Tire

Abstract

This invention provides a tire that improves snow performance without compromising wear resistance. The tread portion (1) is divided into a central tread edge (12c), a middle tread edge (12m), and a shoulder tread edge (12s) by four main grooves (11) extending linearly along the tire circumference. The central tread edge (12c) is divided into multiple central tread blocks (14c) by a central inclined groove (13c), and the middle tread edge (12m) is divided into multiple middle tread blocks (14m) by a central inclined groove (13m). The shoulder tread edge (12s)... The tire is provided with a shoulder circumferential groove (20), a first shoulder transverse groove (21) connected to the shoulder circumferential groove (20) but not reaching the main groove (11), and a second shoulder transverse groove (22) opening into the main groove (11), intersecting the shoulder circumferential groove (20) and terminating in the circumferential land portion. Two or more sipes (16) extending along the tire width direction are respectively provided in the main parts of the central tread block (14c), the intermediate tread block (14m) and the shoulder circumferential land portion (12s).

Description

Technical Field

[0001] This invention relates to a tire with a blocky tread pattern, and more specifically, to a tire that can improve snow performance without compromising wear resistance. Background Technology

[0002] Among tires used on vehicles such as SUVs, a category specifically designed for high-speed driving is known as "Highway Terrain Tire." This category of tires requires a block-pattern tread pattern and the ability to handle various road conditions (dry roads, wet roads, snowy roads) (see, for example, Patent Document 1). In recent years, there has been a growing emphasis on snow performance (driving stability on snow-covered roads). For example, increasing the groove area makes it easier to trap snow, thereby improving snow performance. However, as mentioned above, this type of tire has a block-pattern tread pattern, so increasing the groove area can easily reduce the rigidity of the circumferential grooves, making it difficult to ensure sufficient wear resistance. Therefore, measures are needed to improve snow performance without compromising wear resistance.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-137218 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] The purpose of this invention is to provide a tire that can improve snow performance without compromising wear resistance.

[0008] Methods for solving problems

[0009] The tire of the present invention for achieving the above-mentioned objective has a tread portion that extends in an annular shape along the tire circumference. The tread portion is characterized by having four main grooves extending linearly along the tire circumference and five rows of annular land portions divided by these four main grooves. These five rows of annular land portions include a central annular land portion disposed on the tire equator, intermediate annular land portions disposed on both sides of the central annular land portion in the tire width direction, and a shoulder annular land portion located on the outermost side in the tire width direction. The central annular land portion is divided into a plurality of central tread blocks by a central inclined groove formed at intervals along the tire circumference. The intermediate annular land portions are divided into a plurality of intermediate tread blocks by central inclined grooves formed at intervals along the tire circumference. The shoulder annular land portion has a shoulder circumferential groove parallel to the main grooves located on the outermost side in the tire width direction and extending along the tire circumference, and a first shoulder transverse groove and a second shoulder transverse groove extending along the tire width direction. The first shoulder lateral groove has its outer end in the tire width direction extending beyond the ground contact end and opening. Its inner end in the tire width direction connects to the shoulder circumferential groove and is interrupted, thus not reaching the main groove. The second shoulder lateral groove has a smaller groove width than the first shoulder lateral groove. The second shoulder lateral groove extends obliquely relative to the tire width direction. Its inner end in the tire width direction connects to the main groove, and its outer end in the tire width direction intersects with the shoulder circumferential groove and terminates within the shoulder circumferential land. The central tread block and the intermediate tread block each have two or more sipes extending in the tire width direction, spaced apart along the tire circumferential direction. In the shoulder circumferential groove and the area enclosed by a pair of first shoulder lateral grooves adjacent to each other in the tire circumferential direction, two or more sipes extending in the tire width direction are formed at intervals along the tire circumferential direction.

[0010] Invention Effects

[0011] In the tire of the present invention, since the tread pattern is configured as described above, snow performance can be improved without sacrificing abrasion resistance. Specifically, since the four main grooves extend linearly, the rigidity at the widthwise ends of each tread block can be ensured, thereby ensuring abrasion resistance and uneven wear resistance. The grooves (central inclined groove, intermediate inclined groove) that divide the central land portion and the intermediate land portion are inclined with respect to the tire width direction, so snow performance can be improved. Furthermore, a shoulder circumferential fine groove, a first shoulder transverse groove, and a second shoulder transverse groove are formed in the shoulder land portion. Snow performance is ensured by the first shoulder transverse groove. However, since the first shoulder transverse groove does not reach the main groove but connects to the shoulder circumferential fine groove and terminates, a land portion that extends continuously substantially throughout the circumference of the tire is formed between the outermost main groove in the tire width direction and the shoulder circumferential fine groove, thereby ensuring the rigidity of the tread block. It should be noted that the second shoulder transverse groove extends from the main groove across the shoulder circumferential fine groove and along the tire width direction. However, since the groove width of the second shoulder transverse groove is smaller than that of the first shoulder transverse groove, the rigidity of the tread block is not impaired. Through the second shoulder transverse groove, further improvement in snow performance can be expected. In addition, since sipes extending in the tire width direction are appropriately provided in each tread block and land portion, snow performance can be improved. Through the synergistic effect of these arrangements, abrasion resistance and snow performance can be highly balanced.

[0012] In the present invention, preferably, the inner end of the first shoulder transverse groove in the tire width direction has a tapered shape with the groove width narrowing toward the shoulder circumferential fine groove. By making the first shoulder transverse groove have such a tapered shape, a reduction in the rigidity of the shoulder land portion (especially near the shoulder circumferential fine groove) caused by the formation of the first shoulder transverse groove can be suppressed, which is beneficial for ensuring abrasion resistance.

[0013] In the present invention, preferably, the groove depth Dc of the shoulder circumferential fine 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. Thereby, a good balance is obtained between the snow performance added by each groove and the reduction in the rigidity of the tread block due to the formation of each groove, which is beneficial for balancing snow performance and abrasion resistance.

[0014] In the present invention, preferably, a central shallow groove is provided at the extended position of the intermediate inclined groove in the central tread block. The central shallow groove extends in the same direction as the intermediate inclined groove and terminates within the central tread block without exceeding the tire equator. If a central shallow groove extending in the same direction as the intermediate inclined groove is provided at the extended position of the intermediate inclined groove, the intermediate inclined groove and the central shallow groove function as a series of grooves, and snow performance can be effectively improved. On the other hand, the groove depth of the central shallow groove is smaller than that of the main groove and terminates within the central tread block without exceeding the tire equator, so a reduction in the rigidity of the tread block caused by the provision of the central shallow groove can be suppressed, thereby ensuring abrasion resistance.

[0015] In this invention, it is preferable that the intermediate tread block has a shallow intermediate groove between adjacent sipes in the tire circumferential direction. This shallow intermediate groove opens towards the main groove located on the outermost side in the tire width direction, extends in the same direction as the inclined intermediate groove, and terminates within the intermediate tread block without exceeding the center of the intermediate tread block in the tire width direction. This provides an additional edge effect due to the shallow intermediate groove, further improving snow performance. Furthermore, the shallow intermediate groove has a shallower depth than the main groove and terminates within the intermediate tread block without exceeding its center, thus suppressing any reduction in tread block rigidity caused by the shallow intermediate groove and ensuring wear resistance.

[0016] In this invention, it is preferable to provide a raised bottom portion at the bottom of both the central inclined groove and the intermediate inclined groove. By providing this raised bottom portion, the rigidity of the patterned block can be maintained without reducing the groove area, which is beneficial for balancing snow performance and wear resistance.

[0017] In this invention, preferably, the intermediate sipes formed on the intermediate tread blocks extend in the same direction as the intermediate inclined grooves, the central sipes formed on the central tread blocks extend in the same direction as the central inclined grooves, and the shoulder sipes formed on the shoulder ring extend in the same direction as the first shoulder transverse grooves. By making the inclined grooves and sipes inclined in the same way in each tread block, the rigidity of the tread blocks can be ensured, thereby helping to maintain wear resistance.

[0018] The tire of the present invention is preferably a pneumatic tire, but it can also be a non-pneumatic tire. When it is a pneumatic tire, its interior can be filled with air, nitrogen, or other inert gases. Attached Figure Description

[0019] Figure 1 This is a radial cross-sectional view of a tire constructed according to an embodiment of the present invention.

[0020] Figure 2 This is a front view showing the tread of a tire constructed according to an embodiment of the present invention.

[0021] Figure 3 It is extraction Figure 2 An explanatory diagram showing a portion of the content. Detailed Implementation

[0022] Hereinafter, the structure of the present invention will be described in detail with reference to the accompanying drawings.

[0023] Regarding the tire of the present invention, it is as follows: Figure 1 The pneumatic tire shown includes a tread portion 1 that contacts the road surface, a pair of sidewall portions 2 disposed on both sides of the tread portion 1, and a pair of bead portions 3 disposed radially inside the sidewall portions 2. Figure 1In the attached diagram, CL represents the tire equator, and E represents the ground contact terminal. It should be noted that, due to... Figure 1 This is a radial cross-sectional view, so although it is not depicted, the tread portion 1, sidewall portion 2, and bead portion 3 extend circumferentially along the tire and form a ring, thus constituting the basic annular structure of a pneumatic tire. The following will use... Figure 1 The description is based primarily on the meridian profile shape shown in the illustration, with each tire component extending circumferentially and forming a ring.

[0024] It should be noted that the ground contact point E refers to the end of the tire's width in the ground contact area formed when the tire, in the case of a pneumatic tire, is mounted on a standard rim and filled with the standard internal pressure, placed vertically on a flat surface, and subjected to a standard load. "Standard rim" refers to the rim specified for each tire within a specification system that includes the tire's specifications. For example, if it is JATMA, it is designated as a standard rim; if it is TRA, it is designated as a "design rim"; or if it is ETRTO, it is designated as a "measuring rim". "Standard tire pressure" refers to the air pressure specified for each tire in the specification system, including the specifications on which the tire is based. If it is JATMA, it is set as the maximum air pressure. If it is TRA, it is set as the maximum value recorded in the table "Tire Load Limits at Various Cold Inflation Pressures". If it is ETRTO, it is set as "Inflation Pressure". However, if the tire is for passenger cars, it is set as 180 kPa. "Standard load" refers to the load specified for each tire in the specification system, including the specifications on which the tire is based. If it is JATMA, it is set as the maximum load capacity. If it is TRA, it is set as the maximum value recorded in the table "Tire Load Limits at Various Cold Inflation Pressures". If it is ETRTO, it is set as "Load Capacity". However, if the tire is for passenger cars, it is set as a load equivalent to 88% of the stated load.

[0025] A carcass layer 4 is mounted between a pair of left and right bead portions 3. This carcass layer 4 contains multiple reinforcing cords extending radially along the tire and folded back from the inside to the outside in the tire width direction around the bead core 5 disposed in each bead portion 3. Furthermore, a sidewall core 6 is disposed on the outer periphery of the bead core 5, and this sidewall core 6 is covered by the main body and folded-back portion of the carcass layer 4. On the other hand, multiple layers (in...) are embedded on the outer periphery of the carcass layer 4 in the tread portion 1. Figure 1 The belt layer 7 consists of two layers. Each belt layer 7 includes multiple reinforcing cords inclined relative to the tire circumference, and the reinforcing cords are arranged in a crisscrossing manner between the layers. In these belt layers 7, the inclination angle of the reinforcing cords relative to the tire circumference is, for example, set in the range of 10° to 40°. Furthermore, at least one layer is provided on the outer periphery of the belt layer 7. Figure 1 The belt reinforcement layer 8 consists of two layers. The belt reinforcement layer 8 includes organic fiber cords oriented in the tire circumferential direction. In the belt reinforcement layer 8, the angle of the organic fiber cords relative to the tire circumferential direction is, for example, set to 0° to 5°.

[0026] This invention relates to tread patterns formed on the surface of the tread portion 1 of a tire as described later; therefore, the basic structure (sectional structure) of the tire is not limited to the conventional structure described above. Furthermore, the following description is based on... Figure 1 While the present invention is applied to pneumatic tires as shown, it can be applied to various tires, including non-pneumatic tires, as long as it has a surface that contacts the road surface (the part of the pneumatic tire that corresponds to the tread surface 1).

[0027] like Figure 2 As shown, four main grooves 11 extending linearly along the tire circumference are provided on the surface of the tread portion 1 of the tire according to the present invention. In the following description, a pair of main grooves disposed on both sides of the tire equator CL are sometimes referred to as inner main grooves 11i, and a pair of main grooves disposed on the outer side of each inner main groove 11i in the tire width direction are referred to as outer main grooves 11o. The depth of each main groove 11 is not particularly limited, and can be set to, for example, 7.0 mm to 16.0 mm. In this way, the four main grooves 11 extend in a linear manner, thus ensuring the rigidity of the width direction end of the circumferential land portion 12 (tread block) described later, thereby ensuring wear resistance and resistance to uneven wear.

[0028] These four main grooves 11 divide the tire into five rows of circumferentially extending ring-shaped sections 12. Specifically, the following ring-shaped sections are defined: a central ring-shaped section 12c divided between a pair of inner main grooves 11i; an intermediate ring-shaped section 12m divided between the inner main grooves 11i and the outer main grooves 11o; and a shoulder ring-shaped section 12s divided on the outer side of the outer main groove 11o in the tire width direction. In other words, the central ring-shaped section 12c is a ring-shaped section disposed on the tire equator CL, the intermediate ring-shaped section 12m is a ring-shaped section disposed on both sides of the central ring-shaped section 12c in the tire width direction, adjacent to each other across the inner main grooves 11i, and the shoulder ring-shaped section 12s is a ring-shaped section disposed on the outermost side of the tire width direction, including the contact patch E.

[0029] The central circumferential rim portion 12c is divided into multiple central tread blocks 14c by a central inclined groove 13c formed at intervals along the tire circumference. The intermediate circumferential rim portion 12m is divided into multiple intermediate tread blocks 14m by an intermediate inclined groove 13m formed at intervals along the tire circumference. The central inclined groove 13c extends obliquely relative to the tire width direction, and its two ends open into a pair of inner main grooves 11i disposed on both sides of the central circumferential rim portion 12c. The intermediate inclined groove 13m extends obliquely relative to the tire width direction, and its two ends open into the inner main grooves 11i and the outer main grooves 11o disposed on both sides of the intermediate circumferential rim portion 12m. It is preferable that the central inclined groove 13c and the intermediate inclined groove 13m are inclined in opposite directions relative to the tire width direction. Furthermore, as shown in the example, it is preferable that the central inclined groove 13c extends in a straight line, while the intermediate inclined groove 13m is curved (in the example, the intermediate inclined groove 13m has a serrated shape, which is composed of a first part that opens inward to the main groove 11i and extends in a straight line at an inclination relative to the tire width direction, a second part that extends in a straight line in the same direction as the first part and opens outward to the main groove 11o, and a third part that connects the first part and the second part and is inclined in the opposite direction to the first part and the second part). In the following description, the central inclined groove 13c and the intermediate inclined groove 13m are sometimes collectively referred to as "inclined grooves". These inclined grooves can improve snow performance. In particular, if the central inclined groove 13c and the intermediate inclined groove 13m are inclined in opposite directions, or if the intermediate inclined groove 13m has the aforementioned curved shape, an edge effect can be exerted in all directions, thereby effectively improving snow performance.

[0030] The tilt angle of each inclined groove relative to the tire width direction can be set to, for example, 10° to 50°. Specifically, the tilt angle θc of the central inclined groove 13c relative to the tire width direction is preferably set to 10° to 50°, and more preferably to 10° to 30°. If the tilt direction of the central inclined groove 13c is represented by a positive (+) value, then the tilt angle θm of the intermediate inclined groove 13m relative to the tire width direction is preferably set to -10° to -50°, and more preferably to -10° to -30°. It should be noted that the tilt angle θc and the tilt angle θm can also be the same angle with the tilt direction reversed (positive and negative), and it is preferable that the absolute value of the tilt angle θm is greater than the absolute value of the tilt angle θc. By tilting the intermediate inclined groove 13m more significantly relative to the tire width direction than the central inclined groove 13c, snow performance can be effectively improved. It should be noted that, as Figure 3 As shown, the tilt angles θc and θm are the angles formed by the straight line connecting the centers of the widths of the opening ends of each tilted groove relative to the tire width direction.

[0031] The depth of each inclined groove is preferably set to 20% to 100% of the depth of the main groove 11, and more preferably to 50% to 100%.

[0032] A shoulder circumferential groove 20 extending along the tire circumference and a first shoulder transverse groove 21 and a second shoulder transverse groove 21 extending along the tire width direction are formed at the shoulder circumferential region 12s. Specifically, the shoulder circumferential groove 20 extends parallel to the outermost main groove 11 (i.e., the outer main groove 11o) located in the tire width direction, and a continuous stripe pattern 23 extending substantially throughout the entire tire circumference is formed between the outer main groove 11o and the shoulder circumferential groove 20. The outer end of the first shoulder transverse groove 21 in the tire width direction crosses the ground contact end E and opens, while the inner end in the tire width direction connects to the shoulder circumferential groove 20. The first shoulder transverse groove 21 connects to the shoulder circumferential groove 20 and is interrupted, thus not reaching the continuous stripe pattern 23 or the outer main groove 11o. The second shoulder transverse groove 22 extends obliquely relative to the tire width direction, intersecting the shoulder circumferential groove 20. Its inner end in the tire width direction connects to the outer main groove 11o, and its outer end terminates within the shoulder circumferential portion 12s. The widths of the shoulder circumferential groove 20 and the second shoulder transverse groove 22 are smaller than the first shoulder transverse groove 21. Therefore, the portions defined by the shoulder circumferential groove 20 and the second shoulder transverse groove 22 are not completely cut off compared to the portions defined by the first shoulder transverse groove 21, thus maintaining tread block rigidity. Snow performance is ensured by utilizing the edge effect generated by the grooves formed in the shoulder circumferential portion 12s. As described above, since the first shoulder transverse groove 21 does not reach the outer main groove 11o to form a continuous stripe pattern 23, tread block rigidity can be ensured. At this time, the width of the shoulder circumferential groove 20 and the second shoulder transverse groove 22 is small. Therefore, even if the circumferential land is divided by these grooves in appearance, the rigidity of the tread block will not be significantly reduced, thus ensuring wear resistance.

[0033] As described above, the widths of the shoulder circumferential groove 20 and the second shoulder transverse groove 22 are smaller than those of the first shoulder transverse groove 21. When the width of the shoulder circumferential groove 20 is set to Gc, the width of the first shoulder transverse groove 21 is set to G1, and the width of the second shoulder transverse groove 22 is set to G2, the width G1 of the first shoulder transverse groove 21 is preferably 1.5 to 3.0 times the width Gc of the shoulder circumferential groove 20 or the width G2 of the second shoulder transverse groove 22, and more preferably 1.8 to 2.7 times. It should be noted that, in the case of the pointed shape described later, the width G1 of the first shoulder transverse groove is set to the width of the main portion excluding the narrow portion.

[0034] In addition, when the groove depth of the circumferential shoulder groove 20 is set to Dc, the groove depth of the first transverse shoulder groove 21 is set to D1, and the groove depth of the second transverse shoulder groove 22 is set to D2, it is preferable that these groove depths satisfy the relationship of Dc ≤ D2 < D1. Thereby, a good balance is obtained between the snow performance added by each groove and the rigidity of the tread blocks reduced due to the formation of each groove, which is beneficial to taking into account both snow performance and wear resistance. The specific groove depth is not particularly limited. The groove depth D1 of the first transverse shoulder groove 21 is preferably 60% to 100% of the groove depth of the main groove 11, and more preferably 70% to 90%. The groove depth Dc of the circumferential shoulder groove 20 and the groove depth D2 of the second transverse shoulder groove 22 are preferably 20% to 70% of the groove depth of the main groove 11, and more preferably 30% to 6%.

[0035] The angle θ1 of the first transverse shoulder groove with respect to the tire width direction is preferably set to 0° ± 15°, and more preferably set to 0° ± 10°. The inclination angle θ2 of the second transverse shoulder groove with respect to the tire width direction is preferably set to 10° to 50°, and more preferably set to 10° to 30° (if the inclination direction of the central inclined groove 13c is represented by a positive (+) value, it is preferably set to -10° to -50°, and more preferably set to -10° to -30°). Regarding these angles θ1, θ2, similar to the inclination angles θc, θm, the measured angle is the angle formed by the straight line connecting the center of the groove width at the open end of the main groove 11, the circumferential shoulder groove 20 and the ground contact end E position, and the center of the groove width at the terminal part with respect to the tire width direction.

[0036] On the central tread block 14c and the intermediate tread block 14m, two or more, preferably two to four sipes 16 extending in the tire width direction are formed at intervals in the tire circumferential direction. Regarding the shoulder land part 12s, in each region surrounded by a pair of adjacent first transverse shoulder grooves 21 and circumferential shoulder grooves 20 in the tire circumferential direction, two or more sipes extending in the tire width direction are formed at intervals in the tire circumferential direction, and preferably two to four sipes 16 are formed. The shape of each sipe 16 is not particularly limited, and preferably has a serrated shape on the tread surface of each tread block and land part as shown in the figure. In addition, the groove width of these sipes 16 can be set to 1.5 mm or less, for example, and the groove depth of these sipes 16 can be set to 50% to 100% of the groove depth of the main groove 11, for example. By appropriately providing the sipes 16 in each tread block and land part like this, the snow performance can be effectively improved.

[0037] Since the tire of the present invention has a tread pattern as described above, it can achieve a high degree of balance between wear resistance and snow performance through the synergistic effect of the effects of each element (ensuring wear resistance through the four straight main grooves 11, improving snow performance through the central inclined groove 13c and the middle inclined groove 13m, maintaining wear resistance and improving snow performance through the circumferential grooves 20, the first shoulder lateral groove 21 and the second shoulder lateral groove 22 provided on the shoulder circumferential portion 12s, and improving snow performance through the sipe pattern 16).

[0038] The width of the first shoulder transverse groove 21 does not need to be constant. For at least a portion, preferably all, of the plurality of first shoulder transverse grooves 21, it is preferable that the inner end in the tire width direction has a tapered shape where the groove width narrows towards the shoulder circumferential groove 20. The tapered shape is preferably a structure where the groove width narrows towards the front end of the groove (V-shaped end) or a shape as shown in the example: having a narrow portion with a relatively narrow groove width at the part connecting to the shoulder circumferential groove 20, and having a connecting portion where the groove width gradually decreases from the main portion of the first shoulder transverse groove 21 towards the narrow portion. In the case of having a narrow portion as shown in the example, the groove width of this narrow portion is preferably 0.5 to 2.0 times the groove width of the shoulder circumferential groove 20. Furthermore, the length of the narrow portion is preferably 0% to 30% of the tire width length from the shoulder circumferential groove 20 to the contact end E. By making the first shoulder transverse groove 21 into a pointed shape, the reduction in rigidity of the shoulder ring portion 12s (especially near the shoulder circumferential groove 20) caused by the formation of the first shoulder transverse groove 21 can be suppressed, thereby helping to ensure wear resistance. The narrow portion of the first shoulder transverse groove 21 can also be raised at the bottom relative to the main portion of the first shoulder transverse groove 21.

[0039] A shallow central groove 15c can be formed at the extension of the central inclined groove 13m in the central tread block 14c. This shallow central groove 15c extends in the same direction as the central inclined groove 13m and terminates within the central tread block 14c, not exceeding the tire equator CL. The shallow central groove 15c is a groove with a shallower depth than the main groove 11 and the inclined grooves (especially the central inclined groove 13m). Its depth is preferably set to 10% to 80% of the depth of the main groove 11, more preferably 30% to 60%. The extension of the central inclined groove 13m refers to the extension line of the groove wall of the central inclined groove 13m. Figure 3 The area between the dashed lines ( Figure 3 The position where the sloping portion overlaps with at least a portion of the open end. By setting the central shallow groove 15c, the intermediate inclined groove 13m, and the central shallow groove 15c in this way, they function as a series of grooves, effectively improving snow performance. On the other hand, the groove depth of the central shallow groove 15c is smaller than that of the main groove 11 and terminates within the central tread block 14c, not exceeding the tire equator CL. Therefore, the reduction in tread block rigidity caused by the setting of the central shallow groove 15c can be suppressed, ensuring wear resistance.

[0040] The shape of the central shallow groove 15c is not particularly limited, but preferably, at least a portion, and preferably all of the plurality of central shallow grooves 15c, have a tapered shape in which the groove width narrows towards the end portion. The tapered shape is preferably a structure where the groove width narrows towards the front end of the groove (V-shaped end) or a shape as shown in the example, having a narrow portion with a narrower groove width at the end portion, and a connecting portion where the groove width gradually decreases from the main portion of the central shallow groove 15c towards the narrow portion. By providing the central shallow groove 15c with such a tapered shape, the reduction in rigidity of the central pattern block 14c caused by the formation of the central shallow groove 15c can be suppressed, thereby helping to ensure wear resistance.

[0041] In the intermediate tread block 14m, a shallow intermediate groove 15m can be formed between adjacent sipes 16 in the tire circumferential direction. This shallow intermediate groove 15m opens toward the outermost main groove 11 (outer main groove 11o) located in the tire width direction, extends in the same direction as the intermediate inclined groove 13m, and terminates within the intermediate tread block 14m without exceeding the center of the intermediate tread block 14m in the tire width direction. The shallow intermediate groove 15m is a groove with a shallower depth than the main groove 11 and the inclined groove (especially the intermediate inclined groove 13m). Its depth is preferably set to 10% to 80% of the depth of the main groove 11, and more preferably 30% to 60%. By setting the shallow intermediate groove 15m in this way, the edge effect brought by the shallow intermediate groove 15m is added, which can further improve snow performance. On the other hand, the groove depth of the shallow groove 15m is smaller than that of the main groove 11 and terminates within the center of the shallow groove 14m. Therefore, it can suppress the reduction of the rigidity of the pattern block caused by the setting of the shallow groove 15m and ensure wear resistance.

[0042] It is preferable that the sipes 16 formed on each tread block (central tread block 14c, intermediate tread block 14m) and the circumferential portion (shoulder circumferential portion 12s) extend in the same direction as the grooves (central inclined groove 13c, intermediate inclined groove 13m, first shoulder transverse groove 21) dividing each tread block or circumferential portion. Specifically, it is preferable that the intermediate sipe 16m formed on the intermediate tread block 14m extends in the same direction as the intermediate inclined groove 13m, the central sipe 16c formed on the central tread block 14c extends in the same direction as the central inclined groove 13c, and the shoulder sipe 16s formed on the shoulder circumferential portion 12s extends in the same direction as the first shoulder transverse groove 21. In this way, the rigidity of the tread blocks can be ensured by extending the grooves extending in the width direction in each tread block or circumferential portion substantially parallel to the sipes 16, thereby helping to maintain wear resistance. If the inclination direction of these grooves is opposite to that of the sipe tread pattern 16, it will be difficult to maintain the rigidity of the tread block well. It should be noted that the angle difference between the grooves (central inclined groove 13c, intermediate inclined groove 13m, first shoulder transverse groove 21) extending along the width direction in each tread block and the sipe tread pattern (central sipe tread pattern 16c, intermediate sipe tread pattern 16m, shoulder sipe tread pattern 16s) is preferably 0° to 10°, and more preferably 0° to 5°.

[0043] In this invention, the following specifications can be provided: a bottom raised portion A is provided at the bottom of each of the central inclined groove 13c, the intermediate inclined groove 13m, and the first shoulder transverse groove 21. The bottom raised portion A refers to a part of each groove where the bottom is more raised than other parts. The bottom raised portion A is preferably located where each groove communicates with a groove extending circumferentially along the tire (main groove 11 or shoulder circumferential groove 20). When the bottom raised portion A is located in communication with the main groove 11, its bottom raised amount is preferably 20% to 80% of the depth of the main groove 11, more preferably 40% to 60%. When the bottom raised portion A is located in communication with the shoulder circumferential groove 20, the groove depth of the bottom raised portion A is preferably less than or equal to the depth of the shoulder circumferential groove 20; specifically, its bottom raised amount is preferably 10% to 50% of the depth of the main groove 11, more preferably 20% to 30%. It should be noted that the bottom elevation refers to the height of the bulge from the bottom of the groove where the bottom elevation portion A is formed to the top surface of the bottom elevation portion A. By setting the bottom elevation portion A in this way, the rigidity of the tread block can be maintained without reducing the groove area, which is beneficial for balancing snow performance and abrasion resistance. If the bottom elevation is less than the above range, there is no substantial difference from the case without the bottom elevation portion A, and the effects brought by the bottom elevation portion A cannot be fully anticipated. If the bottom elevation exceeds the above range, the groove depth cannot be sufficiently ensured in the area where the bottom elevation portion A is provided, thus making it difficult to fully ensure snow performance.

[0044] The present invention will be further described below through embodiments, but the scope of the present invention is not limited to these embodiments.

[0045] Example

[0046] Eight types of pneumatic tires, including Conventional Example 1, Comparative Example 1, and Examples 1-6, were manufactured with a tire size of 265 / 70R17 115H, possessing the following characteristics: Figure 1 The basic structure (sectional structure) shown is defined as follows, with the following parameters set as in Table 1: the inclination angle θc of the central inclined groove, the inclination angle θm of the central inclined groove, the presence or absence of the shoulder circumferential groove, the presence or absence of the first shoulder transverse groove, the presence or absence of the second shoulder transverse groove, the number of sipes in each circumferential section (central tread block, intermediate tread block, shoulder circumferential section), the groove depth of each groove (shoulder circumferential groove, first shoulder transverse groove, second shoulder transverse groove) formed in the shoulder circumferential section, the shape of the first shoulder transverse groove, the presence or absence of the central shallow groove, the presence or absence of the intermediate shallow groove, the presence or absence of the bottom raised portion in each inclined groove (central inclined groove, intermediate inclined groove), and the angle difference between the groove (central inclined groove, intermediate inclined groove, first shoulder transverse groove) and the sipe pattern in each tread block or circumferential section.

[0047] In all examples, four straight main grooves are commonly provided. The angle of the first shoulder transverse groove is 0° relative to the tire width direction, and the angle of the second shoulder transverse groove is the same as the angle θm of the middle inclined groove. The width of the shoulder circumferential groove is 2 mm, the width of the first shoulder transverse groove is 5 mm, and the width of the second shoulder transverse groove is 2 mm; these are common. When the first shoulder transverse groove has a pointed shape, the width of its narrow section is set to 2 mm. It should be noted that the previous example 1 did not have a shoulder circumferential groove and a second shoulder transverse groove, so the shoulder circumferential portion was divided into multiple tread blocks by the first shoulder transverse groove, and had a shape that did not contain... Figure 2 The structure shown is a "continuous striped pattern".

[0048] In Table 1, for the columns "Angle θc of the central inclined groove" and "Angle θm of the intermediate inclined groove," a positive (+) value represents the angle θc of the central inclined groove (a negative (-) value means inclined in the opposite direction to the central inclined groove). For the column "Number of sipes in the shoulder ring portion," if the shoulder ring portion is divided into multiple tread blocks (as in Conventional Example 1), the number of sipes in each tread block is recorded. For Examples 1-6, the number of sipes included in the area enclosed by a pair of adjacent first shoulder transverse grooves and shoulder circumferential grooves in the tire circumferential direction is recorded. Comparative Example 1 does not have first shoulder transverse grooves, therefore it does not include the area divided as in Examples 1-6. Except for the absence of first shoulder transverse grooves, the sipe configuration is the same as in Examples 1-6, therefore the same values ​​as in Examples 1-6 are recorded in parentheses for reference. For the column "Groove Depth," the percentage (%) relative to the main groove depth is shown. Regarding the "Shape of the first shoulder transverse groove" field, if the width of the shallow groove is constant, it is indicated as "Constant Width"; if it is a pointed shape, it is indicated as "Pointed". Regarding the "Presence or Absence of Bottom Elevation" field, an example showing "Yes" means that... Figure 2 As shown, each slot is equipped with a raised bottom section and a narrow section.

[0049] For these pneumatic tires, the snow performance and wear resistance were evaluated using the following evaluation method, and the results are shown in Table 1.

[0050] Snow performance

[0051] Each test tire was mounted on a 17×8J rimmed wheel. The front tire pressure was set to 230 kPa, and the rear tire pressure was also set to 230 kPa. The tires were then installed on the test vehicle (a four-wheel-drive SUV). The test driver conducted a sensory evaluation of the driving stability on a test track composed of snow-covered surfaces. The evaluation results were expressed as an index with the value of Example 1 set to 100. A higher index value indicates better snow performance.

[0052] abrasion resistance

[0053] Each test tire was assembled onto a 17×8J rimmed wheel. The front tire pressure was set to 230 kPa, and the rear tire pressure was also set to 230 kPa. The tires were then mounted on a test vehicle (a four-wheel-drive SUV). A test drive was conducted on a test track, and the distance traveled before complete wear was measured [unit: km]. The evaluation results are expressed as an index with the value of Example 1 set to 100. A higher index value indicates a longer distance traveled before complete wear, signifying superior wear resistance.

[0054] [Table 1]

[0055]

[0056] As can be seen from Table 1, the pneumatic tires of Examples 1 to 6, compared with the conventional Example 1, improved snow performance and wear resistance, and balanced these properties. On the other hand, in Comparative Example 1, although there were circumferential grooves and second shoulder lateral grooves in the shoulder ring area, there were no first shoulder lateral grooves, so the snow performance was worse.

[0057] Explanation of reference numerals in the attached figures

[0058] 1: Fetal face

[0059] 2: Side wall portion

[0060] 3: Bead area

[0061] 4: Fetal body layer

[0062] 5: Tire bead core

[0063] 6: Tire sidewall core

[0064] 7: Belt layer

[0065] 8: Belt reinforcement layer

[0066] 11: Main slot

[0067] 11i: Inner main groove

[0068] 11o: Outer main channel

[0069] 12: Coastal Area

[0070] 12c: Central Coastal Area

[0071] 12m: Middle circumferential section

[0072] 12s: Tire shoulder perimeter

[0073] 13c: Central inclined groove

[0074] 13m: Middle inclined trough

[0075] 14c: Central patterned block

[0076] 14m: Central patterned block

[0077] 15: Shallow trench

[0078] 16: Groove pattern

[0079] 16c: Central groove pattern

[0080] 16m: Center groove pattern

[0081] 16s: Shoulder sipes

[0082] 20: Shoulder circumferential grooves

[0083] 21: First shoulder transverse groove

[0084] 22: Second tire shoulder transverse groove

[0085] 23: Continuous striped pattern

[0086] A: Bottom raised section

[0087] B: Narrow section

[0088] CL: Tire Equator

[0089] E: Grounding terminal

Claims

1. A tire, wherein the tire has a tread portion extending in a circumferential direction of the tire and having an annular shape, and is characterized in that the tread portion has four main grooves extending linearly in the circumferential direction of the tire and five rows of land portions divided by the four main grooves. The five rows of land portions include a central land portion disposed on the tire equator, intermediate land portions disposed on both sides of the central land portion in the tire width direction, and shoulder land portions located on the outermost sides in the tire width direction. The central land portion is divided into a plurality of central tread blocks by central inclined grooves formed at intervals in the circumferential direction of the tire, and the intermediate land portions are divided into a plurality of intermediate tread blocks by intermediate inclined grooves formed at intervals in the circumferential direction of the tire. In the shoulder land portion, there are formed shoulder circumferential grooves extending in the circumferential direction of the tire and parallel to the main groove disposed on the outermost side in the tire width direction, a first shoulder transverse groove and a second shoulder transverse groove extending in the tire width direction. The outer end in the tire width direction of the first shoulder transverse groove crosses the grounding end and opens, and its inner end in the tire width direction is connected to the shoulder circumferential groove and interrupted so as not to reach the main groove. The groove width of the second shoulder transverse groove is smaller than that of the first shoulder transverse groove. The second shoulder transverse groove extends obliquely with respect to the tire width direction. Its inner end in the tire width direction is connected to the main groove, and its outer end in the tire width direction intersects the shoulder circumferential groove and terminates within the shoulder land portion. In the central tread blocks and the intermediate tread blocks, there are formed two or more sipes extending in the tire width direction at intervals in the circumferential direction of the tire. In each region surrounded by the shoulder circumferential groove in the shoulder land portion and a pair of the first shoulder transverse grooves adjacent in the circumferential direction, there are formed two or more sipes extending in the tire width direction at intervals in the circumferential direction.

2. The tire according to claim 1, characterized in that, The inner end in the tire width direction of the first shoulder transverse groove has a tapered shape with the groove width narrowing toward the shoulder circumferential groove.

3. The tire according to claim 1 or 2, characterized in that, The groove depth Dc of the shoulder circumferential 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.

4. The tire according to any one of claims 1 to 3, characterized in that, At the extended position of the intermediate inclined groove in the central tread block, there is a central shallow groove. The central shallow groove extends in the same direction as the intermediate inclined groove and terminates within the central tread block without exceeding the tire equator.

5. The tire according to any one of claims 1 to 4, characterized in that, In the intermediate tread block, there is an intermediate shallow groove between the sipes adjacent in the circumferential direction. The intermediate shallow groove opens to the main groove disposed on the outermost side in the tire width direction, extends in the same direction as the intermediate inclined groove, and terminates within the intermediate tread block without exceeding the center in the tire width direction of the intermediate tread block.

6. The tire according to any one of claims 1 to 5, characterized in that, At the bottom of each of the central inclined groove and the intermediate inclined groove, there is provided a bottom elevation portion.

7. The tire according to any one of claims 1 to 6, characterized in that, Among the sipes, the intermediate sipes formed in the intermediate tread block extend in the same direction as the intermediate inclined groove, the central sipes formed in the central tread block extend in the same direction as the central inclined groove, and the shoulder sipes formed in the shoulder land portion extend in the same direction as the first shoulder transverse groove.

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