groove centerline of the second longitudinal narrow groove 38 and the axial center position of the inner shoulder block 35 is 10% or less of the maximum axial width W9 of the inner shoulder block 35. The second longitudinal narrow groove 38 extends linearly in parallel to the tire circumferential direction. As a result, the maximum axial width of the fourth block piece 42 is 40% to 60% of the maximum axial width W9 of the inner shoulder block 35 .

The groove width W10 of the second longitudinal groove 38 is greater than 0.6 mm. The groove width W10 is, for example, 0.8 to 2.0 mm, and preferably 1.0 to 1.5 mm. The depth of the second longitudinal groove 38 is, for example, 1.5 to 3.0 mm. In a preferred embodiment, the depth of the second longitudinal groove 38 is greater than the depth of the first longitudinal groove 19. Such second longitudinal grooves 38 are useful for improving turning performance on ice.

The third block piece 41 is provided with a plurality of third sipes 43. The fourth block piece 42 is provided with a plurality of fourth sipes 44. In this embodiment, the total number N4 of fourth sipes 44 arranged on one fourth block piece 42 is greater than the total number N3 of third sipes 43 arranged on one third block piece 41. This improves braking performance and cornering performance on ice in a well-balanced manner.

In yet another embodiment, the total number N4 of the fourth sipes 44 of the fourth block piece 42 may be the same as the total number N3 of the third sipes 43 of the third block piece 41. In such an embodiment, uneven wear of the inner shoulder block 35 is suppressed, and the frequency bands of the noise generated by the outer shoulder block 20 and the noise generated by the inner shoulder block 35 are dispersed, thereby improving noise performance.

In this embodiment, the total number N3 of the third sipes 43 is, for example, 3 to 5. The total number N4 of the fourth sipes 44 is, for example, 4 to 6. However, the present invention is not limited to such an embodiment.

The third sipe 43 and the fourth sipe 44 have a tire axial component that is larger than the tire circumferential component. It is preferable that the third sipe 43 and the fourth sipe 44 each cross each block piece in the tire axial direction. In a more preferable embodiment, the third block piece 41 and the fourth block piece 42 do not have a sipe whose tire circumferential component is larger than the tire axial component. This further improves traction performance and braking performance on ice.

The configuration of the first sipe 23 described above can also be applied to the third sipe 43 and the fourth sipe 44.

Figure 5 shows an enlarged view of the inner middle land portion 14 and the crown land portion 15. As shown in Figure 5, the inner middle land portion 14 is divided into a number of inner middle blocks 48 by a number of inner middle lateral grooves 46 extending in the tire axial direction.

The inner middle lateral groove 46 is inclined in a first direction with respect to the tire axial direction , for example. The angle θ4 of the inner middle lateral groove 46 with respect to the tire axial direction is, for example, 45° or less and is larger than the angle of the outer shoulder lateral groove 18 with respect to the tire axial direction. Specifically, the angle θ4 of the inner middle lateral groove 46 is 25 to 35°.

The inner middle block 48 is provided with a bent groove 50. The bent groove 50 includes, for example, a first groove portion 51 and a second groove portion 52 that are inclined in a second direction with respect to the tire axial direction, and a third groove portion 53 that is disposed between them and is inclined in a first direction with respect to the tire axial direction. The bent groove 50 is bent in an N-shape by these groove portions, and crosses the inner middle block 48. Such a bent groove 50 provides frictional force in multiple directions when driving on ice and snow.

The first groove portion 51 of the bent groove 50 is connected to the inner crown circumferential groove 7. The second groove portion 52 is connected to the inner shoulder circumferential groove 8. The groove width of the second groove portion 52 is smaller than the groove width of the first groove portion 51. The groove width of the third groove portion 53 is smaller than the groove width of the second groove portion 52. Such bent grooves 50 improve on-ice performance while suppressing uneven wear of the inner middle block 48.

The inner middle block 48 is provided with multiple inner middle sipes 54. The inner middle sipes 54 are inclined, for example, in a second direction relative to the tire axial direction. Such inner middle sipes 54, in combination with other sipes, exert frictional forces in multiple directions, improving braking performance and cornering performance on ice in a well-balanced manner.

The configuration of the first sipe 23 described above can be applied to the inner middle sipe 54.

The crown land portion 15 includes a number of crown blocks 58 divided into a number of crown lateral grooves 56 extending in the tire axial direction.

The crown lateral groove 56 is inclined in the second direction with respect to the tire axial direction , for example. The angle θ5 of the crown lateral groove 56 with respect to the tire axial direction is 45° or less and is larger than the angle θ1 of the outer shoulder lateral groove 18 with respect to the tire axial direction. The angle θ5 of the crown lateral groove 56 is, for example, 15 to 25°.

The crown block 58 is provided with, for example, a first interrupted groove 61 and a second interrupted groove 62. The first interrupted groove 61 extends from the outer crown circumferential groove 6 and terminates within the crown block 58. The second interrupted groove 62 extends from the inner crown circumferential groove 7 and terminates within the crown block 58. Such first interrupted groove 61 and second interrupted groove 62 help improve the performance on ice and on snow while maintaining the rigidity of the crown block 58.

The crown block 58 is provided with a plurality of crown sipes 60. The crown sipes 60 are inclined in a first direction with respect to the tire axial direction, for example. The crown sipes 60 may have the same configuration as the first sipes 23 described above.

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 modified and implemented in various ways.

A tire of size 195/65R15 having the basic tread pattern of FIG. 1 was prototyped based on the specifications of Table 1. As a comparative example, a tire having an outer shoulder land portion a shown in FIG. 6 was prototyped. As shown in FIG. 6, the comparative tire has the same total number N1 of the first sipes c provided in the first block piece b and the same total number N2 of the second sipes e provided in the second block piece d. The comparative tire has substantially the same pattern as that shown in FIG. 1, except for the above-mentioned configuration. Each test tire was tested for braking performance and cornering performance on ice. The common specifications and test methods of each test tire are as follows.
Rim: 15 x 6.0JJ
Tire pressure: front wheel 230kPa, rear wheel 230kPa
Test vehicle: 1500cc engine, front-wheel drive Tire mounting position: all wheels

<Braking performance on ice>
The test vehicle was driven on ice, and the braking performance on ice was evaluated by the driver. The results were scored based on a comparison example score of 100, with a higher score indicating better braking performance on ice.

<Turning performance on ice>
The test vehicle was driven on ice, and the driver's sensory evaluation of the turning performance on ice was performed. The results were scored based on the comparative example being 100, with a higher score indicating better turning performance on ice.
The results of the tests are shown in Table 1.

As shown in Table 1, it was confirmed that the tires of the embodiment have improved braking performance and cornering performance on ice.

2 Tread portion 3 Circumferential groove 4 Land portion 11 Outer shoulder land portion 18 Outer shoulder lateral groove 19 First longitudinal narrow groove 20 Outer shoulder block 21 First block piece 22 Second block piece 23 First sipe 24 Second sipe To Outer tread edge Ti Inner tread edge

Claims (12)

A tire having a tread portion with a specified mounting direction on a vehicle,
The tread portion includes an outer tread end located on the outer side of the vehicle when the tire is mounted on the vehicle, an inner tread end located on the inner side of the vehicle when the tire is mounted on the vehicle, a plurality of circumferential grooves extending continuously in the tire circumferential direction, and a plurality of land portions divided by the plurality of circumferential grooves,
The plurality of land portions include an outer shoulder land portion including the outer tread edge,
The outer shoulder land portion is divided into a plurality of outer shoulder blocks by a plurality of outer shoulder lateral grooves extending in the tire axial direction,
At least one of the outer shoulder blocks is divided into a first block piece on the outer tread end side and a second block piece on the inner tread end side by a first longitudinal narrow groove extending in the tire circumferential direction,
The first block piece is provided with a plurality of first sipes,
The second block piece is provided with a plurality of second sipes,
a total number of the second sipes of the second block piece is greater than a total number of the first sipes of the first block piece,
The first longitudinal groove is curved at at least one point .
tire. The tire according to claim 1, wherein the first sipes and the second sipes are each arranged at an angle of 10° or less relative to the tire axial direction. The tire according to claim 1 or 2, wherein the first longitudinal narrow groove is arranged in a central region when the outer shoulder block is divided into three equal parts in the tire axial direction. The tire according to claim 1 , wherein a depth of the first sipe and a depth of the second sipe are greater than a depth of the first longitudinal narrow groove . A tire having a tread portion with a specified mounting direction on a vehicle,
The tread portion includes an outer tread end located on the outer side of the vehicle when the tire is mounted on the vehicle, an inner tread end located on the inner side of the vehicle when the tire is mounted on the vehicle, a plurality of circumferential grooves extending continuously in the tire circumferential direction, and a plurality of land portions divided by the plurality of circumferential grooves,
The plurality of land portions include an outer shoulder land portion including the outer tread edge,
The outer shoulder land portion is divided into a plurality of outer shoulder blocks by a plurality of outer shoulder lateral grooves extending in the tire axial direction,
At least one of the outer shoulder blocks is divided into a first block piece on the outer tread end side and a second block piece on the inner tread end side by a first longitudinal narrow groove extending in the tire circumferential direction,
The first block piece is provided with a plurality of first sipes,
The second block piece is provided with a plurality of second sipes,
a total number of the second sipes of the second block piece is greater than a total number of the first sipes of the first block piece,
The maximum width in the tire axial direction of the second block piece is 40% to 60% of the maximum width in the tire axial direction of the outer shoulder block.
tire. A tire having a tread portion with a specified mounting direction on a vehicle,
The tread portion includes an outer tread end located on the outer side of the vehicle when the tire is mounted on the vehicle, an inner tread end located on the inner side of the vehicle when the tire is mounted on the vehicle, a plurality of circumferential grooves extending continuously in the tire circumferential direction, and a plurality of land portions divided by the plurality of circumferential grooves,
The plurality of land portions include an outer shoulder land portion including the outer tread edge and an inner shoulder land portion including the inner tread edge,
The outer shoulder land portion is divided into a plurality of outer shoulder blocks by a plurality of outer shoulder lateral grooves extending in the tire axial direction,
At least one of the outer shoulder blocks is divided into a first block piece on the outer tread end side and a second block piece on the inner tread end side by a first longitudinal narrow groove extending in the tire circumferential direction,
The first block piece is provided with a plurality of first sipes,
The second block piece is provided with a plurality of second sipes,
a total number of the second sipes of the second block piece is greater than a total number of the first sipes of the first block piece,
The inner shoulder land portion is divided into a plurality of inner shoulder blocks by a plurality of inner shoulder lateral grooves extending in the tire axial direction,
a maximum width in the axial direction of the inner shoulder block is smaller than a maximum width in the axial direction of the outer shoulder block;
tire. A tire having a tread portion with a specified mounting direction on a vehicle,
The tread portion includes an outer tread end located on the outer side of the vehicle when the tire is mounted on the vehicle, an inner tread end located on the inner side of the vehicle when the tire is mounted on the vehicle, a plurality of circumferential grooves extending continuously in the tire circumferential direction, and a plurality of land portions divided by the plurality of circumferential grooves,
The plurality of land portions include an outer shoulder land portion including the outer tread edge and an inner shoulder land portion including the inner tread edge,
The outer shoulder land portion is divided into a plurality of outer shoulder blocks by a plurality of outer shoulder lateral grooves extending in the tire axial direction,
At least one of the outer shoulder blocks is divided into a first block piece on the outer tread end side and a second block piece on the inner tread end side by a first longitudinal narrow groove extending in the tire circumferential direction,
The first block piece is provided with a plurality of first sipes,
The second block piece is provided with a plurality of second sipes,
a total number of the second sipes of the second block piece is greater than a total number of the first sipes of the first block piece,
The inner shoulder land portion is divided into a plurality of inner shoulder blocks by a plurality of inner shoulder lateral grooves extending in the tire axial direction,
At least one of the inner shoulder blocks is provided with a second longitudinal narrow groove extending in the tire circumferential direction,
The depth of the second longitudinal groove is greater than the depth of the first longitudinal groove.
tire. A tire having a tread portion with a specified mounting direction on a vehicle,
The tread portion includes an outer tread end located on the outer side of the vehicle when the tire is mounted on the vehicle, an inner tread end located on the inner side of the vehicle when the tire is mounted on the vehicle, a plurality of circumferential grooves extending continuously in the tire circumferential direction, and a plurality of land portions divided by the plurality of circumferential grooves,
The plurality of land portions include an outer shoulder land portion including the outer tread edge and an inner shoulder land portion including the inner tread edge,
The outer shoulder land portion is divided into a plurality of outer shoulder blocks by a plurality of outer shoulder lateral grooves extending in the tire axial direction,
At least one of the outer shoulder blocks is divided into a first block piece on the outer tread end side and a second block piece on the inner tread end side by a first longitudinal narrow groove extending in the tire circumferential direction,
The first block piece is provided with a plurality of first sipes,
The second block piece is provided with a plurality of second sipes,
a total number of the second sipes of the second block piece is greater than a total number of the first sipes of the first block piece,
The inner shoulder land portion is divided into a plurality of inner shoulder blocks by a plurality of inner shoulder lateral grooves extending in the tire axial direction,
At least one of the inner shoulder blocks is divided into a third block piece on the inner tread end side and a fourth block piece on the outer tread end side by a second longitudinal narrow groove extending in the tire circumferential direction,
The third block piece is provided with a plurality of third sipes,
The fourth block piece is provided with a plurality of fourth sipes,
The total number of the fourth sipes of the fourth block piece is the same as the total number of the third sipes of the third block piece.
tire. A tire having a tread portion with a specified mounting direction on a vehicle,
The tread portion includes an outer tread end located on the outer side of the vehicle when the tire is mounted on the vehicle, an inner tread end located on the inner side of the vehicle when the tire is mounted on the vehicle, a plurality of circumferential grooves extending continuously in the tire circumferential direction, and a plurality of land portions divided by the plurality of circumferential grooves,
The plurality of land portions include an outer shoulder land portion including the outer tread edge,
The outer shoulder land portion is divided into a plurality of outer shoulder blocks by a plurality of outer shoulder lateral grooves extending in the tire axial direction,
At least one of the outer shoulder blocks is divided into a first block piece on the outer tread end side and a second block piece on the inner tread end side by a first longitudinal narrow groove extending in the tire circumferential direction,
The first block piece is provided with a plurality of first sipes,
The second block piece is provided with a plurality of second sipes,
a total number of the second sipes of the second block piece is greater than a total number of the first sipes of the first block piece,
The plurality of circumferential grooves include an outer shoulder circumferential groove disposed closest to the outer tread end,
the outer shoulder circumferential groove has the smallest groove width among the plurality of circumferential grooves;
tire. A tire having a tread portion with a specified mounting direction on a vehicle,
The tread portion includes an outer tread end located on the outer side of the vehicle when the tire is mounted on the vehicle, an inner tread end located on the inner side of the vehicle when the tire is mounted on the vehicle, a plurality of circumferential grooves extending continuously in the tire circumferential direction, and a plurality of land portions divided by the plurality of circumferential grooves,
The plurality of land portions include an outer shoulder land portion including the outer tread edge,
The outer shoulder land portion is divided into a plurality of outer shoulder blocks by a plurality of outer shoulder lateral grooves extending in the tire axial direction,
At least one of the outer shoulder blocks is divided into a first block piece on the outer tread end side and a second block piece on the inner tread end side by a first longitudinal narrow groove extending in the tire circumferential direction,
The first block piece is provided with a plurality of first sipes,
The second block piece is provided with a plurality of second sipes,
a total number of the second sipes of the second block piece is greater than a total number of the first sipes of the first block piece,
a maximum groove width of the outer shoulder lateral groove at a portion facing the first block piece is larger than a maximum groove width of the outer shoulder lateral groove at a portion facing the second block piece;
tire. A tire having a tread portion with a specified mounting direction on a vehicle,
The tread portion includes an outer tread end located on the outer side of the vehicle when the tire is mounted on the vehicle, an inner tread end located on the inner side of the vehicle when the tire is mounted on the vehicle, a plurality of circumferential grooves extending continuously in the tire circumferential direction, and a plurality of land portions divided by the plurality of circumferential grooves,
The plurality of land portions include an outer shoulder land portion including the outer tread edge,
The outer shoulder land portion is divided into a plurality of outer shoulder blocks by a plurality of outer shoulder lateral grooves extending in the tire axial direction,
At least one of the outer shoulder blocks is divided into a first block piece on the outer tread end side and a second block piece on the inner tread end side by a first longitudinal narrow groove extending in the tire circumferential direction,
The first block piece is provided with a plurality of first sipes,
The second block piece is provided with a plurality of second sipes,
a total number of the second sipes of the second block piece is greater than a total number of the first sipes of the first block piece,
The first sipe and the second sipe each have a tie bar with a raised bottom.
tire. The tire according to claim 11, wherein a depth of the portion where the tie bar is provided is greater than a depth of the first longitudinal narrow groove.

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