JP2021091362A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire that can make both a drainage performance and a dry performance compatible at a high level.SOLUTION: A pneumatic tire comprises: a plurality of inclined grooves 1 which is formed at intervals in a tire circumferential direction and obliquely extended toward one side in a tire circumferential direction, from a center part in a tire width direction of a tread surface toward outside in the tire width direction; and inclined land parts 2 partitioned by the inclined grooves 1. The inclined land part 2 is partitioned into a center block 3, a quarter block 4 and a shoulder block 5, which are arranged from a center part in the tire width direction toward outside in the tire width direction in this order. In an area corresponding to 30-70% of a grounding half-width, ranging from a center line of the tread surface to outside in the tire width direction, a groove depth of the inclined groove 1 gradually increases toward inside in the tire width direction. A length L3 in the tire circumferential direction of the center block 3 is larger than a width W3 as a length in the tire width direction of the center block 3 thereof.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to pneumatic tires.

Patent Documents 1 and 2 describe, respectively, an inclined groove extending from the central portion of the tread surface in the tire width direction toward the outside in the tire width direction toward one side in the tire circumferential direction, and a plurality of inclined grooves defined by the inclined groove and the like. Pneumatic tires with blocks are listed. By providing such an inclined groove, the drainage efficiency to the outside in the tire width direction is enhanced.

The tire described in Patent Document 2 aims to achieve both drainage performance and dry performance (steering stability performance and braking performance on a dry road surface) by reducing the groove depth of the inclined groove toward the ground contact end. There is. However, since the groove depth is large in the central portion of the tread surface in the tire width direction, the rigidity of the block tends to decrease, and the dry performance may not be sufficiently exhibited. This tendency is particularly remarkable when the block pattern is formed and a large number of sipes are formed.

JP-A-2017-1617 Japanese Unexamined Patent Publication No. 2016-578

An object of the present disclosure is to provide a pneumatic tire that can achieve both drainage performance and dry performance at a high level.

A plurality of pneumatic tires of the present disclosure are formed at intervals in the tire circumferential direction, and an inclined groove extending from the central portion of the tread surface in the tire width direction toward the outside in the tire width direction toward one side in the tire circumferential direction. The inclined land portion is provided with an inclined land portion partitioned by the inclined groove, and the inclined land portion is divided into a center block, a quarter block and a shoulder block, and is arranged in this order from the central portion in the tire width direction to the outside in the tire width direction. In the region of 30 to 70% of the ground contact half width from the center line of the tread surface to the outside in the tire width direction, the groove depth of the inclined groove increases toward the inside in the tire width direction, and the center block The length of the center block in the tire circumferential direction is larger than the length of the center block in the tire width direction.

Plane development view showing an example of the tread surface of the pneumatic tire of the present disclosure. Tire meridian semi-cross section of pneumatic tires Top view showing a part of the tread pattern of FIG. 1 extracted. Enlarged view showing part X of FIG. Enlarged view showing the Y part of FIG.

Hereinafter, one embodiment of the present disclosure will be described with reference to the drawings.

FIG. 1 is a plan view of a tread surface Tr included in the pneumatic tire PT of the present embodiment (hereinafter, also simply referred to as “tire PT”). The vertical direction in FIG. 1 corresponds to the tire circumferential direction, and the horizontal direction in FIG. 1 corresponds to the tire width direction. As shown in FIG. 1, the tread pattern formed on the tread surface Tr is a block pattern.

The pneumatic tire PT of the present embodiment is a rotation direction designation type tire in which the rotation direction is designated. In the drawing, the direction of rotation is indicated by an arrow RD. The rotation direction is specified, for example, by attaching a display (for example, an arrow) indicating the rotation direction to the outer surface of the sidewall portion of the tire PT.

The pneumatic tire PT includes a plurality of inclined grooves 1 formed at intervals in the tire circumferential direction, and an inclined land portion 2 partitioned by the inclined grooves 1. The inclined groove 1 extends from the central portion of the tread surface Tr in the tire width direction toward the outside in the tire width direction toward the CD1 on one side in the tire circumferential direction. The CD1 on one side in the tire circumferential direction corresponds to the rear side in the rotation direction RD. The inclined land portion 2 is divided into a center block 3, a quarter block 4, and a shoulder block 5, and is arranged in this order from the central portion in the tire width direction to the outside in the tire width direction. The center block 3, the quarter block 4, and the shoulder block 5 each form a quadrangle (quadrilateral) in a plan view, but the present invention is not limited to this.

Of the blocks constituting the inclined land portion 2, the center block 3 is located on the innermost side in the tire width direction, and the shoulder block 5 is located on the outermost side in the tire width direction. The inclined land portion 2 is divided into three blocks by a pair of connecting grooves 6 and 7. The connection groove 6 partitions the center block 3 and the quarter block 4, and the connection groove 7 partitions the quarter block 4 and the shoulder block 5. The connecting grooves 6 and 7 extend in the tire circumferential direction to connect the inclined grooves 1 to each other. The connecting grooves 6 and 7 are inclined outward in the tire width direction toward the CD2 on the other side in the tire circumferential direction, respectively. The CD2 on the other side in the tire circumferential direction corresponds to the front side in the rotation direction RD.

The pneumatic tire PT of the present embodiment includes a center main groove 8 continuously extending in the tire circumferential direction. As a result, the drainage efficiency is improved, which is convenient for ensuring the drainage performance. The center main groove 8 is arranged at the center of the tread surface Tr in the tire width direction. In the present embodiment, the center main groove 8 passes through the center line CL (tire equator) of the tread surface Tr. The inclined groove 1 extends outward from the center main groove 8 in the tire width direction and reaches the ground contact end TE. The shape of the center main groove 8 is not limited to the straight shape as in the present embodiment, and may be a zigzag shape. Further, the center main groove 8 may not be provided.

The center line CL (and the center main groove 8) divides the tread surface Tr in the tire width direction to form a pair of tread half regions. The tread half region on one side (right side in FIG. 1) includes a center region 3a in which a plurality of center blocks 3 are arranged in the tire circumferential direction, a quarter region 4a in which a plurality of quarter blocks 4 are arranged in the tire circumferential direction, and a tread half region. , A plurality of shoulder blocks 5 have shoulder regions 5a arranged in the tire circumferential direction, and are provided in this order from the central portion in the tire width direction toward the outer side in the tire width direction.

The ground contact end TE is the outermost position in the tire width direction of the ground contact surface when the tire PT is rim-assembled on the regular rim, the tire PT is placed vertically on a flat road surface with the regular internal pressure charged, and a regular load is applied. Is. The ground contact width W is the width of the ground contact surface, and is the distance in the tire width direction between the pair of ground contact ends TE. Half of the ground contact width W is the ground contact half width HW.

A regular rim is a rim defined for each tire in the standard system including the standard on which the tire is based. For example, JATMA is a standard rim, and TRA and ETRTO are "Measuring Rim". The regular internal pressure is the air pressure defined for each tire in the standard system including the standard on which the tire is based. For JATMA, the maximum air pressure, and for TRA, the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". If it is the maximum value described in "ETRTO", it is "INFLATION PRESSURE". If the tire is for a passenger car, the value is 180 kPa, and if the tire is described as Extra Load or Reinforced, the value is 220 kPa. The normal load is the load defined for each tire in the standard system including the standard on which the tire is based. For JATMA, the maximum load capacity, for TRA, the maximum value listed in the above table. If it is ETRTO, it is "LOAD CAPACITY", but if the tires are for passenger cars, it is 88% of the corresponding load of the internal pressure.

FIG. 2 is a half cross-sectional view of the tire meridian showing the tire PT cut in a plane including the tire rotation axis. The right side of FIG. 2 corresponds to the outside in the tire width direction, and the left side corresponds to the inside in the tire width direction. The connecting grooves 6 and 7 are omitted, and the inclined land portion 2 is shown schematically. In this tire PT, the groove depth D1 of the inclined groove 1 increases toward the inside in the tire width direction in the region Ar of 30 to 70% of the ground contact half width HW from the center line CL to the outside in the tire width direction. The groove depth D1 of the inclined groove 1 is the inclined groove 1 from the surface of the inclined land portion 2 in the direction perpendicular to the tread surface Tr with respect to the tire grounded under the above conditions when determining the ground contact width W and the like. It is calculated as the distance to the groove bottom 1B.

In the region Ar, the groove bottom 1B is inclined with respect to the tread surface Tr so that the groove depth D1 gradually increases inward in the tire width direction. The portion where the groove depth D1 changes may protrude to the outside of the region Ar. The groove depth D1a at 30% of the ground contact half width HW from the center line CL to the outside in the tire width direction is also larger than the groove depth D1b at 70% of the ground contact half width HW. Therefore, the groove depth D1a exceeds 100% of the groove depth D1b, and is, for example, 110 to 160% of the groove depth D1b.

Since the groove depth D1 is relatively small in the shoulder region 5a, the rigidity of the shoulder block 5 having a large contribution to the dry performance is secured. Further, since the groove depth D1 is relatively large in the center region 3a, the drainage performance is improved in combination with the provision of the inclined groove 1. As a result, the occurrence of the hydroplaning phenomenon on a wet road surface is suppressed. On the other hand, in the center region 3a, since the groove depth D1 is relatively large, the rigidity of the center block 3 tends to decrease, and the dry performance may not be sufficiently exhibited. Therefore, in this tire PT, a vertically long shape as described later is adopted for the center block 3, thereby suppressing deterioration of dry performance.

As shown in FIG. 3, in this tire PT, the length L3 of the center block 3 in the tire circumferential direction is larger than the length of the center block 3 in the tire width direction (that is, the width W3). As a result, the decrease in rigidity of the center block 3 in the tire circumferential direction can be suppressed, and the deterioration of dry performance can be suppressed. The ratio L3 / W3 of the length L3 to the width W3 is preferably 1.5 or more. As a result, the rigidity of the center block 3 in the tire circumferential direction can be increased, and the dry performance can be effectively improved. The length L3 and the width W3 are obtained based on the shape of the top surface of the center block 3, respectively. The same applies to the lengths L4 and L5 and the widths W4 and W5.

The length L5 of the shoulder block 5 in the tire circumferential direction is preferably the same as or smaller than the length of the shoulder block 5 in the tire width direction (that is, the width W5). In this embodiment, the length L5 is smaller than the width W5. As a result, the rigidity of the shoulder block 5 in the tire width direction can be increased, and the dry performance (particularly, the steering stability performance on a dry road surface) can be effectively improved. In addition, the increase in the edge component due to the shoulder sipe 5s contributes to the improvement of snow traction performance (driving performance on snow). The ratio L5 / W5 of the length L5 to the width W5 is, for example, 0.4 to 1.0 (more specifically, 0.4 or more and less than 1.0). Both the length L5 and the width W5 are obtained in the ground plane.

The length L4 of the quarter block 4 in the tire circumferential direction is preferably the same as or larger than the length of the quarter block 4 in the tire width direction (that is, the width W4). In this embodiment, the length L4 is larger than the width W4. The ratio L4 / W4 of the length L4 to the width W4 is, for example, 1.0 to 1.5. As a result, the decrease in rigidity of the quarter block 4 in the tire circumferential direction can be suppressed, which can contribute to dry performance. Further, by setting the ratio L4 / W4 to 1.5 or less, the inclination angle θ4 which is advantageous for ensuring the drainage performance is adopted, and the steering stability is also advantageous.

The inclination angle θ3 of the inclined groove 1 with respect to the tire width direction in the region where the center block 3 is provided (that is, the center region 3a) is, for example, 40 to 60 degrees. This is convenient in achieving both drainage performance and snow traction performance. The inclination angle θ3 can be obtained as an angle of the block edge extending outward in the tire width direction from the tip of the CD2 on the other side in the tire circumferential direction, which is the stepping side of the center block 3, with respect to the tire width direction. The inclination angle θ3 is preferably larger than the inclination angle θ4 and the inclination angle θ5, which will be described later.

The inclination angle θ4 of the inclined groove 1 with respect to the tire width direction in the region where the quarter block 4 is provided (that is, the quarter region 4a) is, for example, 30 to 50 degrees. This is convenient in achieving both drainage performance and snow traction performance. The inclination angle θ4 can be obtained as an angle with respect to the tire width direction of the block edge extending outward in the tire width direction from the tip of the CD2 on the other side in the tire circumferential direction, which is the stepping side of the quarter block 4. The inclination angle θ4 is preferably larger than the inclination angle θ5 described later.

The inclination angle θ5 of the inclined groove 1 with respect to the tire width direction in the region where the shoulder block 5 is provided (that is, the shoulder region 5a) is, for example, 0 to 20 degrees. This is convenient for achieving both dry braking performance and snow traction performance. The inclination angle θ5 can be obtained as an angle with respect to the tire width direction of the block edge extending outward in the tire width direction from the tip of the CD2 on the other side in the tire circumferential direction, which is the stepping side of the shoulder block 5.

FIG. 4A is an enlarged view showing a portion X in FIG. 3, and the sipe is not shown. The extension line EL3 of the block edge of the CD2 on the other side of the tire circumferential direction of the center block 3 and the extension line EL4 of the block edge of the CD2 on the other side of the tire circumferential direction of the quarter block 4 are shown by broken lines. The extension lines EL3 and EL4 of the block edge are displaced in the tire circumferential direction between the center block 3 and the quarter block 4 adjacent to each other with the connecting groove 6 interposed therebetween, and are in a positional relationship that does not intersect with each other. The extension line EL4 is located on the other side CD2 in the tire circumferential direction with respect to the extension line EL3, but these may be opposite.

FIG. 4B is an enlarged view showing the Y portion of FIG. 3, and the illustration of the sipe is omitted. The extension line EL4 of the block edge of the CD2 on the other side of the tire circumferential direction of the quarter block 4 and the extension line EL5 of the block edge of the CD2 on the other side of the tire circumferential direction of the shoulder block 5 are shown by broken lines. The extension lines EL4 and EL5 of the block edge are displaced in the tire circumferential direction between the quarter block 4 and the shoulder block 5 adjacent to each other with the connecting groove 7 in between, and are in a positional relationship that does not intersect with each other. The extension line EL5 is located on the other side CD2 in the tire circumferential direction with respect to the extension line EL4, but these may be opposite.

As in the present embodiment, the extension line of the block edge is displaced in the tire circumferential direction between the center block 3 and the quarter block 4 and / or between the quarter block 4 and the shoulder block 5. Is preferable. As a result, the edge component can be increased to improve the running performance on snow. Further, the block edge of the CD2 on the other side in the tire circumferential direction, which is the front side in the rotation direction RD, is misaligned, which contributes to driving performance and steering stability performance on snow.

In the present embodiment, as shown in FIG. 4A, the quarter block 4 has a protruding portion 40 protruding from the extension line EL3 on the other side CD2 in the tire circumferential direction. As a result, the protruding portion 40 protruding toward the stepping side exerts an edge effect, and the snow traction performance can be improved. Even in such a configuration, the drainage performance is ensured by the above-mentioned change in the groove depth D1. The protruding portion 40 is formed in a V shape that tapers toward the inclined groove 1. The protrusion amount P40 of the protrusion 40 is preferably 0.5 mm or more, and more preferably 1.0 mm or more. The protrusion amount P40 is obtained as the distance between the inner end in the tire width direction of the block edge of the CD2 on the other side in the tire circumferential direction of the quarter block 4 and the point where the extension line EL3 intersects the quarter block 4.

In the present embodiment, as shown in FIG. 4B, the shoulder block 5 has a protruding portion 50 projecting toward the CD2 on the other side in the tire circumferential direction with respect to the extension line EL4. As a result, the protruding portion 50 protruding toward the stepping side exerts an edge effect, and the snow traction performance can be improved. Even in such a configuration, the drainage performance is ensured by the above-mentioned change in the groove depth D1. The protruding portion 50 is formed in a V shape that tapers toward the inclined groove 1. The protrusion amount P50 of the protrusion 50 is preferably 0.5 mm or more, and more preferably 1.0 mm or more. The protrusion amount P50 is obtained as the distance between the inner end in the tire width direction of the block edge of the CD2 on the other side of the shoulder block 5 in the tire circumferential direction and the point where the extension line EL4 intersects the shoulder block 5.

As shown in FIG. 3, a plurality of center sipes 3s are formed in the center block 3. Both ends of the center sipe 3s are connected to the groove, but one end or both ends may be terminated within the block. The center sipe 3s extends so as to intersect the tire width direction, and extends so as to intersect the block edge of the center block 3 in contact with the inclined groove 1. The center sipe 3s includes a linear sipe 3s1 extending linearly and a bending sipe 3s2 having a bent portion. The straight sipe 3s1 is arranged at the end of the center block 3 in the tire circumferential direction, and the bent sipe 3s2 is arranged at the center of the center block 3 in the tire circumferential direction.

A plurality of quarter sipes 4s are formed in the quarter block 4. Both ends of the quarter sipe 4s are connected to the groove, but the present invention is not limited to this. The quarter sipe 4s extends so as to intersect the tire width direction and intersects the block edge of the quarter block 4 in contact with the inclined groove 1. The quarter sipe 4s includes a linear sipe 4s1 extending linearly and a bending sipe 4s2 having a bent portion. The straight sipe 4s1 is arranged at the end of the quarter block 4 in the tire circumferential direction, and the bent sipe 4s2 is arranged at the center of the quarter block 4 in the tire circumferential direction. The angle θ4s at which the quartersipe 4s intersects the tire width direction is larger than the angle θ3s at which the centersipe 3s intersects the tire width direction.

A plurality of shoulder sipes 5s are formed on the shoulder block 5. One end of the shoulder sipe 5s is connected to the groove, and the other end reaches the grounding end TE, but is not limited to this. The shoulder sipe 5s includes a linear sipe 5s1 extending linearly and a bending sipe 5s2 having a bent portion. The bent portion of the bent sipe 5s2 has a wavy shape, but the present invention is not limited to this, and the same applies to the bent sipe 3s2 and the bent sipe 4s2. The angle θ5s at which the shoulder sipe 5s intersects the tire width direction is smaller than the angle θ4s at which the quarter sipe 4s intersects the tire width direction. The sipes 3s, 4s, and 5s are formed by notches having a width of less than 1.6 mm.

In the present embodiment, a pair of inclined grooves 1 and 11 extending from the central portion of the tread surface Tr in the tire width direction toward both outer sides in the tire width direction toward the CD1 on one side in the tire circumferential direction are provided. The inclined grooves 1 and 11 and the center main groove 8 are the main grooves of the tread surface Tr. In the tread half region on the other side (left side in FIG. 1), a plurality of inclined grooves 11 formed at intervals in the tire circumferential direction and an inclined land portion 12 partitioned by the inclined grooves 11 are provided. .. The inclined groove 11 extends from the central portion of the tread surface Tr in the tire width direction toward the outside in the tire width direction toward the CD1 on one side in the tire circumferential direction. The inclined land portion 12 is divided into a center block 13, a quarter block 14, and a shoulder block 15 by a connecting groove 16 and a connecting groove 17, and is arranged in this order from the central portion in the tire width direction toward the outside in the tire width direction. ..

Since the pattern of the tread half region on the other side has a shape in which the pattern of the tread half region on the one side is inverted with respect to the center line CL, duplicate description will be omitted. The matters described for the tread half region on one side also apply to the tread half region on the other side. Therefore, the shape in which the groove depth D1 changes in the above-mentioned region Ar and the vertically elongated shape of the center block 3 are established in the tread half region on the other side as well as the tread half region on one side. These shapes may be formed in at least one tread half region, but it is preferably formed in both tread half regions as in the present embodiment.

In the present embodiment, the pattern of the tread half region on the other side is shifted (misaligned) in the tire circumferential direction with respect to the pattern of the tread half region on one side. As a result, it is possible to suppress the occurrence of uneven wear such as heel-and-toe wear while achieving both drainage performance and dry performance. The shift length SL (see FIG. 3), which is the amount of this misalignment, is, for example, 10 to 50% of the pitch length P (see FIG. 1). However, the present invention is not limited to this, and the tire circumferential positions of the patterns in the tread half regions on both sides may coincide with each other.

The pneumatic tire PT of the present embodiment has the tread surface Tr of the block pattern as described above and has a large number of sipes 3s, 4s, and 5s formed, and is excellent in drainage performance and dry performance, and also has snow traction. Due to its excellent performance, it is useful as a snow tire or an all-season tire. In the case of a snow tire, the rubber hardness of the tread rubber forming the tread surface Tr is, for example, 55 to 73 °. This rubber hardness is the hardness measured at 25 ° C. according to the durometer hardness test (type A) of JIS K6253.

As described above, a plurality of pneumatic tire PTs of the present embodiment are formed at intervals in the tire circumferential direction, and the tread surface Tr is CD1 on one side in the tire circumferential direction from the central portion in the tire width direction toward the outside in the tire width direction. It is provided with an inclined groove 1 extending so as to be inclined to, and an inclined land portion 2 partitioned by the inclined groove 1. The inclined land portion 2 is divided into a center block 3, a quarter block 4, and a shoulder block 5, and is arranged in this order from the central portion in the tire width direction to the outside in the tire width direction. The groove depth D1 of the inclined groove 1 increases toward the inside in the tire width direction in the region Ar of 30 to 70% of the ground contact half width HW from the center line CL of the tread surface Tr to the outside in the tire width direction. The length L3 of the center block 3 in the tire circumferential direction is larger than the width W3 as the length of the center block 3 in the tire width direction.

According to this tire PT, the provision of the inclined groove 1 enhances the drainage efficiency to the outside in the tire width direction. Further, since the groove depth D1 of the inclined groove 1 increases inward in the tire width direction, the drainage performance can be improved while ensuring the rigidity of the shoulder block 5 which greatly contributes to the dry performance. Further, since the length L3 is larger than the width W3, the decrease in the rigidity of the center block 3 in the tire circumferential direction is suppressed, and the deterioration of the dry performance is suppressed. As a result, both drainage performance and dry performance can be achieved at a high level.

In the pneumatic tire PT of the present embodiment, the ratio L3 / W3 of the length L3 of the center block 3 in the tire circumferential direction to the width W3 as the length of the center block 3 in the tire width direction is 1.5 or more. As a result, the rigidity of the center block 3 in the tire circumferential direction can be increased, and the dry performance can be effectively improved.

In the pneumatic tire PT of the present embodiment, the extension line of the block edge is displaced in the tire circumferential direction between the center block 3 and the quarter block 4 and / or between the quarter block 4 and the shoulder block 5. doing. As a result, the edge component can be increased to improve the running performance on snow.

In the pneumatic tire PT of the present embodiment, the quarter block 4 has a protruding portion 40 protruding from the tire circumferential direction other side CD2 with respect to the extension line EL3 of the block edge of the tire circumferential direction other side CD2 of the center block 3. The protruding portion 40 exerts an edge effect, so that the snow traction performance is improved.

In the pneumatic tire PT of the present embodiment, the shoulder block 5 has a protruding portion 50 protruding from the tire circumferential direction other side CD2 with respect to the extension line EL4 of the block edge of the tire circumferential direction other side CD2 of the quarter block 4. The protruding portion 50 exerts an edge effect, so that the snow traction performance is improved.

In the pneumatic tire PT of the present embodiment, the length L5 of the shoulder block 5 in the tire circumferential direction is smaller than the width W5 of the shoulder block 5 as the length in the tire width direction. As a result, the rigidity of the shoulder block 5 in the tire width direction can be increased, and the dry performance (particularly, the steering stability performance on a dry road surface) can be effectively improved. In addition, the increase in the edge component due to the shoulder sipe 5s contributes to the improvement of snow traction performance.

The pneumatic tire PT can be configured in the same manner as a normal pneumatic tire except that the tread surface Tr is configured as described above, and any conventionally known material, shape, structure, manufacturing method, etc. can be adopted. As schematically shown in FIG. 2, the pneumatic tire PT includes a pair of bead portions 91 and a pair of sidewall portions 92 extending outward in the tire radial direction (upper side in FIG. 2) from each of the bead portions 91. Each of the pair of sidewall portions 92 is provided with a tread portion 93 connected to the outer end in the tire radial direction, and the outer peripheral surface of the tread portion 93 is formed by a tread surface Tr.

Although the embodiments of the present disclosure have been described with reference to the drawings, it should be considered that the specific configuration is not limited to this embodiment. The scope of the present disclosure is shown not only by the description of the above-described embodiment but also by the scope of claims, and further includes all modifications within the meaning and scope equivalent to the scope of claims.

The pneumatic tire of the present disclosure is not limited to the above-described embodiment, and is not limited to the above-mentioned action and effect. The pneumatic tire of the present disclosure can be improved and changed in various ways without departing from the gist thereof.

In order to specifically show the configuration and effect of the pneumatic tire of the present disclosure, the following evaluation tests (1) to (3) have been carried out and will be described. In these evaluation tests, a test tire (tire size: 205 / 55R16 91H) having a tread pattern as shown in Fig. 1 was used, and this was attached to a standard rim of the size specified by JATTA to apply the air pressure specified by the vehicle. Filled. Except for the configurations shown in Table 1, the tire structure and rubber composition in each example are common.

(1) Drainage performance (hydroplaning resistance)
A speed of an actual vehicle (two passengers) equipped with test tires, one wheel running on a waterway with a depth of 10 mm and the other wheel running on a straight road with a dry road, reaching a slip ratio difference of 10% between the left and right wheels. Was measured. The result of the reference example is evaluated by an index of 100, and the larger the value, the better the drainage performance.

(2) Dry performance (dry steering stability performance)
The driver performed a sensory evaluation of steering stability by running on an actual vehicle (two passengers) equipped with test tires, accelerating, braking, and turning on a dry road surface. The result of the reference example is evaluated by an index of 100, and the larger the value, the better the uneven wear resistance performance.

(3) Snow traction performance The actual vehicle (two passengers) equipped with test tires was driven on a snowy road, the time from the stopped state to the arrival at the 20 m point was measured, and the reciprocal was calculated. The result of the reference example is evaluated by an index of 100, and the larger the value, the better the snow traction performance.

As shown in Table 1, in Examples 1 to 5, both drainage performance and dry performance (dry steering stability performance) can be achieved at a higher level than in the reference example. Regarding the dry performance, the evaluation results of Examples 2 to 5 are relatively good. Further, in Examples 3 to 5, the snow traction performance can be improved.

1 ... inclined groove, 2 ... inclined land part, 3 ... center block, 4 ... quarter block, 5 ... shoulder block, 6 ... connection groove, 7 ... connection groove, 8 ... Center main groove, 40 ... Protruding part, 50 ... Protruding part, CD1 ... Tire circumferential direction one side, CD2 ... Tire circumferential direction other side, CL ... Center line, TL・ ・ ・ Tangent, Tr ・ ・ ・ Tread surface,

Claims (6)

A plurality of inclined grooves formed at intervals in the tire circumferential direction and extending from the center of the tread surface in the tire width direction toward the outside in the tire width direction toward one side in the tire circumferential direction.
With an inclined land portion partitioned by the inclined groove,
The inclined land portion is divided into a center block, a quarter block, and a shoulder block, and is arranged in this order from the central portion in the tire width direction toward the outside in the tire width direction.
The groove depth of the inclined groove increases toward the inside in the tire width direction in a region of 30 to 70% of the ground contact half width from the center line of the tread surface to the outside in the tire width direction.
A pneumatic tire in which the length of the center block in the tire circumferential direction is larger than the length of the center block in the tire width direction. The pneumatic tire according to claim 1, wherein the ratio of the length of the center block in the tire width direction to the length of the center block in the tire circumferential direction is 1.5 or more. According to claim 1 or 2, the extension line of the block edge is misaligned in the tire circumferential direction between the center block and the quarter block and / or between the quarter block and the shoulder block. Pneumatic tires listed. The air-filled portion according to any one of claims 1 to 3, wherein the quarter block has a protruding portion protruding to the other side in the tire circumferential direction with respect to an extension line of the block edge on the other side in the tire circumferential direction of the center block. tire. The air-filled portion according to any one of claims 1 to 4, wherein the shoulder block has a protruding portion protruding to the other side in the tire circumferential direction with respect to an extension line of the block edge on the other side in the tire circumferential direction of the quarter block. tire. The pneumatic tire according to any one of claims 1 to 5, wherein the length of the shoulder block in the tire circumferential direction is smaller than the length of the shoulder block in the tire width direction.

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