JP7098948B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire.

Patent Document 1 is known as a pneumatic tire that improves the performance on ice and the performance on snow in a well-balanced manner while suppressing the occurrence of uneven wear.

Japanese Patent No. 4510906

The pneumatic tire described in Patent Document 1 is obtained by adjusting the ratio of the contact width of each land portion of the tread, and is improved in improving the performance on ice and the performance on snow in a well-balanced manner while suppressing the occurrence of uneven wear. There is room for.

The present invention has been made in view of the above, and an object of the present invention is to provide a pneumatic tire capable of improving on-ice performance and on-snow performance while maintaining more uneven wear resistance.

In order to solve the above-mentioned problems and achieve the object, the pneumatic tire according to an embodiment of the present invention has a plurality of circumferential grooves extending in the tire circumferential direction and arranged side by side in the tire width direction, and the above-mentioned A plurality of lug grooves extending in a direction intersecting the circumferential groove and provided side by side in the tire circumferential direction, and a block row partitioned by the plurality of circumferential grooves are included, and the block row includes the plurality of blocks. It has a plurality of blocks partitioned by the lug groove and the circumferential groove, and in the plurality of blocks, the first to fourth blocks continuously arranged in the tire circumferential direction each have a notch, and the said The longitudinal direction of the notch is toward the tire circumferential direction, the notch of the second block is larger than the notch of the first block, and the third block is larger than the notch of the second block. The notch of the block is smaller, the notch of the fourth block is larger than the notch of the third block, and the plurality of circumferential grooves are a plurality of mains extending in the tire circumferential direction. The ratio of the maximum distance in the tire width direction between the block rows located on both sides of the main groove in the tire width direction, including the groove, to the see-through width of the main groove is 1.2 or more and 2.4 or less, and the main The see-through width of the groove is 4 mm or more and 8 mm or less, and the contact area of the center block row located between the two main grooves closest to the tire equatorial plane, the main groove closest to the tire contact end, and the tire contact end. The relationship between the ground contact area of the shoulder block row located between the parts and the ground contact area of the middle block row located between the center block row and the shoulder block row is described from the ground contact area of the middle block row. The ground contact area of the shoulder block row is large, and the ground contact area of the center block row is larger than the ground contact area of the shoulder block row .

The ground contact area of the second block is smaller than the ground contact area of the first block, and the ground contact area of the third block is larger than the ground contact area of the second block. It is preferable that the ground contact area of the fourth block is smaller than the ground contact area.

It is preferable that the plurality of circumferential grooves include two main grooves extending in the tire circumferential direction and a narrow groove provided between the two main grooves and extending in the tire circumferential direction.

In the first and second block rows partitioned by the two main grooves and the fine grooves and adjacent to each other in the tire width direction, a lug groove for partitioning each block of the first block row in the tire circumferential direction. The lug groove that divides each block of the second block row in the tire circumferential direction is inclined and extends in different directions with respect to the tire width direction, and is located at a position deviated from the tire circumferential direction. Is preferable.

Of the plurality of main grooves, a center block row located between the two main grooves closest to the tire equatorial plane, and a position between the main groove closest to the tire contact end and the tire contact end. The plurality of lug grooves included in the center block row are provided with a shoulder block row and a middle block row located between the center block row and the shoulder block row, and the plurality of lug grooves included in the center block row are in the same direction with respect to the tire width direction. The middle block row is provided between the two main grooves and is partitioned by a narrow groove extending in the tire circumferential direction, and the first and second middle block rows are adjacent to each other in the tire width direction. In the block row, the lug groove that divides each block of the first block row in the tire circumferential direction and the lug groove that divides each block of the second block row in the tire circumferential direction are relative to the tire width direction. It is preferable that the tires are inclined and extended in different directions and are displaced in the tire circumferential direction.

The inclination angle of the lug groove with respect to the tire width direction is preferably 10 degrees or more and 25 degrees or less.

It is preferable that the narrow groove is inclined with respect to the tire circumferential direction.

The groove depth of the fine groove is preferably 70% or more and 80% or less of the groove depth of the main groove.

The groove depth of the lug groove is preferably 60% or more and 90% or less of the groove depth of the main groove.

The notch portion has a step portion located between the tread tread surface and the groove bottom of the main groove in the tire meridional cross section, and the main groove with respect to the height from the groove bottom of the main groove to the tread tread surface. The ratio of the height in the tire radial direction from the bottom of the groove to the step portion is preferably 0 or more and 0.7 or less.

The plurality of lug grooves include a first lug groove and a second lug groove having different groove widths, and the first lug groove and the second lug groove are alternately arranged in the tire circumferential direction. Is preferable.

The block has an open sipe and a closed sipe provided in each portion divided by the open sipe, and the open sipe is preferably a three-dimensional shape.

The open sipe has four or more bent portions in the tire width direction and four or more bent portions in the groove depth direction, and the groove depth of the open sipe is the groove of the main groove. It is preferably 50% or more and 70% or less of the depth.

The open sipe includes a bent portion, a groove bottom portion, and a straight portion provided between the bent portion and the groove bottom portion, and the groove bottom portion has a groove width wider than that of the straight portion. It is preferable that the open sipe has a linear shape when the bent portion disappears due to wear of the block, and the groove width becomes larger than that of the straight portion when the block is further worn.

It is preferable that the closed sipe has four or more bent portions in the tire width direction, and the groove depth of the closed sipe is shallower than the groove depth of the open sipe.

The ratio of the groove width of the lug groove to the maximum circumferential length of the block is preferably 0.15 or more and 0.3 or less.

The length of each of the block rows in the tire width direction is preferably 10% or more and 25% or less with respect to the tread contact width.
The pneumatic tire according to another aspect of the present invention extends in the tire circumferential direction and extends in a direction intersecting the plurality of circumferential grooves provided side by side in the tire width direction and the tire. A plurality of lug grooves provided side by side in the circumferential direction and a block row partitioned by the plurality of circumferential grooves are included, and the block row is a plurality of lug grooves partitioned by the plurality of lug grooves and the circumferential groove. The first to fourth blocks that are continuously arranged in the tire circumferential direction in the plurality of blocks each have a notch, and the longitudinal direction of the notch is directed toward the tire circumferential direction. The notch of the second block is larger than the notch of the first block, and the notch of the third block is smaller than the notch of the second block. The notch of the fourth block is larger than the notch of the block, and the plurality of circumferential grooves are provided between the two main grooves extending in the tire circumferential direction and the two main grooves. The first block in the first and second block rows which are divided by the two main grooves and adjacent to each other in the tire width direction, including a narrow groove extending in the tire circumferential direction. The lug groove that divides each block of the row in the tire circumferential direction and the lug groove that divides each block of the second block row in the tire circumferential direction are inclined and extended in different directions with respect to the tire width direction. It is present and is in a position shifted in the tire circumferential direction.
The pneumatic tire according to another aspect of the present invention extends in the tire circumferential direction and extends in a direction intersecting the plurality of circumferential grooves provided side by side in the tire width direction and the tire. A plurality of lug grooves provided side by side in the circumferential direction and a block row partitioned by the plurality of circumferential grooves are included, and the block row is a plurality of lug grooves partitioned by the plurality of lug grooves and the circumferential groove. The first to fourth blocks that are continuously arranged in the tire circumferential direction in the plurality of blocks each have a notch, and the longitudinal direction of the notch is directed toward the tire circumferential direction. The notch of the second block is larger than the notch of the first block, and the notch of the third block is smaller than the notch of the second block. The notch of the fourth block is larger than the notch of the block, and the plurality of circumferential grooves are provided between the two main grooves extending in the tire circumferential direction and the two main grooves. Among the plurality of main grooves, the center block row located between the two main grooves closest to the equatorial plane of the tire and the most at the tire ground contact end, including the narrow grooves extending in the tire circumferential direction. The center block row includes a shoulder block row located between the nearby main groove and the tire ground contact end portion, and a middle block row located between the center block row and the shoulder block row. The plurality of lug grooves extend in an inclined direction in the same direction with respect to the tire width direction, and the middle block row is provided by a narrow groove provided between two main grooves and extending in the tire circumferential direction. In the first and second block rows that are partitioned and adjacent to each other in the tire width direction, a lug groove that divides each block of the first block row in the tire circumferential direction and each block of the second block row are tired. The lug groove that divides in the circumferential direction is located at a position that is inclined and extends in different directions with respect to the tire width direction and is displaced in the tire circumferential direction.
The pneumatic tire according to another aspect of the present invention extends in the tire circumferential direction and extends in a direction intersecting the plurality of circumferential grooves provided side by side in the tire width direction and the tire. A plurality of lug grooves provided side by side in the circumferential direction and a block row partitioned by the plurality of circumferential grooves are included, and the block row is a plurality of lug grooves partitioned by the plurality of lug grooves and the circumferential groove. The first to fourth blocks that are continuously arranged in the tire circumferential direction in the plurality of blocks each have a notch, and the longitudinal direction of the notch is directed toward the tire circumferential direction. The notch of the second block is larger than the notch of the first block, and the notch of the third block is smaller than the notch of the second block. The notch of the fourth block is larger than the notch of the block, and the block has an open sipe and a closed sipe provided in each portion divided by the open sipe. It has a three-dimensional shape, and the open sipe has four or more bent portions in the tire width direction and four or more bent portions in the groove depth direction, and the groove depth of the open sipe is , 50% or more and 70% or less of the groove depth of the main groove.

The pneumatic tire according to the present invention can improve on-ice performance and on-snow performance while maintaining more uneven wear resistance.

FIG. 1 is a cross-sectional view of the meridian of the pneumatic tire according to the present embodiment. FIG. 2 is a plan view showing a tread surface of a pneumatic tire according to the present embodiment. FIG. 3 is a diagram illustrating the size of each notch portion of adjacent blocks. FIG. 4A is a diagram illustrating the relationship between the groove depth of the main groove and the notch portion. FIG. 4B is a diagram illustrating the relationship between the groove depth of the main groove and the notch portion. FIG. 5 is a diagram showing the relationship between the distance between the block rows and the see-through width of the main groove. FIG. 6A is a diagram illustrating an inclination direction of the lug groove. FIG. 6B is a diagram showing the inclination direction of the lug groove of the comparative example. FIG. 7 is an enlarged view showing the block. FIG. 8A is a diagram illustrating the shape of the open sipe. FIG. 8B is a diagram illustrating the shape of the open sipe. FIG. 9A is a diagram showing an example of a change in the tread surface due to wear of a block having an open sipe. FIG. 9B is a diagram showing an example of a change in the tread surface due to wear of a block having an open sipe. FIG. 9C is a diagram showing an example of a change in the tread surface due to wear of a block having an open sipe. FIG. 9D is a diagram showing an example of a change in the tread due to wear of a block having an open sipe. FIG. 10 is a diagram illustrating the relationship between the groove width of the lug groove and the maximum circumferential length of the block.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment. In addition, the components of this embodiment include those that can be easily replaced by those skilled in the art, or those that are substantially the same. Further, the plurality of modifications described in this embodiment can be arbitrarily combined within a range self-evident by those skilled in the art. In addition, some components may not be used.

FIG. 1 is a cross-sectional view of the meridian of the pneumatic tire 1 according to the present embodiment. FIG. 2 is a plan view showing a tread surface of the pneumatic tire 1 according to the present embodiment.

In the following description, the tire radial direction means a direction orthogonal to the rotation axis (not shown) of the pneumatic tire 1, and the tire radial inside is the side toward the rotation axis in the tire radial direction and the tire radial outside. Refers to the side away from the axis of rotation in the tire radial direction. Further, the tire circumferential direction means a circumferential direction with the rotation axis as a central axis. The tire width direction means a direction parallel to the rotation axis, the inside in the tire width direction is the side toward the tire equatorial plane (tire equatorial line) CL in the tire width direction, and the outside in the tire width direction is the tire width direction. Refers to the side away from the tire equatorial plane CL. The tire equatorial plane CL is a plane orthogonal to the rotation axis of the pneumatic tire 1 and passing through the center of the tire width of the pneumatic tire 1. The tire width is the width in the tire width direction between the portions located outside in the tire width direction, that is, the distance between the portions farthest from the tire equatorial plane CL in the tire width direction. The tire equatorial line is a line on the tire equatorial plane CL and along the tire circumferential direction of the pneumatic tire 1. In the present embodiment, the tire equatorial line is designated by the same reference numeral “CL” as the tire equatorial plane.

As shown in FIG. 1, the pneumatic tire 1 according to the present embodiment includes a tread portion 2, shoulder portions 3 on both outer sides in the tire width direction thereof, sidewall portions 4 and bead portions that are sequentially continuous from each shoulder portion 3. Has 5 and. Further, the pneumatic tire 1 includes a carcass layer 6 and a belt layer 7.

The tread portion 2 is made of a rubber material (tread rubber) and is exposed on the outermost side in the tire radial direction of the pneumatic tire 1, and the surface thereof is the contour of the pneumatic tire 1. A tread surface 21 is formed on the outer peripheral surface of the tread portion 2, that is, on the tread surface that comes into contact with the road surface during traveling. The tread surface 21 is provided with a plurality of (four in this embodiment) main grooves 22 extending in the tire circumferential direction. The tread surface 21 extends along the tire circumferential direction due to the plurality of main grooves 22, and the rib-shaped land portions 20ce, 20m1, 20m2, which are lined up in the tire width direction (five in the present embodiment). 20s1 and 20s2 (hereinafter, may be collectively referred to as land portion 20) are formed. The land portion 20 has a narrow groove 26 extending in the tire circumferential direction.

Further, as shown in FIG. 2, the tread surface 21 is provided with lug grooves 24 and 25 extending in the direction intersecting the main groove 22 extending in the tire circumferential direction in each land portion 20. As a result, the land portion 20 may be collectively referred to as a block row 23ce, 23m1, 23m2, 23s1, 23s2 (hereinafter collectively referred to as a block row 23) divided into a plurality of blocks B in the tire circumferential direction by the lug grooves 24 and 25. Is). Therefore, the land portion 20 has a block row 23 partitioned by a circumferential groove. In the block row 23, a plurality of blocks B partitioned by the plurality of lug grooves 24 and 25 are arranged side by side in the tire circumferential direction, and a plurality of the block rows 23 are arranged side by side in the tire width direction. Further, the rib-shaped land portions 20s1 and 20s2 provided on the outermost side in the tire width direction are provided with lug grooves 29 and 30. The block row 23 is provided with a narrow groove 26 extending in the tire circumferential direction. The main groove 22 and the fine groove 26 are circumferential grooves extending in the tire circumferential direction.

The shoulder portion 3 is a portion on both outer sides of the tread portion 2 in the tire width direction. Further, the sidewall portion 4 is exposed to the outermost side in the tire width direction of the pneumatic tire 1. Further, the bead portion 5 has a bead core 51 and a bead filler 52. The bead core 51 is formed by winding a bead wire, which is a steel wire, in a ring shape. The bead filler 52 is a rubber material arranged in a space formed by folding the end portion of the carcass layer 6 in the tire width direction outward at the position of the bead core 51 in the tire width direction.

In the carcass layer 6, each end portion in the tire width direction is folded back from the inside in the tire width direction to the outside in the tire width direction by a pair of bead cores 51, and is hung in a toroid shape in the tire circumferential direction to form a tire skeleton. Is. The carcass layer 6 is formed by coating a plurality of carcass cords (not shown) arranged side by side with an angle in the tire circumferential direction while having an angle with respect to the tire circumferential direction along the tire meridian direction with a coated rubber. The carcass cord is made of steel or organic fiber (such as polyester, rayon or nylon).

The belt layer 7 has, for example, a multi-layer structure in which four layers of belts 71, 72, 73, and 74 are laminated, and is arranged on the outer periphery of the carcass layer 6 in the tread portion 2 on the outer side in the tire radial direction, and the carcass layer 6 is tired. It covers in the circumferential direction. In the belts 71, 72, 73, 74, a plurality of cords (not shown) arranged side by side at a predetermined angle with respect to the tire circumferential direction are coated with coated rubber. The cord is made of steel or organic fiber (such as polyester, rayon or nylon).

The pneumatic tire 1 is applied as a studless tire. Therefore, the closed sipe 27 and the open sipe 28 are formed on the surface of the land portion 20 constituting the tread surface 21. The closed sipe 27 and the open sipe 28 are grooves having a width of less than 1 mm.

In FIG. 2, the block row located between the two main grooves 22 closest to the tire equatorial plane CL is called the center block row 23ce. The block rows located between the main groove 22 closest to the tire ground contact end portion T and the tire ground contact end portion T are referred to as shoulder block rows 23s1 and 23s2. The block rows located between the center block row 23ce and the shoulder block rows 23s1 and 23s2 are called middle block rows 23m1 and 23m2.

The relationship between the ground contact area of the center block row 23ce, the ground contact area of the shoulder block rows 23s1 and 23s2, and the ground contact area of the middle block rows 23m1 and 23m2 is preferably as follows. That is, it is preferable that the ground contact area of the shoulder block row 23s1 is larger than the ground contact area of the middle block row 23m1, and the ground contact area of the center block row 23ce is larger than the ground contact area of the shoulder block row 23s1. Further, it is preferable that the ground contact area of the shoulder block row 23s2 is larger than the ground contact area of the middle block row 23m2, and the ground contact area of the center block row 23ce is larger than the ground contact area of the shoulder block row 23s2.

The ground contact area is calculated by calculating the ground contact width of each block row 23 as a width based on the maximum width position of the main groove 22. The contact area is the tire width direction and the tire circumferential direction in which the tread surface 21 comes into contact with the road surface when the pneumatic tire 1 is rim-assembled on the regular rim, the regular internal pressure is applied, and 70% of the regular load is applied. The area of the area of.

Further, the width Wce in the tire width direction of the center block row 23ce, the widths Wm1 and Wm2 in the tire width direction of the middle block rows 23m1 and 23m2, and the widths Ws1 and Ws2 in the tire width direction of the shoulder block rows 23s1 and 23s2 are treads, respectively. It is preferably 10% or more and 25% or less with respect to the ground contact width WH. When each width Wce, Wm1, Wm2, Ws1, Ws2 is less than 10% with respect to the tread ground contact width WH, the on-ice performance and the on-snow performance are improved, but the uneven wear resistance is deteriorated, and when it is larger than 25%, the uneven wear resistance is deteriorated. Abrasion performance is improved, but on-ice performance and on-snow performance are deteriorated. The ends of the widths Wce, Wm1, Wm2, Ws1, and Ws2 are the maximum width positions of the main groove 22. Each width Wce, Wm1, Wm2, Ws1, Ws2 is a width including the narrow groove 26.

The tread ground contact width is the length in the tire width direction in the ground contact region. The regular rim is a "standard rim" specified by JATMA, a "Design Rim" specified by TRA, or a "Measuring Rim" specified by ETRTO. The normal internal pressure is the "maximum air pressure" specified by JATTA, the maximum value described in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified by TRA, or "INFLATION PRESSURES" specified by ETRTO. The normal load is the "maximum load capacity" specified by JATTA, the maximum value described in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified by TRA, or the "LOAD CAPACITY" specified by ETRTO.

(Notch)
Of the side surfaces on both sides in the tire width direction, one side surface of each block B shown in FIG. 2 is adjacent to the main groove 22, and the other side surface is adjacent to the narrow groove 26. Each block B has a notch BK on the side surface adjacent to the main groove 22. The end of each notch BK faces the main groove 22 side.

FIG. 3 is a diagram illustrating the size of each notch portion of adjacent blocks. FIG. 3 shows an enlarged region 10 in FIG. As shown in FIG. 3, the middle block row 23m2 has a plurality of blocks such as block B11, block B12, block B13, and block B14. In the middle block row 23m2, the rows of blocks B11, block B12, block B13, and block B14 arranged in the tire circumferential direction on the tire equatorial side with the narrow groove 26 sandwiched, and the tire circumferential direction on the ground contact end direction side. There is a row of blocks B21, block B22, block B23, and block B24 arranged side by side. Each block is partitioned in the tire circumferential direction by a lug groove 24, and is partitioned in the tire width direction by a main groove 22 and a fine groove 26, that is, a groove extending in the tire circumferential direction. Block B11, block B12, block B13, block B14, and block B21, block B22, block B23, and block B24 have different positions in the tire width direction and the tire circumferential direction between adjacent blocks, and are arranged in a staggered pattern. There is.

Here, assuming that the block B11 is the first block, the block B12 is the second block, the block B13 is the third block, and the block B14 is the fourth block, the first, second, third, and fourth blocks are used. Are lined up linearly and continuously in the tire circumferential direction. The first block B11, the second block B12, the third block B13, and the fourth block B14 have a notch portion BK11, a notch portion BK12, a notch portion BK13, and a notch portion BK14 (hereinafter collectively referred to as notch portions). BK). The longitudinal direction of the notch BK11, the longitudinal direction of the notch BK12, the longitudinal direction of the notch BK13, and the longitudinal direction of the notch BK14 are oriented in the tire circumferential direction.

The lengths of the notch BK11, the notch BK12, the notch BK13, and the notch BK14 in the tire circumferential direction are length LBK1, length LBK2, length LBK3, and length LBK4. At this time, the length LBK2 is larger than the length LBK1. Also, the length LBK3 is smaller than the length LBK2. Furthermore, the length LBK4 is larger than the length LBK3. That is, the notch BK12 of the second block B12 is larger than the notch BK11 of the first block B11, and the notch BK13 of the third block B13 is smaller than the notch BK12 of the second block B12. The cutout portion BK14 of the fourth block B14 is larger than the cutout portion BK13 of the third block B13. The length LBK1 and the length LBK3 may have the same size or different sizes. Further, the length LBK2 and the length LBK4 may have the same size or different sizes.

Here, focusing on the first block B11, the second block B12, and the third block B13, the notch portion BK11 of the first block B11 and the third block are more than the notch portion BK12 of the second block B12. Both the notch BK13 of B13 are small. Focusing on the second block B12, the third block B13, and the fourth block B14, the notch BK12 of the second block B12 and the fourth block B14 are more important than the notch BK13 of the third block B13. Notch BK14 is both large. Therefore, it can be said that in the middle block row 23m2, a plurality of blocks having notches having different sizes are arranged alternately in the tire circumferential direction with respect to the size of the notch BK. By adjusting the size of the notch BK, the magnitude relationship of the ground contact area of the block can be adjusted. The ground contact area can be reduced by increasing the notch BK. The ground contact area can be increased by reducing the notch BK. By adjusting the size of the notch BK after fixing the groove width of the main groove 22, the blocks having a large contact area and the blocks having a small contact area can be arranged alternately in the tire circumferential direction. That is, the ground contact area of the second block B12 is smaller than the ground contact area of the first block B11, and the ground contact area of the third block B13 is larger than the ground contact area of the second block B12. The ground contact area of the fourth block B14 can be made smaller than the ground contact area of the block B13. Therefore, the blocks B12 and B14 having a large notch and the blocks B11 and B13 having a small notch are arranged alternately in the tire circumferential direction to improve the performance on ice while maintaining the ground contact area, and the portion having a large notch. Maintains performance on snow. Therefore, both can be improved while balancing the performance on ice and the performance on snow.

The above is the case where the notches of the first block B11, the second block B12, the third block B13, and the fourth block B14, which are linearly and continuously arranged in the tire circumferential direction, are arranged alternately in large, small, large, and small. However, the notches may be arranged alternately in large, small, large and small blocks for blocks that are continuously arranged in a staggered pattern in the tire circumferential direction. For example, in FIG. 3, the block B11, the block B21, the block B12, and the block B22 are continuously arranged in a staggered pattern in the tire circumferential direction. With respect to the blocks B11, the block B21, the block B12, and the block B22 which are continuously arranged in a staggered manner in the tire circumferential direction in this way, the notches may be arranged alternately in large, small, large, and small. This means that for the block rows adjacent in the tire width direction, the ground contact area of the other block row can be made larger or smaller than the ground contact area of the entire block row of one.

The case of the middle block row 23m2 has been described above, but similarly, in the middle block row 23m1, a plurality of blocks having notches having different sizes are arranged alternately in the tire circumferential direction with respect to the size of the notches. There is. In this way, the blocks having a large notch and the blocks having a small notch are arranged alternately in the tire circumferential direction, so that both can be improved while balancing the performance on ice and the performance on snow.

Further, similarly to the other block rows 23, a plurality of blocks having notches having different sizes may be arranged alternately in the tire circumferential direction with respect to the size of the notches. If at least one block row 23 is arranged in the tire circumferential direction alternately in terms of the size of the notch, both can be improved while balancing the performance on ice and the performance on snow.

(Shape of notch)
4A and 4B are diagrams illustrating the relationship between the groove depth of the main groove 22 and the notched portion BK. 4A and 4B show an enlarged example of the side surface of the block B adjacent to the main groove 22. 4A and 4B are views showing a cross section of the tire meridian.

In FIG. 4A, block B has a notch BK. The cutout portion BK has the shape of a step ST existing between the ground contact surface of the block B and the groove bottom 22BT of the main groove 22. Therefore, the cutout portion BK is different from the chamfered portion that may be provided on the outermost side of the main groove 22 in the tire radial direction. The portion along the tire radial direction from the step ST to the groove bottom 22BT is the boundary SS between the notch portion BK and the main groove 22.

Here, the distance in the tire radial direction from the ground contact surface of the block B to the groove bottom 22BT of the main groove 22, that is, the groove depth of the main groove 22 is defined as H22. Further, the distance in the tire radial direction from the groove bottom 22BT to the notch BK is defined as HST. At this time, the value of the ratio HST / H22 of the distance HST with respect to the groove depth H22 is preferably 0 or more and 0.7 or less. The value of the ratio HST / H22 is more preferably 0.1 or more and 0.5 or less. The groove depth H22 of the main groove 22 is, for example, 16 mm or more and 22 mm or less.

FIG. 4B is a diagram showing a case where the value of the ratio HST / H22 is 0. As shown in FIG. 4B, when the ratio HST / H22 of the distance HST to the groove depth H22 is 0, the position of the notch BK in the tire radial direction of the step ST and the position of the groove bottom 22BT in the tire radial direction coincide with each other. do.

FIG. 5 is a diagram showing the relationship between the distance between the block rows and the see-through width of the main groove. As shown in FIG. 5, block rows 23 are located on both sides of the main groove 22 in the tire width direction. The main groove 22 has a see-through structure.

The see-through structure is a structure in which a continuous space is formed when the main groove 22 is projected in the tire circumferential direction. Even if the block rows 23 are present on both sides of the main groove 22 in the tire width direction, a see-through portion remains at the center position in the tire width direction. The distance of the see-through portion in the tire width direction is the groove width of the main groove 22. The ratio W / Ws of the maximum distance W in the tire width direction between the block rows 23 to the distance in the tire width direction of the see-through portion, that is, the see-through width Ws of the main groove 22 is 1.2 or more and 2.4 or less. Is preferable. Further, the see-through width Ws of the main groove 22 is preferably 4 mm or more and 8 mm or less. When the above ratio and the value of the see-through width Ws of the main groove 22 are in the above range, it is possible to improve the on-ice performance and the on-snow performance while maintaining the uneven wear resistance.

(Inclination of lug groove)
FIG. 6A is a diagram illustrating an inclination direction of the lug groove. FIG. 6A shows an enlarged part of the block row 23m2 of FIG. In FIG. 6A, the lug grooves 241 and 242 are located on both sides in the tire width direction with the narrow groove 26 interposed therebetween. The lug groove 241 is inclined at an angle θ1 with respect to the tire width direction and extends in a direction away from the narrow groove 26. Further, the lug groove 242 is inclined at an angle θ2 with respect to the tire width direction and extends in a direction away from the narrow groove 26. The angle θ1 and the angle θ2 are different in the inclination direction with respect to the tire width direction. That is, the lug groove 241 which is the first lug groove and the lug groove 242 which is the second lug groove extend so as to be inclined in different directions with respect to the tire width direction. Further, the lug groove 241 which is the first lug groove and the lug groove 242 which is the second lug groove are not the same in the position in the tire circumferential direction, but are arranged at positions shifted in the tire circumferential direction. Therefore, there is no deviation in slipperiness on ice or snow. That is, there is no bias in slipperiness on ice or snow in each direction of the arrows Y11, Y12, Y21, and Y22.

Here, the angle θ1 and the angle θ2 with respect to the tire width direction are preferably 10 degrees or more and 25 degrees or less, and more preferably 14 degrees or more and 20 degrees or less. The ratio θ1 / θ2 between the angle θ1 and the angle θ2 is preferably 0.95 ≦ θ1 / θ2 ≦ 1.05.

By the way, as shown in FIG. 2, the tread surface 21 has a non-directional pattern in which the rotation direction is not specified when the tread surface 21 is mounted on the vehicle. In such a non-directional pattern, in the center block row 23ce, a plurality of lug grooves 24 are inclined and extend in the same direction with respect to the tire width direction, and in the middle block rows 23m1 and 23m2 on both sides thereof, the plurality of lug grooves 24 extend in the same direction. The plurality of lug grooves 24 are inclined and extend in different directions with respect to the tire width direction. In this example, in the middle block rows 23m1 and 23m2, as shown in FIG. 6A, the lug grooves 241 and the lug grooves 242 having different inclination directions with respect to the tire width direction are adopted, so that the lug grooves are slippery on ice or snow. There is no bias in the tires. Therefore, it is possible to improve the performance on ice and the performance on snow while maintaining the uneven wear resistance.

FIG. 6B is a diagram showing the inclination direction of the lug groove of the comparative example. As in the lug grooves 240a and 240b shown in FIG. 6B, when the inclination direction is the same even if the angle θ3 is inclined with respect to the tire width direction, the slipperiness on ice or snow is biased. That is, it is slippery in the direction of the arrows Y12 and Y21 rather than the direction of the arrows Y11 and Y22, and the slipperiness is biased.

As a means of improving the on-ice performance and the on-snow performance of studless tires, the volume of the lug groove may be increased in order to increase the snow column shear force. However, when the volume of the lug groove is increased, the block rigidity is lowered and the heel-and-toe wear resistance is lowered. A method of inclining the lug groove so that the block does not easily fall down can be considered. However, with this method, the peak angle of the snow column shear force in the block row is biased, and it may become slippery in a certain direction. Therefore, in the present embodiment, as described above, by reversing the inclination direction of the lug groove in the block row, both the performance on ice and the performance on snow and the heel-and-toe wear resistance are realized.

(Blocks and sipes)
FIG. 7 is an enlarged view of block B. As shown in FIG. 7, the adjacent blocks B are partitioned in the tire width direction by the narrow grooves 26 which are circumferential grooves. Since the adjacent blocks B are divided in the tire width direction by the narrow grooves 26, the force applied to the blocks B at the time of touchdown is dispersed, and the uneven wear resistance performance is improved.

Each block B has an open sipe 28. The open sipe 28 has one end opened in the narrow groove 26 which is a circumferential groove and the other end opens in the main groove 22 which is a circumferential groove. The open sipe 28 preferably has four or more bent portions in the tire width direction. When the number of bent portions in the tire width direction is less than four (that is, three or less), the open sipe 28 is not preferable because the effect of suppressing the decrease in block rigidity is low and the effect of increasing the edge component is low.

Each block B is divided into a plurality of parts by the open sipe 28. In this example, the two open sipes 28 divide the parts into three parts Ba, Bb and Bc. The portions Ba, Bb and Bc divided into a plurality by the open sipe 28 each have a closed sipe 27.

The closed sipe 27 has four or more bent portions in the tire width direction. Since the closed sipe 27 is provided in each of the portions Ba, Bb and Bc divided into a plurality of parts, the open sipe 28 and the closed sipe 27 having a three-dimensional shape maintain the uneven wear resistance while maintaining the performance on ice and the performance on snow. Can be improved.

Here, it is preferable that at least a part of the open sipe 28 has a three-dimensional shape. Here, the fact that the sipe has a three-dimensional shape means that the sipe extends by bending or the like in the groove depth direction. Since the open sipe 28 has a three-dimensional shape, it is possible to suppress a decrease in block rigidity and increase an edge component, so that it is possible to improve on-ice performance and on-snow performance while maintaining uneven wear resistance. can.

(Open sipe)
8A and 8B are diagrams illustrating the shape of the open sipe 28. FIG. 8A is a diagram showing a cross section of a portion AA of FIG. 7. FIG. 8B is a diagram showing a cross section of a portion BB of FIG. 7. As shown in FIG. 8A, the open sipe 28 has bends K11, K12, K13, K14 and K15 in the depth direction. Further, as shown in FIG. 8B, the open sipe 28 has bent portions K21, K22, K23, K24 and K25 in the depth direction. As can be understood from FIGS. 8A and 8B, the bending portions K11 and the bending portion K21 have bending directions opposite to each other. Similarly, the bending directions of the bending portion K12 and the bending portion K22, the bending portion K13 and the bending portion K23, the bending portion K14 and the bending portion K24, and the bending portion K15 and the bending portion K25 are opposite to each other. The open sipe 28 preferably has four or more bent portions in the groove depth direction. When the number of bent portions in the groove depth direction is less than four (that is, three or less), the open sipe 28 is not preferable because the effect of suppressing the decrease in block rigidity is low and the effect of increasing the edge component is low.

Further, as shown in FIG. 8A, the portion deeper than the bent portion K15 of the open sipe 28 includes a straight portion T1 that does not bend with a constant width and a groove bottom portion R1 in which the groove volume is widened. As shown in FIG. 8B, the portion deeper than the bent portion K25 of the open sipe 28 includes a straight portion T2 that does not bend with a constant width and a groove bottom portion R2 having a wide groove volume. If the straight portion T1 and the straight portion T2 have the same shape, the portions of the straight portion T1 and the straight portion T2 of the open sipe 28 become a flat plate-shaped space. If the groove bottom portion R1 and the groove bottom portion R2 are circular in the same shape, the groove bottom portion R1 and the groove bottom portion R2 of the open sipe 28 become a cylindrical space.

As shown in FIGS. 8A and 8B, the open sipe 28 is composed of a bending region HK, a linear region HT, and a groove bottom region HR. Referring to FIG. 8A, the bent region HK includes bent portions K11, K12, K13, K14 and K15. The linear region HT includes the linear portion T1. The groove bottom region HR includes the groove bottom portion R1. Referring to FIG. 8B, the bent region HK includes bent portions K21, K22, K23, K24 and K25. The linear region HT includes the linear portion T2. The groove bottom region HR includes the groove bottom portion R2.

The depth H28 in the tire radial direction of the open sipe 28 is preferably 50% or more and 70% or less with respect to the groove depth of the main groove 22. If the groove depth of the open sipe 28 is shallower than 50% of the groove depth of the main groove 22, the uneven wear resistance is improved, but the on-ice performance and the on-snow performance are deteriorated. When the groove depth of the open sipe 28 is deeper than 70% of the groove depth of the main groove 22, the on-ice performance and the on-snow performance are improved, but the uneven wear resistance is deteriorated.

The bending region HK may be used up to a groove depth of 50% of the groove depth of the main groove 22, or the bending region HK may be used up to the depth H28. The ratio of the depth of the bending region HK, the linear region HT, and the groove bottom region HR to the depth H28 of the open sipe 28 is not limited to the case shown in FIGS. 8A and 8B. For example, the bending region HK may be 60% or more and 80% or less of the depth H28. Further, the linear region HT may be 0.5% or more and 2% or less of the depth H28. The combined depth of the linear region HT and the groove bottom region HR may be 70% or more and 90% or less of the depth H28.

(Block wear)
9A to 9D are diagrams showing an example of a change in the tread due to wear of the block B having the open sipe 28 adopting the shapes shown in FIGS. 7, 8A and 8B. FIG. 9A is a diagram showing a state in which the block B is worn by 0% or more and less than 40% with respect to the groove depth of the main groove 22. With reference to FIG. 9A, since the wear of the block B is in the initial stage, the shapes of both the open sipe 28 and the closed sipe 27 can be confirmed.

FIG. 9B is a diagram showing a state in which the block B is worn by 40% or more and less than 50% with respect to the groove depth of the main groove 22. At the stage shown in FIG. 9B, the shape of the open sipe 28 can be confirmed, but the shape of the closed sipe 27 cannot be confirmed. The groove depth of the closed sipe 27 is shallower than the groove depth of the open sipe 28, and when the groove bottom of the closed sipe 27 is worn, the shape of the closed sipe 27 cannot be confirmed as shown in FIG. 9B.

FIG. 9C is a diagram showing a state in which the block B is worn by 50% or more and less than 55% with respect to the groove depth of the main groove 22. When the wear progresses to the stage shown in FIG. 9C, the bent region HK of the open sipe 28 shown in FIGS. 8A and 8B wears and disappears. Therefore, at the stage shown in FIG. 9C, the linear region HT shown in FIGS. 8A and 8B can be confirmed in the open sipe 28. The open sipe 28 can be confirmed as a linear shape instead of a bent shape.

FIG. 9D is a diagram showing a state in which the block B is worn by 55% or more and 65% or less with respect to the groove depth of the main groove 22. When the wear progresses to the stage shown in FIG. 9D, the open sipe 28 wears and disappears in the linear region HT shown in FIGS. 8A and 8B. Therefore, at the stage shown in FIG. 9D, the groove bottom region HR shown in FIGS. 8A and 8B can be confirmed in the open sipe 28. Since the groove bottom region HR has a groove width larger than that of the straight region region HT, the open sipe 28 can be confirmed as having a shape in which the groove width is wider than that at the stage shown in FIG. 9C.

As described with reference to FIGS. 9A to 9D, the open sipe 28 becomes a linear shape when the bent portion disappears due to wear of the block B. When the open sipe 28 is further worn, the groove width becomes larger than that of the linear shape.

(Groove depth of open sipe and closed sipe)
If the groove depth of the closed sipe 27 is too shallow than the groove depth of the open sipe 28, the uneven wear resistance is improved, but the on-ice performance and the on-snow performance are deteriorated. If the groove depth of the closed sipe 27 is too deeper than the groove depth of the open sipe 28, the on-ice performance and the on-snow performance are improved, but the uneven wear resistance is deteriorated. The groove depth of the closed sipe 27 is, for example, 5 mm or more and 15 mm or less. The groove depth of the open sipe 28 is, for example, 6 mm or more and 20 mm or less.

(Groove width of lug groove and maximum circumferential length of block)
FIG. 10 is a diagram illustrating the relationship between the groove width of the lug groove 24 and the maximum circumferential length of the block B. In FIG. 10, the groove width of the lug groove 24 is WL, and the length of the block having the maximum tire circumferential length among the plurality of blocks B in the tire circumferential direction is defined as LB. It is preferable that the ratio WL / LB of the groove width WL of the lug groove 24 to the maximum circumferential length LB of the block B is 0.15 or more and 0.3 or less.

When the ratio WL / LB is smaller than 0.15, the uneven wear resistance performance is improved, but the ice performance and the snow performance are deteriorated. When the ratio WL / LB is larger than 0.3, the performance on ice and the performance on snow are improved, but the uneven wear resistance is deteriorated. The lug groove width WL is preferably 5 mm or more and 9 mm or less.

(Small groove)
Further, as shown in FIG. 10, the narrow groove 26 extends in the tire circumferential direction, and each block B is divided in the tire width direction. The narrow groove 26 extends in the tire circumferential direction while changing the position in the tire width direction. That is, the narrow groove 26 extends in the tire circumferential direction while bending in the left-right direction in the drawing. Since the narrow groove 26 is bent, it extends in the tire circumferential direction while alternately repeating a state of being inclined in one direction with respect to the tire circumferential direction and a state of being inclined in the other direction. Since the fine groove 26 is inclined with respect to the tire circumferential direction, the effect of supporting the adjacent blocks across the fine groove 26 is produced, and the blocks are less likely to shift from each other. This improves uneven wear resistance.

The inclination angle θ of the narrow groove 26 with respect to the tire circumferential direction is preferably 10 degrees or more and 40 degrees or less. If the inclination angle θ is less than 10 degrees, the effect of supporting the adjacent blocks is reduced. If the inclination angle θ exceeds 40 degrees, the uneven wear resistance performance deteriorates.

The narrow groove 26 has a groove width of, for example, 1 mm or more and 5 mm or less. The groove depth of the fine groove 26 is preferably 70% to 80% of the main groove 22. The groove depth of the fine groove 26 is, for example, 14 mm or more and 16 mm or less.

(Groove width and groove depth of lug groove)
The lug groove for partitioning each block included in the center block row 23ce includes a lug groove 24 having a wide groove width and a lug groove 25 having a narrow groove width. The lug grooves 24 having a wide groove width and the lug grooves 25 having a narrow groove width are alternately arranged in the tire circumferential direction. The groove width of the lug groove 25 is narrower than the groove width of the lug groove 24. The groove width of the lug groove 25 having a narrow groove width is about the same as the groove width of the fine groove 26.

The depth of the lug grooves 24 and 25 is preferably 60% or more and 90% or less, and more preferably 70% or more and 80% or less of the depth of the main groove 22. If the depth of the lug grooves 24 and 25 is shallower than 60% of the depth of the main groove 22, the uneven wear resistance performance is improved, but the on-ice performance and the on-snow performance are deteriorated. When the depth of the lug grooves 24 and 25 is deeper than 90% of the depth of the main groove 22, the performance on ice and the performance on snow are improved, but the uneven wear resistance is deteriorated.

(summary)
For the continuous blocks of the block row on the tread surface of the pneumatic tire, by arranging the notches alternately in size and setting the ground contact area of each block appropriately, the performance on ice and the performance on snow while maintaining the uneven wear resistance. And can be improved.

In this embodiment, performance tests on snow performance (snow start performance) and ice performance (ice braking performance) were performed on a plurality of types of pneumatic tires with different conditions in the test course (Tables 1 to 4). See). In all cases, pneumatic tires with four main grooves were used.

In this performance test, a heavy-duty pneumatic tire with a tire size of 275 / 80R22.5 is assembled on a regular rim and filled with regular internal pressure to test a 2-D4 (front 2 wheels-4 drive wheels) test vehicle. I attached it to.

In the performance test of snow performance, the above test vehicle starts and runs on a snowy uphill road from a vehicle stop state, and is evaluated by the feeling of a test driver, and the evaluation result is based on the conventional pneumatic tire (100). ) Is shown by the index. The larger this index value is, the better the performance on snow (starting performance on snow).

In the performance test of the performance on ice, the braking distance from the braking position to the stopped position is measured by braking the flat ice road surface from a speed of 40 [km / h] per hour in the above test vehicle. Then, based on this measurement result, an index evaluation is performed with the conventional pneumatic tire as a reference (100). As for the evaluation result, the larger the value, the better the performance on ice (braking performance on ice).

Regarding the uneven wear resistance performance, a rim equipped with a pneumatic tire 1 was attached to the drive shaft of the vehicle, and the amount of heel-and-toe wear after traveling 20,000 km was measured by a market monitor. The measurement results were indexed using the conventional pneumatic tire as a reference (100). The larger the index value, the better the performance.

In Table 1, the tires of the conventional example are tires in which the block does not have a notch, the ratio is W / Ws = 1, and the positions of the lug grooves in the tire circumferential direction are all the same.

In Table 1, in the tire of Comparative Example 1, the block does not have a notch and the ratio W / Ws = 1. As described with reference to FIG. 6B, the tire of Comparative Example 1 has the same inclination direction of the lug groove with respect to the tire width direction in the block row in the center region and the middle region.

In Table 1, in the tire of Comparative Example 2, each block has a notch having the same size, and the ratio W / Ws = 1. In the tire of Comparative Example 2, the inclination direction of the lug groove with respect to the tire width direction is the same in the block row in the center region and the middle region. The tire of Comparative Example 2 has fine grooves, but the fine grooves are not inclined with respect to the tire circumferential direction. In the tire of Comparative Example 2, the ratio of the groove depth of the fine groove to the groove depth of the main groove is 60%, and the groove depth of the lug groove to the groove depth of the main groove is 50%.

The tire of Comparative Example 3 is a tire in which each block has notches of different sizes, but is not arranged alternately in size but irregularly arranged. The tire of Comparative Example 3 has a ratio of W / Ws = 1. In the tire of Comparative Example 3, the inclination direction of the lug groove with respect to the tire width direction is the same in the block row in the center region and the middle region. The tire of Comparative Example 3 has fine grooves, but the fine grooves are not inclined with respect to the tire circumferential direction. In the tire of Comparative Example 3, the ratio of the groove depth of the fine groove to the groove depth of the main groove is 60%, and the groove depth of the lug groove to the groove depth of the main groove is 50%.

With reference to Examples 1 to 47 in Tables 1 to 4, it can be seen that good results can be obtained when the notches are arranged alternately in large and small. Further, when the ratio W / Ws is 1.2 or more and 2.4 or less, when Ws is 4 mm or more and 8 mm or less, when the relationship of the contact area is center> shoulder> middle, the lug groove in the tire width direction When the inclination direction is different, when the inclination angle of the lug groove with respect to the tire width direction is 10 degrees or more and 25 degrees or less, when the position of the lug groove in the tire circumferential direction is deviated, the narrow groove is located with respect to the tire circumferential direction. When there is an inclination, the ratio of the fine groove depth to the main groove depth is 70% or more and 80% or less, the ratio of the lug groove depth to the main groove depth is 60% or more and 90% or less. When the ratio of the height of the notch to the depth of the main groove is 0 or more and 0.7 or less, the groove widths of the lug grooves are different, and when they are arranged alternately, the shape of the open sipe is three-dimensional. When the number of bent portions of the open sipe is 4 or more, the ratio of the open sipe groove depth to the main groove depth is 50% or more and 70% or less, and the number of bent portions of the closed sipe is 4 or more, it is open. When the groove depth of the closed sipe is shallower than the groove depth of the sipe, the ratio of the groove width of the lug groove to the maximum circumferential length of the block is 0.15 or more and 0.3 or less, the block row with respect to the tread contact width. It can be seen that good results are obtained when the width ratio is 10% or more and 25% or less.

1 Pneumatic tire 2 Tread part 3 Shoulder part 4 Side wall part 5 Bead part 6 Carcass layer 7 Belt layer 20 Land part 21 Tread surface 22 Main groove 23 Block row 24, 25 Rug groove 26 Fine groove 27 Closed sipe 28 Open sipe 51 Bead core 52 Bead filler
71, 72, 73, 74 Belt B, B11 to B14, B21 to B24 Block BK, BK11 to BK14 Notch

Claims (20)

A plurality of circumferential grooves extending in the tire circumferential direction and arranged side by side in the tire width direction, and a plurality of lug grooves extending in a direction intersecting the circumferential groove and provided side by side in the tire circumferential direction. And a block row partitioned by the plurality of circumferential grooves.
The block row has a plurality of blocks partitioned by the plurality of lug grooves and the circumferential groove.
In the plurality of blocks, the first to fourth blocks that are continuously arranged in the tire circumferential direction each have a notch.
The longitudinal direction of the notch is oriented in the tire circumferential direction.
The notch of the second block is larger than the notch of the first block.
The notch of the third block is smaller than the notch of the second block.
The notch of the fourth block is larger than the notch of the third block.
The plurality of circumferential grooves include a plurality of main grooves extending in the circumferential direction of the tire.
The ratio of the maximum distance in the tire width direction between the block rows located on both sides of the main groove in the tire width direction to the see-through width of the main groove is 1.2 or more and 2.4 or less, and the see-through width of the main groove. Is 4 mm or more and 8 mm or less,
The ground contact area of the center block row located between the two main grooves closest to the tire equatorial plane, and the ground contact of the shoulder block row located between the main groove closest to the tire ground contact end and the tire ground contact end. The relationship between the area and the ground contact area of the middle block row located between the center block row and the shoulder block row is such that the ground contact area of the shoulder block row is larger than the ground contact area of the middle block row, and the shoulder block. The ground contact area of the center block row is larger than the ground contact area of the row.
Pneumatic tires. The ground contact area of the second block is smaller than the ground contact area of the first block.
The ground contact area of the third block is larger than the ground contact area of the second block.
The pneumatic tire according to claim 1, wherein the contact area of the fourth block is smaller than the contact area of the third block. According to claim 1, the plurality of circumferential grooves include two main grooves extending in the tire circumferential direction and a narrow groove provided between the two main grooves and extending in the tire circumferential direction. Pneumatic tires listed. In the first and second block rows partitioned by the two main grooves and the fine grooves and adjacent to each other in the tire width direction, a lug groove for partitioning each block of the first block row in the tire circumferential direction. The lug groove that divides each block of the second block row in the tire circumferential direction is a claim that extends at an angle different from each other in the tire width direction and is located at a position deviated from the tire circumferential direction. Item 3. The pneumatic tire according to Item 3. Among the plurality of main grooves, the center block row located between the two main grooves closest to the tire equatorial plane, and the position between the main groove closest to the tire contact end and the tire contact end. A middle block row located between the center block row and the shoulder block row is provided.
The plurality of lug grooves included in the center block row extend in the same direction with respect to the tire width direction.
The middle block row is the first block row provided between the two main grooves and partitioned by a narrow groove extending in the tire circumferential direction and adjacent to each other in the tire width direction. The lug groove that divides each block of the block row in the tire circumferential direction and the lug groove that divides each block of the second block row in the tire circumferential direction are inclined in different directions with respect to the tire width direction. The pneumatic tire according to claim 3 , which is extended and is located at a position shifted in the tire circumferential direction. The pneumatic tire according to claim 5 , wherein the inclination angle of the lug groove with respect to the tire width direction is 10 degrees or more and 25 degrees or less. The pneumatic tire according to any one of claims 3 to 6, wherein the narrow groove is inclined with respect to the tire circumferential direction. The pneumatic tire according to any one of claims 3 to 7, wherein the groove depth of the fine groove is 70% or more and 80% or less of the groove depth of the main groove. The pneumatic tire according to any one of claims 1 to 8 , wherein the groove depth of the lug groove is 60% or more and 90% or less of the groove depth of the main groove. The notch portion has a step portion located between the tread tread surface and the groove bottom of the main groove in the tire meridional cross section, and the main groove with respect to the height from the groove bottom of the main groove to the tread tread surface. The pneumatic tire according to any one of claims 1 to 9 , wherein the ratio of the heights in the tire radial direction from the bottom of the groove to the step portion is 0 or more and 0.7 or less. The plurality of lug grooves include a first lug groove and a second lug groove having different groove widths, and the first lug groove and the second lug groove are alternately arranged in the tire circumferential direction. The pneumatic tire according to any one of claims 1 to 10 . The block has an open sipe and a closed sipe provided in a portion divided by the open sipe, and the open sipe has a three-dimensional shape according to any one of claims 1 to 11 . Pneumatic tires listed. The open sipe has four or more bent portions in the tire width direction and four or more bent portions in the groove depth direction.
The pneumatic tire according to claim 12 , wherein the groove depth of the open sipe is 50% or more and 70% or less of the groove depth of the main groove. The open sipe includes a bent portion, a groove bottom portion, and a straight portion provided between the bent portion and the groove bottom portion, and the groove bottom portion has a groove width wider than that of the straight portion.
The pneumatic tire according to claim 13 , wherein the open sipe becomes a linear shape when the bent portion disappears due to wear of the block, and the groove width becomes larger than that of the straight portion when further worn. The closed sipe has four or more bent portions in the tire width direction, and the groove depth of the closed sipe is shallower than the groove depth of the open sipe according to any one of claims 12 to 14. Pneumatic tires listed. The pneumatic tire according to any one of claims 1 to 13 , wherein the ratio of the groove width of the lug groove to the maximum circumferential length of the block is 0.15 or more and 0.3 or less. The pneumatic tire according to any one of claims 1 to 16 , wherein the length of each of the block rows in the tire width direction is 10% or more and 25% or less with respect to the tread contact width. A plurality of circumferential grooves extending in the tire circumferential direction and arranged side by side in the tire width direction, and a plurality of lug grooves extending in a direction intersecting the circumferential groove and provided side by side in the tire circumferential direction. And a block row partitioned by the plurality of circumferential grooves.
The block row has a plurality of blocks partitioned by the plurality of lug grooves and the circumferential groove.
In the plurality of blocks, the first to fourth blocks that are continuously arranged in the tire circumferential direction each have a notch.
The longitudinal direction of the notch is oriented in the tire circumferential direction.
The notch of the second block is larger than the notch of the first block.
The notch of the third block is smaller than the notch of the second block.
The notch of the fourth block is larger than the notch of the third block.
The plurality of circumferential grooves include two main grooves extending in the tire circumferential direction and a narrow groove provided between the two main grooves and extending in the tire circumferential direction.
In the first and second block rows partitioned by the two main grooves and the fine grooves and adjacent to each other in the tire width direction, a lug groove for partitioning each block of the first block row in the tire circumferential direction. The lug groove that divides each block of the second block row in the tire circumferential direction is an air that is inclined and extends in different directions with respect to the tire width direction and is located at a position deviated from the tire circumferential direction. Tires with tires. A plurality of circumferential grooves extending in the tire circumferential direction and arranged side by side in the tire width direction, and a plurality of lug grooves extending in a direction intersecting the circumferential groove and provided side by side in the tire circumferential direction. And a block row partitioned by the plurality of circumferential grooves.
The block row has a plurality of blocks partitioned by the plurality of lug grooves and the circumferential groove.
In the plurality of blocks, the first to fourth blocks that are continuously arranged in the tire circumferential direction each have a notch.
The longitudinal direction of the notch is oriented in the tire circumferential direction.
The notch of the second block is larger than the notch of the first block.
The notch of the third block is smaller than the notch of the second block.
The notch of the fourth block is larger than the notch of the third block.
The plurality of circumferential grooves include two main grooves extending in the tire circumferential direction and a narrow groove provided between the two main grooves and extending in the tire circumferential direction.
Among the plurality of main grooves, the center block row located between the two main grooves closest to the tire equatorial plane, and the position between the main groove closest to the tire contact end and the tire contact end. A middle block row located between the center block row and the shoulder block row is provided.
The plurality of lug grooves included in the center block row extend in the same direction with respect to the tire width direction.
The middle block row is the first block row provided between the two main grooves and partitioned by a narrow groove extending in the tire circumferential direction and adjacent to each other in the tire width direction. The lug groove that divides each block of the block row in the tire circumferential direction and the lug groove that divides each block of the second block row in the tire circumferential direction are inclined in different directions with respect to the tire width direction. Pneumatic tires that are extended and offset in the tire circumferential direction. A plurality of circumferential grooves extending in the tire circumferential direction and arranged side by side in the tire width direction, and a plurality of lug grooves extending in a direction intersecting the circumferential groove and provided side by side in the tire circumferential direction. And a block row partitioned by the plurality of circumferential grooves.
The block row has a plurality of blocks partitioned by the plurality of lug grooves and the circumferential groove.
In the plurality of blocks, the first to fourth blocks that are continuously arranged in the tire circumferential direction each have a notch.
The longitudinal direction of the notch is oriented in the tire circumferential direction.
The notch of the second block is larger than the notch of the first block.
The notch of the third block is smaller than the notch of the second block.
The notch of the fourth block is larger than the notch of the third block.
The plurality of circumferential grooves include a plurality of main grooves extending in the circumferential direction of the tire.
The block has an open sipe and a closed sipe provided in each portion divided by the open sipe, and the open sipe has a three-dimensional shape.
The open sipe has four or more bent portions in the tire width direction and four or more bent portions in the groove depth direction.
A pneumatic tire in which the groove depth of the open sipe is 50% or more and 70% or less of the groove depth of the main groove.

Images