tire

Abstract

To provide a tire which makes it possible to enhance snow performance without impairing abrasion resistance.SOLUTION: There is provided a tire having a tread part including a center land part which is partitioned by four main grooves extending linearly along a tire circumference direction, an intermediate land part, and a shoulder land part. The center land part is partitioned into a plurality of center blocks by a center inclined groove, the intermediate hand part is partitioned into a plurality of intermediate blocks by an intermediate inclined groove, and the shoulder land part is partitioned into a plurality of shoulder blocks by a shoulder lateral groove. The center inclined groove and the intermediate inclined groove are inclined to an inverse direction of a tire width direction. At an extension position of the intermediate inclined groove in the center block, a shallow groove is provided extending in the same direction as that of the intermediate inclined groove and ending within the center block so as not to exceed a tire equator. At least two sipes which extend along the tire width direction are provided to the center block, the intermediate block and the shoulder block, respectively.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a tire having a block-based tread pattern, and more particularly to a tire that enables improved snow performance without compromising wear resistance. [Background technology]

[0002] Among tires for vehicles such as SUVs, "highway terrain tires" are known as a category of tires that are particularly designed for high-speed driving. Tires in this category have a block-based pattern and are required to be able to handle various road conditions (dry roads, wet roads, snowy roads) (see, for example, Patent Document 1). In recent years, there has been a tendency to emphasize snow performance (driving stability on snowy roads). For example, if the groove area is increased, it becomes easier to bite into snow and snow performance can be improved, but as mentioned above, since tires in this category are block-based, if the groove area is increased, the rigidity of the land part is likely to decrease, making it difficult to ensure sufficient wear resistance. Therefore, measures are required to improve snow performance without compromising wear resistance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-137218 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a tire which enables improved snow performance without impairing wear resistance. [Means for solving the problem]

[0005] In order to achieve the above object, the tire of the present invention has a tread portion extending in a circumferential direction of the tire to form an annular shape, the tread portion has four main grooves extending linearly along the tire circumferential direction, and five rows of land portions partitioned by these four main grooves, the five rows of land portions including a center land portion disposed on the tire equator, intermediate land portions disposed on both sides of the center land portion in the tire width direction, and shoulder land portions located on the outermost sides in the tire width direction, the center land portion being partitioned into a plurality of center blocks by center inclined grooves formed at intervals in the tire circumferential direction, and the intermediate land portions being formed at intervals in the tire circumferential direction. The shoulder land portion is divided into a plurality of intermediate blocks by intermediate inclined grooves formed in the tire circumferential direction, the shoulder land portion is divided into a plurality of shoulder blocks by shoulder lateral grooves formed at intervals in the tire circumferential direction, the center inclined groove and the intermediate inclined groove are inclined in opposite directions with respect to the tire width direction, and a shallow groove is provided at an extension position of the intermediate inclined groove in the center block, which extends in the same direction as the intermediate inclined groove and terminates within the center block without passing the tire equator, and the center block, the intermediate block, and the shoulder block each have two or more sipes formed at intervals in the tire circumferential direction and extending along the tire width direction. a bottom-raised portion is provided at the bottom of each of the center inclined groove and the intermediate inclined groove, and at least one end of the center inclined groove and / or the intermediate inclined groove has a narrow portion having a small groove width, and both the narrow portion and the bottom-raised portion are disposed at an end opening into the main groove. It is characterized by: Effect of the Invention

[0006] Since the tire of the present invention has a tread pattern configured as described above, it is possible to improve snow performance without impairing wear resistance. Specifically, since the four main grooves extend linearly, the rigidity of the widthwise end of each block can be ensured, and wear resistance and uneven wear resistance can be ensured. The grooves (center inclined groove, middle inclined groove) that divide the center land portion and the middle land portion are inclined with respect to the tire width direction, and further, the center inclined groove and the middle inclined groove are inclined in the opposite direction, so that snow performance can be effectively improved. Since a shallow groove extending in the same direction as the middle inclined groove is provided at the extension position of the middle inclined groove, the middle inclined groove and the shallow groove function as a series of grooves, and snow performance can be effectively improved. On the other hand, since the shallow groove has a groove depth smaller than that of the main groove and terminates within the center block without exceeding the tire equator, it is possible to suppress the decrease in block rigidity due to the provision of the shallow groove and ensure wear resistance. Since two or more sipes extending along the tire width direction are provided in each block, it is possible to improve snow performance. These cooperations make it possible to achieve a high degree of both wear resistance and snow performance.

[0007] In the present invention, it is preferable that the intermediate sipes formed in the intermediate block open to the main groove at both ends, and the center sipes formed in the center block terminate within the center block at both ends. That is, for the center block in which the shallow groove is formed, the sipes (center sipes) are terminated within the block to ensure block rigidity, and for the intermediate block in which the shallow groove is not formed, the sipes (intermediate sipes) are opened to the main groove to obtain sufficient snow performance, which is advantageous for achieving both snow performance and wear resistance. In addition, the combination of sipes described above (the center sipes that terminate within the block and the intermediate sipes that open to the main groove) suppresses the rigidity difference between the center block and the intermediate block, and wear resistance can be effectively ensured.

[0008] In the present invention, As mentioned earlier, At least a portion of the shallow groove has a tapered shape in which the groove width narrows toward the terminal end. do.By making the shallow grooves tapered in this manner, a decrease in rigidity of the center block caused by the formation of the shallow grooves can be suppressed, which is advantageous in ensuring wear resistance.

[0009] In the present invention, As mentioned earlier, A bottom-raised portion is provided at the bottom of each of the center inclined groove and the intermediate inclined groove. do. By providing such a bottom-raised portion, block rigidity can be maintained without reducing the groove area, which is advantageous in achieving both snow performance and wear resistance.

[0010] In the present invention, it is preferable that the center oblique groove or the intermediate oblique groove has a narrow portion with a small groove width at least at one end. In this way, the groove width of each oblique groove is narrowed at the portion communicating with the main groove, thereby ensuring block rigidity. In this case, the groove width is ensured at the center portion (other than the narrow portion) of each groove, so that snow performance can be sufficiently ensured, which is advantageous for achieving both snow performance and wear resistance.

[0011] In the present invention, it is preferable that the intermediate sipes formed in the intermediate block extend in the same direction as the intermediate inclined grooves, the center sipes formed in the center block extend in the same direction as the center inclined grooves, and the shoulder sipes formed in the shoulder blocks extend in the same direction as the shoulder lateral grooves. By inclining the inclined grooves and sipes in the same manner in each block, block rigidity can be ensured, which is advantageous for maintaining wear resistance.

[0012] 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 inside of the tire can be filled with air, an inert gas such as nitrogen, or other gases. [Brief description of the drawings]

[0013] [Figure 1] 1 is a meridian cross-sectional view of a tire according to an embodiment of the present invention. [Diagram 2]1 is a front view showing a tread surface of a tire according to an embodiment of the present invention. [Diagram 3] FIG. 3 is an explanatory diagram showing a part of FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The configuration of the present invention will be described in detail below with reference to the accompanying drawings.

[0015] When the tire of the present invention is a pneumatic tire as shown in FIG. 1, it includes a tread portion 1 that contacts the road surface, a pair of sidewall portions 2 arranged on both sides of the tread portion 1, and a pair of bead portions 3 arranged on the tire radial inner side of the sidewall portions 2. In FIG. 1, the symbol CL indicates the tire equator, and the symbol E indicates the ground contact edge. Although not depicted in FIG. 1 because it is a meridian cross section, the tread portion 1, the sidewall portions 2, and the bead portions 3 each extend in the tire circumferential direction to form an annular shape, thereby forming a toroidal basic structure of a pneumatic tire. The following explanation using FIG. 1 is basically based on the meridian cross section shown in the figure, but each tire component extends in the tire circumferential direction to form an annular shape.

[0016] A carcass layer 4 is installed between a pair of left and right bead portions 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction, and is folded back from the inner side to the outer side in the tire width direction around the bead cores 5 arranged in each bead portion 3. A bead filler 6 is arranged on the outer periphery of the bead cores 5, and the bead filler 6 is wrapped by the main body and folded back parts of the carcass layer 4. Meanwhile, a plurality of belt layers 7 (two layers in FIG. 1) are embedded on the outer periphery side of the carcass layer 4 in the tread portion 1. Each belt layer 7 includes a plurality of reinforcing cords inclined with respect to the tire circumferential direction, and the reinforcing cords are arranged so as to cross each other between the layers. In these belt layers 7, the inclination angle of the reinforcing cords with respect to the tire circumferential direction is set to, for example, a range of 10° to 40°. Furthermore, at least one belt reinforcing layer 8 (two layers in FIG. 1) is provided on the outer periphery side of the belt layer 7. The belt reinforcing layer 8 includes organic fiber cords oriented in the tire circumferential direction. In the belt reinforcing layer 8, the organic fiber cords are set at an angle of, for example, 0° to 5° with respect to the tire circumferential direction.

[0017] As described below, the present invention relates to a tread pattern formed on the surface of the tread portion 1 of a tire, and therefore the basic structure (cross-sectional structure) of the tire is not limited to the general structure described above. In addition, the following description will be based on the pneumatic tire shown in Fig. 1 etc., but the present invention can be applied to various tires, including non-pneumatic tires, as long as they have a surface that comes into contact with the road surface (a portion corresponding to the surface of the tread portion 1 in a pneumatic tire).

[0018] As shown in Fig. 2, the surface of the tread portion 1 of the tire of the present invention is provided with four main grooves 11 extending linearly along the tire circumferential direction. In the following description, a pair of the four main grooves 11 arranged on both sides of the tire equator CL may be referred to as the inner main groove 11i, and a pair arranged on the outer side of each inner main groove 11i in the tire width direction may be referred to as the outer main groove 11o. The depth of each main groove 11 is not particularly limited, but may be set to, for example, 7.0 mm to 16.0 mm. Since the four main grooves 11 extend linearly in this way, the rigidity of the width direction end of the land portion 12 (block) described later can be ensured, and wear resistance and uneven wear resistance can be ensured.

[0019] These four main grooves 11 define five rows of land portions 12 extending along the tire circumferential direction. Specifically, a center land portion 12c defined between a pair of inner main grooves 11i, an intermediate land portion 12m defined between the inner main groove 11i and the outer main groove 11o, and a shoulder land portion 12s defined on the outer side of the outer main groove 11o in the tire width direction are defined. In other words, the center land portion 12c is a land portion disposed on the tire equator CL, the intermediate land portion 12m is a land portion disposed adjacent to the center land portion 12c on both sides in the tire width direction with the inner main groove 11i in between, and the shoulder land portion 12s is a land portion disposed on the outermost side in the tire width direction including the ground contact edge E.

[0020] The center land portion 12c is divided into a plurality of center blocks 14c by the center inclined grooves 13c formed at intervals in the tire circumferential direction. The intermediate land portion 12m is divided into a plurality of intermediate blocks 14m by the intermediate inclined grooves 13m formed at intervals in the tire circumferential direction. The shoulder land portion 12s is divided into a plurality of shoulder blocks 14s by the shoulder lateral grooves 13s formed at intervals in the tire circumferential direction. The center inclined groove 13c is a groove that extends at an incline with respect to the tire width direction, and both ends of the groove open to each of a pair of inner main grooves 11i arranged on both sides of the center land portion 12c. The intermediate inclined groove 13m is a groove that extends at an incline with respect to the tire width direction, and both ends of the groove open to each of the inner main groove 11i and the outer main groove 11o arranged on both sides of the intermediate land portion 12m. The shoulder lateral groove 13s is a groove that extends along the tire width direction, one end of which opens to the outer main groove 11o, and the other end of which opens to the outside in the tire width direction beyond the ground contact edge E. The center inclined groove 13c and the middle inclined groove 13m are inclined in opposite directions with respect to the tire width direction. In the following description, the center inclined groove 13c and the middle inclined groove 13m may be collectively referred to as "inclined grooves." Since the center inclined groove 13c and the middle inclined groove 13m are inclined with respect to the tire width direction and further the center inclined groove 13c and the middle inclined groove 13m are inclined in opposite directions, snow performance can be effectively improved.

[0021] The inclination angle of each inclined groove can be set to, for example, 10° to 50° with respect to the tire width direction. Specifically, the inclination angle θc of the center inclined groove 13c with respect to the tire width direction can be set to preferably 10° to 50°, more preferably 10° to 30°. The inclination angle θm of the intermediate inclined groove 13m with respect to the tire width direction can be set to preferably -10° to -50°, more preferably -10° to -30°, when the inclination direction of the above-mentioned center inclined groove 13c is expressed as a positive (+) value. Unlike these inclined grooves, the shoulder lateral groove 13s may extend along the tire width direction, and the angle with respect to the tire width direction can be set to 0°±15°. Note that the inclination angle θc and the inclination angle θm may be the same angle with the inclination direction (positive and negative) reversed, but it is preferable that the absolute value of the inclination angle θm is larger than the absolute value of the inclination angle θc. In this way, the intermediate inclined groove 13m is inclined more with respect to the tire width direction than the center inclined groove 13c, so that the snow performance can be effectively improved.

[0022] The inclination angles θc and θm are angles formed with a straight line connecting the groove width centers at the opening ends of the inclined grooves with respect to the tire width direction, as shown in Fig. 3. The angle of the shoulder lateral groove 13s is measured as an angle formed with a straight line connecting the groove width center at the opening end of the main groove 11 and the groove width center at the ground contact edge E with respect to the tire width direction, similar to the inclination angles θc and θm.

[0023] The groove depth of each inclined groove is preferably set to 20% to 100%, more preferably 50% to 100%, of the groove depth of the main groove 11. The groove depth of the shoulder lateral groove 13s is preferably set to 50% to 100%, more preferably 70% to 100%, of the groove depth of the main groove 11.

[0024] At the extension position of the intermediate inclined groove 13m in the center block 14c, a shallow groove 15 is formed that extends in the same direction as the intermediate inclined groove 13m and terminates within the center block 14c without passing the tire equator CL. The shallow groove 15 is a groove that is smaller in depth than the main groove 11 and the inclined grooves (particularly the intermediate inclined groove 13m), and the groove depth is preferably set to 10% to 80%, more preferably 30% to 60% of the groove depth of the main groove 11. The extension position of the intermediate inclined groove 13m is a position where at least a part of the opening end overlaps with the region (hatched part in FIG. 3) between the extension lines (broken lines in FIG. 3) of the groove walls of the intermediate inclined groove 13m. By providing the shallow groove 15 in this way, the intermediate inclined groove 13m and the shallow groove 15 function as a continuous groove, and snow performance can be effectively improved. On the other hand, since the shallow groove 15 has a groove depth smaller than that of the main groove 11 and terminates within the center block 14c without passing the tire equator CL, the reduction in block rigidity caused by the provision of the shallow groove 15 is suppressed, and wear resistance can be ensured.

[0025] The center block 14c, the intermediate block 14m, and the shoulder block 14s each have two or more, preferably two to four, sipes 16 extending along the tire width direction, spaced apart in the tire circumferential direction. The shape of the sipes 16 is not particularly limited, but it is preferable that the sipes 16 have a zigzag shape on the tread surface of each block as shown in the figure. The groove width of these sipes 16 can be set to, for example, 1.5 mm or less, and the groove depth of these sipes 16 can be set to, for example, 50% to 100% of the groove depth of the main groove 11. Since the sipes 16 are appropriately provided in each block in this manner, snow performance can be effectively improved.

[0026] Since the tire of the present invention has a tread pattern configured as described above, the above-mentioned effects of each element (ensuring wear resistance through the four straight main grooves 11, improving snow performance through the center inclined grooves 13c and intermediate inclined grooves 13m, maintaining wear resistance and improving snow performance through the shallow grooves 15, and improving snow performance through the sipes 16) work together to achieve a high level of both wear resistance and snow performance.

[0027] Among the sipes 16 formed in each block, the intermediate sipes 16m formed in the intermediate block 14m should have both ends open to the main groove. On the other hand, the center sipes 16c formed in the center block 14c should have both ends terminated within the center block 14c. In other words, for the center block 14c in which the shallow groove 15 is formed, the sipes 16 (center sipes 16c) should terminate within the block to ensure block rigidity, and for the intermediate block 14m in which the shallow groove 15 is not formed, the sipes 16 (intermediate sipes 16m) should open into the main groove 11 to obtain sufficient snow performance. This is advantageous for achieving both snow performance and wear resistance. In addition, the combination of the sipes 16 described above (the center sipes 16c that terminate within the block and the intermediate sipes 16m that open into the main groove 11) suppresses the rigidity difference between the center block 14c and the intermediate block 14m, and wear resistance can be effectively ensured. If the relationship between the opening and the end of the sipes 16 deviates from the above-mentioned combination, it becomes difficult to achieve a good balance between improved snow performance and sufficient block rigidity, making it difficult to fully achieve both of these performance characteristics.

[0028] The sipes 16 formed in each block preferably extend in the same direction as the grooves (center inclined groove 13c, intermediate inclined groove 13m, shoulder lateral groove 13s) that divide each block. In detail, the intermediate sipes 16m formed in the intermediate block 14m preferably extend in the same direction as the intermediate inclined groove 13m, the center sipes 16c formed in the center block 14c preferably extend in the same direction as the center inclined groove 13c, and the shoulder sipes 16s formed in the shoulder block 14s preferably extend in the same direction as the shoulder lateral groove 13s. In this way, the grooves extending in the width direction in each block and the sipes 16 extend approximately parallel to each other, thereby ensuring block rigidity and being advantageous for maintaining wear resistance. If the inclination directions of these grooves and the sipes 16 are opposite to each other, it becomes difficult to maintain good block rigidity. In addition, the angle difference between the grooves (center inclined groove 13c, intermediate inclined groove 13m, shoulder lateral groove 13s) extending in the width direction in each block and the sipes (center sipes 16c, intermediate sipes 16m, shoulder sipes 16s) is preferably 0° to 10°, and more preferably 0° to 5°.

[0029] The shape of the shallow groove 15 is not particularly limited, but it is preferable that at least some of the shallow grooves 15 have a tapered shape in which the groove width narrows toward the end. The tapered shape may be a structure in which the groove width converges toward the end of the groove (a V-shaped end), or a shape having a narrow portion with a narrow groove width at the end and a connecting portion in which the groove width gradually decreases from the main portion of the shallow groove toward the narrow portion, as in the illustrated example. In the illustrated example, the shallow grooves 15 are opened on one side of the main groove 11 adjacent to the center land portion, and are arranged at intervals in the tire circumferential direction, and every other shallow groove 15 has a tapered shape. In other words, the tapered shallow grooves 15 and the shallow grooves 15 with a constant groove width are arranged alternately in the tire circumferential direction. In the illustrated example, in one center block 14c, when the shallow groove 15 opening into the main groove 11 on one side of the tire equator CL has a tapered shape, the shallow groove 15 opening into the main groove 11 on the other side has a constant groove width. By providing the shallow groove 15 with a tapered shape in this manner, it is possible to suppress a decrease in rigidity of the center block due to the formation of the shallow groove 15, which is advantageous for ensuring wear resistance.

[0030] In the present invention, it is preferable to provide a bottom-up portion A at the bottom of each of the center inclined groove 13c and the intermediate inclined groove 13m. The bottom-up portion A is a portion where the bottom of each groove is raised higher than the other portions. The bottom-up portion A may be provided at a position where each inclined groove communicates with the main groove 11. The bottom-up amount of the bottom-up portion A is preferably 20% to 80% of the depth of the main groove 11, more preferably 40% to 60%. The bottom-up amount is the height of the protrusion from the bottom of the groove where the bottom-up portion A is formed to the top surface of the bottom-up portion A. By providing the bottom-up portion A in this way, the block rigidity can be maintained without reducing the groove area, which is advantageous for achieving both snow performance and wear resistance. If the bottom-up amount is less than 20% of the depth of the main groove 11, there is no substantial difference from when the bottom-up portion A does not exist, and the effect of the bottom-up portion A cannot be expected to be sufficient. If the amount of bottom raising exceeds 80% of the depth of the main groove 11, the groove depth cannot be ensured sufficiently in the region where the bottom raising portion A is provided, making it difficult to ensure sufficient snow performance.

[0031] The groove width of the center inclined groove 13c and the intermediate inclined groove 13m does not need to be constant, and each groove may have a narrow portion B with a small groove width at one end. In particular, at least a part of the center inclined grooves 13c and at least a part of the intermediate inclined grooves 13m may have a narrow portion B at one end. In the illustrated example, all the intermediate inclined grooves 13m have a narrow portion B at one end. In the illustrated example, the intermediate inclined grooves 13m having a narrow portion B at the end opening to the inner main groove 11i and the intermediate inclined grooves 13m having a narrow portion B at the end opening to the outer main groove 11o are alternately arranged in the tire circumferential direction. In the illustrated example, the center inclined groove 13c does not have a narrow portion B, but the center inclined groove 13c may have a narrow portion B at some or all of them. In this way, the block rigidity can be ensured by narrowing the groove width of the portion of each inclined groove that communicates with the main groove 11. In this case, the groove width is secured in the center of each main groove 11 (other than the narrow portion B), so that snow performance is also secured sufficiently, which is advantageous for achieving both snow performance and wear resistance. The groove width in the narrow portion B is preferably 20% to 80%, more preferably 40% to 60%, of the groove width in the main portion (other portion) of the same groove. In addition, when providing the narrow portion, one groove wall of the groove in which the narrow portion is provided should be common to the narrow portion and the main portion (extending in a straight line). In other words, the other groove wall of the groove in which the narrow portion is provided should have a bent portion between the narrow portion and the main portion so that the groove width gradually decreases from the main portion toward the narrow portion. In addition, since both the narrow portion B and the above-mentioned bottom-up portion A are preferably provided at the end opening into the main groove 11, they can also be provided at the same position.

[0032] The present invention will be further described below with reference to examples, but the scope of the present invention is not limited to these examples. EXAMPLES

[0033] Eight types of pneumatic tires, namely, Conventional Example 1, Comparative Example 1, and Examples 1 to 6, were manufactured, each having a tire size of 265 / 70R17 115H and a basic structure (cross-sectional structure) as illustrated in FIG. 1, in which the number of main grooves, the shape of the main groove, the inclination angle θc of the center inclined groove, the inclination angle θm of the intermediate inclined groove, the number of sipes in each block (center block, intermediate block, shoulder block), the shape of the center sipe, the shape of the intermediate sipe, the shape of the shallow groove, the presence or absence of bottom-up portions in each inclined groove (center inclined groove, intermediate inclined groove), the presence or absence of narrow portions in each inclined groove (center inclined groove, intermediate inclined groove), and the angle difference between the grooves in each block (center inclined groove, intermediate inclined groove, shoulder lateral groove) and the sipes were set as shown in Table 1. (Note that Examples 1 to 4, which do not have a narrow width portion or a bottom raised portion, are reference examples.) .

[0034] In Table 1, in the column of "shape of main groove", the case where the main groove extends in a straight line along the main direction is indicated as "straight line". In the columns of "angle θc of center inclined groove" and "angle θm of intermediate inclined groove", the angle θc of the center inclined groove is indicated as a positive (+) value (negative (-) value means that it is inclined in the opposite direction to the center inclined groove). In the columns of "shape of center sipe" and "shape of intermediate sipe", the case where both ends open to the main groove is indicated as "open", and the case where both ends terminate within the block is indicated as "terminating". In the column of "shape of shallow groove", the case where the groove width of the shallow groove is constant is indicated as "constant width", and the case where the shallow groove has a tapered shape is indicated as "tapered". In the columns of "presence or absence of bottom raised portion" and "presence or absence of narrow width portion", the example indicated as "present" means that each groove has a bottom raised portion or a narrow width portion as shown in Figure 2.

[0035] The snow performance and wear resistance of these pneumatic tires were evaluated by the following evaluation methods, and the results are shown in Table 1.

[0036] Snow Performance Each test tire was mounted on a wheel with a rim size of 17x8J, and the front tire was set to an air pressure of 230kPa, and the rear tire was set to an air pressure of 230kPa. The test vehicle (four-wheel drive SUV) was then fitted with each tire, and a sensory evaluation of the steering stability was carried out by a test driver on a test course consisting of a snowy road surface. The evaluation results were expressed as an index, with the value of Conventional Example 1 being 100. The higher the index value, the better the snow performance.

[0037] Abrasion resistance Each test tire was mounted on a wheel with a rim size of 17x8J, and the front tire air pressure was set to 230kPa, and the rear tire air pressure was set to 230kPa. The test vehicle (four-wheel drive SUV) was then fitted with the tire, and a test driver performed a test run on a test course to measure the distance traveled (unit: km) until complete wear. The evaluation results were expressed as an index, with the value of Conventional Example 1 being 100. The higher the index value, the longer the distance traveled until complete wear and the better the wear resistance.

[0038] [Table 1]

[0039] As is clear from Table 1, the pneumatic tires of Examples 1 to 6 had improved snow performance and wear resistance, and achieved a good balance between these performances, compared to Conventional Example 1. On the other hand, Comparative Example 1 had deteriorated snow performance because shallow grooves were not provided at the extension position of the intermediate inclined groove in the center block and sipes were not formed in each block.

[0040] The present disclosure includes the following inventions. Invention [1] A tire having a tread portion extending in a circumferential direction of the tire and forming an annular shape, The tread portion has four main grooves extending linearly along the tire circumferential direction and five rows of land portions defined by the four main grooves, the five rows of land portions including a center land portion disposed on the tire equator, intermediate land portions disposed on both sides of the center land portion in the tire width direction, and shoulder land portions positioned on the outermost sides in the tire width direction, the center land portion is partitioned into a plurality of center blocks by center inclined grooves formed at intervals in the tire circumferential direction, the intermediate land portion is partitioned into a plurality of intermediate blocks by intermediate inclined grooves formed at intervals in the tire circumferential direction, the shoulder land portion is partitioned into a plurality of shoulder blocks by shoulder lateral grooves formed at intervals in the tire circumferential direction, the center inclined groove and the intermediate inclined groove are inclined in opposite directions with respect to the tire width direction, a shallow groove extending in the same direction as the intermediate inclined groove and terminating within the center block without passing the tire equator, at an extension position of the intermediate inclined groove; The center block, intermediate block, and shoulder block each have two or more sipes extending along the tire width direction and spaced apart in the tire circumferential direction. 、 A bottom-raised portion is provided at the bottom of each of the center inclined groove and the intermediate inclined groove, and at least one end of the center inclined groove and / or the intermediate inclined groove has a narrow portion having a small groove width, and both the narrow portion and the bottom-raised portion are disposed at an end that opens into the main groove. A tire characterized by: Invention [2] A tire as described in invention [1], characterized in that, of the sipes, the intermediate sipes formed in the intermediate block have both ends opening into the main groove, and the center sipes formed in the center block have both ends terminating within the center block. Invention [3] The tire according to invention [1] or [2], characterized in that at least a part of the shallow groove has a tapered shape in which the groove width narrows toward the terminal end. 。 Departure Light [ 4 Among the sipes, the intermediate sipes formed in the intermediate block extend in the same direction as the intermediate inclined groove, the center sipes formed in the center block extend in the same direction as the center inclined groove, and the shoulder sipes formed in the shoulder block extend in the same direction as the shoulder lateral groove. 3 ] A tire described in any one of the following. [Explanation of symbols]

[0041] 1 Tread section 2 Sidewall 3 Bead section 4 Carcass layer 5 Bead Core 6 Bead Filler 7 Belt layer 8 Belt reinforcement layer 11 Main groove 11i Inner main groove 11o Outer main groove 12 Land 12c Center Land Section 12m intermediate land area 12s Shoulder Land Section 13c Center inclined groove 13m intermediate slope groove 13s Shoulder groove 14c Center Block 14m intermediate block 14s shoulder block 15 Shallow Groove 16 Sipe 16c center sipe 16m intermediate sipe 16s shoulder sipes A Bottom raised part B Narrow part CL Tire Equator E Ground end

Claims

1. A tire having a tread portion extending in a circumferential direction of the tire and forming an annular shape, The tread portion includes four main grooves extending linearly along the tire circumferential direction and five rows of land portions defined by the four main grooves, the five rows of land portions including a center land portion disposed on the tire equator, intermediate land portions disposed on both sides of the center land portion in the tire width direction, and shoulder land portions positioned on the outermost sides in the tire width direction, the center land portion is partitioned into a plurality of center blocks by center inclined grooves formed at intervals in the tire circumferential direction, the intermediate land portion is partitioned into a plurality of intermediate blocks by intermediate inclined grooves formed at intervals in the tire circumferential direction, the shoulder land portion is partitioned into a plurality of shoulder blocks by shoulder lateral grooves formed at intervals in the tire circumferential direction, the center inclined groove and the intermediate inclined groove are inclined in opposite directions with respect to the tire width direction, a shallow groove extending in the same direction as the intermediate inclined groove and terminating within the center block without passing the tire equator, at an extension position of the intermediate inclined groove in the center block; The center block, the intermediate block, and the shoulder block each have two or more sipes extending along the tire width direction formed at intervals in the tire circumferential direction, A tire characterized in that a bottom-raised portion is provided at the bottom of each of the center oblique groove and the intermediate oblique groove, and at least one end of the center oblique groove and / or the intermediate oblique groove has a narrow portion having a small groove width, and the narrow portion and the bottom-raised portion are both located at ends that open into the main groove.

2. 2. The tire according to claim 1, wherein among the sipes, an intermediate sipe formed in the intermediate block has both ends open into the main groove, and a center sipe formed in the center block has both ends terminated within the center block.

3. 3. The tire according to claim 1, wherein at least a portion of the shallow groove has a tapered shape in which the groove width narrows toward an end portion.

4. 3. The tire according to claim 1, wherein, of the sipes, intermediate sipes formed in the intermediate block extend in the same direction as the intermediate inclined groove, center sipes formed in the center block extend in the same direction as the center inclined groove, and shoulder sipes formed in the shoulder block extend in the same direction as the shoulder lateral groove.

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