tire

Abstract

The present invention provides a tire that improves braking performance and cornering performance on ice. The tire has a tread portion (2) with a designated orientation for installation on a vehicle. An outer shoulder land portion (11) is divided into a plurality of outer shoulder tread blocks (20) by an outer shoulder lateral groove (18). At least one of the outer shoulder tread blocks (20) is divided into a first tread block piece (21) and a second tread block piece (22) by a first longitudinal fine groove (19). A plurality of first sipes (23) are provided on the first tread block piece (21). A plurality of second sipes (24) are provided on the second tread block piece (22). The total number of the second sipes (24) of the second tread block piece (22) is greater than the total number of the first sipes (23) of the first tread block piece (21).

Description

Technical Field

[0001] The present invention relates to tires. Background Art

[0002] Patent Document 1 listed below proposes a pneumatic tire that improves cornering performance and extreme behavior when cornering on icy and snowy roads in a balanced manner by defining pattern elements of the tread portion.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2013-237360

[0004] In recent years, with the advancement of vehicle performance, tires designed for winter use have been required to have further improved braking performance on ice and cornering performance. Summary of the invention

[0005] The present invention has been made in view of the above-mentioned actual situation, and a main object of the present invention is to provide a tire having improved braking performance and cornering performance on ice.

[0006] The present invention is a tire having a tread portion with a designated orientation for installation on a vehicle, wherein the tread portion includes: an outer tread end located on the outer side of the vehicle when installed on the vehicle, an inner tread end located on the inner side of the vehicle when installed on the vehicle, a plurality of circumferential grooves extending continuously in the circumferential direction of the tire, and a plurality of land portions divided by the plurality of circumferential grooves, the plurality of land portions including an outer shoulder land portion, the outer shoulder land portion including the outer tread end, the outer shoulder land portion divided by a plurality of outer tread ends extending in the axial direction of the tire The shoulder transverse groove is divided into a plurality of outer shoulder pattern blocks, at least one of the plurality of outer shoulder pattern blocks is divided into a first pattern block piece at the outer tread end side and a second pattern block piece at the inner tread end side by a first longitudinal fine groove extending in the tire circumferential direction, a plurality of first sipes are provided in the first pattern block piece, a plurality of second sipes are provided in the second pattern block piece, and the total number of the second sipes of the second pattern block piece is greater than the total number of the first sipes of the first pattern block piece.

[0007] In the tire of the present invention, preferably, the plurality of first sipes and the plurality of second sipes are each arranged at an angle of 10° or less with respect to the tire axial direction.

[0008] In the tire of the present invention, preferably, the first longitudinal narrow groove is disposed in a central region when the outer shoulder block is divided into three equal parts in the tire axial direction.

[0009] In the tire of the present invention, preferably, the first longitudinal narrow groove is curved at at least one location.

[0010] In the tire of the present invention, preferably, the depth of the first sipe and the depth of the second sipe are greater than the depth of the first longitudinal narrow groove.

[0011] In the tire of the present invention, preferably, the maximum width of the second block piece in the tire axial direction is 40% to 60% of the maximum width of the outer shoulder block in the tire axial direction.

[0012] In the tire of the present invention, preferably, each of the first sipe and the second sipe has a tie bar formed by a raised bottom.

[0013] In the tire of the present invention, preferably, a depth of a portion where the tie bar is provided is greater than a depth of the first longitudinal narrow groove.

[0014] Preferably, based on the tire of the present invention, the above-mentioned multiple land portions include an inner shoulder land portion, the inner shoulder land portion includes the above-mentioned inner tread end, the above-mentioned inner shoulder land portion is divided into multiple inner shoulder pattern blocks by multiple inner shoulder lateral grooves extending in the axial direction of the tire, and the maximum width of the above-mentioned inner shoulder pattern block in the axial direction of the tire is smaller than the maximum width of the above-mentioned outer shoulder pattern block in the axial direction of the tire.

[0015] Preferably, on the basis of the tire of the present invention, the above-mentioned multiple land portions include an inner shoulder land portion, the inner shoulder land portion includes the above-mentioned inner tread end, the above-mentioned inner shoulder land portion is divided into a plurality of inner shoulder pattern blocks by a plurality of inner shoulder lateral grooves extending in the axial direction of the tire, and at least one inner shoulder pattern block among the above-mentioned multiple inner shoulder pattern blocks is provided with a second longitudinal groove extending in the circumferential direction of the tire, and the depth of the above-mentioned second longitudinal groove is greater than the depth of the above-mentioned first longitudinal groove.

[0016] Preferably, on the basis of the tire of the present invention, the above-mentioned multiple land portions include an inner shoulder land portion, the inner shoulder land portion includes the above-mentioned inner tread end, the above-mentioned inner shoulder land portion is divided into a plurality of inner shoulder pattern blocks by a plurality of inner shoulder lateral grooves extending in the tire axial direction, at least one inner shoulder pattern block among the above-mentioned multiple inner shoulder pattern blocks is divided into a third pattern block piece on the inner tread end side and a fourth pattern block piece on the outer tread end side by a second longitudinal fine groove extending in the tire circumferential direction, a plurality of third knife grooves are provided in the above-mentioned third pattern block piece, a plurality of fourth knife grooves are provided in the above-mentioned fourth pattern block piece, and the total number of the above-mentioned fourth knife grooves of the above-mentioned fourth pattern block piece is the same as the total number of the above-mentioned third knife grooves of the above-mentioned third pattern block piece.

[0017] In the tire of the present invention, preferably, the plurality of circumferential grooves include an outer shoulder circumferential groove disposed closest to the outer tread end, and the outer shoulder circumferential groove has the smallest groove width among the plurality of circumferential grooves.

[0018] In the tire of the present invention, preferably, a maximum groove width of a portion of the outer shoulder lateral groove facing the first block is greater than a maximum groove width of a portion of the outer shoulder lateral groove facing the second block.

[0019] The pneumatic tire of the present invention can improve braking performance and cornering performance on ice by adopting the above-mentioned structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a development view of the tread portion of the tire according to one embodiment of the present invention.

[0021] Figure 2 yes Figure 1 An enlarged view of the outer shoulder land portion and the outer middle land portion.

[0022] Figure 3 yes Figure 2 AA line section view.

[0023] Figure 4 yes Figure 1 An enlarged view of the inner shoulder land portion.

[0024] Figure 5 yes Figure 1 An enlarged view of the inner middle land portion and the crown land portion.

[0025] Figure 6 It is an enlarged view of the outer shoulder land portion of the tire of the comparative example.

[0026] Description of Reference Numerals

[0027] 2…tread portion; 3…circumferential groove; 4…land portion; 11…outer shoulder land portion; 18…outer shoulder lateral groove; 19…first longitudinal fine groove; 20…outer shoulder tread block; 21…first tread block piece; 22…second tread block piece; 23…first sipe; 24…second sipe; To…outer tread end; Ti…inner tread end. DETAILED DESCRIPTION

[0028] Hereinafter, one embodiment of the present invention will be described based on the drawings.

[0029] Figure 1 FIG. 2 is a development diagram of the tread portion 2 of the tire 1 according to the present embodiment. Figure 1 As shown, the tire 1 of this embodiment is used as a pneumatic tire for a passenger car that is used in winter, for example. However, the tire 1 of the present invention is not limited to such a form.

[0030] The tire 1 of the present embodiment has, for example, a tread portion 2 for specifying the orientation of the tire to be mounted on a vehicle. For example, the orientation of the tire to be mounted on a vehicle is indicated by characters or symbols on the sidewall portion or the like (not shown).

[0031] The tread portion 2 is composed of four circumferential grooves 3 extending continuously in the tire circumferential direction between the outer tread end To and the inner tread end Ti, and five land portions 4 divided by the circumferential grooves 3. That is, the tire 1 of the present invention is a so-called five-rib tire. However, the tire 1 of the present invention is not limited to such a form, and for example, it may be a so-called four-rib tire composed of three circumferential grooves 3 and four land portions 4.

[0032] The outer tread end To is the tread end intended to be located on the outer side of the vehicle when installed on the vehicle, and the inner tread end Ti is the tread end intended to be located on the inner side of the vehicle when installed on the vehicle. The outer tread end To and the inner tread end Ti are respectively equivalent to the outermost ground contact position of the tire axial direction when a normal load is applied to the tire 1 in a normal state and the tire contacts the flat surface at a camber angle of 0°.

[0033] "Normal state" refers to a state where the tire is assembled on a regular rim, filled with a regular internal pressure and unloaded, in the case of pneumatic tires with various specifications specified. In the case of tires with various specifications not specified or non-pneumatic tires, the above-mentioned normal state refers to a standard usage state corresponding to the purpose of use of the tire and a state where the tire is not installed on a vehicle and unloaded. In this specification, unless otherwise specified, the dimensions of various parts of the tire are values ​​measured under the above-mentioned normal state. In addition, each structure described in this specification allows for the normal errors contained in rubber molded products.

[0034] "Regular rims" are rims whose specifications are specified for each tire in a standard system that includes the specifications that the tire complies with. For example, JATMA means "standard rim", TRA means "design rim", and ETRTO means "measuring rim".

[0035] "Normal internal pressure" is the air pressure specified for each tire in the specification system including the specifications on which the tire is based. If it is JATMA, it means "maximum air pressure". If it is TRA, it means the maximum value recorded in the table "TIRE LOAD LIMITS ATVARIOUS COLD INFLATION PRESSURES". If it is ETRTO, it means "INFLATION PRESSURE".

[0036] "Normal load" refers to the load specified for each specification for each tire in the specification system including the specification to which the tire is based when various specifications of pneumatic tires are specified. If it is JATMA, it means "maximum load capacity", if it is TRA, it means the maximum value recorded in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", and if it is ETRTO, it means "LOAD CAPACITY". In addition, in the case of tires without various specifications or non-pneumatic tires, "Normal load" refers to the load acting on a tire under the standard use state of the tire. The above-mentioned "standard use state" refers to the state in which the tire is installed on a standard vehicle corresponding to the purpose of use of the tire and the above-mentioned vehicle is stationary on a flat road surface in a state where it can travel.

[0037] 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 end To side among the plurality of circumferential grooves 3. The outer crown circumferential groove 6 is adjacent to the inner tread end 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 end Ti. The inner shoulder circumferential groove 8 is provided between the inner crown circumferential groove 7 and the inner tread end Ti.

[0038] The circumferential groove 3 can be in various forms, such as a form extending in a straight line in the tire circumferential direction or a form extending in a zigzag shape. In the present embodiment, the outer shoulder circumferential groove 5, the inner crown circumferential groove 7, and the inner shoulder circumferential groove 8 extend in parallel in a straight line in the tire circumferential direction. On the other hand, the outer crown circumferential groove 6 extends in a zigzag shape. However, the tire 1 of the present invention is not limited to such a form.

[0039] The tire 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 tire 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 preferred embodiment, the tire axial distance from the groove centerline of the inner crown circumferential groove 7 to the tire equator C is greater than the tire axial distance from the groove centerline of the outer crown circumferential groove 6 to the tire equator C. In addition, the tread width TW is the tire axial distance from the outer tread end To to the inner tread end Ti in the above-mentioned normal state.

[0040] The groove width W1 of the circumferential groove 3 is preferably at least 3 mm. In a preferred embodiment, the groove width W1 of the circumferential groove 3 is 2.0% to 5.0% of the tread width TW. In this embodiment, among the four circumferential grooves 3, the outer shoulder circumferential groove 5 has the smallest groove width.

[0041] 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 an outer tread end 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 an inner tread end Ti.

[0042] exist Figure 2 FIG. 2 shows an enlarged view of the outer shoulder land portion 11 and the outer middle land portion 12. Figure 2 As shown, the outer shoulder land portion 11 is divided into a plurality of outer shoulder blocks 20 by a plurality of outer shoulder lateral grooves 18 extending in the tire axial direction.

[0043] At least one of the outer shoulder blocks 20 is divided into a first block piece 21 on the outer tread end To side and a second block piece 22 on the inner tread end Ti side by a first longitudinal narrow groove 19 extending in the tire circumferential direction.

[0044] 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.

[0045] In this specification, "slot" refers to a groove element with a small width, and the width between two groove walls facing each other is less than 0.6 mm. The above width of the groove is preferably 0.1 to 0.5 mm, and more preferably 0.2 to 0.4 mm. For the groove of the present embodiment, the above width is within the above range throughout its entire depth. In addition, in this specification, in the cross section of a groove element, for a groove element in which an area with a width of less than 0.6 mm occupies more than 50% of its entire depth, even if it partially includes an area with a width of more than 0.6 mm, it is treated as a groove (a groove including a groove element). In addition, in the cross section of a groove element, for a groove element in which an area with a width greater than 0.6 mm occupies more than 50% of its entire depth, even if it partially includes an area with a width of less than 0.6 mm, it is treated as a groove (a groove including a groove element).

[0046] In the present invention, the total number N2 of the second sipes 24 arranged in one second pattern block 22 is greater than the total number N1 of the first sipes 23 arranged in one first pattern block 21. The pneumatic tire of the present invention can improve the braking performance and cornering performance on ice by adopting the above-mentioned structure. The reason for this is presumably the following mechanism.

[0047] In order to prevent the collapse of the pattern block during braking on ice, it is preferred that the number of sipes on the outer tread end To side of the outer shoulder pattern block 20 is small. On the other hand, when turning at a normal speed on ice, there is a tendency that the lateral acceleration G is smaller than when driving on a dry road, and the maximum length of the contact patch is formed in the area relatively axially inward of the tire in the tread of the outer shoulder land portion 11. In the present invention, it is presumed that by making the total number N2 of the second sipes 24 greater than the total number N1 of the first sipes 23, the collapse of the pattern block can be prevented, and a large number of sipes can be arranged in the above-mentioned area, thereby improving the braking performance and turning performance on ice.

[0048] The following describes a more detailed structure of the present embodiment. In addition, each structure described below represents a specific form of the present embodiment. Therefore, it goes without saying that the present invention can exert the above-mentioned effects even if it does not have the structure described below. In addition, even if any one of the structures described below is applied alone to the tire of the present invention having the above-mentioned characteristics, it is possible to expect performance improvements corresponding to each structure. Moreover, in the case where several of the structures described below are applied in combination, it is possible to expect composite performance improvements corresponding to each structure.

[0049] The tire axial width W2 of the outer shoulder pattern block 20 is, for example, the tread width TW (eg Figure 1 ) is 15% to 30%. However, the present invention is not limited to such a form.

[0050] The outer shoulder lateral groove 18 extends at an angle θ1 of less than 10° relative to the tire axial direction, for example. The outer shoulder lateral groove 18 includes a main body 18a connected to the outer shoulder circumferential groove 5, and a widened portion 18b connected to the outer tread end To side of the main body 18a. The main body 18a has a length of, for example, more than 50% of the entire length of the outer shoulder lateral groove 18. In addition, the groove width W3 of the main body 18a is greater than the groove width W4 of the outer shoulder circumferential groove 5. The widened portion 18b has, for example, a groove width W5 greater than that of the main body 18a. The groove width W5 of the widened portion 18b is 103% to 110% of the groove width W3 of the main body 18a. As a result, the maximum groove width of the portion of the outer shoulder lateral groove 18 facing the first pattern block 21 is greater than the maximum groove width of the portion of the outer shoulder lateral groove 18 facing the second pattern block 22. Such an outer shoulder lateral groove 18 helps to achieve excellent snow performance.

[0051] The first longitudinal narrow groove 19 is, for example, arranged in the central area when the outer shoulder pattern block 20 is divided into three equal parts in the tire axial direction. The distance in the tire axial direction between the groove center line of the first longitudinal narrow groove 19 and the center position in the tire axial direction of the outer shoulder pattern block 20 is less than 10% of the tire axial width W2 of the outer shoulder pattern block 20. In addition, the first longitudinal narrow groove 19 is connected to the main body 18a of the outer shoulder lateral groove 18. Thus, the maximum width of the second pattern block piece 22 in the tire axial direction is 40% to 60% of the maximum width of the outer shoulder pattern block 20 in the tire axial direction.

[0052] The first longitudinal narrow groove 19 is bent at least at one location. The first longitudinal narrow groove 19 of the present embodiment is bent at two locations at an obtuse angle. Such a first longitudinal narrow groove 19 provides frictional force in multiple directions on ice. In addition, in this specification, "groove bending" refers to a state in which the length of the region including at least the bending of the groove centerline is less than 3 mm.

[0053] The groove width W6 of the first longitudinal narrow groove 19 is larger than 0.6 mm. The groove width W6 is, for example, 0.8 to 2.0 mm, preferably 1.0 to 1.5 mm. The depth of the first longitudinal narrow groove 19 is, for example, 1.5 to 3.0 mm. Such a first longitudinal narrow groove 19 maintains the rigidity of the outer shoulder block 20 and improves the cornering performance on ice.

[0054] The total number N1 of the first sipes 23 of the present embodiment 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, the total number N2 is preferably 1.10 to 2.50 times the total number N1. However, the present invention is not limited to such a form.

[0055] For the first sipes 23 and the second sipes 24, the tire axial component is greater than the tire circumferential component. Preferably, the first sipes 23 and the second sipes 24 cross each tread block in the tire axial direction. In the present embodiment, the first sipes 23 and the second sipes 24 are respectively arranged at an angle of less than 10° relative to the tire axial direction. In the case where each sipe extends in a zigzag shape, the above angle is measured on an imaginary line connecting the two ends of the sipes. In addition, the first sipes 23 and the second sipes 24 are arranged approximately parallel to the outer shoulder transverse groove 18. Here, approximately parallel refers to a form in which the angle difference between the sipes and the transverse grooves is less than 5°. In addition, in the first tread block 21 and the second tread block 22, no sipes whose tire circumferential component is greater than the tire axial component are provided. As a result, the traction performance and braking performance on ice are further improved.

[0056] At least one of the first sipe 23 and the second sipe 24 extends in a zigzag shape in the longitudinal direction thereof. In a preferred embodiment, at least one of the first sipe 23 and the second sipe 24 is configured as a so-called 3D sipe that also extends in a zigzag shape in the depth direction thereof. Such first sipe 23 and second sipe 24 suppress excessive collapse of the tread block when the sipe walls facing each other contact each other, thereby improving braking performance on ice.

[0057] It is preferred that at least the sipes adjacent to the outer shoulder lateral groove 18 among the plurality of first sipes 23 arranged in the tire circumferential direction and the plurality of second sipes 24 arranged in the tire circumferential direction are configured as 3D sipes. As a more preferred form, in the present embodiment, all the sipes provided in the outer shoulder block 20 are configured as 3D sipes. Thus, the above-mentioned effect can be reliably exerted.

[0058] exist Figure 3 In the figure, as a diagram for explaining the structure of the first blade groove 23 and the second blade groove 24, Figure 2 AA line cross-sectional view of the first sipe 23. In addition, the structure of the first sipe 23 described below can also be applied to the second sipe 24. Figure 3 In FIG. 1 , the double-dashed line shows the bent portion of the first sipe 23 constituting the 3D sipe. Figure 3 As shown, the maximum depth d1 of the first sipe 23 is preferably greater than the maximum depth of the first longitudinal narrow groove 19. The depth d1 of the first sipe 23 is 2.50 to 4.00 times the depth of the first longitudinal narrow groove 19. Such first sipe 23 can exhibit excellent water absorption.

[0059] The first sipe 23 of the present embodiment has a tie bar 25 formed by a raised bottom. The tie bar 25 includes, for example, an end tie bar 26 provided at the end of the first sipe 23 on the side opposite to the first longitudinal groove 19, and a central tie bar 27 provided at the central portion 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 preferred embodiment, at least a portion of the central tie bar 27 overlaps with the central position of the first sipe 23 in the longitudinal direction. Such end tie bars 26 and central tie bars 27 can suppress the first sipe 23 from being excessively opened, thereby improving the braking performance on ice.

[0060] 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. In addition, the width W7 of the central tie bar 27 is smaller than the width of the end tie bar 26. In addition, 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 maintain the water absorption of the first sipe 23 and can suppress the excessive opening of the first sipe 23. In addition, the width W7 is measured at a height of 50% of the maximum height of the central tie bar 27, for example.

[0061] From a similar viewpoint, it is preferable that the depth of the portion where the tie rod 25 is provided is greater than the depth of the first longitudinal narrow groove 19 .

[0062] like Figure 2 As shown, a plurality of outer middle lateral grooves 29 extending in the tire axial direction are provided in the outer middle land portion 12. The outer middle lateral grooves 29 cross the outer middle land portion 12. Thus, the outer middle land portion 12 is divided into a plurality of outer middle blocks 30.

[0063] The outer middle lateral groove 29 is inclined, for example, in a first direction (lower right in each drawing of this specification) relative to the tire axial direction. The angle θ2 of the outer middle lateral groove 29 relative to the tire axial direction is, for example, less than 45°, preferably 15 to 25°. Such an outer middle lateral groove 29 improves the braking performance and cornering performance on ice in a balanced manner.

[0064] It is preferred that the end of the outer middle lateral groove 29 on the outer tread end To side overlaps with a region formed by extending the end of the inner tread end Ti side of the outer shoulder lateral groove 18 parallel to the tire axial direction. Thus, when running on snow, a hard snow column is generated at the intersection of the outer shoulder circumferential groove 5, the outer shoulder lateral groove 18, and the outer middle lateral groove 29, and a large reaction force is obtained by shearing it. Therefore, the performance on snow is improved.

[0065] 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 than the long inclined portion 6a, and at least one of the outer middle lateral grooves 29 communicates with the short inclined portion 6b. In a more preferred embodiment, the outer middle lateral grooves 29 communicating with the short inclined portion 6b and the outer middle lateral grooves 29 communicating with the long inclined portion 6a are alternately arranged in the tire circumferential direction. Such outer middle lateral grooves 29 can form hard snow pillars at the intersection portion with the short inclined portion 6b.

[0066] The outer middle block 30 is provided with a middle interrupted groove 32. The middle interrupted groove 32 extends from the outer crown circumferential groove 6 and is interrupted in the outer middle block 30. In addition, the groove width W8 of the middle interrupted 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 interrupted groove 32 can maintain the rigidity of the outer middle block 30 and can improve the braking performance on ice.

[0067] The middle interrupted groove 32 is inclined in the first direction with respect to the tire axial direction, for example. In a preferred embodiment, the angle difference between the middle interrupted groove 32 and the outer middle lateral groove 29 is 5° or less. Such a middle interrupted groove 32 helps to suppress uneven wear of the outer middle block 30.

[0068] The outer middle tread block 30 is provided with a plurality of outer middle sipes 33. The outer middle sipes 33 are inclined, for example, in a second direction (upper right in each of the drawings of this specification) opposite to the first direction relative to the tire axial direction. The angle of the outer middle sipes 33 relative to the tire axial direction is, for example, 15 to 25 degrees. In addition, when the sipes extend in a sawtooth shape, the direction and angle of the inclination are measured at an imaginary straight line connecting the two ends of the sipes.

[0069] exist Figure 4 FIG. 2 shows an enlarged view of the inner shoulder land portion 13. Figure 4 As shown, the inner shoulder land portion 13 is divided into a plurality of inner shoulder blocks 35 by a plurality of inner shoulder lateral grooves 34 extending in the tire axial direction.

[0070] The inner shoulder lateral groove 34 is inclined, for example, in the second direction relative to the tire axial direction. In the present embodiment, the angle θ3 of the inner shoulder lateral groove 34 relative to the tire axial direction is greater than the angle of the outer shoulder lateral groove 18 relative to the tire axial direction. Specifically, the angle θ3 of the inner shoulder lateral groove 34 relative to the tire axial direction is 5 to 15 degrees. Such an inner shoulder lateral groove 34 improves the braking performance and the cornering performance on ice in a balanced manner.

[0071] 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 preferred 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. As a result, the steering feel during cornering becomes linear, thereby improving steering stability.

[0072] At least one of the inner shoulder blocks 35 is divided into a third block piece 41 on the inner tread end Ti side and a fourth block piece 42 on the outer tread end To side by the second longitudinal narrow groove 38 extending in the tire circumferential direction.

[0073] The second longitudinal narrow groove 38 is, for example, arranged in the central area when the inner shoulder pattern block 35 is divided into three equal parts in the tire axial direction. The distance in the tire axial direction between the groove center line of the second longitudinal narrow groove 38 and the center position in the tire axial direction of the inner shoulder pattern block 35 is 10% or less of the maximum width W9 in the tire axial direction of the inner shoulder pattern block 35. In addition, the second longitudinal narrow groove 38 extends in a straight line parallel to the tire circumferential direction. Thus, the maximum width in the tire axial direction of the fourth pattern block piece 42 is 40% to 60% of the maximum width in the tire axial direction of the inner shoulder pattern block 35.

[0074] The groove width W10 of the second longitudinal narrow groove 38 is greater than 0.6 mm. The groove width W10 is, for example, 0.8 to 2.0 mm, preferably 1.0 to 1.5 mm. The depth of the second longitudinal narrow groove 38 is, for example, 1.5 to 3.0 mm. In a preferred embodiment, the depth of the second longitudinal narrow groove 38 is greater than the depth of the first longitudinal narrow groove 19. Such a second longitudinal narrow groove 38 contributes to improving the turning performance on ice.

[0075] A plurality of third sipes 43 are provided on the third tread block 41. A plurality of fourth sipes 44 are provided on the fourth tread block 42. In the present embodiment, the total number N4 of the fourth sipes 44 arranged on one fourth tread block 42 is greater than the total number N3 of the third sipes 43 arranged on one third tread block 41. Thus, the braking performance on ice and the cornering performance are improved in a balanced manner.

[0076] In another embodiment, the total number N4 of the fourth sipes 44 of the fourth tread block 42 may be the same as the total number N3 of the third sipes 43 of the third tread block 41. In such an embodiment, the partial 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 the noise performance.

[0077] The total number N3 of the third sipes 43 in the present embodiment 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 a form.

[0078] The tire axial component of the third sipe 43 and the fourth sipe 44 is greater than the tire circumferential component. Preferably, the third sipe 43 and the fourth sipe 44 cross each tread block in the tire axial direction. In a more preferred form, the third tread block 41 and the fourth tread block 42 are not provided with a sipe whose tire circumferential component is greater than the tire axial component. As a result, the traction performance and braking performance on ice are further improved.

[0079] In addition, the structure of the first sipe 23 described above can be applied to the third sipe 43 and the fourth sipe 44 .

[0080] exist Figure 5FIG. 2 shows an enlarged view of the inner middle land portion 14 and the crown land portion 15. Figure 5 As shown, inner middle land portion 14 is divided into a plurality of inner middle blocks 48 by a plurality of inner middle lateral grooves 46 extending in the tire axial direction.

[0081] The inner middle lateral groove 46 is inclined, for example, in the first direction relative to the tire axial direction. The angle θ4 of the inner middle lateral groove 46 relative to the tire axial direction is, for example, 45° or less and is greater than the angle of the outer shoulder lateral groove 18 relative to the tire axial direction. Specifically, the angle θ4 of the inner middle lateral groove 46 is 25 to 35°.

[0082] The inner middle tread block 48 is provided with a bending groove 50. The bending groove 50 includes, for example, a first groove portion 51 and a second groove portion 52 which are inclined in the second direction with respect to the tire axial direction, and a third groove portion 53 which is arranged between them and inclined in the first direction with respect to the tire axial direction. The bending groove 50 is bent in an N-shape by these groove portions and crosses the inner middle tread block 48. Such a bending groove 50 provides friction in multiple directions when running on ice or snow.

[0083] The first groove portion 51 of the bending 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 a bending groove 50 suppresses uneven wear of the inner middle block 48 and improves the performance on ice.

[0084] The inner middle block 48 is provided with a plurality of inner middle sipes 54. The inner middle sipes 54 are inclined, for example, in the second direction relative to the tire axial direction. Such inner middle sipes 54 interact with other sipes to exert friction in multiple directions, thereby improving braking performance and cornering performance on ice in a balanced manner.

[0085] The structure of the first sipe 23 described above can be applied to the inner middle sipe 54 .

[0086] The crown land portion 15 includes a plurality of crown blocks 58 divided by a plurality of crown lateral grooves 56 extending in the tire axial direction.

[0087] 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 degrees 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 degrees.

[0088] For example, the crown block 58 is provided with 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 is interrupted in the crown block 58. The second interrupted groove 62 extends from the inner crown circumferential groove 7 and is interrupted in the crown block 58. Such first interrupted groove 61 and second interrupted groove 62 help maintain the rigidity of the crown block 58 and improve the performance on ice and snow.

[0089] A plurality of crown sipes 60 are provided in the crown block 58. The crown sipes 60 are inclined, for example, in a first direction with respect to the tire axial direction. The structure of the first sipe 23 described above can be applied to the crown sipe 60.

[0090] As mentioned above, although the tire which concerns on one embodiment of this invention was demonstrated in detail, this invention is not limited to the said specific embodiment, It can be implemented by changing into various forms.

[0091] [Example]

[0092] Based on the specifications in Table 1, we have produced Figure 1 A tire with a basic tread pattern of 195 / 65R15 was produced as a comparative example. Figure 6 The tire has an outer shoulder land portion a as shown. Figure 6 As shown, for the tire of the comparative example, the total number N1 of the first sipes c provided on the first pattern block piece b is the same as the total number N2 of the second sipes e provided on the second pattern block piece d. In addition to the above-mentioned structure, the tire of the comparative example has the same Figure 1 The patterns shown are substantially the same. For each test tire, the braking performance and cornering performance on ice were tested. The general specifications and test methods of each test tire are as follows.

[0093] Installed rim: 15×6.0JJ

[0094] Tire internal pressure: front wheel 230kPa, rear wheel 230kPa

[0095] Test vehicle: 1500cc displacement, front-wheel drive

[0096] Tire installation position: All wheels

[0097] <Braking performance on ice>

[0098] The test vehicle was driven on ice, and the braking performance on ice was evaluated by the driver's senses. The results were expressed as a score with the comparative example being 100, and a larger value indicates a better braking performance on ice.

[0099] <Cornering performance on ice>

[0100] The test vehicle was driven on ice, and the driver's sense of turning performance on ice was evaluated. The results were expressed as a score with the comparative example being 100, and a larger value indicated a better turning performance on ice.

[0101] The test results are shown in Table 1.

[0102]

Table 1

[0103]

[0104] As shown in Table 1, it can be confirmed that the tires of the examples improve the braking performance and cornering performance on ice.

Claims

1. A tire having a tread portion oriented in a direction for installation on a vehicle, wherein: The tread portion includes: an outer tread end located on the outer side of the vehicle when installed on the vehicle, an inner tread end located on the inner side of the vehicle when installed 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 end, 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. Each of the plurality of 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. A plurality of first sipes are provided on each of the first pattern blocks. A plurality of second sipes are provided on each of the second pattern blocks. In each of the plurality of outer shoulder blocks, the total number of the second sipes of the second tread block piece is greater than the total number of the first sipes of the first tread block piece, The first knife groove and the second knife groove each have a tensioning bar formed by a raised bottom. The depth of the portion where the tie rod is provided is greater than the depth of the first longitudinal narrow groove.

2. The tire according to claim 1, wherein: The plurality of first sipes and the plurality of second sipes are respectively arranged at an angle of 10° or less with respect to the tire axial direction.

3. The tire according to claim 1 or 2, wherein: The first longitudinal narrow groove is arranged in the central area when the outer shoulder block is divided into three equal parts in the tire axial direction.

4. The tire according to claim 1 or 2, wherein: The first longitudinal narrow groove is bent at least at one location.

5. The tire according to claim 1 or 2, wherein: The depth of the first sipe and the depth of the second sipe are greater than the depth of the first longitudinal narrow groove.

6. The tire according to claim 1 or 2, wherein: The maximum width of the second tread block in the tire axial direction is 40% to 60% of the maximum width of the outer shoulder tread block in the tire axial direction.

7. The tire according to claim 1 or 2, wherein: The plurality of land portions include an inner shoulder land portion including the inner tread end, 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. The maximum width of the inner shoulder pattern block in the tire axial direction is smaller than the maximum width of the outer shoulder pattern block in the tire axial direction.

8. The tire according to claim 1 or 2, wherein: The plurality of land portions include an inner shoulder land portion including the inner tread end, 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 plurality of inner shoulder blocks is provided with a second longitudinal narrow groove extending in the tire circumferential direction. The depth of the second longitudinal narrow groove is greater than the depth of the first longitudinal narrow groove.

9. The tire according to claim 1 or 2, wherein: The plurality of land portions include an inner shoulder land portion including the inner tread end, 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 plurality of inner shoulder blocks is divided into a third block piece at the inner tread end side and a fourth block piece at the outer tread end side by a second longitudinal narrow groove extending in the tire circumferential direction. The third tread block is provided with a plurality of third sipes. The fourth tread block 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.

10. The tire according to claim 1 or 2, wherein: 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.

11. The tire according to claim 1 or 2, wherein: The maximum groove width of a portion of the outer shoulder lateral groove facing the first block piece is greater than the maximum groove width of a portion of the outer shoulder lateral groove facing the second block piece.

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