Tire

Abstract

Provided is a tire capable of improving snow performance without impairing wear resistance. A tread portion (1) is provided with at least three bent main grooves (10) extending in a zigzag shape along a tire circumferential direction, a land portion (20) between the bent main grooves (10) is divided into a plurality of blocks (20B) by a plurality of lug grooves (30), a pair of sipes (40) and a pair of cutout grooves (50) are provided on a tread surface of each of the plurality of blocks (20B), the pair of sipes (40) extend in the same direction within an angular difference of 10 DEG, and the pair of cutout grooves (50) extend in the same direction within an angular difference of 10 DEG. One end of each of the pair of sipes (40) opens into the main bending groove (10) and the other end of each of the pair of sipes (40) terminates within the block (20B), and the pair of cutout grooves (50) extend in the same direction within an angular difference of 10 DEG or less such that one end of each of the pair of cutout grooves (50) opens into the main bending groove (10) and the other end of each of the pair of cutout grooves (50) terminates within the block (20B).

Description

Technical Field

[0001] The present invention relates to a tire intended for traveling on unpaved roads and the like, and more particularly to a tire capable of improving snow performance without impairing wear resistance. Background Art

[0002] Tires designed to travel on unpaved roads (rough, muddy, sandy, rocky, etc.) in addition to paved roads (e.g., high-travel tires (All-Terrain Tires), all-terrain tires, etc.) are required to have excellent off-road performance. Furthermore, in order to achieve stable driving even in snowfall, excellent snow performance is also required. In recent years, snow performance has received particular attention among these performance characteristics, with sufficient performance required even on snowy roads in extremely harsh cold regions. For such tires, there is a tendency to adopt tread patterns that are mainly composed of lug grooves and blocks with a large edge component and a large groove area (e.g., see Patent Document 1). Furthermore, multiple sipes and notched grooves are provided on the tread of block and rib patterns (e.g., see Patent Document 2). On the other hand, tread patterns with a large groove area or those with many sipes and notched grooves tend to reduce the rigidity of the blocks, and measures are also required to maintain sufficient wear resistance. Based on the above, a high degree of balance between snow performance and wear resistance is required.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-137218

[0006] Patent Document 2: Japanese Patent Application Publication No. 2019-043307 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] An object of the present invention is to provide a tire capable of improving snow performance without impairing wear resistance.

[0009] Means for solving problems

[0010] The tire of the present invention for achieving the above-mentioned purpose comprises a tread portion extending in an annular shape in the circumferential direction of the tire, characterized in that the tread portion comprises at least three bent main grooves extending in a zigzag shape along the circumferential direction of the tire, and at least two rows of land portions divided between the bent main grooves are divided into a plurality of blocks by a plurality of lug grooves arranged at intervals in the circumferential direction of the tire, and a pair of sipes and a pair of notch grooves are provided on the tread surfaces of each of the plurality of blocks, the pair of sipes extending in the same direction within a range of an angular difference of not more than 10 degrees, one end of each of the pair of sipes opening in the bent main groove and the other end forming a terminal end in the block, and the pair of notch grooves extending in the same direction within a range of an angular difference of not more than 10 degrees, one end of each of the pair of notch grooves opening in the bent main groove and the other end forming a terminal end in the block.

[0011] Effects of the Invention

[0012] Since the tire of the present invention has sipes and notches arranged as described above in a pattern divided into a plurality of blocks, it is possible to improve snow performance without compromising wear resistance. In particular, by providing a pair of sipes and notches, it is possible to efficiently improve snow performance while suppressing the total number of sipes and notches. On the other hand, since the sipes and notches each terminate within a block, wear resistance can be well maintained. Moreover, since a pair of sipes extend in approximately parallel directions (with an angle difference of less than 10°) and a pair of notches extend in approximately parallel directions (with an angle difference of less than 10°), it is possible to exert an edge effect in the same direction, effectively improving traction performance on snowy roads and effectively exerting snow performance. Furthermore, the aforementioned substantially parallel arrangement ensures that the spacing between the sipes and notches is substantially uniform, which can suppress any differences in rigidity caused by differences in spacing (e.g., a localized decrease in block rigidity at locations where the spacing between the sipes and notches is narrow). This allows for better maintenance of block rigidity and wear resistance compared to situations where the sipes and notches are arranged in random directions. This synergy allows for a high degree of balance between wear resistance and snow performance.

[0013] In the present invention, it is preferred that each of the pair of sipes extends in the same direction as the groove wall of either of the pair of lug grooves adjacent to the block in which the pair of sipes are provided, within an angular difference of 10°. This arrangement allows the edge effect produced by the lug groove walls (block walls) and the edge effect produced by the sipes to align in direction, thereby achieving excellent snow performance through their synergistic effect. Furthermore, by arranging the sipes and lug groove walls approximately parallel to each other and thus maintaining approximately the same spacing between them, it is possible to suppress differences in rigidity caused by differences in spacing (e.g., a localized decrease in block rigidity at locations with narrow spacing), thereby maintaining excellent wear resistance.

[0014] In the present invention, preferably, a land portion defined outside the bent main groove disposed on the outermost side in the tire width direction is divided into a plurality of shoulder blocks by a plurality of shoulder lug grooves spaced apart in the tire circumferential direction. A pair of shoulder sipes and a pair of shoulder notch grooves are provided on the tread surface of each of the plurality of shoulder blocks. One end of each of the pair of shoulder sipes opens into the bent main groove and the other end terminates within the shoulder block. Each of the pair of shoulder notch grooves is disposed within a region of the shoulder lug groove located closer to the bent main groove than the tire width center of the shoulder block and closer to the tire circumferential side than the tire circumferential center of the shoulder block. One end of each shoulder notch groove opens into the bent main groove and the other end terminates within the shoulder block. By providing the shoulder blocks in this manner and providing the shoulder sipes and shoulder notch grooves in the shoulder blocks, edge effects and snow column shearing forces can be enhanced in the shoulder blocks, thereby contributing to improved snow performance. Furthermore, by setting the number and arrangement of the shoulder sipes and shoulder notch grooves as described above, the block rigidity of the shoulder blocks can be maintained, and good wear resistance can be maintained.

[0015] In this case, it is preferred that the notch groove depth be 25% to 95% of the depth of the bent main groove, and the shoulder notch groove depth be greater than the notch groove depth. By increasing the notch groove depth on the shoulder side, the balance between edge effect and block rigidity can be improved according to the position of the block in the width direction, which is beneficial for achieving a good balance between snow performance and wear resistance.

[0016] Furthermore, it is preferred that the sipe length be 35% to 75% of the maximum length of the shoulder sipe. By increasing the sipe length toward the shoulder, the balance between edge effect and block rigidity can be improved depending on the block width position, which helps achieve a good balance between snow performance and wear resistance.

[0017] In the present invention, the length of the notch groove is preferably 30% to 100% of the maximum length of the sipes within the same block. This improves the balance between the lengths of the sipes and notch grooves within a single block, facilitating a well-balanced balance between snow performance and wear resistance.

[0018] In the present invention, it is preferred that a pair of sipes and a pair of notched grooves be arranged in a staggered pattern within the block. This arrangement prevents the sipes and notched grooves from being biased toward one side within the block, thereby achieving a good balance between edge effect and block rigidity, which is beneficial for achieving both snow performance and wear resistance.

[0019] The tire of the present invention is preferably a pneumatic tire, but may also be a non-pneumatic tire. In the case of a pneumatic tire, the interior thereof can be filled with an inert gas such as air, nitrogen, or other gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a meridian cross-sectional view of a tire according to an embodiment of the present invention.

[0021] Figure 2 This is a front view showing the tread surface of a tire according to the embodiment of the present invention.

[0022] Figure 3 It will Figure 2 An explanatory diagram showing an extracted portion of the image. DETAILED DESCRIPTION

[0023] Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.

[0024] The tire of the present invention is Figure 1 In the case of the pneumatic tire shown in FIG. 1 , the tire includes a tread portion 1 that contacts the road surface, a pair of sidewall portions 2 disposed on both sides of the tread portion 1, and a pair of bead portions 3 disposed radially inward of the sidewall portions 2. Figure 1 In FIG, reference numeral CL represents the tire equator, and reference numeral E represents the ground contact end. Figure 1 Since this is a meridian cross-sectional view, it is not described, but the tread portion 1, the sidewall portion 2, and the bead portion 3 extend in the tire circumferential direction and form a ring shape, thereby forming the basic ring-shaped structure of the pneumatic tire. Figure 1 The description is basically based on the meridian cross-sectional shape shown in the figure, but each tire component is a ring-shaped component extending in the tire circumferential direction.

[0025] A carcass layer 4 is provided between a pair of left and right bead portions 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the radial direction of the tire and folded back from the inner side to the outer side in the tire width direction around the bead core 5 provided at each bead portion 3. In addition, a bead filler 6 is provided on the outer periphery of the bead core 5, and the bead filler 6 is wrapped by the main body and the folded back portion of the carcass layer 4. On the other hand, a plurality of layers (in the outer periphery of the carcass layer 4 at the tread portion 1) are embedded. Figure 1 The belt layer 7 is composed of two layers. Each belt layer 7 includes a plurality of reinforcing cords inclined relative to the tire circumferential direction, and is arranged in a manner that the reinforcing cords intersect each other between layers. In these belt layers 7, the inclination angle of the reinforcing cords relative to the tire circumferential direction is set in the range of 10° to 40°, for example. In addition, at least one layer (in the outer peripheral side of the belt layer 7) is provided. Figure 1 The belt reinforcement layer 8 includes two layers (two layers in the tire). The belt reinforcement layer 8 includes organic fiber cords oriented in the tire circumferential direction. In the belt reinforcement layer 8, the angle of the organic fiber cords relative to the tire circumferential direction is set to, for example, 0° to 5°.

[0026] Since the present invention relates to a tread pattern formed on the surface of the tread portion 1 of the tire as described later (especially the structure and arrangement of the sipes 40 and the notch grooves 50 described later), the basic structure (cross-sectional structure) of the tire is not limited to the general structure described above. Figure 1 However, if the present invention is a tire having a surface that contacts the road surface (a portion corresponding to the surface of the tread portion 1 in a pneumatic tire), it can be applied to various tires including non-pneumatic tires.

[0027] The surface of the tread portion 1 in the tire of the present invention is as follows Figure 2 As shown, at least three (four in the figure) bending main grooves 10 are provided that extend in a zigzag shape along the circumferential direction of the tire. The zigzag shape refers to a shape in which a straight line portion inclined in one direction relative to the circumferential direction of the tire is alternately connected with a straight line portion inclined in another direction in the circumferential direction of the tire. In the example shown in the figure, as the bending main grooves 10, a pair of inner bending main grooves 11 arranged on both sides of the tire equator CL and a pair of outer bending main grooves 12 arranged on the outer side in the tire width direction are provided. Among these four bending main grooves, a pair of outer bending main grooves 12 are arranged on the outermost side in the tire width direction. In the following description, the area on the inner side (the tire equator CL side) of the outer bending main groove 12 in the tire width direction is sometimes referred to as the central area, and the area on the outer side of the outer bending main groove 12 in the tire width direction is sometimes referred to as the shoulder area.

[0028] The shape of the curved main groove 10 is not particularly limited as long as it maintains the aforementioned zigzag shape. However, it is preferred that the inner curved main groove 11 and the outer curved main groove 12 each have the shapes shown in the figure. Specifically, the outer curved main groove 12 has a shape in which a linear portion (first outer linear portion 12a) inclined in one direction relative to the tire circumferential direction is alternately connected with a linear portion (second outer linear portion 12b) inclined in the other direction. These first outer linear portions 12a and second outer linear portions 12b preferably have the same groove width. Furthermore, the circumferential length of the first outer linear portion 12a in the tire circumferential direction is preferably 50% to 70% of the circumferential length of the second outer linear portion 12b in the tire circumferential direction. Meanwhile, the inner curved main groove 11 has a shape in which a linear portion (first inner linear portion 11a) inclined in one direction relative to the tire circumferential direction is alternately connected with a linear portion (second inner linear portion 11b) inclined in the other direction. The groove width of the second inner linear portion 11b is preferably smaller than that of the first inner linear portion 11a. Specifically, the groove width of the second inner linear portion 11b is preferably 55% to 75% of the groove width of the first inner linear portion 11a. Furthermore, the tire circumferential length of the second inner linear portion 11b is preferably 15% to 35% of the tire circumferential length of the first outer linear portion 11a.

[0029] In at least two rows (three rows in the figure) of land portions 20 demarcated between the bending main grooves 10, a plurality of lug grooves 30 extending in the tire width direction are provided at intervals in the tire circumferential direction. These lug grooves 30 divide the land portion 20 into a plurality of blocks 20B by connecting both ends with the bending main grooves. In the illustrated example, the land portion 20 includes: one row of land portions (central land portion 21) demarcated between a pair of inner bending main grooves 11; and two rows of land portions (intermediate land portions 22) demarcated between the inner bending main grooves 11 and the outer bending main grooves 12. In the following description, the lug grooves 30 provided in the central land portion 21 are sometimes referred to as central lug grooves 31, and the blocks 20B demarcated by the central lug grooves 31 are sometimes referred to as central blocks 21B. Likewise, the lug grooves 30 provided in the middle land portion 22 may be referred to as middle lug grooves 32 , and the blocks 20B defined by the middle lug grooves 32 may be referred to as middle blocks 22B.

[0030] In particular, in the illustrated example, the central lug grooves 31 include first central lug grooves 31a inclined in one direction and second central lug grooves 31b inclined in the opposite direction to the first central lug grooves 31a. These first central lug grooves 31a and second central lug grooves 31b are alternately arranged in the tire circumferential direction. Furthermore, while the first central lug grooves 31a are curved, the second central lug grooves 31b extend straight. The ends of the first central lug grooves 31a communicate with the first inner straight portions 11a on either side in the tire width direction, while the second central lug grooves 31b communicate with the bend points of the inner curved main grooves 11 on either side in the tire width direction. The middle lug grooves 32 include first middle lug grooves 32a that communicate with the bending point of the outer curved main groove 12 and the bending point of the inner curved main groove 11, and second middle lug grooves 32b that communicate with the bending point of the outer curved main groove 12 and the first inner straight portion 11a. These first middle lug grooves 32a and second middle lug grooves 32b are alternately arranged in the tire circumferential direction. Preferably, the first middle lug grooves 32a and second middle lug grooves 32b are inclined in the same direction and have the same curved shape.

[0031] A pair of sipes 40 and a pair of notched grooves 50 are provided on the tread surfaces of each of the plurality of blocks B demarcated by the aforementioned bent main grooves 10 and lug grooves 30. In other words, only two sipes 40 and two notched grooves 50 are provided in each block B. In the following description, the sipes 40 and notched grooves 50 provided in the center block 21B are sometimes referred to as center sipes 41 and notched grooves 51. Similarly, the sipes 40 and notched grooves 50 provided in the middle block 22B are sometimes referred to as middle sipes 42 and middle notched grooves 52. The sipes 40 are fine grooves having a groove width of, for example, 0.5 mm to 2.0 mm and a groove depth of, for example, 2 mm to 15 mm. The shape of the sipes 40 is not particularly limited and can adopt various shapes commonly used in tires, such as a straight line or a sawtooth shape as shown. The notch groove 50 is a groove having a short length of 50% or less of the block width, terminating in the block B, and having a tapered shape with the groove width narrowing toward the terminal end (eg, a triangular or trapezoidal terminal end).

[0032] The pair of sipes 40 provided in each block B extend in the same direction with an angular difference of no more than 10°, preferably within a range of 0° to 5°. In other words, the pair of sipes 40 extend generally parallel to each other. Furthermore, one end of each pair of sipes 40 opens into the main bending groove 10, and the other end terminates within block B. Similarly, the pair of notched grooves 50 provided in each block B extend in the same direction with an angular difference of no more than 10°, preferably within a range of 0° to 5°. In other words, the pair of notched grooves 50 also extend generally parallel to each other. Furthermore, one end of each pair of notched grooves 50 opens into the main bending groove 10, and the other end terminates within block B.

[0033] Providing a pair of sipes 40 and a pair of notched grooves 52 in each block B improves snow performance without compromising wear resistance. Specifically, by providing a pair of sipes 40 and a pair of notched grooves 50, snow performance can be effectively improved while minimizing the total number of sipes 40 and notched grooves 50. Furthermore, since the sipes 40 and notched grooves 50 terminate within the block B, excellent wear resistance is maintained. Furthermore, since the sipes 40 and notched grooves 50 extend substantially parallel to each other, an edge effect is achieved in the same direction, effectively enhancing traction on snowy roads and enhancing snow performance. Furthermore, the aforementioned substantially parallel arrangement makes the spacing between the sipes 40 and the notched grooves 50 substantially uniform, which can suppress any differences in rigidity caused by differences in spacing (e.g., a localized decrease in block rigidity at locations where the spacing between the sipes 40 and notched grooves 50 is narrow). This allows for better block rigidity and wear resistance compared to situations where the sipes 40 and notched grooves 50 are oriented in random directions. This synergy allows for a high degree of balance between wear resistance and snow performance.

[0034] If the number of sipes 40 and notches 50 provided in each block B is more than one to one, the block rigidity cannot be fully maintained and the wear resistance is reduced. If the sipes 40 and notches 50 do not form a terminal end in the block B, the block rigidity cannot be fully maintained and the wear resistance is reduced. If the angle difference between the sipes 40 or the notches 50 exceeds 10° and is not roughly parallel, the spacing between the sipes 40 and notches 50 becomes different. In the areas where the spacing is narrowed, the block rigidity is locally reduced and the wear resistance deteriorates. In addition, it is not possible to expect the effect of improving traction performance on snowy roads by exerting an edge effect in the same direction through a roughly parallel configuration as described above. As a result, the balance between the edge effect and the block rigidity is deteriorated, and the effect of balancing snow performance and wear resistance cannot be fully achieved.

[0035] When a pair of sipes 40 and a pair of notched grooves 50 are provided within a single block B, they are preferably arranged in a staggered pattern. Specifically, in the present invention, four groove elements, including a pair of sipes 40 and a pair of notched grooves 50, are provided within a single block B. However, it is preferred that adjacent groove elements in the tire circumferential direction within a single block B be of different types (a combination of sipes 40 and notched grooves 50), and that adjacent groove elements in the tire width direction be of different types (a combination of sipes 40 and notched grooves 50). Furthermore, it is preferred that adjacent groove elements separated by lug grooves 30 also be of different types (a combination of sipes 40 and notched grooves 50). This arrangement prevents the sipes 40 and notched grooves 50 from being biased toward one side within the block B. This ensures a good balance between edge effect and block rigidity, which is beneficial for achieving both snow performance and wear resistance.

[0036] The pair of sipes 40 are not only approximately parallel to each other but also approximately parallel to the groove walls of either of the pair of lug grooves 30 adjacent to the block B in which they are provided. Specifically, they preferably extend in the same direction, with an angle difference preferably within 10°, more preferably within a range of 0° to 8°. For example, in the illustrated example, the middle sipe 42 provided in the middle block 22B extends approximately parallel to the middle lug groove 32. Furthermore, the central sipe 41 provided in the center block 21B extends approximately parallel to the first center lug groove 31a. This arrangement aligns the edge effect produced by the groove walls (block walls) of the lug groove 30 with the edge effect produced by the sipes, thereby achieving excellent snow performance through their synergistic effect. Furthermore, by having the sipes and lug groove walls approximately parallel to each other, their spacing is substantially uniform, which reduces stiffness differences caused by spacing differences (e.g., a localized decrease in block stiffness at narrower spacing locations), thereby maintaining excellent wear resistance. If the angle difference between the sipes 40 and the lug groove walls exceeds 10° and they are not substantially parallel, the aforementioned effect of improving snow performance cannot be fully expected. Furthermore, since the sipes and lug groove walls are not substantially parallel, the spacing between them is not uniform. There is a concern that the area where the spacing is narrow may experience a localized decrease in block rigidity.

[0037] The pair of notched grooves 50 are not only approximately parallel to each other but also approximately parallel to the groove walls of either of the pair of lug grooves 30 adjacent to the block B in which they are located. That is, they preferably extend in the same direction, with an angle difference preferably within 10°, more preferably within a range of 0° to 8°. For example, in the illustrated example, the middle notched groove 52 provided in the middle block 22B extends approximately parallel to the middle lug groove 32. Furthermore, the central notched groove 51 provided in the central block 21B extends approximately parallel to the second central lug groove 31b. This arrangement aligns the edge effects generated by the groove walls (block walls) of the lug groove 30 and the edge effects generated by the notched grooves, thereby achieving excellent snow performance through their synergistic effect. Furthermore, by having the notched grooves and lug groove walls approximately parallel to each other, their spacing is roughly uniform, which suppresses any differences in stiffness caused by spacing differences (e.g., a localized decrease in block stiffness at locations with narrow spacing), thereby maintaining excellent wear resistance. If the angle difference between the notch grooves 50 and the lug groove walls exceeds 10° and is not substantially parallel, the aforementioned effect of improving snow performance cannot be fully expected. Furthermore, since the notch grooves and lug groove walls are not substantially parallel, the spacing between them is not uniform, and there is a concern that the block rigidity may be locally reduced in areas where the spacing is narrow.

[0038] In particular, in the illustrated example, in the center block 21B, the inclination direction of the pair of substantially parallel center sipes 41 is opposite to the inclination direction of the pair of substantially parallel center notched grooves 51, with these inclination directions intersecting. Consequently, the center sipes 41 and the center notched grooves 51 each extend converging toward the center of the center block 21B. This arrangement of the pair of sipes 40 and the pair of notched grooves 50 in the block B on the tire equator CL can further effectively enhance edge effects.

[0039] In each block B (central block 21B and intermediate block 22B), the length of the notch groove 50 is preferably 30% to 100% of the maximum length of the sipe 40 provided within the same block B, more preferably 30% to 90%. This improves the balance between the lengths of the sipe 40 and the notch groove 50 provided within a single block B, facilitating a well-balanced balance between snow performance and wear resistance. If the length of the notch groove 50 is less than 30% of the maximum length of the sipe 40, the notch groove 50 is too short, and the full edge effect achieved by providing the notch groove 50 cannot be expected. If the length of the notch groove 50 exceeds 100% of the maximum length of the sipe 40, it becomes difficult to maintain adequate block rigidity.

[0040] The structure of the shoulder region is not particularly limited, but as shown in the illustrated example, the land portion 20 (shoulder land portion 23) defined on the outer side of the bent main groove 10 (outer bent main groove 12) disposed in the tire widthwise direction is preferably divided into a plurality of shoulder blocks 23B by a plurality of shoulder lug grooves 33 spaced apart in the tire circumferential direction. Furthermore, a pair of shoulder sipes 43 and a single shoulder notch groove 53 are preferably provided on the tread surface of each of these plurality of shoulder blocks 23B. By providing the shoulder blocks 23B in this manner and providing the shoulder sipes 43 and shoulder notch groove 53 in these shoulder blocks 23B, the edge effect and snow column shear force can be enhanced in the shoulder blocks 23B, contributing to improved snow performance.

[0041] At this time, it is preferable that the pair of shoulder sipes 23B extend in the same direction with an angle difference preferably within 10°, more preferably within the range of 0° to 8°. In other words, it is preferable that the pair of shoulder sipes 43 extend approximately parallel to each other. It is preferable that one end of each of the pair of shoulder sipes 43 opens in the bent main groove and the other end terminates in the shoulder block 23B. In addition, the pair of shoulder sipes 43 are not only approximately parallel to each other, but also approximately parallel to the groove wall of either side of the pair of shoulder lug grooves 33 adjacent to the shoulder block 23B on which the pair of shoulder sipes 43 are provided, that is, preferably extend in the same direction with an angle difference preferably within 10°, more preferably within the range of 0° to 8°. By arranging the shoulder sipes 43 in this way, it is possible to improve snow performance while maintaining the block rigidity of the shoulder block 23B, which is conducive to achieving a good balance between snow performance and wear resistance.

[0042] It is preferable that one end of each shoulder notch groove 53 opens into the bending main groove 10 (outer bending main groove 12) and the other end terminates in the shoulder block 23B. Furthermore, it is preferable that the shoulder notch groove 53 is arranged in the area of ​​the shoulder lug groove 33 that is closer to the bending main groove 10 than the center of the shoulder block 23B in the tire width direction and closer to one side of the shoulder block 23B in the tire circumferential direction. Specifically, Figure 3 As shown, it is assumed that a quadrilateral region is enclosed by a straight line passing through the innermost point of the shoulder block 23B in the tire width direction and extending in the tire circumferential direction, the contact end E, a straight line passing through the end point on one side of the shoulder block 23B in the tire circumferential direction and extending in the tire width direction, and a straight line passing through the end point on the other side of the shoulder block 23B in the tire circumferential direction and extending in the tire width direction. Of the four regions obtained by bisecting the region in the tire width direction and in the tire circumferential direction, the shoulder notch groove 53 is preferably disposed offset in the region on the inner side in the tire width direction and on one side in the tire circumferential direction (the hatched portion in the figure). Providing the shoulder notch groove 53 in such a position is advantageous in improving snow performance while maintaining good block rigidity of the shoulder block 23B.

[0043] In addition, the ground contact end E is the end in the tire width direction of the ground contact area formed when the tire rim is assembled to a regular rim (in Japanese: 正規リム) and filled with the regular internal pressure (in Japanese: 正規内圧), and a regular load (in Japanese: 正規荷重) is applied while it is vertically placed on a plane. The "regular rim" refers to the rim determined for each tire according to the standard in the standard system including the standard on which the tire is based. For example, in the case of JATMA, it is the standard rim (in Japanese: 標準リム); in the case of TRA, it is the "Design Rim"; or in the case of ETRTO, it is the "Measuring Rim". The "regular internal pressure" refers to the air pressure determined for each tire according to the standard in the standard system including the standard on which the tire is based. In the case of JATMA, it is the maximum air pressure; in the case of TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES"; in the case of ETRTO, it is the "INFLATION PRESSURE". However, when the tire is for a passenger car, it is set to 180 kPa. The "regular load" is the load determined for each tire according to the standard in the standard system including the standard on which the tire is based. In the case of JATMA, it is the maximum load capacity; in the case of TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES"; in the case of ETRTO, it is the "LOAD CAPACITY". However, when the tire is for a passenger car, it is set to a load equivalent to 88% of the said load.

[0044] When the shoulder sipes 43 and the shoulder notch grooves 53 are provided as described above, it is preferable that the groove depth of the shoulder notch groove 53 is larger than the groove depth of the notch groove 50 in the central region. In addition, when there are three or more land portions in the central region, it is preferable that the groove depth of the notch groove 50 in the land portion closer to the tire equator CL is smaller. In the case of the illustrated example, there are three land portions in the central region, which are composed of one central land portion 21 and two intermediate land portions 22. However, it is preferable that the groove depth of the intermediate notch groove 52 provided in the intermediate block 22B demarcated in the intermediate land portion 22 is larger than the groove depth of the central notch groove 51 provided in the central block 21B demarcated in the central land portion 21. By increasing the groove depth of the notch groove 50 more towards the outer side in the tire width direction in this way, the balance between the edge effect and the block rigidity can be made good according to the position in the width direction of the block, which is beneficial to taking into account both snow performance and wear resistance.

[0045] The groove depth of the notch groove 50 (central notch groove 51, middle notch groove 52) and the shoulder notch groove 53 is preferably 25% to 95% of the groove depth of the bending main groove 10, and more preferably 30% to 95% regardless of the position of the block B. By setting the groove depth to such a level, the edge effect produced by the notch groove 50 and the shoulder notch groove 53 and the block rigidity can be well balanced. If the groove depth of the notch groove 50 and the shoulder notch groove 53 is less than 25% of the groove depth of the bending main groove 10, the notch groove 50 and the shoulder notch groove 53 are too shallow, and therefore the edge effect cannot be fully expected. If the groove depth of the notch groove 50 and the shoulder notch groove 53 exceeds 95% of the groove depth of the bending main groove 10, it is difficult to maintain the block rigidity well.

[0046] When the groove depth of the notched groove 50 increases toward the outer side in the tire width direction as described above, the groove depth of the notched groove 50 in the central region (central notched groove 51 and intermediate notched groove 52) is preferably 25% to 40% of the groove depth of the bending main groove 10, and more preferably 30% to 40%. In particular, when the central land portion 21 and the intermediate land portion 22 are formed in the central region as shown in the figure, and the groove depth of the notched groove 50 (central notched groove 51 and intermediate notched groove 52) is different between these land portions, the groove depth of the central notched groove 51 is preferably 25% to 35% of the groove depth of the bending main groove 10, and more preferably 30% to 35%. The groove depth of the intermediate notched groove 52 is preferably 30% to 40% of the groove depth of the bending main groove 10, and more preferably 35% to 40%. On the other hand, the groove depth of the shoulder notch groove 53 is preferably 80% to 90% of the groove depth of the bent main groove 10 , and more preferably 85% to 90%.

[0047] When shoulder sipes 43 are provided as described above, the length of the sipes 40 (central sipe 41 and intermediate sipe 42) provided in the central region is preferably 35% to 75% of the maximum length of the shoulder sipe 43, and more preferably 40% to 70%. This length relationship allows for a good balance between edge effect and block stiffness depending on the tire widthwise position, which is beneficial for achieving both snow performance and wear resistance. If the length of the sipes 40 provided in the central region is less than 35% of the maximum length of the shoulder sipe 43, the length of the sipes 40 is too short, limiting the edge effect produced by the sipes 40. If the length of the sipes 40 provided in the central region exceeds 75% of the maximum length of the shoulder sipe 43, it becomes difficult to maintain sufficient block stiffness in the central region. The lengths of the sipes 40 (the central sipe 41 and the middle sipe 42) and the shoulder sipes 43 are lengths measured along the extending direction of the sipes 40 or the shoulder sipes 43. When these sipes have a zigzag shape, the length of a straight line connecting the ends of the sipes (the open end and the terminal end in the illustrated example) is defined as the sipe length.

[0048] Hereinafter, the present invention will be further described with reference to Examples, but the scope of the present invention is not limited to these Examples.

[0049] Example

[0050] The tire size is LT265 / 70R17 121 / 118S and has Figure 1 The basic structure (cross-sectional structure) shown in the example is Figure 2 The tread pattern is used as the basis, and the shape of the main groove, the number of sipes in the block in the central area, the end of the sipe, the inclination direction of the sipes relative to the groove wall of the lug groove, the number of notch grooves, the end of the notch groove, the inclination direction of the notch grooves relative to each other, the arrangement of the sipes and the notch grooves, the ratio of the notch groove length to the sipe length [unit: %], the number of sipes in the block in the shoulder area, the terminal position of the sipe, the inclination direction of the sipes relative to each other, the number of notch grooves, the arrangement of the notch grooves, the relationship between the groove depth of the notch grooves between the shoulder area and the central area, and the relationship between the sipe length between the shoulder area and the central area are set as shown in Table 1 for 10 pneumatic tires, namely, Conventional Example 1, Comparative Examples 1 to 2, and Examples 1 to 7.

[0051] In addition, the conventional example 1 is a Figure 2The bent main grooves in the tread pattern of the tire are all replaced with main grooves extending linearly along the tire circumferential direction, and no sipes or notches are provided as shown in the table. Comparative Example 1 is an example in which the number of sipes and notches provided in each block is one, and the number of notches provided in the tread pattern of the tire is Figure 2 The structure is that two sipes are provided in each and one of the notch grooves is deleted.

[0052] In Table 1, the columns "Ends of Sipes" and "Ends of Notched Grooves" indicate "open" when both ends communicate with the main groove, and "terminated" when the end not communicating with the main groove terminates within the block. The columns "Inclination Direction of Sipes" and "Inclination Direction of Notched Grooves" indicate "substantially parallel" when the sipes or notched grooves extend in the same direction within an angle difference of 10° or less, and "non-parallel" when the angle difference exceeds 10°. Similarly, the columns "Inclination Direction of Sipes with Respect to the Lug Groove Walls" indicate "substantially parallel" when the angle difference is within 10°, and "non-parallel" when the angle difference exceeds 10°. Regarding the "Arrangement of Sipes and Notches", the case where a pair of sipes and a pair of notches are arranged in a staggered pattern within a block as in the example shown in the figure is indicated as "Staggered Arrangement", and the case where both of a pair of sipes are arranged only on one side in the tire width direction and both of a pair of notches are arranged only on the other side in the tire width direction is indicated as "Single-Sided Arrangement". Figure 3 The case where the notch groove is arranged offset in the oblique line portion is represented as "within the partition", and the notch groove is arranged at the circumferential center position of the block (at Figure 3 In the "Sh / Ce Regions" column, the case where the notch groove depth is the same in the shoulder and center regions is represented as "Sh = Ce," and the case where the notch groove depth is greater in the shoulder region is represented as "Sh > Ce." In the "Sh / Ce Regions" column, the case where the sipe length is the same in the shoulder and center regions is represented as "Sh = Ce," and the case where the sipe length is greater in the shoulder region is represented as "Sh > Ce."

[0053] These pneumatic tires were evaluated for snow performance and wear resistance by the following evaluation methods, and the results are shown in Table 1.

[0054] Snow performance

[0055] Each test tire was assembled onto a wheel with a rim size of 17×8J. The front tires were inflated to 450 kPa, and the rear tires were inflated to 550 kPa. The tires were then installed on a test vehicle (traction test vehicle). A test driver conducted a sensory evaluation of traction (starting performance) on a snowy test course. The evaluation results were expressed as an index, with the value of Conventional Example 1 set to 100. A higher index value indicates better snow performance.

[0056] Wear resistance

[0057] Each test tire was assembled onto a wheel with a 17×8J rim size. The front tires were inflated to 450 kPa, and the rear tires were inflated to 550 kPa. The tires were then installed on a test vehicle (a four-wheel-drive SUV). A test driver drove the tires along a test route. The estimated wear life was calculated based on the wear after 8,000 km of driving. The evaluation results were expressed as an index, with the value of Conventional Example 1 set to 100. A larger index value indicates a longer distance traveled until complete wear, indicating superior wear resistance.

[0058] [Table 1]

[0059] Table 1

[0060]

[0061] As can be seen from Table 1, the pneumatic tires of Examples 1 to 7 exhibit improved snow performance and wear resistance compared to Conventional Example 1, achieving a well-balanced balance between these properties. On the other hand, while Comparative Example 1 has a small number of sipes and notches, the sipes are open at both ends, resulting in poor wear resistance. Comparative Example 2, because the sipes or notches are not parallel in the central region, fails to achieve sufficient improvements in snow performance and wear resistance.

[0062] Description of Reference Numerals

[0063] 1. Tread

[0064] 2 Sidewall

[0065] 3 Bead

[0066] 4 carcass layers

[0067] 5 Bead core

[0068] 6 Bead filler

[0069] 7 Belt

[0070] 8 belt reinforcement layer

[0071] 10 Bending main groove

[0072] 11 Inner bending main groove

[0073] 11a First inner straight portion

[0074] 11b Second inner straight line

[0075] 12 Outer bending main groove

[0076] 12a First outer straight portion

[0077] 12b Second outer straight portion

[0078] 20 Lubu

[0079] 20B block

[0080] 21 Central Land Department

[0081] 21B Central Block

[0082] 22 Middle land

[0083] 22B middle block

[0084] 23 shoulder land

[0085] 23B shoulder blocks

[0086] 30 horizontal grooves

[0087] 31 central horizontal groove

[0088] 31a First central transverse groove

[0089] 31b Second central transverse groove

[0090] 32 middle horizontal grooves

[0091] 32a First middle transverse groove

[0092] 32b Second middle transverse groove

[0093] 33 shoulder grooves

[0094] 40 sipes

[0095] 41 center sipes

[0096] 42 Middle sipe

[0097] 43 shoulder sipes

[0098] 50 notched slots

[0099] 51 Central notch slot

[0100] 52 middle notch slot

[0101] 53 Shoulder notch groove

[0102] CL Tire Equator

[0103] E Ground terminal

Claims

1. A tire comprising a tread portion extending in a circumferential direction of the tire and forming an annular shape, wherein: The tread portion includes at least three bent main grooves extending in a zigzag pattern along the tire circumferential direction. At least two rows of land portions defined between the bent main grooves are divided into a plurality of blocks by a plurality of lug grooves arranged at intervals in the tire circumferential direction. A pair of sipes and a pair of notched grooves are provided on the treads of each of the multiple blocks, the pair of sipes extending in the same direction within an angular difference of 10°, one end of each of the pair of sipes opening in the bending main groove and the other end forming a terminal end in the block, and the pair of notched grooves extending in the same direction within an angular difference of 10°, one end of each of the pair of notched grooves opening in the bending main groove and the other end forming a terminal end in the block.

2. The tire according to claim 1, wherein Each of the pair of sipes extends in the same direction as a groove wall of one of a pair of lug grooves adjacent to the block in which the pair of sipes are provided, with the angle difference being within a range of 10°.

3. The tire according to claim 1 or 2, characterized in that The land portion defined on the outer side of the bent main groove in the tire width direction is divided into a plurality of shoulder blocks by a plurality of shoulder lug grooves arranged at intervals in the tire circumferential direction. A pair of shoulder sipes and a pair of shoulder notch grooves are provided on the tread surfaces of the plurality of shoulder blocks, wherein one end of each of the pair of shoulder sipes opens in the bent main groove and the other end terminates in the shoulder block. Each of the pair of shoulder notch grooves is arranged in an area of ​​the shoulder transverse groove that is closer to the bending main groove side than the tire width center of the shoulder block and closer to the tire circumferential side than the tire circumferential center of the shoulder block. One end of each shoulder notch groove opens in the bending main groove and the other end forms a terminal end in the shoulder block.

4. The tire according to claim 3, characterized in that The groove depth of the notch groove is 25% to 95% of the groove depth of the bent main groove, and the groove depth of the shoulder notch groove is greater than the groove depth of the notch groove.

5. The tire according to claim 3 or 4, characterized in that The length of the sipe is 35% to 75% of the maximum length of the shoulder sipe.

6. The tire according to any one of claims 1 to 5, characterized in that The length of the notch groove is 30% to 100% of the maximum length of the sipe pattern arranged in the same block.

7. The tire according to any one of claims 1 to 6, characterized in that The pair of sipes and the pair of notched grooves are arranged in a staggered pattern within the block.

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