tire

Abstract

The main subject of the present invention is to provide a tire that suppresses clogging of the sipe pattern by snow. The present invention is a tire having a tread portion (2). The tread portion (2) includes a first land portion (11) divided by a circumferential groove (3) extending continuously in the circumferential direction of the tire, and a plurality of first transverse grooves (14) inclined in a first direction relative to the tire axial direction and crossing the first land portion (11). The first land portion (11) includes a plurality of first pattern blocks (15) divided by the first transverse grooves (14). At least one sipe pattern (16) inclined in a second direction opposite to the first direction relative to the tire axial direction is provided in the first pattern block (15). The sipe pattern (16) includes a portion having a depth deeper than the maximum depth of the first transverse groove and a portion having a depth shallower than the maximum depth of the first transverse groove (14).

Description

Technical Field

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

[0002] For example, Patent Document 1 listed below proposes a tire capable of exhibiting excellent snow performance by using pattern elements in a specific tread portion.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2018-001804

[0004] In recent years, tires have been required to have further improved on-snow performance. The inventors conducted various experiments and found that suppressing the clogging of sipes by snow can further improve on-snow performance, leading to the completion of the present invention. 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 that suppresses clogging of sipes by snow.

[0006] The present invention is a tire having a tread portion, wherein the tread portion includes a first land portion divided by circumferential grooves extending continuously in the tire circumferential direction, and a plurality of first lateral grooves inclined in a first direction relative to the tire axial direction and transverse to the first land portion, the first land portion includes a plurality of first pattern blocks divided by the first lateral grooves, and the first pattern blocks are provided with at least one sipe pattern inclined in a second direction opposite to the first direction relative to the tire axial direction, the sipe pattern including a portion having a depth deeper than the maximum depth of the first lateral groove and a portion having a depth shallower than the maximum depth of the first lateral groove.

[0007] In the tire of the present invention, preferably, the first lateral groove has an angle of 15 to 25 degrees with respect to the tire axial direction.

[0008] Preferably, in the tire of the present invention, the angle of the sipe relative to the tire axial direction is 15 to 25 degrees.

[0009] Preferably, in the tire of the present invention, the sipe includes a rib that rises from a bottom thereof toward the outside in the tire radial direction.

[0010] In the tire of the present invention, the tie bars are preferably provided at positions overlapping with longitudinal centers of the sipes.

[0011] Preferably, in the tire of the present invention, the height of the tie bars in the tire radial direction is 40% to 70% of the maximum depth of the sipes.

[0012] Preferably, in the tire of the present invention, the sipes extend in a zigzag shape in the longitudinal direction thereof, and the width of the tie bars in the tire axial direction is 10% to 40% of the wavelength of the sipes.

[0013] Preferably, in the tire of the present invention, a second lateral groove connected to the circumferential groove and interrupted within the first tread block is provided, and the sipe pattern includes a portion having a depth deeper than the maximum depth of the second lateral groove and a portion having a depth shallower than the maximum depth of the second lateral groove.

[0014] In the tire of the present invention, preferably, the maximum depth of a portion of the sipe deeper than the maximum depth of the first lateral groove is 105% to 145% of the maximum depth of the first lateral groove.

[0015] In the tire of the present invention, preferably, the minimum depth of the portion of the sipe shallower than the maximum depth of the first lateral groove is 30% to 70% of the maximum depth of the first lateral groove.

[0016] The tire of the present invention can effectively suppress clogging of the sipes by snow by adopting the above-mentioned structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a development view of the tread portion of a tire according to one embodiment of the present invention.

[0018] Figure 2 yes Figure 1 An enlarged view of the first land part.

[0019] Figure 3 yes Figure 2 AA line section view.

[0020] Figure 4 yes Figure 1 Enlarged views of the first, second, and third land parts of the .

[0021] Figure 5 yes Figure 4 BB line cross-sectional view.

[0022] Figure 6 yes Figure 4 CC line cross-sectional view.

[0023] Figure 7 It is a cross-sectional view of a sipe of a comparative example.

[0024] Description of Reference Numerals

[0025] 2…tread portion; 3…circumferential groove; 11…first land portion; 14…first lateral groove; 15…first lug block; 16…sipe. DETAILED DESCRIPTION

[0026] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

[0027] Figure 1 FIG is a development diagram of the tread portion 2 of the tire 1 of this embodiment. Figure 1 As shown, the tire 1 of this embodiment is used as a pneumatic tire for a passenger car, for example, which is assumed to be used in winter. However, the tire 1 of the present invention is not limited to such a form.

[0028] The tire 1 of this embodiment includes, for example, a tread portion 2 having a designated orientation for mounting on a vehicle. The orientation for mounting on a vehicle is indicated by characters or markings on the sidewall portion, for example (not shown).

[0029] 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 defined by these circumferential grooves 3. In other words, 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 this configuration; for example, a so-called four-rib tire consisting of three circumferential grooves 3 and four land portions 4 is also possible.

[0030] The outer tread end To is the end of the tread intended to be located on the outside of the vehicle when installed on the vehicle, and the inner tread end Ti is the end of the tread intended to be located on the inside of the vehicle when installed on the vehicle. The outer tread end To and the inner tread end Ti each correspond to the axially outermost ground contact position of the tire when a normal load is applied to the tire 1 in a normal state and the tire contacts a flat surface at a camber angle of 0°.

[0031] "Normal condition" refers to the condition in which the tire is assembled on a standard rim, inflated to the standard internal pressure, and unloaded, for pneumatic tires with specified specifications. For tires without specified specifications or non-pneumatic tires, the "normal condition" refers to the standard usage condition corresponding to the tire's intended use and unloaded. Unless otherwise specified, the dimensions of various tire components in this specification are values ​​measured under the "normal condition." Furthermore, the various structures described in this specification allow for the typical tolerances inherent in rubber molded products.

[0032] "Regular rims" are rims whose specifications are specified for each tire within the standard system that includes the specifications to which the tire is based. For example, JATMA means "standard rim," TRA means "design rim," and ETRTO means "measuring rim."

[0033] "Normal internal pressure" is the air pressure specified for each tire in the specification system including the specifications to 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".

[0034] For pneumatic tires with various specifications, the "normal load" refers to the load specified for each tire within the standard system, including the specifications to which the tire conforms. For JATMA, this refers to the "maximum load capacity," for TRA, it refers to the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and for ETRTO, it refers to "LOAD CAPACITY." Furthermore, for tires without various specifications or non-pneumatic tires, the "normal load" refers to the load acting on a tire under standard usage conditions. These "standard usage conditions" refer to the state in which the tire is mounted on a standard vehicle corresponding to the tire's intended use, and the vehicle is stationary on a flat road surface in a drivable state.

[0035] The circumferential grooves 3 include, for example, an outer crown circumferential groove 5, an inner crown circumferential groove 6, an outer shoulder circumferential groove 7, and an inner shoulder circumferential groove 8. The outer crown circumferential groove 5 is provided between the tire equator C and the outer tread end To. The inner crown circumferential groove 6 is provided between the tire equator C and the inner tread end Ti. The outer shoulder circumferential groove 7 is provided between the outer crown circumferential groove 5 and the outer tread end To. The inner shoulder circumferential groove 8 is provided between the inner crown circumferential groove 6 and the inner tread end Ti.

[0036] The circumferential grooves 3 can take various forms, such as grooves extending linearly or in a zigzag pattern in the tire circumferential direction. In this embodiment, the inner crown circumferential groove 6, the inner shoulder circumferential groove 8, and the outer shoulder circumferential groove 7 extend linearly and parallel to the tire circumferential direction. Meanwhile, the outer crown circumferential groove 5 extends in a zigzag pattern. However, the tire 1 of the present invention is not limited to such forms.

[0037] The axial distance L1 from the groove centerline of the outer shoulder circumferential groove 7 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 5 or the inner crown circumferential groove 6 to the tire equator C is, for example, 3% to 15% of the tread width TW. In a preferred embodiment, the axial distance from the groove centerline of the inner crown circumferential groove 6 to the tire equator C is greater than the axial distance from the groove centerline of the outer crown circumferential groove 5 to the tire equator C. The tread width TW is the axial distance from the outer tread end To to the inner tread end Ti in the normal state described above.

[0038] The groove width W1 of the circumferential groove 3 is preferably at least 3 mm. In a preferred embodiment, the groove width W1 of the circumferential groove 3 is 2.0% to 5.0% of the tread width TW. In this embodiment, of the four circumferential grooves 3, the inner crown circumferential groove 6 has the largest groove width.

[0039] The land portion 4 includes a first land portion 11. In the present embodiment, the first land portion 11 is defined, for example, between the outer crown circumferential groove 5 and the inner crown circumferential groove 6. However, the position of the first land portion 11 is not limited to this configuration.

[0040] exist Figure 2 FIG shows an enlarged view of the first land portion 11. Figure 2 As shown, a plurality of first lateral grooves 14 are provided in the first land portion 11. First lateral grooves 14 are inclined in a first direction (upper right in the drawings of this specification) relative to the tire axial direction and extend across the first land portion 11. Thus, the first land portion 11 includes a plurality of first blocks 15 defined by the first lateral grooves 14.

[0041] The first block 15 is provided with at least one sipe 16 that is inclined in a second direction (downward and right in the drawings of this specification) with respect to the tire axial direction, which is opposite to the first direction. Furthermore, when the sipe 16 extends in a zigzag pattern as in the present embodiment, the inclination direction of the sipe 16 is determined by the inclination direction of a virtual straight line connecting the two ends of the sipe 16.

[0042] In this specification, a "sipe" refers to a cutout element having a small width, wherein the width between two opposing sipe walls is 1.5 mm or less. The width of the sipe is preferably 0.1 to 1.0 mm, more preferably 0.2 to 0.8 mm. For the sipe of this embodiment, the width is within the above-mentioned range throughout its entire depth. In addition, in this specification, in a cross section of a certain cutout element, a cutout element that includes an area with a width of 1.5 mm or less for more than 50% of its entire depth is treated as a sipe (a sipe including a groove element), even if it partially includes an area with a width exceeding 1.5 mm. In addition, in a cross section of a certain cutout element, a cutout element that includes an area with a width greater than 1.5 mm for more than 50% of its entire depth is treated as a groove (a groove including a sipe element), even if it partially includes an area with a width of less than 1.5 mm.

[0043] exist Figure 3 Shown in Figure 2 AA line section view. Figure 3 As shown, the sipe pattern 16 includes a plurality of grooves 14 (such as Figure 2 As shown, the same shall apply hereinafter. ) a portion 17 (hereinafter referred to as "first portion 17") having a maximum depth greater than that of the first transverse groove 14, and a portion 18 (hereinafter referred to as "second portion 18") having a shallower maximum depth than that of the first transverse groove 14. Figure 3 In the figure, the groove bottom 14d of the first lateral groove 14 is indicated by a dotted line. The tire of the present invention, by adopting the above-described structure, can effectively suppress the clogging of the sipes by snow. The following mechanism is presumed to be the reason for this. Furthermore, in this specification, "suppressing snow clogging" is not limited to snow but also includes suppressing the clogging of the sipes by small pieces of ice.

[0044] Because the first lateral grooves 14 and sipes 16 have different inclinations, when ground pressure is applied to the tread portion 2, the portion of the sipe 16 closer to the first lateral groove 14 closes first, while the portion farther from the first lateral groove 14 closes later. The same behavior occurs when the ground pressure on the tread portion 2 decreases and the sipes 16 open. This opening and closing of the sipes 16 facilitates snow removal, preventing snow clogging.

[0045] Furthermore, since the sipe 16 comprises a first portion 17 and a second portion 18, it has portions with larger openings and smaller openings, resulting in the aforementioned opening and closing motion. This facilitates the sipe 16 to open and close in an undulating manner, making it easier to drain snow from the sipe 16. Furthermore, by preventing the sipe 16 from becoming clogged with snow, the edges of the sipe 16 exert sufficient friction, improving on-ice performance. Furthermore, the reduction in the groove volume of the grooves that define the blocks, caused by snow clogging, can be suppressed, thereby improving on-snow performance.

[0046] The following describes the structure of this embodiment in more detail. Furthermore, each of the structures described below represents a specific aspect of this embodiment. Therefore, it goes without saying that the present invention can achieve the aforementioned effects even without the structures described below. Furthermore, even if any of the structures described below is applied individually to a tire of the present invention that lacks the aforementioned features, performance improvements corresponding to each structure can be expected. Furthermore, if several of the structures described below are applied in combination, performance improvements corresponding to the combined performance of each structure can be expected.

[0047] like Figure 2 As shown, the first land portion 11 is provided, for example, on the tire equator C. In a more preferred embodiment, the center position of the first land portion 11 in the tire axial direction is located closer to the inner tread end Ti than the tire equator C.

[0048] The first lateral grooves 14 are inclined in the first direction at an angle of, for example, 45° or less relative to the tire axial direction. The angle θ1 of the first lateral grooves 14 relative to the tire axial direction is 15 to 25°. Such first lateral grooves 14 contribute to improved cornering performance on snow. In this specification, groove angles are measured relative to the groove centerline.

[0049] As a more preferred embodiment, the groove width of the end portion of the first lateral groove 14 on the outer crown circumferential groove 5 side increases toward the outer crown circumferential groove 5. Such a first lateral groove 14 can strongly compact snow at the end portion, thereby improving on-snow performance.

[0050] The maximum depth of the first lateral groove 14 is, for example, 4.0 to 7.0 mm. The first lateral groove 14 of this embodiment has a constant depth throughout the entirety. However, the first lateral groove 14 is not limited to this form.

[0051] The sipes 16 (hereinafter referred to as the first sipes 16) provided in the first tread block 15 extend in a zigzag shape, for example, when the tread is viewed from above. The peak-to-peak amplitude of the first sipes 16 is, for example, 0.50 to 2.00 mm, preferably 1.20 to 1.50 mm. The wavelength of the first sipes 16 is, for example, 2.0 to 5.0 mm. Such first sipes 16 can increase the apparent rigidity of the first tread block 15 when the opposing sipe walls contact each other. However, the first sipes 16 are not limited to such a form and may also be, for example, linear.

[0052] The first block 15 is provided with a plurality of first sipes 16. The shortest distance between adjacent first sipes 16 is, for example, 2.0 to 5.0 mm. When the plurality of first sipes 16 extending in a zigzag pattern are provided as in this embodiment, the shortest distance between the center lines of the first sipes 16 is preferably 3.0 to 6.0 mm. This allows the first sipes 16 to be arranged in a properly aligned manner while maintaining the rigidity of the first block 15.

[0053] The angle of the first sipe 16 relative to the tire axial direction is, for example, 15 to 25 degrees. When the first sipe 16 extends in a zigzag pattern, the angle is measured using a virtual straight line connecting the two ends of the first sipe 16. Preferably, the angle between the first sipe 16 and the first lateral groove 14 is 35 to 45 degrees.

[0054] like Figure 3 As shown in FIG. 1 , the first sipe 16 is formed as a so-called 3D (three-dimensional) sipe extending in a zigzag shape in the depth direction. This makes it possible to more reliably maintain the rigidity of the first tread block 15. Figure 3 In FIG, the apex of the bend of the first sipe 16 is shown by a two-dot chain line.

[0055] The maximum depth d5 ​​of the first portion 17 of the first sipe 16 is preferably 105% to 145% of the maximum depth of the first lateral groove 14, more preferably 110% to 140%, and even more preferably 115% to 135%. Furthermore, the minimum depth d6 of the second portion 18 of the first sipe 16 is preferably 30% to 70% of the maximum depth of the first lateral groove 14, more preferably 35% to 65%, and even more preferably 40% to 60%.

[0056] The total length of the second portion 18 along the length of the first sipe 16 is preferably shorter than the total length of the first portion 17 along the same length. Specifically, the total length of the second portion 18 is 20% to 40% of the length of the first sipe 16. The total length of the first portion 17 is 60% to 80% of the length of the first sipe 16. This arrangement of the first and second portions 17, 18 maintains the rigidity of the first block 15 while reliably preventing clogging by snow.

[0057] The first sipe 16 includes a rib 20 that bulges outward in the tire radial direction from its bottom. The ribs 20 in this embodiment include a first rib 21 provided at one axial end of the first sipe 16, a second rib 22 provided at the other axial end, and a third rib 23 provided between the first and second ribs 21 and 22. This reliably reduces the amount of opening of the first sipe 16, further preventing snow from clogging the first sipe 16.

[0058] In order to further enhance the above-mentioned effect, the third tie rod 23 is preferably provided at a position overlapping with the center of the first sipe 16 in the longitudinal direction, for example.

[0059] The maximum height h1 of the tie bar 20 in the tire radial direction is 40% to 70% of the maximum depth d1 of the first sipe 16. This can maintain the on-ice performance and suppress clogging by snow.

[0060] From the same perspective, the axial width W2 of one tie bar 20 is preferably 10% to 40% of the wavelength of the first sipe 16 when the tread is viewed from above. The width W2 of the tie bar 20 is measured at the center of the tie bar 20 in the height direction.

[0061] The width of the third reinforcement bar 23 in the tire axial direction is preferably smaller than the width of the first reinforcement bar 21 in the tire axial direction, or smaller than the width of the second reinforcement bar in the tire axial direction. The width of the third reinforcement bar 23 is 30% to 50% of the width of the first reinforcement bar 21 or the second reinforcement bar 22. In addition, the height of the third reinforcement bar 23 in the tire radial direction is preferably smaller than the height of the first reinforcement bar 21 in the tire radial direction, or smaller than the height of the second reinforcement bar in the tire radial direction. The height of the third reinforcement bar 23 is 75% to 95% of the height of the first reinforcement bar 21 or the second reinforcement bar 22. Such a third reinforcement bar 23 can increase the friction provided by the edge of the first sipe 16, thereby improving the performance on ice.

[0062] The total width of the tie bars 20 along the longitudinal direction of the first sipe 16 is, for example, 15% to 35%, preferably 20% to 30% of the length of the first sipe 16 .

[0063] like Figure 2 As shown, in this embodiment, the first land portion 11 is provided with second lateral grooves 25 that communicate with the circumferential grooves 3 and are interrupted within the first block 15. Specifically, the second lateral grooves 25 include outer second lateral grooves 26 that communicate with the outer crown circumferential grooves 5, and inner second lateral grooves 27 that communicate with the inner crown circumferential grooves 6. These second lateral grooves 25 maintain the rigidity of the first block 15 while improving performance on ice and snow.

[0064] Second lateral grooves 25 do not pass through the axial center of first land portion 11 but are interrupted within first land portion 11. Axial length L3 of second lateral grooves 25 is, for example, 20% to 30% of the maximum axial width W3 of first land portion 11.

[0065] The second lateral grooves 25 are preferably inclined in the second direction, for example. The angle of the second lateral grooves 25 relative to the tire axial direction is, for example, 15 to 25 degrees. This facilitates the opening and closing of the first sipes 16, further preventing the first sipes 16 from being clogged by snow.

[0066] The maximum depth of the second lateral grooves 25 is, for example, ±2 mm of the maximum depth of the first lateral grooves 14. In a more preferred embodiment, the maximum depth of the second lateral grooves 25 is the same as the maximum depth of the first lateral grooves 14. Thus, the first sipes 16 include portions deeper than the maximum depth of the second lateral grooves 25 and portions shallower than the maximum depth of the second lateral grooves.

[0067] like Figure 1 As shown, the tread portion 2 of this embodiment includes, in addition to the first land portion 11 described above, a second land portion 12 and a third land portion 13. The second land portion 12 is adjacent to the inner tread end Ti side of the first land portion 11 and is defined between the inner crown circumferential groove 6 and the inner shoulder circumferential groove 8. The third land portion 13 is adjacent to the outer tread end To side of the first land portion 11 and is defined between the outer crown circumferential groove 5 and the outer shoulder circumferential groove 7.

[0068] exist Figure 4 FIG shows an enlarged view of the first land portion 11, the second land portion 12, and the third land portion 13. Figure 4 As shown, a plurality of third lateral grooves 30 are provided in the second land portion 12. Thus, the second land portion 12 includes a plurality of second blocks 32 defined by the third lateral grooves 30.

[0069] The plurality of third lateral grooves 30 are inclined in the same direction relative to the tire axial direction. In this embodiment, the third lateral grooves 30 are inclined in the second direction. Preferably, the angle θ2 of the third lateral grooves 30 relative to the tire axial direction is greater than the angle θ1 of the first lateral grooves 14 relative to the tire axial direction. Specifically, the angle θ2 of the third lateral grooves 30 is 20 to 40 degrees. Such third lateral grooves 30 improve traction and cornering performance on snow.

[0070] The third lateral grooves 30 of the present embodiment extend linearly with a constant groove width, for example. The groove width of the third lateral grooves 30 is, for example, 1.0 to 8.0 mm, preferably 2.0 to 6.0 mm.

[0071] exist Figure 5 Shown in Figure 4 BB line cross-sectional view. Figure 5 As shown, the maximum depth d2 of the third lateral groove 30 is, for example, 3.0 to 11.0 mm, preferably 6.0 to 9.5 mm. The maximum depth d2 of the third lateral groove 30 is preferably greater than the maximum depth of the first lateral groove 14, and more preferably greater than the maximum depth of the first sipe 16. As a result, the third lateral groove 30 is easily opened, thereby preventing snow from being retained between the third lateral groove 30 and the inner crown circumferential groove 6 (such as Figure 4 shown).

[0072] The groove bottom surface of the third lateral groove 30, for example, includes a protrusion 30a that partially protrudes outward in the tire radial direction. The protrusion 30a is provided, for example, at the axial end of the third lateral groove 30. In this embodiment, the protrusion 30a is provided at the end of the third lateral groove 30 on the inner crown circumferential groove 6 side. The radial height h2 of the protrusion 30a is, for example, 0.5 to 2.0 mm. The axial length of the protrusion 30a is preferably no more than 30% of the axial length of the third lateral groove 30, more preferably 5 to 15%. Such a protrusion 30a prevents snow and ice debris from clogging the third lateral groove 30.

[0073] like Figure 4 As shown, the end of the third lateral groove 30 on the inner crown circumferential groove 6 side does not overlap with a hypothetical region formed by extending the end of the first lateral groove 14 on the inner crown circumferential groove 6 side parallel to the tire axial direction. Similarly, the end of the third lateral groove 30 on the inner crown circumferential groove 6 side does not overlap with a hypothetical region formed by extending the end of the inner second lateral groove 27 on the inner crown circumferential groove 6 side parallel to the tire axial direction. This arrangement of the third lateral groove 30 reliably prevents snow from being retained in the inner crown circumferential groove 6.

[0074] The second block 32 is provided with a bending groove 35 that crosses the second block 32. The bending groove 35 includes, for example, a first inclined portion 36 connected to the inner crown circumferential groove 6 and extending obliquely in the first direction, a second inclined portion 37 connected to the inner shoulder circumferential groove 8 and extending obliquely in the first direction, and a third inclined portion 38 communicating between the first inclined portion 36 and the second inclined portion 37 and extending obliquely in the second direction.

[0075] The first inclined portion 36 and the second inclined portion 37 are preferably inclined at a larger angle relative to the tire axial direction than the first lateral groove 14. An angle θ3 of the first inclined portion 36 and the second inclined portion 37 relative to the tire axial direction is, for example, 20 to 40 degrees.

[0076] The third inclined portion 38 is inclined, for example, at a greater angle relative to the tire axial direction than the first lateral groove 14. The angle θ4 of the third inclined portion 38 relative to the tire axial direction is, for example, 50 to 70 degrees. Furthermore, the angle between the first inclined portion 36 and the third inclined portion 38, and the angle between the second inclined portion 37 and the third inclined portion 38, are preferably 80 to 100 degrees, respectively. The folded groove 35 including such a third inclined portion 38 exerts friction in multiple directions, thereby improving performance on ice, and can strongly compact snow within it, thereby also improving performance on snow.

[0077] exist Figure 6 Shown in Figure 4 The CC line cross-sectional view. Figure 6 As shown, the depths of the first inclined portion 36 and the second inclined portion 37 are preferably greater than the depth of the third inclined portion 38. Furthermore, the depths of the first inclined portion 36 and the second inclined portion 37 increase from the third inclined portion 38 toward the end of the bending groove 35. In a preferred embodiment, the maximum depth d3 of the first inclined portion 36 is greater than the maximum depth d4 of the second inclined portion 37. As a result, the rigidity of the second block 32 increases toward the inner tread end Ti, thereby improving steering stability on dry roads.

[0078] like Figure 4 As shown, the second block 32 is provided with a plurality of second sipes 33 extending obliquely in the first direction. In this embodiment, the maximum depth of the second sipes 33 is 0.90 to 1.10 times the maximum depth of the first sipes 16. In a more preferred embodiment, these depths are equal. This prevents the second sipes 33 from becoming clogged with snow.

[0079] In a more preferred embodiment, it is preferred that each second sipe 33 does not communicate with the bending groove 35. This can suppress a decrease in the rigidity of the second block 32, thereby improving the steering stability on a dry road surface.

[0080] The second sipe 33 is configured as a 3D sipe extending in the longitudinal direction and the depth direction to form an amplitude. In addition, the dimensions of the first sipe 16 described above can be applied to various dimensions of the second sipe 33 .

[0081] The third land portion 13 is provided with a plurality of fourth lateral grooves 40 that completely cross the third land portion 13 , and a plurality of interrupted grooves 41 that are connected to the outer crown circumferential grooves 5 and interrupted within the third land portion 13 .

[0082] The fourth lateral grooves 40 are inclined, for example, in the second direction. An angle θ5 of the fourth lateral grooves 40 relative to the tire axial direction is, for example, 15 to 30 degrees. Such fourth lateral grooves 40 improve traction performance on snow and cornering performance in a well-balanced manner.

[0083] Fourth lateral groove 40 faces outer second lateral groove 26 across outer crown circumferential groove 5. Furthermore, this configuration means that a virtual region extending along the length of fourth lateral groove 40 toward first land portion 11 overlaps at least a portion of outer second lateral groove 26. This allows fourth lateral groove 40, outer crown circumferential groove 5, and outer second lateral groove 26 to cooperate with each other to form a harder snow column, further improving on-snow performance.

[0084] The interruption groove 41 is inclined, for example, in the second direction. Thus, the interruption groove 41 is inclined with respect to the tire axial direction in the same direction as the fourth lateral groove 40. An angle θ4 of the interruption groove 41 with respect to the tire axial direction is, for example, 15 to 30 degrees.

[0085] The axial length L4 of the interrupted groove 41 is, for example, 40% to 60% of the maximum axial width W4 of the third land portion 13. Furthermore, the maximum groove width of the interrupted groove 41 is smaller than the maximum groove width of the fourth lateral groove 40. Such interrupted grooves 41 maintain the rigidity of the second land portion 12 while improving on-snow performance.

[0086] In a more preferred embodiment, a virtual region formed by extending the end of the interrupted groove 41 on the outer crown circumferential groove 5 side in parallel in the tire axial direction overlaps at least a portion of the end of the first lateral groove 14 on the outer crown circumferential groove 5 side. Thus, the interrupted groove 41, the outer crown circumferential groove 5, and the first lateral groove 14 can cooperate with each other to compact snow, thereby improving on-snow performance.

[0087] The third land portion 13 includes a plurality of third blocks 43 defined by a plurality of fourth lateral grooves 40. A plurality of third sipes 44 are provided in the third blocks 43. The third sipes 44 are inclined, for example, in the first direction. The structure of the first sipes 16 described above can be applied to the third sipes 44.

[0088] like Figure 2As shown, in order to improve the handling stability on dry roads and the performance on ice in a well-balanced manner, the land ratio of the tread portion 2 is preferably 60% to 75%. In this specification, the land ratio refers to the ratio of the total area of ​​the actual contact patch of the tread portion 2 to the total area of ​​the virtual contact patch formed by filling all the grooves in the tread portion.

[0089] From the same viewpoint, the rubber hardness of the tread rubber constituting the tread portion 2 is, for example, 45 to 65°. The rubber hardness refers to the Durometer A hardness measured at 23°C using a Durometer A durometer in accordance with JIS-K6253.

[0090] As mentioned above, the tire according to one embodiment of the present invention has been described in detail. However, the present invention is not limited to the above-described specific embodiment, and can be implemented in various modified forms.

[0091] [Example]

[0092] Based on the specifications in Table 1, we have produced Figure 1 The basic tread pattern is a tire of size 195 / 65R15. As a comparative example, Figure 7 As shown in FIG, a tire without a rib in the first sipe a was produced. The overall depth of the first sipe a of the comparative tire is greater than the maximum depth of the first transverse groove. In addition to the above-mentioned structure, the comparative tire has the same Figure 1 The structures shown are substantially the same. Each test tire was tested for both on-ice and on-snow performance. The general specifications and test methods for 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] <On-ice performance>

[0098] The test vehicle's driving performance on ice was evaluated by the driver's sensory evaluation. The results were scored with the comparative example as 100, with larger values ​​indicating better performance on ice.

[0099] Snow performance

[0100] The driving performance of the test vehicle on snow was evaluated by the driver's sensory organs. The results were scored with the comparative example as 100, with larger values ​​indicating better on-snow performance.

[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 respective Examples exhibit excellent on-ice performance and on-snow performance by suppressing clogging of the sipes by snow.

Claims

1. A tire having a tread portion, The tire is characterized in that The tread portion includes a first land portion defined by circumferential grooves extending continuously in the tire circumferential direction, and a plurality of first lateral grooves inclined in a first direction with respect to the tire axial direction and crossing the first land portion. The first land portion includes a plurality of first blocks divided by the first lateral grooves. The first block is provided with at least one sipe inclined in a second direction opposite to the first direction with respect to the tire axial direction. The sipe includes a portion having a depth deeper than the maximum depth of the first lateral groove and a portion having a depth shallower than the maximum depth of the first lateral groove. The sipe pattern includes a rib that rises from its bottom toward the outer side in the tire radial direction. The tie bars include a first tie bar provided at one axial end of the sipe, a second tie bar provided at the other axial end of the sipe, and a third tie bar provided between the first tie bar and the second tie bar. The width of the third reinforcement in the tire axial direction is smaller than the width of the first reinforcement in the tire axial direction, or smaller than the width of the second reinforcement in the tire axial direction, and the height of the third reinforcement in the tire radial direction is smaller than the height of the first reinforcement in the tire radial direction, or smaller than the height of the second reinforcement in the tire radial direction.

2. The tire according to claim 1, wherein The first block is provided with a second lateral groove that is connected to the circumferential groove and is interrupted in the first block. The second transverse groove is inclined toward the second direction.

3. The tire according to claim 1, wherein: The angle of the first lateral groove relative to the tire axial direction is 15 to 25 degrees.

4. The tire according to any one of claims 1 to 3, characterized in that The angle of the sipe relative to the tire axial direction is 15 to 25 degrees.

5. The tire according to claim 1, wherein The tie rod is provided at a position overlapping with the center of the sipe in the longitudinal direction.

6. The tire according to claim 1 or 5, characterized in that The height of the tie bar in the tire radial direction is 40% to 70% of the maximum depth of the sipe.

7. The tire according to claim 1, wherein The sipes extend in a zigzag shape in the longitudinal direction thereof, The width of the tie bar in the tire axial direction is 10% to 40% of the wavelength of the sipe.

8. The tire according to claim 2, wherein: The sipe includes a portion having a depth deeper than the maximum depth of the second lateral groove and a portion having a depth shallower than the maximum depth of the second lateral groove.

9. The tire according to any one of claims 1 to 3, characterized in that The maximum depth of a portion of the sipe that is deeper than the maximum depth of the first lateral groove is 105% to 145% of the maximum depth of the first lateral groove.

10. The tire according to any one of claims 1 to 3, characterized in that The minimum depth of a portion of the sipe that is shallower than the maximum depth of the first lateral groove is 30% to 70% of the maximum depth of the first lateral groove.

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