tire

Abstract

The present invention provides a tire capable of exhibiting excellent cornering performance on ice. The tire has a tread portion (2). The tread portion (2) includes a first land portion (11) divided by a circumferential groove (3), and a plurality of first transverse grooves (16) crossing the first land portion (11). The first land portion (11) includes a plurality of first tread blocks (18) divided by the first transverse grooves (16). A sipe pattern (25) and a second transverse groove (20) that disconnects the first tread block (18) in the tire circumferential direction are formed in at least one of the first tread blocks (18). The second transverse groove (20) includes a pair of two end portions (21) inclined in a first direction relative to the tire axial direction, and a central portion (22) located between the two end portions (21) and inclined in a second direction opposite to the first direction.

Description

Technical Field

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

[0002] Patent Document 1 below proposes a pneumatic tire having longitudinal grooves and sidewall fine grooves provided in outer shoulder blocks. The longitudinal grooves increase the edge component in the tire circumferential direction, thereby improving cornering performance on icy roads.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-082308

[0004] In recent years, tires intended for use in winter have been required to have further improved cornering performance on ice.

[0005] The inventors have discovered that water film on ice can be effectively removed by improving the shapes of lateral grooves and sipes, and have thus completed the present invention. Summary of the Invention

[0006] 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 can exhibit excellent cornering performance on ice.

[0007] 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 transverse to the first land portion, the first land portion includes a plurality of first pattern blocks divided by the first lateral grooves, a sipe is formed in at least one of the first pattern blocks, and a second lateral groove that divides the first pattern block in the tire circumferential direction, the second lateral groove includes a pair of two end portions inclined in a first direction relative to the tire axial direction, and a central portion located between the two end portions and inclined in a second direction opposite to the first direction.

[0008] Preferably, in the tire of the present invention, the groove width of the second lateral groove is smaller than the groove width of the first lateral groove.

[0009] In the tire of the present invention, preferably, the groove width of each of the pair of end portions is larger than the groove width of the central portion.

[0010] In the tire of the present invention, preferably, the length of each of the pair of end portions in the tire axial direction is smaller than the length of the center portion in the tire axial direction.

[0011] Preferably, in the tire of the present invention, each of the first lateral grooves is inclined toward the second direction.

[0012] In the tire of the present invention, preferably, an angle of the central portion with respect to the tire axial direction is larger than an angle of the first lateral groove with respect to the tire axial direction.

[0013] In the tire of the present invention, preferably, the maximum depth of the central portion is smaller than the maximum depth of the sipes.

[0014] In the tire of the present invention, preferably, the sipes are inclined in the first direction.

[0015] Preferably, in the tire of the present invention, the sipes do not communicate with the second lateral grooves.

[0016] In the tire of the present invention, the sipes are preferably three-dimensional sipes extending in a wave shape in the longitudinal direction and the depth direction.

[0017] In the tire of the present invention, preferably, the angle of the first lateral groove relative to the tire axial direction is 20 to 40 degrees.

[0018] In the tire of the present invention, preferably, the angle of the central portion relative to the tire axial direction is 50 to 70 degrees.

[0019] In the tire of the present invention, preferably, the angles of the two end portions relative to the tire axial direction are 20 to 40 degrees.

[0020] The tire of the present invention is preferably designated for installation in a vehicle, wherein the tread portion includes an inner tread end located inside the vehicle when installed in the vehicle, and the first land portion is provided between the tire equator and the inner tread end.

[0021] Preferably, in the tire of the present invention, the tread portion includes a plurality of circumferential grooves, the circumferential grooves including an inner crown circumferential groove adjacent to the tire equator side of the first land portion, and the inner crown circumferential groove has the largest groove width among the plurality of circumferential grooves.

[0022] The tire of the present invention can exhibit excellent cornering performance on ice by adopting the above-mentioned structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a development view of the tread portion of a tire according to one embodiment of the present invention.

[0024] Figure 2 yes Figure 1 An enlarged view of the first land part.

[0025] Figure 3 yes Figure 2 An enlarged view of the second transverse groove.

[0026] Figure 4 yes Figure 2 AA line section view.

[0027] Figure 5 yes Figure 2 BB line cross-sectional view.

[0028] Figure 6 yes Figure 2 An enlarged perspective view of the sipe wall of the sipe pattern.

[0029] Figure 7 yes Figure 1 Enlarged views of the first, second, and third land parts of the .

[0030] Figure 8 yes Figure 1 Enlarged view of the 4th and 5th land parts.

[0031] Figure 9 This is an enlarged view of the first land portion according to another embodiment of the present invention.

[0032] Figure 10 This is an enlarged view of the first land portion according to another embodiment of the present invention.

[0033] Figure 11 It is an enlarged view of the first land portion of the tire of the comparative example.

[0034] Description of Reference Numerals

[0035] 2…tread portion; 3…circumferential groove; 11…first land portion; 16…first lateral groove; 18…first lug block; 20…second lateral groove; 21…end portions; 22…center portion; 25…sipes. DETAILED DESCRIPTION

[0036] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

[0037] 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.

[0038] 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).

[0039] 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.

[0040] 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°.

[0041] "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.

[0042] "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."

[0043] "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".

[0044] 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.

[0045] The circumferential grooves 3 include, for example, an inner crown circumferential groove 5, an inner shoulder circumferential groove 6, an outer crown circumferential groove 7, and an outer shoulder circumferential groove 8. The inner crown circumferential groove 5 is provided between the tire equator C and the inner tread end Ti. The inner shoulder circumferential groove 6 is provided between the inner crown circumferential groove 5 and the inner tread end Ti. The outer crown circumferential groove 7 is provided between the tire equator C and the outer tread end To. The outer shoulder circumferential groove 8 is provided between the outer crown circumferential groove 7 and the outer tread end To.

[0046] 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 5, the inner shoulder circumferential groove 6, and the outer shoulder circumferential groove 8 extend linearly and parallel to the tire circumferential direction. Meanwhile, the outer crown circumferential groove 7 extends in a zigzag pattern. However, the tire 1 of the present invention is not limited to such forms.

[0047] The axial distance L1 from the groove centerline of the outer shoulder circumferential groove 8 or the inner shoulder circumferential groove 6 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 7 or the inner crown circumferential groove 5 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 5 to the tire equator C is greater than the axial distance from the groove centerline of the outer crown circumferential groove 7 to the tire equator C. Furthermore, 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.

[0048] 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 5 has the largest groove width.

[0049] The land portion 4 includes a first land portion 11. The first land portion 11 is preferably provided, for example, between the tire equator C and the inner tread end Ti. The first land portion 11 of this embodiment is defined between the inner crown circumferential groove 5 and the inner shoulder circumferential groove 6.

[0050] exist Figure 2 FIG shows an enlarged view of the first land portion 11. Figure 2 As shown, a plurality of first lateral grooves 16 are provided in the first land portion 11 so as to cross the first land portion 11. Thus, the first land portion 11 includes a plurality of first blocks 18 defined by the first lateral grooves 16.

[0051] At least one of the first blocks 18 has a plurality of sipes 25 and a second lateral groove 20 that divides the first block 18 in the tire circumferential direction. The second lateral groove 20 of this embodiment divides the first block 18 by extending from the inner crown circumferential groove 5 to the inner shoulder circumferential groove 6.

[0052] In this specification, "sipe" refers to a cutout element having a small width, and the width between two opposing sipe walls is 0.6 mm or less. The width of the sipe is preferably 0.1 to 0.5 mm, more preferably 0.2 to 0.4 mm. For the sipe of this embodiment, the width is within the above range throughout its entire depth. In addition, in this specification, in the cross section of a certain cutout element, a cutout element including an area with a width of 0.6 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 0.6 mm. In addition, in the cross section of a certain cutout element, a cutout element including an area with a width greater than 0.6 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 0.6 mm.

[0053] exist Figure 3 FIG shows an enlarged view of the second transverse groove 20. Figure 3As shown, the second lateral groove 20 includes a pair of end portions 21 inclined in a first direction relative to the tire axial direction, and a center portion 22 located between the end portions 21 and inclined in a second direction opposite to the first direction. In this specification, "inclined in the first direction" refers to inclination toward the upper right, and "inclined in the second direction" refers to inclination toward the lower right. The tire 1 of the present invention, by adopting the above-described structure, exhibits excellent cornering performance on ice. The reason for this is presumably the following mechanism.

[0054] When driving on ice, the tire 1 of the present invention uses the first transverse groove 16 to break the water film on the ice in the tire circumferential direction. On the other hand, the second transverse groove 20 includes a central portion 22 and two end portions 21, so that the edge of the second transverse groove 20 includes a portion protruding toward one side of the tire circumferential direction and a portion protruding toward the other side of the tire circumferential direction. Therefore, the edge of the second transverse groove 20 can further break the water film broken by the first transverse groove 16 in the tire axial direction. In addition, the sipes 25 effectively absorb the water film broken by the first transverse groove 16 and the second transverse groove 20. Through such an action, the edges of each groove and the sipe can exert greater friction even on ice. In addition, the edges of the central portion 22 and the two end portions 21 of the second transverse groove 20 provide friction in the tire axial direction, thereby improving the cornering performance on ice.

[0055] 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 the tire of the present invention having 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.

[0056] like Figure 2 As shown, the plurality of first lateral grooves 16 are inclined in the same direction relative to the tire axial direction. In this embodiment, the first lateral grooves 16 are inclined in the second direction. The angle θ1 of the first lateral grooves 16 relative to the tire axial direction is, for example, 20 to 40 degrees. Such first lateral grooves 16 can provide axial friction even on ice.

[0057] The first lateral grooves 16 of the present embodiment extend linearly with a constant groove width, for example. The groove width W2 of the first lateral grooves 16 is, for example, 1.0 to 8.0 mm, preferably 2.0 to 6.0 mm.

[0058] exist Figure 4 Shown in Figure 2 AA line section view. Figure 4As shown, the maximum depth d1 of the first lateral groove 16 is, for example, 3.0 to 11.0 mm, and preferably 6.0 to 9.5 mm.

[0059] The groove bottom surface of the first lateral groove 16, for example, includes a protrusion 16a that partially protrudes outward in the tire radial direction. The protrusion 16a is provided, for example, at the axial end of the first lateral groove 16. In this embodiment, it is provided at the end of the first lateral groove 16 on the inner crown circumferential groove 5 side. The radial height h1 of the protrusion 16a is, for example, 0.5 to 2.0 mm. The axial length of the protrusion 16a is preferably no more than 30% of the axial length of the first lateral groove 16, more preferably 5 to 15%. Such a protrusion 16a prevents snow and ice debris from clogging the first lateral groove 16.

[0060] like Figure 2 As shown, the acute outer corner 28 formed by the first lateral groove 16 and the inner crown circumferential groove 5 is formed with a chamfered portion 28a that is obliquely connected to the tread surface of the first block 18. Such a chamfered portion 28a contributes to improving the rigidity of the first block 18.

[0061] The second lateral groove 20 has a smaller groove width than the groove width W2 of the first lateral groove 16. Specifically, the second lateral groove 20 has a maximum groove width W3 formed at one of its pair of end portions 21, and this groove width W3 is smaller than the groove width W2 of the first lateral groove 16. The groove width W3 of the second lateral groove 20 is 40% to 60% of the groove width W2 of the first lateral groove 16. These second lateral grooves 20 contribute to a well-balanced improvement in cornering performance on ice and steering stability on dry roads (hereinafter referred to simply as "steering stability").

[0062] like Figure 3 As shown, the central portion 22 of the second transverse groove 20 passes through the first land portion 11 (e.g. Figure 2 The axial length L3 of the center portion 22 is the axial width W4 of the first land portion 11 (as shown). Figure 2 As shown, the same applies below. ) 25% to 45%. In addition, in this specification, the length of the groove is measured at the groove center line.

[0063] The central portion 22 is inclined at a constant angle relative to the tire axial direction and extends in a straight line. Preferably, the angle θ2 of the central portion 22 relative to the tire axial direction is greater than the angle θ1 of the first transverse groove 16 relative to the tire axial direction (e.g., Figure 2 Specifically, the angle of the central portion 22 is 50 to 70 degrees, preferably 55 to 65 degrees.

[0064] like Figure 2As shown, the groove width W5 of the central portion 22 constitutes the minimum groove width of the second lateral groove 20. The groove width W5 of the central portion 22 is, for example, greater than 0.6 mm and less than 3.0 mm. In this embodiment, the central portion 22 is configured as a narrow groove, for example, with a groove width greater than 0.6 mm and less than 2.0 mm. This allows the two opposing groove walls in the central portion 22 to contact each other, thereby improving the rigidity of the first block 18. This prevents the first block 18 from tipping over, thereby enhancing steering stability.

[0065] The depth of the central portion 22 is preferably less than the depth of the first lateral groove 16. In a more preferred embodiment, the maximum depth of the central portion 22 is less than the maximum depth of the sipe 25. The depth of the central portion 22 is preferably 20% to 40% of the depth of the sipe 25. The depth of the central portion 22 is, for example, 0.2 to 5.0 mm, preferably 0.5 to 3.0 mm. This improves cornering performance on ice and steering stability in a well-balanced manner.

[0066] In this embodiment, the two end portions 21 are formed by a first end portion 23 connected to the inner crown circumferential groove 5 and a second end portion 24 connected to the inner shoulder circumferential groove 6. Furthermore, the first end portion 23 and the second end portion 24 are each inclined at a constant angle relative to the tire axial direction and extend in a straight line. Thus, the second lateral groove 20 of this embodiment is configured as an N-shaped lateral groove, including a central portion 22, a first end portion 23 extending from the central portion 22 to the inner crown circumferential groove 5, and a second end portion 24 extending from the central portion 22 to the inner shoulder circumferential groove 6.

[0067] like Figure 3 As shown, the angle θ3 formed by the two end portions 21 relative to the tire axial direction is, for example, 10 to 50°, preferably 20 to 40°. Furthermore, the angle θ4 between the center portion 22 and the first end portion 23, and the angle θ5 between the center portion 22 and the second end portion 24, are each 70 to 110°, preferably 80 to 100°. This allows the edges of the second lateral grooves 20 to more easily cut through the water film on ice, thereby improving cornering performance on ice.

[0068] The groove width W6 of the two end portions 21 is, for example, greater than 0.6 mm and less than 5.0 mm. The groove width W6 of the two end portions 21 in this embodiment is, for example, 1.0 to 4.0 mm, preferably 2.0 to 3.0 mm. In a more preferred embodiment, the groove width W6 of each of the pair of two end portions 21 is greater than the groove width W5 of the central portion 22. Specifically, the groove width W6 is 2.0 to 3.5 times the groove width W5. In addition, the groove width of the second end portion 24 is smaller than the groove width of the first end portion 23. Such two end portions 21 can effectively improve the turning performance on ice.

[0069] To improve cornering performance and steering stability on ice in a balanced manner, the axial length L4 of each of the pair of end portions 21 is, for example, greater than the axial length L3 of the center portion 22. The axial length L4 of each of the pair of end portions 21 is, for example, 25% to 40% of the axial width W4 of the first land portion 11.

[0070] exist Figure 5 Shown in Figure 2 BB line cross-sectional view. Figure 5 As shown, the depth of the two end portions 21 is preferably smaller than the depth of the first lateral groove 16 and larger than the depth of the central portion 22. The maximum depth of the two end portions 21 is, for example, 2.0 to 7.0 mm, preferably 3.0 to 7.0 mm.

[0071] The depths of the first end portion 23 and the second end portion 24 increase from the center portion 22 toward the end of the second lateral groove 20. In a preferred embodiment, the maximum depth d2 of the first end portion 23 is greater than the maximum depth d3 of the second end portion 24. As a result, the rigidity of the first block 18 increases toward the inner tread end Ti, thereby improving steering stability on dry roads.

[0072] like Figure 2 As shown, the first block 18 is provided with a plurality of sipes 25 inclined with respect to the tire axial direction. In this embodiment, at least one of the sipes 25 is inclined in the first direction. In a preferred embodiment, each sipe 25 provided in the first block 18 is inclined in the first direction. The angle of each sipe 25 with respect to the tire axial direction is, for example, 10 to 50 degrees, preferably 20 to 40 degrees. These sipes 25 cooperate with the first lateral grooves 16 and the second lateral grooves 20 to provide friction in multiple directions, thereby improving cornering performance on ice.

[0073] In this embodiment, each sipe 25 extends in a zigzag shape. In this case, the above-mentioned inclination direction and angle are determined by the inclination direction and angle of the straight line connecting the two ends of the sipe.

[0074] Preferably, at least one of the sipes 25 does not communicate with the second lateral groove 20. In a more preferred embodiment, each sipe 25 provided in the first block 18 does not communicate with the second lateral groove 20. The distance between one end of each sipe 25 and the second lateral groove 20 is, for example, 0.5 to 2.0 mm, preferably 0.8 to 1.2 mm. This ensures a sufficient length for each sipe 25 while maintaining the rigidity of the first block 18.

[0075] exist Figure 6 FIG shows an enlarged perspective view of the sipe wall 25w of the sipe pattern 25. Figure 6As shown, each sipe 25 in this embodiment is, for example, a 3D (three-dimensional) sipe extending in a wavy pattern in its longitudinal and depth directions. This increases the apparent rigidity of the first block 18 when two opposing sipe walls 25w contact each other, thereby improving steering stability. However, the present invention is not limited to this configuration; the sipes 25 may also extend linearly in their longitudinal and depth directions, for example.

[0076] In order to improve the cornering performance on ice and the steering stability on dry roads in a well-balanced manner, the depth of the sipes 25 is, for example, 2.0 to 9.0 mm, and preferably 4.0 to 8.0 mm.

[0077] 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, a third land portion 13, a fourth land portion 14, and a fifth land portion 15. 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 shoulder circumferential groove 6 and the inner tread end Ti. 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 7 and the inner crown circumferential groove 5. The fourth land portion 14 is adjacent to the outer tread end To side of the third land portion 13 and is defined between the outer crown circumferential groove 7 and the outer shoulder circumferential groove 8. The fifth land portion 15 is adjacent to the outer tread end To side of the fourth land portion 14 and is defined between the outer shoulder circumferential groove 8 and the outer tread end To.

[0078] exist Figure 7 FIG shows an enlarged view of the first land portion 11, the second land portion 12, and the third land portion 13. Figure 7 As shown, a plurality of inner shoulder lateral grooves 30 are provided in the second land portion 12 so as to cross the second land portion 12. Thus, the second land portion 12 includes a plurality of inner shoulder blocks 31.

[0079] The inner shoulder lateral groove 30 is inclined, for example, in the first direction. The angle of the inner shoulder lateral groove 30 relative to the tire axial direction is, for example, 5 to 15 degrees. In a more preferred embodiment, the angle of the inner shoulder lateral groove 30 relative to the tire axial direction is smaller than the angle of the first lateral groove 16 relative to the tire axial direction. Such inner shoulder lateral grooves 30 can improve traction on ice.

[0080] The inner shoulder lateral groove 30 includes a first groove edge 30a and a second groove edge 30b. The first groove edge 30a extends in a straight line, for example. The second groove edge 30b is curved in a zigzag shape, for example. More specifically, the second groove edge 30b includes a gently inclined edge 30c and a steeply inclined edge 30d alternatingly along its length. The gently inclined edge 30c extends in the axial direction of the tire. The angle of the steeply inclined edge 30d relative to the axial direction of the tire is greater than the angle of the gently inclined edge 30c relative to the axial direction of the tire. In addition, the length of the steeply inclined edge 30d is less than the length of the gently inclined edge 30c. The inner shoulder lateral groove 30 having such a second groove edge 30b can compact snow and ice chips therein.

[0081] In this embodiment, the region of the inner shoulder lateral groove 30 extending parallel to the inner shoulder circumferential groove 6 in the tire axial direction overlaps at least a portion of the inner shoulder circumferential groove 6 end of the first lateral groove 16. Thus, the inner shoulder lateral groove 30 and the first lateral groove 16 cooperate to improve traction on ice.

[0082] The inner shoulder blocks 31 are provided with inner shoulder longitudinal narrow grooves 32 extending in the tire circumferential direction. For example, the inner shoulder longitudinal narrow grooves 32 connect two inner shoulder lateral grooves 30 adjacent to each other in the tire circumferential direction. These inner shoulder longitudinal narrow grooves 32 provide axial friction on ice.

[0083] The inner shoulder block 31 includes a first segment 33 defined between the inner shoulder circumferential groove 6 and the inner shoulder narrow longitudinal groove 32 , and a second segment 34 defined closer to the inner tread end Ti than the inner shoulder narrow longitudinal groove 32 .

[0084] The first and second treads 33 and 34 are each provided with a plurality of inner shoulder sipes 35 extending in a zigzag pattern. Each inner shoulder sipe 35 is inclined, for example, in the first direction. In a preferred embodiment, the angle of each inner shoulder sipe 35 relative to the tire's axial direction is smaller than the angle of the sipes 25 provided in the first tread block 18 relative to the tire's axial direction. This improves both cornering performance on ice and traction performance on ice in a well-balanced manner.

[0085] In a preferred embodiment, the sipe spacing of the plurality of inner shoulder sipes 35 provided on the first sheet 33 is preferably greater than the sipe spacing of the plurality of sipes 25 provided on the first block 18. In a more preferred embodiment, the sipe spacing of the plurality of inner shoulder sipes 35 provided on the second sheet 34 is preferably greater than the sipe spacing of the plurality of inner shoulder sipes 35 provided on the first sheet 33. This increases the rigidity of the second land portion 12 relative to the rigidity of the first land portion 11, improving steering stability on dry roads. Furthermore, the "sipe spacing" refers to the minimum distance between two sipes.

[0086] A plurality of crown lateral grooves 40 are provided in the third land portion 13 so as to cross the third land portion 13. Thus, the third land portion 13 includes a plurality of crown blocks 41 defined by the crown lateral grooves 40.

[0087] The crown lateral grooves 40 are inclined, for example, in the first direction. The angle of the crown lateral grooves 40 relative to the tire axial direction is, for example, 15 to 25 degrees. In a more preferred embodiment, the angle of the crown lateral grooves 40 relative to the tire axial direction is smaller than the angle of the first lateral grooves 16 relative to the tire axial direction. Furthermore, the angle of the crown lateral grooves 40 relative to the tire axial direction is greater than the angle of the inner shoulder lateral grooves 30 relative to the tire axial direction. Thus, the crown lateral grooves 40, the first lateral grooves 16, and the inner shoulder lateral grooves 30 cooperate to provide friction in multiple directions, thereby improving cornering performance and traction on ice.

[0088] The end of the crown lateral groove 40 on the inner crown circumferential groove 5 side preferably does not overlap with a region formed by extending the end of the first lateral groove 16 on the inner crown circumferential groove 5 side parallel to the tire axial direction. Furthermore, the end of the crown lateral groove 40 on the inner crown circumferential groove 5 side preferably overlaps with a region formed by extending the first end 23 of the second lateral groove 20 along its longitudinal direction. Thus, the crown lateral groove 40 and the first lateral groove 16 cooperate to improve traction on ice.

[0089] For example, the crown lateral groove 40 preferably has a groove width that increases toward the outer tread end To at the end portion thereof on the outer crown circumferential groove 7. Such a crown lateral groove 40 is less likely to be clogged with snow or ice.

[0090] The crown block 41 is provided with, for example, a first interrupted groove 43 , a second interrupted groove 44 , and a plurality of crown sipes 45 extending in a zigzag pattern.

[0091] The first interruption groove 43 extends from the inner crown circumferential groove 5 and is interrupted within the crown block 41. The second interruption groove 44 extends from the outer crown circumferential groove 7 and is interrupted within the crown block 41. In this embodiment, the first interruption groove 43 and the second interruption groove 44 are interrupted before reaching the axial center of the crown block 41. Furthermore, the first interruption groove 43 and the second interruption groove 44 are each inclined in the second direction. This arrangement of the first interruption groove 43 and the second interruption groove 44 contributes to a well-balanced improvement in cornering performance and handling stability on ice.

[0092] Each crown sipe 45 is inclined, for example, in the second direction. The angle of the crown sipe 45 relative to the tire axial direction is smaller than the angle of the sipe 25 provided in the first block 18 relative to the tire axial direction. Such crown sipes 45 improve cornering performance and traction performance on ice in a well-balanced manner.

[0093] exist Figure 8FIG shows an enlarged view of the fourth land portion 14 and the fifth land portion 15. Figure 8 As shown, a plurality of outer middle lateral grooves 46 are provided in fourth land portion 14 so as to cross fourth land portion 14. Thus, fourth land portion 14 includes a plurality of outer middle blocks 47 defined by outer middle lateral grooves 46.

[0094] The outer middle lateral groove 46 is inclined, for example, in the second direction. The angle of the outer middle lateral groove 46 relative to the tire axial direction is, for example, 15 to 25 degrees. In a more preferred embodiment, the angle of the outer middle lateral groove 46 relative to the tire axial direction is smaller than the angle of the first lateral groove 16 relative to the tire axial direction.

[0095] The outer middle block 47 is provided with an outer middle interrupted groove 48 and a plurality of outer middle sipes 49 extending in a zigzag pattern.

[0096] Outer middle interrupted groove 48 extends, for example, from outer crown circumferential groove 7 and interrupts within outer middle block 47. Outer middle interrupted groove 48 is inclined, for example, in the second direction. The angle of outer middle interrupted groove 48 relative to the tire axial direction is, for example, 10 to 20 degrees. This outer middle interrupted groove 48 helps maintain the rigidity of outer middle block 47 and improves traction on ice.

[0097] like Figure 1 As shown, the outer middle interrupted groove 48 preferably has its end on the outer crown circumferential groove 7 side overlapped with a region formed by extending the outer crown lateral groove 40 end on the outer crown circumferential groove 7 side in parallel with the tire axial direction. Thus, the outer middle interrupted groove 48 and the crown lateral groove 40 cooperate to improve traction on ice.

[0098] like Figure 8 As shown, the outer middle sipe 49 is inclined, for example, in the first direction. Preferably, the angle of the outer middle sipe 49 relative to the tire axial direction is smaller than the angle of the sipe 25 provided in the first block 18 relative to the tire axial direction. Such outer middle sipe 49 provides friction in multiple directions, thereby contributing to improved cornering performance on ice.

[0099] A plurality of outer shoulder lateral grooves 50 are provided in fifth land portion 15 so as to cross fifth land portion 15. Thus, fifth land portion 15 includes a plurality of outer shoulder blocks 51 defined by outer shoulder lateral grooves 50.

[0100] The outer shoulder lateral groove 50 extends at an angle of, for example, 10° or less relative to the tire axial direction. In a preferred embodiment, the end of the outer shoulder lateral groove 50 on the outer shoulder circumferential groove 8 side preferably overlaps with a region formed by extending the end of the outer middle lateral groove 46 on the outer shoulder circumferential groove 8 side parallel to the tire axial direction.

[0101] The outer shoulder block 51 is provided with an outer shoulder longitudinal narrow groove 52 extending in the tire circumferential direction and a plurality of outer shoulder sipes 53 extending in a zigzag pattern.

[0102] The outer shoulder narrow grooves 52 connect the outer shoulder lateral grooves 50 adjacent to each other in the tire circumferential direction. The outer shoulder narrow grooves 52 are preferably partially bent, for example. Such outer shoulder narrow grooves 52 can provide frictional force around the tire circumference on ice.

[0103] It is preferable that the angle of the outer shoulder sipe 53 with respect to the tire axial direction is smaller than the angle of the sipe 25 provided in the first block 18 with respect to the tire axial direction.

[0104] like Figure 1 As shown, the land ratio of the tread portion 2 of this embodiment is, for example, 70% to 90%, preferably 80% to 88%. This improves cornering performance on ice and handling stability on dry roads in a well-balanced manner. In this specification, "land ratio" refers to the ratio of the actual tread contact patch area to the tread portion 2 contact patch area after all grooves and sipes provided in the tread portion 2 are filled.

[0105] In the drawings showing the other embodiment, the same reference numerals as those in the above description are given to the elements already described, and the above configuration can be applied.

[0106] exist Figure 9 and Figure 10 In FIG, an enlarged view of the first land portion 11 of another embodiment is shown. Figure 9 In the illustrated embodiment, the second lateral groove 20 has an angle θ2 of the center portion 22 and an angle θ3 of the end portions 21 relative to the tire axial direction that are greater than the angle θ1 of the first lateral groove 16. This further improves cornering performance on ice.

[0107] In addition, Figure 9 In the embodiment shown, the angle θ4 between the center portion 22 and the first end portion 23 and the angle θ5 between the center portion 22 and the second end portion 24 are both acute angles, preferably 60 to 80 degrees.

[0108] exist Figure 10 In the illustrated embodiment, the second lateral groove 20 has an angle θ2 of the center portion 22 and an angle θ3 of the end portions 21 thereof smaller than the angle θ1 of the first lateral groove 16 thereof.

[0109] In addition, Figure 10In the illustrated embodiment, the angle θ4 between the center portion 22 and the first end portion 23 and the angle θ5 between the center portion 22 and the second end portion 24 are both obtuse angles, preferably 130 to 150 degrees. This improves the rigidity of the first block 18 and provides excellent steering stability.

[0110] 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-mentioned specific embodiment, and can be implemented in various modified forms.

[0111] [Example]

[0112] 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 11 The tire of the first land portion a shown. Figure 11 As shown, the block b divided into the first land portion a of the comparative example is provided with an interrupted groove d extending from the inner shoulder circumferential groove c and interrupted in the block b. In addition to the above-mentioned structure, the tire of the comparative example has the same Figure 1 The tread patterns shown are substantially the same. Each test tire was tested for cornering performance on ice and handling stability on dry roads. The general specifications and testing methods for each test tire are as follows.

[0113] Installed rim: 15×6.0JJ

[0114] Tire internal pressure: front wheel 230kPa, rear wheel 230kPa

[0115] Test vehicle: 1500cc displacement, front-wheel drive

[0116] Tire installation position: all wheels

[0117] <Ice cornering performance>

[0118] The driver's sensory evaluation of the turning performance of the test vehicle on ice was performed. The results were scored with the comparative example as 100, with larger values ​​indicating better turning performance on ice.

[0119] Handling stability on dry roads

[0120] The test vehicle was used to evaluate the steering stability of the vehicle while driving on a dry road using the driver's sensory perception. The results were scored with the comparative example as 100, with larger values ​​indicating better steering stability on a dry road.

[0121] The test results are shown in Table 1.

[0122]

Table 1

[0123]

[0124] As shown in Table 1, it was confirmed that each Example having the second lateral groove of the present invention exhibited excellent cornering performance on ice. In addition, it was also confirmed that each Example maintained steering stability on dry roads.

[0125] For those with Figure 2 In the embodiment of the first land portion shown, test tires were produced with varying lengths and depths of the center portion, and the above-described tests were performed. Furthermore, the width of the first land portion and the depth of the sipes were common across the various examples.

[0126] The test results are shown in Table 2.

[0127]

Table 2

[0128]

[0129] As shown in Table 2, it can be confirmed that the length and depth of the center portion have a high correlation with the cornering performance on ice and the steering stability on dry roads.

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 crossing the first land portion. The first land portion includes a plurality of first blocks divided by the first lateral grooves. At least one of the first blocks is formed with a sipe and a second lateral groove that divides the first block in the tire circumferential direction. The second lateral groove includes a pair of both ends inclined in a first direction relative to the tire axial direction, and a central portion located between the both ends and inclined in a second direction opposite to the first direction. The first transverse grooves are inclined toward the second direction, The sipes are inclined toward the first direction, The tire is designated with respect to the vehicle in which it is to be mounted. The tread portion includes an inner tread end located on the inner side of the vehicle when the tread portion is mounted on the vehicle. The first land portion is provided between the tire equator and the inner tread end.

2. The tire according to claim 1, wherein The groove width of the second transverse groove is smaller than the groove width of the first transverse groove.

3. The tire according to claim 1 or 2, characterized in that The groove width of each of the pair of end portions is larger than the groove width of the central portion.

4. The tire according to claim 1 or 2, characterized in that The length of each of the pair of end portions in the tire axial direction is smaller than the length of the central portion in the tire axial direction.

5. The tire according to claim 1 or 2, characterized in that An angle of the central portion relative to the tire axial direction is greater than an angle of the first lateral groove relative to the tire axial direction.

6. The tire according to claim 1 or 2, characterized in that The maximum depth of the central portion is smaller than the maximum depth of the sipes.

7. The tire according to claim 1 or 2, characterized in that The sipes do not communicate with the second lateral grooves.

8. The tire according to claim 1 or 2, characterized in that The sipes are three-dimensional sipes extending in a wave-like shape in the longitudinal direction and the depth direction.

9. The tire according to claim 1 or 2, characterized in that The angle of the first lateral groove relative to the tire axial direction is 20 to 40 degrees.

10. The tire according to claim 1 or 2, characterized in that The angle of the central portion relative to the tire axial direction is 50 to 70 degrees.

11. The tire according to claim 1 or 2, characterized in that The angles of the two end portions relative to the tire axial direction are 20 to 40 degrees.

12. The tire according to claim 1 or 2, characterized in that The tread portion includes a plurality of circumferential grooves. The circumferential grooves include an inner crown circumferential groove adjacent to the tire equator side of the first land portion, The inner crown circumferential groove has the largest groove width among the plurality of circumferential grooves.

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