Tire

Abstract

To provide a tire capable of improving snow performance without impairing abrasion resistance.SOLUTION: A tread part 1 is provided with a center land part 12c, an intermediate land part 12m, and a shoulder land part 12s, which are divided by four main grooves 11 extending linearly along the tire circumferential direction. The center land part 12c is divided into a plurality of center blocks 14c by a center inclination groove 13c. The intermediate land part 12m is divided into a plurality of intermediate blocks 14m by an intermediate inclination groove 13m. The shoulder land part 12s is provided with a shoulder circumferential narrow groove 20, a first shoulder transverse groove 21 connected to the shoulder circumferential narrow groove 20 and not reaching the main groove 11, and a second shoulder transverse groove 22 opening into the main groove 11, intersecting the shoulder circumferential narrow groove 20 and terminating in the land part. Two or more sipes 16 extending along the tire width direction are provided in main parts of each of the center block 14c, the intermediate block 14m, and the shoulder land part 12s.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 defined 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 defined into a plurality of center blocks by center inclined grooves formed at intervals in the tire circumferential direction, the intermediate land portion being defined into a plurality of intermediate blocks by intermediate inclined grooves formed at intervals in the tire circumferential direction, the shoulder land portions being defined into a plurality of shoulder circumferential narrow grooves extending along the tire circumferential direction in parallel with the main grooves disposed on the outermost sides in the tire width direction, and a first shoulder lateral groove extending along the tire width direction. and a second shoulder lateral groove are formed, the first shoulder lateral groove having an outer end in the tire width direction that is open beyond the ground contact edge and an inner end in the tire width direction that connects to the shoulder circumferential narrow groove and is discontinued so as not to reach the main groove, the second shoulder lateral groove has a groove width smaller than that of the first shoulder lateral groove, extends at an angle with respect to the tire width direction, has an inner end in the tire width direction that connects to the main groove and an outer end in the tire width direction that intersects the shoulder circumferential narrow groove and terminates within the shoulder land portion, two or more sipes extending along the tire width direction are formed in the center block and the intermediate block at intervals in the tire circumferential direction, and two or more sipes extending along the tire width direction are formed at intervals in the tire circumferential direction in each of areas surrounded by the shoulder circumferential narrow groove and a pair of the first shoulder lateral grooves adjacent in the tire circumferential direction in the shoulder land portion. 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. Since the grooves (center inclined groove, intermediate inclined groove) that divide the center land portion and the intermediate land portion are inclined with respect to the tire width direction, it is possible to improve snow performance. Furthermore, the shoulder land portion is formed with a shoulder circumferential narrow groove, a first shoulder lateral groove, and a second shoulder lateral groove, and the snow performance is ensured by the first shoulder lateral groove, but since the first shoulder lateral groove does not reach the main groove and is connected to the shoulder circumferential narrow groove and is interrupted, a land portion that extends continuously substantially around the entire tire is formed between the outermost main groove in the tire width direction and the shoulder circumferential narrow groove, and this ensures block rigidity. The second shoulder lateral groove extends from the main groove beyond the shoulder circumferential narrow groove in the tire width direction, but the second shoulder lateral groove has a smaller groove width than the first shoulder lateral groove, so the block rigidity is not impaired and the second shoulder lateral groove is expected to further improve snow performance. In addition, the snow performance can be improved by providing an appropriate amount of sipes extending along the tire width direction in each block and land portion. These cooperations allow a high level of both wear resistance and snow performance to be achieved.

[0007] In the present invention, it is preferable that the inner end of the first shoulder lateral groove in the tire width direction has a tapered shape in which the groove width narrows toward the shoulder circumferential narrow groove. By having the first shoulder lateral groove have such a tapered shape, it is possible to suppress a decrease in rigidity of the shoulder land portion (especially in the vicinity of the shoulder circumferential narrow groove) caused by forming the first shoulder lateral groove, which is advantageous for ensuring wear resistance.

[0008] In the present invention, it is preferable that the groove depth Dc of the circumferential shoulder groove, the groove depth D1 of the first transverse shoulder groove, and the groove depth D2 of the second transverse shoulder groove satisfy the relationship Dc ≤ D2 < D1. By doing so, the balance between the snow performance added by each groove and the block rigidity reduced by the formation of each groove becomes good, which is advantageous for achieving both snow performance and wear resistance.

[0009] In the present invention, it is preferable that at the extension position of the intermediate inclined groove in the center block, there is a center shallow groove that extends in the same direction as the intermediate inclined groove and terminates within the center block without exceeding the tire equator. When a center shallow groove that extends in the same direction as the intermediate inclined groove is provided at the extension position of the intermediate inclined groove, the intermediate inclined groove and the center shallow groove function as a series of grooves, and the snow performance can be effectively improved. On the other hand, since the center shallow groove has a smaller groove depth than the main groove and terminates within the center block without exceeding the tire equator, the decrease in block rigidity due to the provision of the center shallow groove can be suppressed, and wear resistance can be ensured.

[0010] In the present invention, it is preferable that between the sipes adjacent in the tire circumferential direction in the intermediate block, there is an intermediate shallow groove that opens to the main groove arranged at the outermost side in the tire width direction, extends in the same direction as the intermediate inclined groove, and terminates within the intermediate block without exceeding the center in the tire width direction of the intermediate block. Thereby, the edge effect by the intermediate shallow groove is added, and the snow performance can be further improved. On the other hand, since the intermediate shallow groove has a smaller groove depth than the main groove and terminates within the intermediate block without exceeding the center of the intermediate block, the decrease in block rigidity due to the provision of the intermediate shallow groove can be suppressed, and wear resistance can be ensured.

[0011] In the present invention, it is preferable to provide a bottom raising portion at the bottom of each of the center inclined groove and the intermediate inclined groove. By providing the bottom raising portion 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.

[0012] 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 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 land portion extend in the same direction as the first shoulder lateral groove. By inclining the inclined grooves and the sipes in each block in the same manner, block rigidity can be ensured, which is advantageous for maintaining wear resistance.

[0013] 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]

[0014] [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

[0015] The configuration of the present invention will be described in detail below with reference to the accompanying drawings.

[0016] 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.

[0017] In addition, in the case of a pneumatic tire, the contact edge E is the end in the tire width direction of the contact area formed when the tire is mounted on a regular rim, inflated to the regular internal pressure, placed vertically on a flat surface, and subjected to a regular load. The "regular rim" is a rim determined for each tire by the standard system including the standard on which the tire is based, for example, the standard rim for JATMA, the "Design Rim" for TRA, or the "Measuring Rim" for ETRTO. The "regular internal pressure" is the air pressure determined for each tire by each standard in the standard system including the standard on which the tire is based, for example, the maximum air pressure for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and "INFLATION PRESSURE" for ETRTO, but is 180 kPa when the tire is for a passenger car. "Normal load" refers to the load determined for each tire by each standard in the system of standards, including the standards 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", and in the case of ETRTO, it is the "LOAD CAPACITY". However, if the tire is for passenger cars, it is a load equivalent to 88% of the above load.

[0018] 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.

[0019] 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).

[0020] 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.

[0021] 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.

[0022] The center land portion 12c is divided into a plurality of center blocks 14c by 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 intermediate inclined grooves 13m 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 center inclined groove 13c and the intermediate inclined groove 13m are preferably inclined in opposite directions with respect to the tire width direction. In addition, as shown in the illustrated example, the center inclined groove 13c extends linearly, while the middle inclined groove 13m is curved (in the illustrated example, the middle inclined groove 13m has a zigzag shape consisting of a first portion that opens into the inner main groove 11i and extends linearly at an incline with respect to the tire width direction, a second portion that extends linearly in the same direction as the first portion and opens into the outer main groove 11o, and a third portion that connects the first portion and the second portion and is inclined in the opposite direction to the first portion and the second portion). In the following description, the center inclined groove 13c and the middle inclined groove 13m may be collectively referred to as "inclined grooves". These inclined grooves can improve snow performance. In particular, if the center inclined groove 13c and the middle inclined groove 13m are inclined in opposite directions or the middle inclined groove 13m has the above-mentioned curved shape, an edge effect can be exerted in various directions, and snow performance can be effectively improved.

[0023] 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 center inclined groove 13c described above is expressed as a positive (+) value. 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 to make the absolute value of the inclination angle θm larger than the absolute value of the inclination angle θc. In this way, the snow performance can be effectively improved by making the intermediate inclined groove 13m more inclined with respect to the tire width direction than the center inclined groove 13c. Note that the inclination angles θc and θm are angles formed with the tire width direction by a straight line connecting the groove width centers at the opening ends of each inclined groove, as shown in FIG. 3.

[0024] The groove depth of each inclined groove is preferably set to 20% to 100% of the groove depth of the main groove 11, and more preferably 50% to 100%.

[0025] In the shoulder land portion 12s, a shoulder circumferential narrow groove 20 extending along the tire circumferential direction, and a first shoulder lateral groove 21 and a second shoulder lateral groove 21 extending along the tire width direction are formed. In detail, the shoulder circumferential narrow groove 20 extends along the tire circumferential direction in parallel with the main groove 11 arranged on the outermost side in the tire width direction (i.e., the outer main groove 11o), and a continuous rib 23 extending continuously around substantially the entire tire circumference is formed between the outer main groove 11o and the shoulder circumferential narrow groove 20. The first shoulder lateral groove 21 has an outer end in the tire width direction that is open beyond the ground contact edge E, and an inner end in the tire width direction that is connected to the shoulder circumferential narrow groove 20. The first shoulder lateral groove 21 is interrupted by connecting to the shoulder circumferential narrow groove 20, and does not reach the continuous rib 23 or the outer main groove 11o. The second shoulder lateral groove 22 extends at an angle to the tire width direction so as to intersect with the shoulder circumferential narrow groove 20, with its inner end in the tire width direction connecting to the outer main groove 11o and its outer end in the tire width direction terminating within the shoulder land portion 12s. The shoulder circumferential narrow groove 20 and the second shoulder lateral groove 22 have a groove width smaller than that of the first shoulder lateral groove 21, so that the area defined by the shoulder circumferential narrow groove 20 and the second shoulder lateral groove 22 is not completely divided compared to the area defined by the first shoulder lateral groove 21, and the block rigidity is maintained. Snow performance is ensured by the edge effect of each groove formed in the shoulder land portion 12s, but as described above, the first shoulder lateral groove 21 does not reach the outer main groove 11o and forms a continuous rib 23, so that the block rigidity can be ensured. At this time, the shoulder circumferential narrow groove 20 and the second shoulder lateral groove 22 have a groove width smaller than that of the first shoulder lateral groove 21, so that the block rigidity is not significantly reduced even if the land portion is apparently defined by these grooves, and wear resistance can be ensured.

[0026] As described above, the circumferential shoulder narrow groove 20 and the second transverse shoulder groove 22 have a smaller groove width than the first transverse shoulder groove 21. When the groove width of the circumferential shoulder narrow groove 20 is Gc, the groove width of the first transverse shoulder groove 21 is G1, and the groove width of the second transverse shoulder groove 22 is G2, the groove width G1 of the first transverse shoulder groove 21 is preferably 1.5 to 3.0 times, more preferably 1.8 to 2.7 times the groove width Gc of the circumferential shoulder narrow groove 20 or the groove width G2 of the second transverse shoulder groove 22. Note that, in the case of the tapered shape described later, the groove width G1 of the first transverse shoulder groove is the groove width of the main part excluding the narrow part.

[0027] Also, when the groove depth of the circumferential shoulder narrow groove 20 is Dc, the groove depth of the first transverse shoulder groove 21 is D1, and the groove depth of the second transverse shoulder groove 22 is D2, it is preferable that these groove depths satisfy the relationship Dc ≤ D2 < D1. Thereby, the balance between the snow performance added by each groove and the block rigidity reduced by the formation of each groove is improved, which is advantageous for achieving both snow performance and wear resistance. Although the specific groove depth is not particularly limited, the groove depth D1 of the first transverse shoulder groove 21 is preferably 60% to 100%, more preferably 70% to 90% of the groove depth of the main groove 11. The groove depth Dc of the circumferential shoulder narrow groove 20 and the groove depth D2 of the second transverse shoulder groove 22 are preferably 20% to 70%, more preferably 30% to 60% of the groove depth of the main groove 11.

[0028] The angle θ1 of the first transverse shoulder groove with respect to the tire width direction can be preferably set to 0° ± 15°, more preferably 0° ± 10°. The inclination angle θ2 of the second transverse shoulder groove with respect to the tire width direction can be preferably set to 10° to 50°, more preferably 10° to 30° (when the inclination direction of the center inclined groove 13c is represented by a positive (+) value, preferably -10° to -50°, more preferably -10° to -30°). Regarding these angles θ1 and θ2, similar to the inclination angles θc and θm, they are measured as the angle formed by the straight line connecting the groove width center at the opening end with respect to the main groove 11 and the circumferential shoulder narrow groove 20 and the groove width center at the ground contact end E position and the end portion with respect to the tire width direction.

[0029] In the center block 14c and the intermediate block 14m, two or more sipes 16, preferably two to four sipes 16, extending along the tire width direction, are formed at intervals in the tire circumferential direction. In the shoulder land portion 12s, two or more sipes, preferably two to four sipes 16, extending along the tire width direction, are formed at intervals in the tire circumferential direction in each region surrounded by a pair of first shoulder lateral grooves 21 and shoulder circumferential narrow grooves 20 adjacent to each other in the tire circumferential direction. The shape of each sipe 16 is not particularly limited, but it is preferable that each block or land portion has a zigzag shape on the tread surface as shown in the figure. In addition, 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. By providing the sipes 16 appropriately in each block or land portion in this way, snow performance can be effectively improved.

[0030] 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 by the four straight main grooves 11, improving snow performance by the center inclined groove 13c and the intermediate inclined groove 13m, maintaining wear resistance and improving snow performance by the shoulder circumferential narrow grooves 20, first shoulder lateral grooves 21, and second shoulder lateral grooves 22 provided in the shoulder land portion 12s, and improving snow performance by the sipes 16) work together to achieve a high level of both wear resistance and snow performance.

[0031] The groove width of the first shoulder lateral groove 21 does not need to be constant, and it is preferable that at least some, and preferably all, of the multiple first shoulder lateral grooves 21 have a tapered shape in which the groove width narrows toward the shoulder circumferential narrow groove 20 at the inner end in the tire width direction. The tapered shape may be a structure in which the groove width converges toward the groove tip (V-shaped end), or a shape having a narrow width portion where the groove width is narrow at the portion connecting to the shoulder circumferential narrow groove 20 and a connecting portion where the groove width gradually decreases from the main portion of the first shoulder lateral groove 21 toward the narrow width portion, as in the illustrated example. When the first shoulder lateral groove 21 has a narrow width portion as in the illustrated example, the groove width at the narrow width portion is preferably 0.5 to 2.0 times the groove width of the shoulder circumferential groove 20. In addition, the length of the narrow width portion is preferably 0% to 30% of the tire width direction length from the shoulder circumferential groove 20 to the ground contact edge E. By forming the first shoulder lateral groove 21 in such a tapered shape, it is possible to suppress a decrease in rigidity of the shoulder land portion 12s (particularly in the vicinity of the shoulder circumferential narrow groove 20) caused by the formation of the first shoulder lateral groove 21, which is advantageous in ensuring wear resistance.

[0032] At the extension position of the intermediate inclined groove 13m in the center block 14c, a center shallow groove 15c can be formed that extends in the same direction as the intermediate inclined groove 13m and terminates within the center block 14c without crossing the tire equator CL. The center shallow groove 15c 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 center shallow groove 15c in this way, the intermediate inclined groove 13m and the center shallow groove 15c function as a continuous groove, and snow performance can be effectively improved. On the other hand, since the center shallow groove 15c has a groove depth smaller than that of the main groove 11 and terminates within the center block 14c without passing beyond the tire equator CL, the provision of the center shallow groove 15c suppresses a decrease in block rigidity and ensures wear resistance.

[0033] The shape of the center shallow groove 15c is not particularly limited, but it is preferable that at least a part, preferably all, of the plurality of center shallow grooves 15c 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 tip of the groove (a V-shaped end), or, as shown in the example, 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 center shallow groove 15c toward the narrow portion. By providing the center shallow groove 15c with such a tapered shape, it is possible to suppress the decrease in rigidity of the center block 14c caused by forming the center shallow groove 15c, which is advantageous for ensuring wear resistance.

[0034] In the intermediate block 14m, an intermediate shallow groove 15m can be formed between adjacent sipes 16 in the tire circumferential direction, opening into the main groove 11 (outer main groove 11o) arranged on the outermost side in the tire width direction, extending in the same direction as the intermediate inclined groove 13m, and terminating within the intermediate block 14m without passing the center of the intermediate block 14m in the tire width direction. The intermediate shallow groove 15m is a groove having a groove depth smaller than that of the main groove 11 and the inclined groove (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. By providing the intermediate shallow groove 15m in this way, an edge effect due to the intermediate shallow groove 15m is added, and snow performance can be further improved. On the other hand, since the intermediate shallow groove 15m has a groove depth smaller than that of the main groove 11 and terminates within the intermediate block 14m without passing the center of the intermediate block 14m, a decrease in block rigidity due to the provision of the intermediate shallow groove 15m can be suppressed, and wear resistance can be ensured.

[0035] The sipes 16 formed in each block (center block 14c, intermediate block 14m) or land portion (shoulder land portion 12s) preferably extend in the same direction as the grooves (center inclined groove 13c, intermediate inclined groove 13m, first shoulder lateral groove 21) that divide each block or land portion. 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 land portion 12s preferably extend in the same direction as the first shoulder lateral groove 21. In this way, the grooves extending in the width direction in each block or land portion 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, first shoulder lateral groove 21) extending in the width direction in each block and the sipes (center sipe 16c, intermediate sipe 16m, shoulder sipe 16s) is preferably 0° to 10°, and more preferably 0° to 5°.

[0036] In the present invention, the center inclined groove 13c, the intermediate inclined groove 13m, and the first shoulder lateral groove 21 may each have a bottom-raised portion A at their bottom. The bottom-raised portion A is a portion of each groove where the bottom is raised higher than the other portions. The bottom-raised portion A may be provided at a position where each groove communicates with a groove (main groove 11 or shoulder circumferential narrow groove 20) extending along the tire circumferential direction. When the bottom-raised portion A is provided at a position where it communicates with the main groove 11, the bottom-raised amount is preferably 20% to 80%, more preferably 40% to 60% of the depth of the main groove 11. When the bottom-raised portion A is provided at a position where it communicates with the shoulder circumferential narrow groove 20, the groove depth at the bottom-raised portion A may be equal to or less than that of the shoulder circumferential narrow groove 20, and specifically, the bottom-raised amount is preferably 10% to 50%, more preferably 20% to 30% of the depth of the main groove 11. The amount of bottom-up is the height of the groove from the bottom of the groove in which 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 manner, the block rigidity can be maintained without reducing the groove area, which is advantageous for achieving both snow performance and wear resistance. If the amount of bottom-up is less than the above-mentioned range, 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-up is more than the above-mentioned range, the groove depth cannot be sufficiently ensured in the area in which the bottom-up portion A is provided, making it difficult to ensure sufficient snow performance.

[0037] 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

[0038] 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 inclination angle θc of the center inclined groove, the inclination angle θm of the intermediate inclined groove, the presence or absence of shoulder circumferential narrow grooves, the presence or absence of first shoulder lateral grooves, the presence or absence of second shoulder lateral grooves, the number of sipes in each land portion (center block, intermediate block, shoulder land portion), the groove depth of each groove (shoulder circumferential narrow groove, first shoulder lateral groove, second shoulder lateral groove) formed in the shoulder land portion, the shape of the first shoulder lateral groove, the presence or absence of a center shallow groove, the presence or absence of an intermediate shallow groove, the presence or absence of a bottom-up portion in each inclined groove (center inclined groove, intermediate inclined groove), and the angle difference between the grooves (center inclined groove, intermediate inclined groove, first shoulder lateral groove) and the sipes in each block or land portion were set as shown in Table 1.

[0039] In each example, four straight main grooves were provided. The angle of the first shoulder lateral groove was 0° relative to the tire width direction, and the angle of the second shoulder lateral groove, if provided, was the same as the angle θm of the intermediate inclined groove. The groove width of the shoulder circumferential narrow groove was 2 mm, the groove width of the first shoulder lateral groove was 5 mm, and the groove width of the second shoulder lateral groove was 2 mm. When the first shoulder lateral groove had a tapered shape, the groove width at the narrow part was 2 mm. Note that Conventional Example 1 is a pattern in which the shoulder circumferential narrow groove and the second shoulder lateral groove are not provided, and therefore the shoulder land portion is divided into multiple blocks by the first shoulder lateral groove, and has a structure that does not include a "continuous rib" as shown in Figure 2.

[0040] In Table 1, in the columns "Center inclined groove angle θc" and "Middle inclined groove angle θm", the angle θc of the center inclined groove is shown as a positive (+) value (negative (-) value means that it is inclined in the opposite direction to the center inclined groove). In the column "Number of sipes in shoulder land portion", when the shoulder land portion is divided into multiple blocks (conventional example 1), the number of sipes in each block is recorded, and in Examples 1 to 6, the number of sipes included in the area surrounded by a pair of first shoulder lateral grooves and shoulder circumferential narrow grooves adjacent to each other in the tire circumferential direction is recorded. Comparative Example 1 does not have a first shoulder lateral groove, so it does not include a divided area like Examples 1 to 6, but since the arrangement of the sipes is common to Examples 1 to 6 except for the fact that it does not have a first shoulder lateral groove, the same values ​​as Examples 1 to 6 are recorded in parentheses for reference. In the column "Groove depth", the ratio (%) to the depth of the main groove is shown. In the column "Shape of first shoulder lateral groove", a groove with a constant width is indicated as "constant width", and a tapered shape is indicated as "tapered". In the column "Whether or not there is a bottom raised part", the example with "Yes" means that each groove has a bottom raised part or a narrow part as shown in Figure 2.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] [Table 1]

[0045] 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 worse snow performance because it had shoulder circumferential narrow grooves and second shoulder lateral grooves in the shoulder land portion but no first shoulder lateral grooves.

[0046] 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 divided into a plurality of center blocks by center inclined grooves formed at intervals in the tire circumferential direction, and the intermediate land portion is divided into a plurality of intermediate blocks by intermediate inclined grooves formed at intervals in the tire circumferential direction, In the shoulder land portion, a shoulder circumferential narrow groove extending along the tire circumferential direction in parallel with the main groove disposed on the outermost side in the tire width direction, and a first shoulder lateral groove and a second shoulder lateral groove extending along the tire width direction are formed, The first shoulder transverse groove has an outer end in the tire width direction opening beyond the grounding end, and an inner end in the tire width direction connecting to the shoulder circumferential narrow groove and terminating without reaching the main groove. The second shoulder transverse groove has a groove width smaller than that of the first shoulder transverse groove, extends obliquely with respect to the tire width direction, has an inner end in the tire width direction connecting to the main groove, and an outer end in the tire width direction intersecting the shoulder circumferential narrow groove and terminating within the shoulder land portion. Two or more sipes extending along the tire width direction are formed at intervals in the tire circumferential direction in the center block and the intermediate block respectively, and two or more sipes extending along the tire width direction are formed at intervals in the tire circumferential direction in each of the regions surrounded by the shoulder circumferential narrow groove and a pair of the first shoulder transverse grooves adjacent in the tire circumferential direction in the shoulder land portion. A tire characterized by this. The tire according to invention [1], wherein the inner end of the first shoulder transverse groove in the tire width direction has a tapered shape with a groove width narrowing toward the shoulder circumferential narrow groove. The tire according to invention [1] or [2], wherein the groove depth Dc of the shoulder circumferential narrow groove, the groove depth D1 of the first shoulder transverse groove, and the groove depth D2 of the second shoulder transverse groove satisfy the relationship Dc ≤ D2 < D1. The tire according to any one of inventions [1] to [3], having a center shallow groove extending in the same direction as the intermediate inclined groove at the extension position of the intermediate inclined groove in the center block and terminating within the center block without exceeding the tire equator. The tire according to any one of inventions [1] to [4], having an intermediate shallow groove opening to the main groove arranged at the outermost side in the tire width direction between the sipes adjacent in the tire circumferential direction in the intermediate block, extending in the same direction as the intermediate inclined groove, and terminating within the intermediate block without exceeding the center in the tire width direction of the intermediate block. The tire according to any one of inventions [1] to [5], wherein a bottom raising portion is provided at the bottom of each of the center inclined groove and the intermediate inclined groove. Invention [7] A tire according to any one of inventions [1] to [6], characterized in that, of 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 land portion extend in the same direction as the first shoulder lateral groove. [Explanation of symbols]

[0047] 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 14c Center Block 14m intermediate block 15 Shallow Groove 16 Sipe 16c center sipe 16m intermediate sipe 16s shoulder sipes 20 Shoulder circumferential narrow groove 21 First shoulder groove 22 Second shoulder groove 23 Continuous Rib 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 divided into a plurality of center blocks by center inclined grooves formed at intervals in the tire circumferential direction, and the intermediate land portion is divided into a plurality of intermediate blocks by intermediate inclined grooves formed at intervals in the tire circumferential direction, In the shoulder land portion, a shoulder circumferential narrow groove extending along the tire circumferential direction in parallel with the main groove disposed on the outermost side in the tire width direction, and a first shoulder lateral groove and a second shoulder lateral groove extending along the tire width direction are formed, The first shoulder lateral groove has an outer end in the tire width direction that is open beyond the ground contact edge, and an inner end in the tire width direction that is connected to the shoulder circumferential narrow groove and does not reach the main groove, the second shoulder lateral groove has a groove width smaller than that of the first shoulder lateral groove, extends at an incline with respect to the tire width direction, an inner end in the tire width direction is connected to the main groove, and an outer end in the tire width direction intersects with the shoulder circumferential narrow groove and terminates within the shoulder land portion, a pair of first shoulder lateral grooves adjacent to each other in the tire circumferential direction in each of the shoulder land portions, the pair of first shoulder lateral grooves adjacent to each other in the tire circumferential direction in each of the shoulder land portions, and the pair of first shoulder lateral grooves adjacent to each other in the tire circumferential direction in each of the shoulder land portions.

2. The tire according to claim 1, wherein an inner end in the tire width direction of the first shoulder lateral groove has a tapered shape in which the groove width narrows toward the shoulder circumferential narrow groove.

3. 3. The tire according to claim 1, wherein a groove depth Dc of the shoulder circumferential narrow groove, a groove depth D1 of the first shoulder lateral groove, and a groove depth D2 of the second shoulder lateral groove satisfy a relationship of Dc≦D2<D1.

4. 3. The tire according to claim 1, further comprising a center 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.

5. 3. The tire according to claim 1, further comprising an intermediate shallow groove disposed between adjacent sipes in the tire circumferential direction in the intermediate block, the intermediate shallow groove opening into the main groove disposed at the outermost side in the tire width direction, extending in the same direction as the intermediate oblique groove, and terminating within the intermediate block without passing beyond the center of the intermediate block in the tire width direction.

6. 3. The tire according to claim 1, wherein a bottom raised portion is provided at the bottom of each of the center oblique groove and the intermediate oblique groove.

7. The tire according to claim 1 or 2, characterized in that, 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 land portion extend in the same direction as the first shoulder lateral groove.

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