JP2021000863A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire improved in dry steering stability performance, uneven wear resistance, snow braking performance, snow handling performance and drainage performance with good balance.SOLUTION: A tread pattern of a pneumatic tire 10 includes: three or more circumferential main grooves extending in a tire circumferential direction; a plurality of lug grooves 13 provided in land parts partitioned by the circumferential main grooves; and sipes 16 provided between the adjacent lug grooves 13. The sipes 16 are complex sipes having two-dimensional parts and three-dimensional parts. Bottom raised parts 130 are provided at opening ends at the same sides as end parts of the sipes 16 provided with the two-dimensional parts, of opening ends at both sides of the lug grooves 13.SELECTED DRAWING: Figure 2

Description

The present invention relates to a pneumatic tire.

Patent Document 1 discloses a pneumatic tire that achieves both steering stability performance and drainage performance. In Patent Document 1, a narrow groove penetrating the lug groove is arranged on the shoulder portion of the tread, a bottom raising portion is provided at one end of the fine groove, and the other end of the fine groove is connected to the lug groove outside the ground contact end. Therefore, we are trying to achieve both steering stability performance and drainage performance. Further, Patent Document 2 discloses a pneumatic tire that achieves both drainage performance and uneven wear resistance. In Patent Document 2, a recess is provided in the groove wall of the main groove, and a sipe that communicates with the recess and a shallow groove that avoids the recess and communicates with the recess are provided.

JP-A-2017-97087 JP-A-2017-43208

The pneumatic tires of Patent Documents 1 and 2 described above do not take into consideration the improvement of braking performance on snowy road surface, that is, snow braking performance, and steering stability performance, that is, snow handling performance on snowy road surface, and are improved. There is room. In addition, it is necessary to consider dry steering stability performance, uneven wear resistance performance, and drainage performance, which are steering stability performance on a dry road surface.

The present invention has been made in view of the above, and an object of the present invention is a pneumatic tire having improved dry steering stability performance, uneven wear resistance performance, snow braking performance, snow handling performance, and drainage performance in a well-balanced manner. Is to provide.

In order to solve the above-mentioned problems and achieve the object, the pneumatic tire according to an embodiment of the present invention is a pneumatic tire having a tread pattern, and the tread pattern extends in the tire circumferential direction. A land portion defined by two or more circumferential main grooves, two or more circumferential main grooves among the three or more circumferential main grooves, and a plurality of lug grooves provided in the land portion. The lug groove includes a sipe provided in the land portion and provided between the adjacent lug grooves, and the lug groove extends from the outer edge in the tire width direction of the land portion to the inner edge in the tire width direction. It extends continuously and penetrates the land portion, and the sipe continuously extends from the outer edge of the land portion in the tire width direction to the inner edge of the tire width direction and extends the land portion. The sipe is a composite sipe having a two-dimensional portion and a three-dimensional portion, the two-dimensional portion is provided at one opening end of the sipe, and the three-dimensional portion is the other opening of the sipe. A bottom raising portion provided at an end and further provided at an opening end on the same side as the end portion of the sipe provided with the two-dimensional portion among the open ends on both sides of the lug groove in the land portion. It is a pneumatic tire equipped with.

Of the open ends on both sides of the lug groove on the land portion, it is preferable that the open end on the same side as the end portion of the sipe provided with the three-dimensional portion is not provided with a bottom raising portion.

The ratio of the length of the three-dimensional portion in the tire width direction to the ground contact width in the tire width direction of the land portion is preferably 0.25 or more and 0.80 or less.

The ratio of the length of the raised portion in the tire width direction to the ground contact width in the tire width direction of the land portion is preferably 0.15 or more and 0.50 or less.

In the lug groove, the ratio of the groove depth of the portion where the bottom raising portion is provided to the groove depth of the portion where the bottom raising portion is not provided is preferably 0.40 or more and 0.80 or less. ..

The ratio of the groove depth of the composite sipe to the groove depth of the circumferential main groove is preferably 0.50 or more and 0.85 or less.

A portion of the composite sipe that further includes a sipe bottom raising portion provided in the two-dimensional portion, and in the composite sipe, a portion in which the sipe bottom raising portion is provided with respect to a groove depth of a portion in which the sipe bottom raising portion is not provided. The ratio of the groove depths of is preferably 0.50 or more and 0.85 or less.

The three-dimensional portion of the composite sipe includes a straight portion near the opening end and a portion deeper than the straight portion, and the portion deeper than the straight portion has an amplitude of bending or bending with respect to the sipe depth direction. It has a shape, and the ratio of the amplitude to the groove width of the straight portion is preferably 0.40 or more and 0.80 or less.

The sipe has a Z-shape having two bent portions, and of the two bent portions, the bent portion closer to the center line passing through the midpoint position in the tire width direction of the land portion and the center line. It is preferable that the ratio of the distance in the tire width direction to the width of the land portion in the tire width direction is 0 or more and 0.40 or less.

The outer edge of the land portion in the tire width direction is a zigzag-shaped zigzag edge having irregularities whose position in the tire width direction changes periodically, and the inner edge of the land portion in the tire width direction is a straight shape. The three-dimensional portion of the sipe is preferably connected to the zigzag edge.

It is preferable that the sipe is connected to the maximum amplitude position of the zigzag edge in the tire width direction.

The ratio of the minimum value of the distance between the convex portions of the zigzag shape to the maximum value of the distance between the convex portions of the zigzag shape is preferably 0.50 or more.

The land portion preferably has two or more of the sipes and three or more of the zigzag-shaped protrusions between adjacent lug grooves.

The distance in the tire circumferential direction between the connecting portions of the two or more sipes provided between the adjacent lug grooves to the circumferential main groove on the inner side in the tire width direction is Ls1, Ls2, ..., Lsn (n is When it is a natural number of 3 or more), it is preferable that Ls1 <Lsn.

The distance in the tire circumferential direction between the connection portions of the two or more sipes provided between the adjacent lug grooves to the circumferential main groove on the inner side in the tire width direction is Ls1, Ls2, ..., Lsn (n is A natural number of 3 or more), and the distance in the tire circumferential direction between the convex portions of the connection portions of the plurality of sipes provided between the adjacent lug grooves to the circumferential main groove on the outer side in the tire width direction is Lz1. In the case of Lz2, ..., Lzn (n is a natural number of 3 or more), it is preferable that Ls1 <Lz1 and Lsn> Lzn.

According to the present invention, it is possible to obtain the effect of improving dry steering stability performance, uneven wear resistance performance, snow braking performance, snow handling performance, and drainage performance in a well-balanced manner.

FIG. 1 is a cross-sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a developed view showing an example of a tread pattern of the pneumatic tire shown in FIG. FIG. 3 is a cross-sectional view taken along the extending direction of the lug groove. FIG. 4 is an enlarged view of a part of the middle land portion of the tread pattern shown in FIG. FIG. 5 is a plan view showing an example of sipe. FIG. 6 is an enlarged view of a part of the middle land portion of the tread pattern shown in FIG. FIG. 7 is an enlarged view of a part of the middle land portion of the tread pattern shown in FIG. FIG. 8A is an enlarged view of a part of the middle land portion of the tread pattern shown in FIG. FIG. 8B is an enlarged view of a part of FIG. 8A. FIG. 9A is a diagram showing another example of the middle land area. FIG. 9B is an enlarged view of a part of FIG. 9A. FIG. 10A is a diagram showing another example of the middle land area. FIG. 10B is an enlarged view of a part of FIG. 10A. FIG. 11 is an enlarged view of a part of the shoulder land portion of the tread pattern shown in FIG. FIG. 12 is a cross-sectional view showing an example of a three-dimensional portion of the composite sipe in FIG. FIG. 13 is a cross-sectional view taken along the extending direction of the sipe of FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description of each embodiment, the same or equivalent components as those of the other embodiments are designated by the same reference numerals, and the description thereof will be simplified or omitted. The present invention is not limited to each embodiment. In addition, the components of each embodiment include those that can be easily replaced by those skilled in the art, or those that are substantially the same. The plurality of modifications described in this embodiment can be arbitrarily combined within the range of those skilled in the art. In addition, the configuration may be omitted, replaced or changed without departing from the gist of the invention.

[Pneumatic tires]
FIG. 1 is a cross-sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment of the present invention. FIG. 1 shows a cross-sectional view of a one-sided region in the tire radial direction. Further, FIG. 1 shows a radial tire for a passenger car as an example of a pneumatic tire.

The cross section in the tire meridian direction is a cross section when the tire is cut on a plane including the tire rotation axis (not shown). Further, the reference numeral CL is a tire equatorial plane, and refers to a plane that passes through the center point of the tire in the tire rotation axis direction and is perpendicular to the tire rotation axis. The tire radial direction refers to a direction orthogonal to the rotation axis (not shown) of the pneumatic tire 10, the inner side in the tire radial direction is the side toward the rotation axis in the tire radial direction, and the outer side in the tire radial direction is the tire radial direction. Refers to the side away from the axis of rotation. Further, the tire circumferential direction refers to a circumferential direction centered on the rotation axis. Further, the tire width direction means a direction parallel to the rotation axis. The inside in the tire width direction means the side toward the tire equatorial plane CL in the tire width direction, and the outside in the tire width direction means the side away from the tire equatorial plane CL in the tire width direction.

The tire equatorial plane CL is a plane that is orthogonal to the rotation axis of the pneumatic tire 10 and passes through the center of the tire width of the pneumatic tire 10. 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 along the tire circumferential direction of the pneumatic tire 10. In the present embodiment, the tire equatorial line is designated by the same code “CL” as the tire equatorial plane.

As shown in FIG. 1, the pneumatic tire 10 of the present embodiment includes a tread portion 1 extending in the tire circumferential direction to form an annular shape, and a pair of sidewall portions 2 arranged on both sides of the tread portion 1. 2 and a pair of bead portions 3 and 3 arranged inside the sidewall portions 2 in the tire radial direction are provided.

A carcass layer 4 is mounted between the pair of bead portions 3 and 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction, and is folded back from the inside to the outside of the tire around the bead core 5 arranged in each bead portion 3. A bead filler 6 made of a rubber composition having a triangular cross section is arranged on the outer periphery of the bead core 5.

On the other hand, a plurality of belt layers 7 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. These belt layers 7 include a plurality of reinforcing cords that are inclined with respect to the tire circumferential direction, and the reinforcing cords are arranged so as to intersect each other between the layers. In the belt layer 7, the inclination angle of the reinforcing cord with respect to the tire circumferential direction is set in the range of, for example, 10 degrees to 40 degrees. A steel cord is preferably used as the reinforcing cord of the belt layer 7. On the outer peripheral side of the belt layer 7, at least one layer of the belt cover layer 8 formed by arranging the reinforcing cords at an angle of, for example, 5 degrees or less with respect to the tire circumferential direction is arranged for the purpose of improving high-speed durability. There is. As the reinforcing cord of the belt cover layer 8, an organic fiber cord such as nylon or aramid is preferably used.

The tire internal structure described above is a typical example of a pneumatic tire, and is not limited thereto.

[Tread section]
FIG. 2 is a developed view showing an example of a tread pattern of the pneumatic tire 10 shown in FIG. In FIGS. 1 and 2, reference numeral T indicates a tire ground contact end.

As shown in FIG. 2, the pneumatic tire 10 of this example includes four circumferential main grooves 11A, 11B, 12A, and 12B in the tread portion 1. The circumferential main grooves 12A and 12B extend in the tire circumferential direction at positions outside the tire width direction of the tire equatorial plane CL. The circumferential main groove 11A extends in the tire circumferential direction at a position closer to the tire equatorial plane CL than the circumferential main groove 12A. The circumferential main groove 11B extends in the tire circumferential direction at a position closer to the tire equatorial plane CL than the circumferential main groove 12B.

The circumferential main grooves 11A, 11B, 12A and 12B are circumferential grooves having a wear indicator indicating the end of wear, and generally have a groove width of 5.0 [mm] or more and a groove depth of 7.5 [mm] or more. Has The groove width and groove depth of the circumferential main grooves 11A, 11B, 12A and 12B are not limited to the above ranges.

Further, the lug groove described later means a lateral groove having a groove width of 2.0 [mm] or more and a groove depth of 3.0 [mm] or more. Further, the sipe described later is a notch formed in the land portion, and generally has a groove width of less than 1.5 [mm].

In FIG. 2, the center land portion Rc is partitioned by the two circumferential main grooves 11A and 11B. Further, the middle land portion Rm is partitioned by the two circumferential main grooves 11A and 12A, and the other middle land portion Rm is partitioned by the two circumferential main grooves 11B and 12B. The outer side of the circumferential main groove 12A in the tire width direction is the shoulder land portion Rs. The outer side of the circumferential main groove 12B in the tire width direction is another shoulder land portion Rs. When there are three main grooves in the circumferential direction, the center land portion Rc is not provided, and the middle land portion Rm on both sides of the equator line CL and the shoulder land portion Rs on the outer side in the tire width direction of the middle land portion Rm are formed. Become a tread part.

The center land portion Rc (hereinafter, may be simply referred to as the land portion Rc) is located on the tire equatorial line CL. The land Rc has a plurality of sipes 15. The sipe 15 extends in the tire circumferential direction and the tire width direction. One end of the sipe 15 is connected to the circumferential main groove 11A, and the other end of the sipe 15 is connected to the circumferential main groove 11B. The sipe 15 is a penetrating sipe that penetrates the land Rc. In this example, the edges on both sides of the land portion Rc have a straight shape.

The middle land portion Rm (hereinafter, may be simply referred to as a land portion Rm) has a plurality of lug grooves 13. The lug groove 13 extends in the tire width direction and the tire circumferential direction. One end of the lug groove 13 on the inner side in the tire width direction opens in the circumferential main groove 11A or 11B. The other end of the lug groove 13 on the outer side in the tire width direction opens in the circumferential main groove 12A or 12B. The land portion Rm has a bottom raising portion 130 in the lug groove 13. The bottom raising portion 130 is a portion in which the groove bottom of the lug groove 13 is raised to make the groove depth shallower than the other portions. The bottom raising portion 130 is provided at the inner end portion of the lug groove 13 in the tire width direction. Further, the land portion Rm has a plurality of sipes 16 between adjacent lug grooves 13. The sipe 16 extends in the tire circumferential direction and the tire width direction. One end of the sipe 16 is connected to the circumferential main groove 11A or 11B, and the other end of the sipe 16 is connected to the circumferential main groove 12A or 12B. The sipe 16 is a penetrating sipe that penetrates the land Rm.

In this example, the outer edge of the land portion Rm in the tire width direction, that is, the edge on the circumferential direction main groove 12A or 12B side has a zigzag shape. The zigzag shape is a shape having irregularities whose position in the tire width direction changes periodically. The inner edge of the land portion Rm in the tire width direction, that is, the edge on the circumferential direction main groove 11A or 11B side has a straight shape having no unevenness.

The shoulder land portion Rs (hereinafter, may be simply referred to as a land portion Rs) has a plurality of lug grooves 14A and 14B. The lug grooves 14A and 14B extend in the tire width direction from the inside in the tire width direction to the outside in the tire width direction. The lug grooves 14A and 14B extend from the circumferential main groove 12A or 12B to a position outside the tire ground contact end T. The land portion Rs has a plurality of sipes 17 between the lug groove 14A and the lug groove 14B. The sipe 17 extends in the tire width direction. One end of the sipe 17 is connected to the circumferential main groove 12A or 12B, and the other end of the sipe 17 is connected to the decorative groove 18 outside the tire ground contact end T.

[Sipe]
In FIG. 2, sipes 15, 16 and 17 are composite sipes having a two-dimensional portion (so-called plane sipe) section and a three-dimensional portion (so-called three-dimensional sipe) section. The two-dimensional portion refers to a portion of the sipe having a linear sipe wall surface in a cross-sectional view perpendicular to the length direction thereof. The three-dimensional portion refers to a portion of the sipe having a sipe wall surface bent in the sipe width direction in a cross-sectional view perpendicular to the length direction of the sipe. These sipes 15, 16 and 17 secure the edge components of the land parts Rc, Rm and Rs, and improve the traction property of the pneumatic tire 10.

In FIG. 2, the section of the sipe 15 in the region 20A is a three-dimensional portion. The section of the sipe 15 other than the region 20A is a two-dimensional portion. The section of the sipe 16 within the region 20B is a three-dimensional portion. The section of the sipe 16 other than the region 20B is a two-dimensional portion. The section of the sipe 17 within the region 20C is a three-dimensional portion. The section of the sipe 17 other than the region 20C is a two-dimensional portion.

The two-dimensional portion has a straight-shaped sipe wall surface in an arbitrary cross-sectional view (cross-sectional view including the sipe width direction and the sipe depth direction) with the sipe length direction as the normal direction. The three-dimensional portion has a bent-shaped sipe wall surface having an amplitude in the sipe width direction in both a cross-sectional view in which the sipe length direction is the normal direction and a cross-sectional view in which the sipe depth direction is the normal direction. Compared with the two-dimensional part, the three-dimensional part has a stronger meshing force between the facing sipe wall surfaces, and thus has an effect of reinforcing the rigidity of the land part. By increasing the rigidity of the zigzag-shaped portion of the land portion, the chipping resistance can be improved.

Here, focusing on the land portion Rm partitioned by the circumferential main groove 11A and the circumferential main groove 12A, the edge on the circumferential main groove 12A side has a zigzag shape. That is, one of the edges of the land portion Rm in the tire width direction has a zigzag shape. Further, there is a region 20B on the edge side having a zigzag shape. That is, the three-dimensional portion of the sipe 16 is connected to an edge having a zigzag shape, that is, a zigzag edge. Therefore, the land portion Rm has improved snow performance due to the zigzag shape edge effect. Further, since the sipe 16 of the portion connected to the circumferential main groove 12A on the edge side having a zigzag shape is a three-dimensional portion, the block rigidity of the zigzag shape portion is increased and the chipping resistance is improved. To do.

Focusing on the land portion Rs, the edge on the circumferential direction main groove 12A side has a zigzag shape. That is, one of the edges of the land portion Rs in the tire width direction has a zigzag shape. Further, there is a region 20C on the edge side having a zigzag shape. That is, the three-dimensional portion of the sipe 17 is connected to an edge having a zigzag shape, that is, a zigzag edge. Therefore, the land area Rs has improved snow performance due to the zigzag-shaped edge effect. Further, since the sipe 17 of the portion connected to the circumferential main groove 12A on the edge side having a zigzag shape is a three-dimensional portion, the block rigidity of the zigzag shape portion is increased and the chipping resistance is improved. To do.

[Relationship between sipes and raised parts of lug grooves]
Here, the two-dimensional portion of the sipe 16 of the land portion Rm is provided at the inner end portion of the sipe 16 in the tire width direction. On the other hand, the three-dimensional portion of the sipe 16 of the land portion Rm is provided at the outer end portion of the sipe 16 in the tire width direction. Further, as described above, in the land portion Rm, the bottom raising portion 130 of the lug groove 13 is provided at the opening end inside the lug groove 13 in the tire width direction. Therefore, among the open ends on both sides of the lug groove 13, the bottom raising portion 130 is provided at the open end on the same side as the end portion of the sipe 16 provided with the two-dimensional portion. In the lug groove 13, the bottom raising portion 130 is provided at the end portion on the same side as the end portion of the sipe provided with the two-dimensional portion having a lower rigidity than the three-dimensional portion. Since the bottom raising portion 130 for increasing the rigidity is provided at the end portion on the two-dimensional portion side having low rigidity, the rigidity can be made uniform in the tire circumferential direction.

Further, among the open ends on both sides of the lug groove 13, the open end on the same side as the end of the sipe 16 provided with the three-dimensional portion is not provided with a bottom raising portion. Since the bottom raising portion 130 is provided only at the inner end in the tire width direction where the two-dimensional portion is provided and the bottom raising portion is not provided at the outer end in the tire width direction where the three-dimensional portion is provided, the drainage performance is improved. The decrease can be suppressed.

Due to the manufacturing convenience of the pneumatic tire 10, an arbitrary cross-sectional view (a cross-sectional view including the sipe width direction and the sipe depth direction) with the sipe length direction as the normal direction is outside the tire width direction of the three-dimensional portion. ) May provide a straight sipe wall surface. The straight-shaped portion provided for such manufacturing convenience is included in the three-dimensional portion. That is, the straight-shaped sipe wall surface provided in the range of 15% of the sipe length from the outer end of the sipe 16 in the tire width direction is regarded as a part of the three-dimensional portion.

FIG. 3 is a cross-sectional view taken along the extending direction of the lug groove 13. The ratio DL / Dg of the groove depth DL of the lug groove 13 to the groove depth Dg of the circumferential main groove 11A is preferably 0.50 or more and 0.85 or less. If the ratio DL / Dg is larger than 0.85, the block rigidity is lowered and the wear resistance is lowered, which is not preferable. If the ratio DL / Dg is smaller than 0.50, the snow performance deteriorates, which is not preferable.

As shown in FIG. 3, a bottom raising portion 130 is provided at the connecting portion of the lug groove 13 to the circumferential main groove 11A. The ratio of the groove depth of the portion where the bottom raising portion 130 is provided to the groove depth of the portion where the bottom raising portion 130 is not provided, that is, the ratio of the groove depth DL of the lug groove 13 to the groove depth DL of the bottom raising portion 130. The ratio Du / DL of the groove depth Du is preferably 0.40 or more and 0.80 or less. If the ratio Du / DL is less than 0.40, the drainage performance deteriorates, which is not preferable. If the ratio Du / DL exceeds 0.80, sufficient block rigidity cannot be obtained and the wear resistance performance deteriorates, which is not preferable.

Here, in FIG. 3, a depth of 80% of the groove depth DL of the lug groove 13 (one-dot chain line in FIG. 3) is defined as a depth of 0.8 DL. Let W be the length of the bottom raising portion 130 in the tire width direction at a depth of 0.8 DL.

[Middle land]
FIG. 4 is an enlarged view of a part of the middle land portion Rm of the tread pattern shown in FIG. In FIG. 4, the maximum width of the land portion Rm in the tire width direction is W1. In FIG. 4, the distance from the connection portion of the sipe 16 to the main groove 12A in the circumferential direction to the inner end portion in the tire width direction of the region 20B which is a section of the three-dimensional portion is defined as Wc2. At this time, the ratio Wc2 / W1 is preferably 0.30 or more and 0.80 or less. If the ratio Wc2 / W1 is less than 0.30, sufficient block rigidity cannot be obtained and the steering stability performance deteriorates, which is not preferable. If the ratio Wc2 / W1 exceeds 0.80, the block rigidity becomes too high and the uneven wear resistance performance deteriorates, which is not preferable.

Here, the ratio Wu / W1 of the length Wu (see FIG. 3) of the bottom raising portion 130 in the tire width direction to the maximum width W1 of the land portion Rm in the tire width direction is 0.15 or more and 0.50 or less. Is preferable. If the ratio Wu / W1 is less than 0.15, sufficient block rigidity cannot be obtained and the uneven wear resistance performance deteriorates, which is not preferable. If the ratio Wu / W1 exceeds 0.50, the block rigidity on the three-dimensional portion side of the sipe 16 becomes too high, and the uneven wear resistance performance deteriorates, which is not preferable.

Further, in FIG. 4, the distance from the connection portion of the sipe 16 to the main groove 11A in the circumferential direction to the inner end portion in the tire width direction of the region 20B which is a section of the three-dimensional portion is defined as Wc1. The distance Wc1 is the length of the two-dimensional portion of the sipe 16 in the tire width direction. At this time, the ratio Wc1 / W1 is preferably 0.20 or more and 0.70 or less. If the ratio Wc1 / W1 is less than 0.20, the block rigidity on the circumferential main groove 11A side of the sipe 16 becomes too high, which is not preferable. If the ratio Wc1 / W1 exceeds 0.70, the block rigidity on the circumferential main groove 11A side of the sipe 16 becomes too low, which is not preferable.

[Z-shaped]
FIG. 5 is a plan view showing an example of the sipe 16. In FIG. 5, one end of the sipe 16 is connected to the circumferential main groove 11A, and the other end is connected to the circumferential main groove 12A. Referring to FIG. 5, the sipe 16 of this example is composed of straight portions ST1, ST2 and ST3, and bent portions C1 and C2. The straight portion ST1 is arranged on the circumferential main groove 11A side, that is, on the inner side in the tire width direction. The straight portion ST1 is connected to the inner edge of the land portion Rm in the tire width direction. The straight portion ST3 is arranged on the circumferential main groove 12A side, that is, on the outer side in the tire width direction. The straight portion ST3 is connected to the outer edge of the land portion Rm in the tire width direction. The length of the straight portion ST1 in the extending direction is shorter than the length of the straight portion ST3 in the extending direction.

One end of the straight portion ST1 is connected to the circumferential main groove 11A, and the other end of the straight portion ST1 is connected to one end of the bent portion C1. The other end of the bent portion C1 is connected to the straight portion ST2. One end of the straight portion ST3 is connected to the circumferential main groove 12A, and the other end of the straight portion ST3 is connected to one end of the bent portion C2. The other end of the bent portion C2 is connected to the straight portion ST2. As described above, the sipe 16 has a substantially Z shape by providing the bent portion C1 between the straight portion ST1 and the straight portion ST2 and the bent portion C2 between the straight portion ST2 and the straight portion ST3. There is. The Z-shape is a shape including at least two bent portions and the straight portions are connected by the bent portions. The Z-shape may include an S-shape composed of an arc. In the following description, of the straight portion ST1 and the straight portion ST3, the straight portion ST1 close to the equatorial plane CL may be referred to as an inner straight portion, and the straight portion ST3 far from the equatorial plane CL may be referred to as an outer straight portion.

FIG. 6 is an enlarged view of a part of the middle land portion Rm of the tread pattern shown in FIG. In FIG. 6, among a plurality of lug grooves 13 penetrating the land portion Rm, in the block partitioned by the adjacent lug grooves 13, the length of the zigzag edge between the adjacent lug grooves 13 in the tire circumferential direction is determined. Let it be L1. Let L2 be the distance between the zigzag-shaped protrusions in the tire circumferential direction. The ratio L2 / L1 of the distance L2 to the length L1 is preferably 0.15 or more and 0.55 or less. If this ratio L2 / L1 is larger than 0.55, the edge effect cannot be sufficiently obtained and the snow performance is not improved, which is not preferable. If this ratio L2 / L1 is smaller than 0.15, the zigzag-shaped unevenness becomes too fine and easily chipped, which is not preferable. The length L1 of the zigzag edge in the tire circumferential direction is measured with reference to the corner of the intersection of the lug groove 13 and the circumferential main groove 12A.

Further, in FIG. 6, the maximum width of the land portion Rm in the tire width direction is W1. The length (that is, width) in the tire width direction from the connection point of the sipe 16 with the circumferential main groove 11A on the inner side in the tire width direction to the end point K1 on the outer side in the tire width direction of the inner straight portion ST1 is defined as W2. Of the plurality of lug grooves 13 penetrating the land portion Rm, in the block partitioned by the adjacent lug grooves 13, the width twice the amplitude in the tire width direction of the zigzag shape is defined as W3. The width W3 is the distance in the tire width direction between the corners 21 and the corners 22 of the opening of the sipe 16.

At this time, the ratio W2 / W1 of the width W2 to the width W1 is preferably 0.10 or more and 0.40 or less. If this ratio W2 / W1 is smaller than 0.10, the edge effect becomes small and the snow performance deteriorates, which is not preferable. If this ratio W2 / W1 is larger than 0.40, the bent portion C1 becomes close to the zigzag portion, and the chipping resistance is inferior, which is not preferable.

The ratio W3 / W2 of the width W3 to the width W2 is preferably 0.15 or more and 0.45 or less. If this ratio W3 / W2 is smaller than 0.15, the edge effect of the zigzag groove becomes small and the snow performance deteriorates, which is not preferable. If this ratio W3 / W2 is larger than 0.45, the drainage property is lowered and the edge effect of the sipe 16 is also reduced, which is not preferable because the snow performance is lowered.

Further, the ratio W3 / W1 of the width W3 to the maximum width W1 of the land portion Rm in the tire width direction is preferably 0.03 or more and 0.15 or less. If this ratio W3 / W1 is larger than 0.15, the drainage property is hindered and the drainage performance is deteriorated, which is not preferable. If this ratio W3 / W1 is smaller than 0.03, the edge effect is not produced and the snow performance is not improved, which is not preferable.

By the way, in the land portion Rm, two or more sipes 16 are provided between the adjacent lug grooves 13, and three or more zigzag-shaped convex portions are provided between the adjacent lug grooves 13. Is preferable. If the number of sipes 16 between the adjacent lug grooves 13 is less than two, the number of zigzag-shaped convex portions is reduced and the snow performance is not improved, which is not preferable.

Further, in FIG. 6, the straight portions ST3 of each of the plurality of sipes 16 are parallel to each other. Here, "parallel" means that the angle formed by the two straight lines L16 extending the center lines of the two sipes 16 is within ± 5 °. When the two straight lines L16 are completely parallel, the angle formed by the two straight lines L16 is 0 °.

Further, in FIG. 6, the plurality of lug grooves 13 are parallel to each other. Here, "parallel" means that the angle formed by the two straight lines L13 extending the center lines of the two lug grooves 13 is within ± 5 °. When the two straight lines L13 are completely parallel, the angle formed by the two straight lines L13 is 0 °.

FIG. 7 is an enlarged view of a part of the middle land portion Rm of the tread pattern shown in FIG. In FIG. 7, the distances between the zigzag-shaped convex portions between the adjacent lug grooves 13 are Lz1, Lz2, ..., Lzn (n is a natural number of 3 or more), respectively. The distance Lz1 and the distance Lzn are distances in the tire circumferential direction measured with reference to the lug grooves 13 which are different from each other. At this time, it is preferable that the ratio Lzmin / Lzmax of the shortest distance Lzmin to the longest distance Lzmax among the distances Lz1 to Lzn is 0.50 or more. That is, the ratio of the minimum value of the distance between the zigzag-shaped convex portions to the maximum value of the distance between the zigzag-shaped convex portions is preferably 1.05 or more. When the ratio Lzmin / Lzmax is 0.50 or more, it means that the distance between the convex portions is not evenly divided. By making the distances between the convex portions different rather than evenly divided, the dispersion of the sound generated when the pneumatic tire 10 touches the road surface is improved, and the pattern noise is improved. The minimum values of the distances Lz1, Lz2, ..., Lzn are 3.0 [mm].

Further, in FIG. 7, the distances in the tire circumferential direction of the connecting portions to the circumferential main groove 11A inside the tire width direction between the plurality of sipes 16 provided between the adjacent lug grooves 13 are Ls1, Ls2, ... , Lsn (n is a natural number of 3 or more). The distances Ls1, Ls2, ..., Lsn are all the distances in the tire circumferential direction measured with reference to the connection portion of the inner straight portion ST1 to the circumferential main groove 11A. The distance Ls1 and the distance Lsn are distances in the tire circumferential direction measured with reference to the lug grooves 13 which are different from each other. At this time, it is preferable that the relationship between the distance Ls1 and the distance Lsn is Ls1 <Lsn. That is, it is preferable that the distance Lsn at the other end is longer than the distance Ls1 at one end in the tire circumferential direction. By changing the distance of the inner straight portion ST1 of the Z-shaped sipe 16, the edge effect can be exhibited in a wider angle and the snow performance can be improved. The minimum values of the distances Ls1, Ls2, ..., Lsn are 2.5 [mm].

In FIG. 7, the distances in the tire circumferential direction between the convex portions of the connecting portions to the circumferential main groove 12A on the outer side in the tire width direction between the plurality of sipes 16 provided between the adjacent lug grooves 13 are Lz1 and Lz2, respectively. , ..., Lzn (n is a natural number of 3 or more). The distance Lz1 and the distance Ls1 are distances in the tire circumferential direction measured with reference to the same lug groove 13. Since the same lug groove 13 is used as a reference, the distance Lz1 and the distance Ls1 have a relationship between the inside and the outside in the tire width direction, and both are in corresponding positions. Further, the distance Lzn and the distance Lsn are distances in the tire circumferential direction measured with reference to the same lug groove 13. Since the same lug groove 13 is used as a reference, the distance Lzn and the distance Lsn have a relationship between the inside and the outside in the tire width direction, and both are at corresponding positions. At this time, it is preferable that Ls1 <Lz1 and Lsn> Lzn. That is, in the tire circumferential direction, the relationship between the distance Ls1 at the corresponding position and the distance Lz1 is preferably larger at the distance Lz1 at the position outside the tire width direction than at the distance Ls1 at the position inside the tire width direction. Since the distance Lz1 is larger than the distance Ls1, the length of the sipe in the extending direction becomes longer, so that the edge effect becomes larger and the snow performance is improved. Further, in the tire circumferential direction, the relationship between the distance Lsn at the corresponding position and the distance Lzn is preferably smaller for the distance Lzn for the position outside the tire width direction than for the distance Lsn for the position inside the tire width direction. Since the distance Lzn is smaller than the distance Lsn, the length of the sipe in the extending direction becomes longer, so that the edge effect becomes larger and the snow performance is improved.

In FIG. 7, the sipe 16 is connected to the maximum amplitude position of the width W3, which is twice the amplitude of the zigzag edge in the tire width direction. As a result, when stress is applied in the tire circumferential direction, the stress applied to the convex portion that is likely to be chipped can be dispersed along the groove wall of the sipe 16, and the chipping resistance is improved. For example, when stress is applied in the tire circumferential direction as shown by arrow YA, the stress can be dispersed along the groove wall of the sipe 16 as shown by arrow YB. As a result, the chipping resistance of the convex portion, which is easily chipped, is improved.

FIG. 8A is an enlarged view showing a part of the middle land portion Rm of the tread pattern shown in FIG. FIG. 8B is an enlarged view of a part of FIG. 8A. In FIGS. 8A and 8B, the two bent portions C1 and C2 of the sipe 16 are arranged inside the center line RL passing through the center of the land portion Rm in the tire width direction in the tire width direction. Of the two bent portions C1 and C2, the bent portion C2 is located closer to the center line RL than the bent portion C1. The boundary between the bent portion C2 and the straight portion ST3 is the end point K2. Let Db be the distance between the end point K2 and the center line RL in the tire width direction. The ratio Db / W1 of the distance Db to the maximum width W1 of the land portion Rm in the tire width direction is preferably 0 or more and 0.40 or less.

Here, the length in the tire circumferential direction from the connection point 23 of the sipe 16 with the circumferential main groove 11A on the inner side in the tire width direction to the end point K2 on the inner side in the tire width direction of the outer straight portion ST3 is defined as L3. The ratio L3 / L1 of the length L3 to the length L1 is preferably 0.15 or more and 0.45 or less. If the ratio L3 / L1 is larger than 0.45, the number of sipes cannot be increased, which is not preferable because the snow performance is not improved. When the ratio L3 / L1 is smaller than 0.15, the length of the portion connecting the straight portion ST1 and the straight portion ST3 extending from both edge sides of the land portion Rm (that is, the bent portion C1, the straight portion ST2 and the bent portion C2). Is not preferable because the edge effect is reduced and the snow performance is not improved.

Further, the ratio L3 / W1 of the length L3 to the maximum width W1 is preferably 0.15 or more and 0.65 or less. If the ratio L3 / W1 is smaller than 0.15, the edge effect becomes small and the snow performance deteriorates, which is not preferable. If the ratio L3 / W1 is larger than 0.65, the number of sipes cannot be increased and the snow performance is not improved, which is not preferable.

FIG. 9A is a diagram showing another example of the middle land area Rm. FIG. 9B is an enlarged view of a part of FIG. 9A. In FIGS. 9A and 9B, the bent portions C1 and C2 of the sipes 16A and 16B are arranged inside the center line RL passing through the center of the land portion Rm in the tire width direction in the tire width direction. In the sipe 16A, of the two bent portions C1 and C2, the bent portion C2 is located closer to the center line RL than the bent portion C1. The boundary between the bent portion C2 and the straight portion ST3 is the end point K2. Let Dba be the distance between the end point K2 and the center line RL in the tire width direction. The ratio Dba / W1 of the distance Dba to the maximum width W1 in the tire width direction of the land portion Rm is preferably 0 or more and 0.40 or less.

Further, in the sipe 16B, of the two bent portions C1 and C2, the bent portion C1 is located closer to the center line RL than the bent portion C2. The boundary between the bent portion C1 and the straight portion ST1 is the end point K1. The distance between the end point K1 and the center line RL in the tire width direction is defined as Dbb. The ratio Dbb / W1 of the distance Dbb to the maximum width W1 in the tire width direction of the land portion Rm is preferably 0 or more and 0.40 or less.

FIG. 10A is a diagram showing another example of the middle land area Rm. FIG. 10B is an enlarged view of a part of FIG. 10A. In FIGS. 10A and 10B, the bent portion C1 of the sipe 16C is arranged inside the center line RL passing through the center of the land portion Rm in the tire width direction in the tire width direction. The bent portion C2 of the sipe 16B is located on the center line RL. More specifically, the end point K2, which is the boundary between the bent portion C2 and the straight portion ST3, is located on the center line RL. In this case, since the distance between the end point K2 and the center line RL in the tire width direction is 0, the ratio Db / W1 = 0. The same applies to the bent portion C2 of the sipe 16D.

Therefore, also in the case of FIGS. 10A and 10B, the land portion Rm of the distance in the tire width direction between the bent portion C2 closer to the center line RL passing through the midpoint position in the tire width direction of the land portion Rm and the center line RL. Satisfies the condition that the ratio of tires to the width in the tire width direction is 0 or more and 0.40 or less. One of the two bent portions C1 and C2 is provided inside the center line RL passing through the midpoint position in the tire width direction of the land portion Rm, and the other one is located on the center line RL. You may be doing it.

As described above, of the two bent portions C1 and C2, the distance between the bent portion of the bent portion closer to the center line RL passing through the midpoint position in the tire width direction of the land portion Rm and the center line RL in the tire width direction. When the ratio of the land portion Rm to the maximum width W1 in the tire width direction is 0 or more and 0.40 or less, the following effects can be obtained. That is, the edge effect is increased by providing the zigzag groove and the substantially Z-shaped sipe 16. If the substantially Z-shaped bending point and the zigzag portion are close to each other, the block rigidity in the vicinity of the zigzag portion decreases, and there is a concern about chipping. Therefore, by providing the bending point of the sipe 16 and the zigzag portion at a position separated from each other, it is possible to achieve both snow performance and chipping resistance.

Further, the groove width is measured as the maximum value of the distance between the left and right groove walls at the groove opening in a no-load state in which the tire is mounted on the specified rim and the specified internal pressure is filled. In a configuration in which the land portion has a notch or a chamfered portion at the edge portion, the groove width is set based on the intersection of the tread tread and the extension line of the groove wall in a cross-sectional view with the groove length direction as the normal direction. Be measured. Further, in the configuration in which the grooves extend in a zigzag shape or a wavy shape in the tire circumferential direction, the groove width is measured with reference to the center line of the amplitude of the groove wall.

The tire ground contact end T is a contact surface between the tire and the flat plate when the tire is mounted on the specified rim to apply a specified internal pressure and the tire is placed perpendicular to the flat plate in a stationary state and a load corresponding to the specified load is applied. It is defined as the maximum width position in the tire axial direction in.

Here, the specified rim means an "applicable rim" specified in JATTA, a "Design Rim" specified in TRA, or a "Measuring Rim" specified in ETRTO. The specified internal pressure means the "maximum air pressure" specified in JATTA, the maximum value of "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified in TRA, or "INFLATION PRESSURES" specified in ETRTO. The specified load means the "maximum load capacity" specified in JATTA, the maximum value of "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified in TRA, or the "LOAD CAPACITY" specified in ETRTO. However, in JATTA, in the case of a passenger car tire, the specified internal pressure is an air pressure of 180 [kPa], and the specified load is 88 [%] of the maximum load capacity.

[Shoulder land]
FIG. 11 is an enlarged view of a part of the shoulder land portion Rs of the tread pattern shown in FIG. In FIG. 11, the land portion Rs on the outer side in the tire width direction of the circumferential main groove 12B has a sipe 17. Let Ws2 be the length (that is, width) of the three-dimensional portion of the sipe 17 in the tire width direction. The length Ws2 is the length (that is, width) in the tire width direction from the edge of the circumferential main groove 12B of the land portion Rs to the outer end of the three-dimensional portion of the sipe 17 in the tire width direction. Further, the length from the edge of the circumferential main groove 12B of the land portion Rs to the ground contact end T, that is, the ground contact width of the land portion Rs in the tire width direction is defined as Ws1. At this time, the ratio Ws2 / Ws1 is preferably 0.25 or more and 0.65 or less. If the ratio Ws2 / Ws1 is less than 0.25, sufficient block rigidity cannot be obtained, which hinders the improvement of chipping resistance. If the ratio Ws2 / Ws1 exceeds 0.65, the block rigidity becomes too high and the pattern noise deteriorates, which is not preferable.

In FIG. 11, the land portion Rs has a plurality of shoulder lug grooves 14A and 14B extending from the circumferential main groove 12B on the inner side in the tire width direction toward the outer side in the tire width direction. The plurality of shoulder lug grooves 14A and 14B preferably extend to at least the ground contact end T. The drainage performance can be improved by extending the plurality of shoulder lug grooves 14A and 14B to the ground contact end T.

By the way, in the land portion Rs, the length of the zigzag-shaped edge between the adjacent shoulder lug grooves 14A and 14B in the tire circumferential direction is defined as Ls1. Further, the distance between the zigzag-shaped convex portions in the tire circumferential direction is defined as Ls2. At this time, the ratio Ls2 / Ls1 is preferably 0.15 or more and 0.55 or less. If the ratio Ls2 / Ls1 is less than 0.15, the zigzag-shaped unevenness becomes too fine and easily chipped, which is not preferable. If the ratio Ls2 / Ls1 exceeds 0.55, the edge effect cannot be sufficiently obtained and the snow performance is not improved.

Further, in the land portion Rs, the ground contact width in the tire width direction is Ws1. Further, in the land portion Rs, the length of Ws3 is twice the amplitude in the tire width direction of the zigzag shape of the edge on the circumferential direction main groove 12B side. The length Ws3 is the length (that is, the width) of the zigzag-shaped convex portion in the tire width direction. At this time, the ratio Ws2 / Ws1 is preferably 0.02 or more and 0.15 or less. If the ratio Ws2 / Ws1 is less than 0.02, the edge effect does not appear and the snow performance does not improve. If the ratio Ws2 / Ws1 exceeds 0.15, the drainage property is hindered and the drainage performance deteriorates.

In the above description, the land portion Rs outside the tire width direction of the circumferential main groove 12B has been described, but the same description applies to the land portion Rs outside the tire width direction of the circumferential main groove 12A.

[Three-dimensional part of compound sipe]
FIG. 12 is a cross-sectional view showing an example of a three-dimensional portion of the composite sipe 16 in FIG. FIG. 12 is a diagram showing a cross section obtained by cutting a section of a three-dimensional portion of the composite sipe 16 at a plane orthogonal to the extending direction (that is, the length direction) of the sipe. In FIG. 12, the length in the sipe depth direction from the opening end 9A to the tread of the composite sipe 16 to the groove bottom 9B, that is, the groove depth is DS. The groove width (that is, the sipe width) of the composite sipe 16 is Ts.

The vicinity of the opening end 9A of the composite sipe 16 is a straight line portion 9 along the sipe depth direction. The composite sipe 16 has a curved or bent shape with respect to the sipe depth direction. The amplitude of the curve or bend in the sipe width direction about the line 9L which is an extension of the center line of the straight line portion 9 is As. The ratio As / Ts of the amplitude As to the groove width Ts is preferably 0.40 or more and 0.80 or less. If the ratio As / Ts exceeds 0.80, the mold will not come off easily during vulcanization molding, resulting in failure, which is not preferable. If the ratio As / Ts is less than 0.40, the collapse cannot be suppressed, the block rigidity does not increase, and the wear resistance performance does not improve, which is not preferable.

Further, in FIG. 12, one cycle of bending or bending of the composite sipe 16 is S. The composite sipe 16 preferably has a curved shape or a bent shape having one cycle or more and three cycles or less. If it is less than one cycle, the effect of suppressing the collapse becomes insufficient and the block rigidity does not increase, which is not preferable. If it exceeds 3 cycles, the mold will not come out easily during vulcanization molding and a failure will occur, which is not preferable.

The other composite sipe 15 and 17 in FIG. 2 also have the same structure as the above composite sipe 16.

[Groove depth]
FIG. 13 is a cross-sectional view taken along the extending direction of the sipe 16 of FIG. FIG. 13 shows the two-dimensional portion and the three-dimensional portion without distinguishing them. The ratio DS / Dg of the groove depth DS of the sipe 16 to the groove depth Dg of the circumferential main groove 11A is preferably 0.50 or more and 0.85 or less. If the ratio DS / Dg is larger than 0.85, the block rigidity is lowered and the wear resistance is lowered, which is not preferable. If the ratio DS / Dg is smaller than 0.50, the edge effect is insufficient and the snow performance is lowered, which is not preferable.

As shown in FIG. 13, a bottom raising portion 160 is provided at the connecting portion of the sipe 16 to the circumferential main groove 11A. The bottom raising portion 160 is a sipe bottom raising portion provided on the sipe 16. The ratio DS1 / DS of the groove depth DS1 of the sipe 16 in the bottom raising portion 160 to the groove depth DS of the sipe 16 is preferably 0.50 or more and 0.85 or less. If the ratio DS1 / DS is larger than 0.85, the block rigidity is lowered and the wear resistance is lowered, which is not preferable. If the ratio DS1 / DS is smaller than 0.50, the edge effect is insufficient and the snow performance is lowered, which is not preferable.

[Modification example]
The above has described the case where the four circumferential main grooves 11A, 11B, 12A and 12B are provided. It suffices to have three or more main grooves in the circumferential direction. When there are three circumferential main grooves, the tread portion has one tread portion in FIG. 2 with two circumferential main grooves 11A and 11B, and the center land portion Rc does not exist.

[Example]
Tables 1 to 4 are tables showing the results of performance tests of pneumatic tires according to the present invention. In this performance test, different pneumatic tires were evaluated for chipping resistance, snow braking performance, snow handling performance, and drainage performance. In these performance tests, test tires of size 225 / 65R17 102H were mounted on rims of rim size 17 × 7.0J and an air pressure of 230 [kPa] was applied. Further, as a test vehicle, an FF (Front engine Front drive) SUV (Sport Utility Vehicle) vehicle having a displacement of 2500 [cc] was used.

In the evaluation of dry steering stability performance, the test vehicle runs on a test course on a dry road surface having a flat circuit at 60 [km / h] to 100 [km / h]. Then, the test driver performed a sensory evaluation on the steerability at the time of lane change and cornering and the stability at the time of going straight. This evaluation is performed by an index evaluation based on the conventional example (100), and the larger the value, the more preferable.

In the evaluation of uneven wear resistance performance, the test vehicle traveled 10,000 [km] on a paved road, and then the amount of wear and the tire width direction of the inner edge in the tire width direction (center land side) having the raised portion of the lug groove. The amount of wear on the outer edge (on the land side of the shoulder) was measured, and the uneven wear amount ratio was calculated. The uneven wear amount ratio was evaluated by an index based on the conventional example described later (100). The larger the index value, the more preferable.

The snow braking performance was evaluated by indexing the braking distance at a speed of 30 km / h on a snowy road surface. This evaluation was evaluated by an index based on the conventional example (100) described later. The larger the value of the index, the more preferable.

The snow handling performance was evaluated by indexing the feeling of the test driver for steering stability on snowy roads. This evaluation was evaluated by an index based on the conventional example (100) described later. The larger the value of the index, the more preferable.

The drainage performance was evaluated by an index that traveled in a hydropool at a water depth of 10 ± 1 [mm], measured the speeds at which slip rates reached 10% and 15%, and compared them with the conventional example described later as 100. This evaluation was evaluated by an index based on the conventional example (100). The larger the value of the index, the more preferable.

The pneumatic tires of Examples 1 to 25 include a plurality of lug grooves provided on land and sipes provided between adjacent lug grooves. Further, in the pneumatic tires of Examples 1 to 25, the lug groove continuously extends from the outer edge in the tire width direction of the land portion to the inner edge in the tire width direction, penetrates the land portion, and sipes. Continuously extends from the outer edge in the tire width direction of the land portion to the inner edge in the tire width direction and penetrates the land portion. Further, in the pneumatic tires of Examples 1 to 25, the sipe is a composite sipe having a two-dimensional portion and a three-dimensional portion, the two-dimensional portion is provided at one open end of the sipe, and the three-dimensional portion is provided. It is provided at the other open end of the sipe. Further, the pneumatic tires of Examples 1 to 25 include a bottom raising portion provided at the end of the lug groove on the same side as the end of the sipe provided with the two-dimensional portion on the land portion.

For the pneumatic tires of Examples 1 to 25, the settings are as shown in Tables 1 to 4. That is, the ratio Wc2 / W1 of the length Wc2 of the three-dimensional portion to the width W1 of the land portion Rm is 0.25 or more and 0.80 or less, and the bottom raising portion with respect to the width W1 of the land portion Rm. The ratio Wu / W1 of the length Wu is 0.15 or more and 0.50 or less, and the ratio Du / DL of the groove depth Du at the bottom raising portion of the lug groove to the groove depth DL of the lug groove is Those having 0.40 or more and 0.80 or less and those not having it, and those having a ratio DS / Dg of the groove depth Ds of the sipe to 0.50 or more and 0.85 or less with respect to the groove depth Dg of the main groove in the circumferential direction. And not, the ratio DS1 / DS of the groove depth DS1 of the sipe bottom raising part to the groove depth DS of the sipe is 0.50 or more and 0.85 or less and not, the groove width Ts of the three-dimensional part The ratio As / Ts of the amplitude As to 0.40 or more and 0.80 or less is 0.40 or more and 0.80 or less, and the ratio Db / W1 of the distance between the bent portion and the center line to the width of the land portion is 0 or more and 0. We prepared the ones with 40 or less and the ones without. The sipe shape was substantially Z-shaped.

In Table 1, the pneumatic tire of the conventional example is a tire which is a 2D sipe in which the entire tread portion has a straight shape and is composed of only a two-dimensional portion. Further, in Table 1, the pneumatic tire of the comparative example is a tire in which the entire sipe of the tread portion has a straight shape and is a 3D sipe composed of only the three-dimensional portion.

In Tables 1 to 4, the sipe shape "2D" indicates that the sipe is a sipe composed of only two-dimensional portions. The sipe-shaped "3D" indicates that the sipe is composed of only three-dimensional parts. The sipe shape "2D + 3D" indicates that it is a composite sipe composed of a two-dimensional part and a three-dimensional part.

For these pneumatic tires, dry steering stability performance, uneven wear resistance performance, snow braking performance, snow handling performance, and drainage performance were evaluated by the above evaluation method, and the results are shown in Tables 1 to 4 together. Indicated.

As shown in Tables 1 to 4, when the ratio Wc2 / W1 of the length Wc2 of the three-dimensional portion to the width W1 of the land portion Rm is 0.30 or more and 0.80 or less, it is relative to the width W1 of the land portion Rm. When the ratio Wu / W1 of the length Wu of the bottom raising portion is 0.15 or more and 0.50 or less, the ratio Du / DL of the groove depth Du of the bottom raising portion to the lug groove depth DL is 0.40 or more and 0. When it is .80 or less, the ratio DS / Dg of the groove depth DS of the sipe to the groove depth Dg of the circumferential main groove is 0.50 or more and 0.85 or less, the groove depth DS of the sipe. When the ratio DS1 / DS of the groove depth DS1 of the sipe bottom raising portion is 0.50 or more and 0.85 or less, the ratio As / Ts of the amplitude As to the groove width Ts of the three-dimensional portion is 0.40 or more and 0.80. In the following cases, good results were obtained when the ratio Db / W1 of the distance between the bent portion and the center line to the width of the land portion was 0 or more and 0.40 or less.

1 Tread part 2 sidewall part 3 bead part 4 carcass layer 5 bead core 6 bead filler 7 belt layer 8 belt cover layer 10 pneumatic tires 11A, 11B, 12A, 12B circumferential main grooves 13, 14A, 14B lug grooves 15, 16 , 17 Sipe 18 Decorative groove 130, 160 Bottom raising part As Amplitude CL Tire equatorial plane Rc Center land part Rm Middle land part Rs Shoulder land part T Tire ground contact end Ts Groove width

Claims (15)

Pneumatic tires with a tread pattern
The tread pattern is
Three or more circumferential main grooves extending in the tire circumferential direction,
Of the three or more circumferential main grooves, the land portion partitioned by the two circumferential main grooves and
A plurality of lug grooves provided in the land area and
A sipe provided on the land portion and between the adjacent lug grooves,
Including
The lug groove continuously extends from the outer edge in the tire width direction of the land portion to the inner edge in the tire width direction and penetrates the land portion.
The sipe extends continuously from the outer edge of the land portion in the tire width direction to the inner edge of the tire width direction, and penetrates the land portion.
The sipe is a composite sipe having a two-dimensional part and a three-dimensional part.
The two-dimensional portion is provided at one open end of the sipe.
The three-dimensional portion is provided at the other open end of the sipe.
Further, a pneumatic tire including a bottom raising portion provided at an opening end on the same side as the end portion of the sipe provided with the two-dimensional portion among the opening ends on both sides of the lug groove in the land portion. The first aspect of claim 1, wherein the opening ends on both sides of the lug groove on the land portion on the same side as the end portion of the sipe provided with the three-dimensional portion do not have a bottom raising portion. Pneumatic tires. The pneumatic tire according to claim 1 or 2, wherein the ratio of the length of the three-dimensional portion in the tire width direction to the ground contact width in the tire width direction of the land portion is 0.25 or more and 0.80 or less. .. The ratio of the length of the raised portion in the tire width direction to the ground contact width in the tire width direction of the land portion is 0.15 or more and 0.50 or less according to any one of claims 1 to 3. Pneumatic tires. 1. The ratio of the groove depth of the portion of the lug groove where the bottom raising portion is provided to the groove depth of the portion where the bottom raising portion is not provided is 0.40 or more and 0.80 or less. The pneumatic tire according to any one of claims 4. The pneumatic tire according to any one of claims 1 to 5, wherein the ratio of the groove depth of the composite sipe to the groove depth of the circumferential main groove is 0.50 or more and 0.85 or less. .. Further including a sipe bottom raising portion provided in the two-dimensional portion of the composite sipe,
In the composite sipe, the ratio of the groove depth of the portion provided with the sipe bottom raising portion to the groove depth of the portion not provided with the sipe bottom raising portion is 0.50 or more and 0.85 or less. The pneumatic tire according to any one of claims 1 to 6. The three-dimensional portion of the composite sipe includes a straight portion near the opening end and a portion deeper than the straight portion.
The portion deeper than the straight portion has a shape having an amplitude of bending or bending in the sipe depth direction.
The pneumatic tire according to any one of claims 1 to 7, wherein the ratio of the amplitude to the groove width of the straight portion is 0.40 or more and 0.80 or less. The sipe has a Z-shape with two bends
Of the two bent portions, the distance between the bent portion closer to the center line passing through the midpoint position in the tire width direction of the land portion and the center line in the tire width direction is the distance in the tire width direction of the land portion. The pneumatic tire according to any one of claims 1 to 8, wherein the ratio to the width is 0 or more and 0.40 or less. The outer edge of the land portion in the tire width direction is a zigzag-shaped zigzag edge having irregularities whose position in the tire width direction changes periodically, and the inner edge of the land portion in the tire width direction is a straight shape.
The pneumatic tire according to any one of claims 1 to 9, wherein the three-dimensional portion of the sipe is connected to the zigzag edge. The pneumatic tire according to claim 10, wherein the sipes are connected to the maximum amplitude position in the tire width direction of the zigzag edge. The pneumatic tire according to claim 10 or 11, wherein the ratio of the minimum value of the distance between the zigzag-shaped protrusions to the maximum value of the distance between the zigzag-shaped protrusions is 0.50 or more. The land portion according to any one of claims 10 to 12, wherein the land portion has two or more said sipes and three or more said zigzag-shaped convex portions between adjacent lug grooves. Pneumatic tires. The distance in the tire circumferential direction between the connection portions of the two or more sipes provided between the adjacent lug grooves to the circumferential main groove on the inner side in the tire width direction is Ls1, Ls2, ..., Lsn (n is The pneumatic tire according to claim 13, wherein Ls1 <Lsn, where 3 or more is a natural number). The distance in the tire circumferential direction between the connecting portions of the two or more sipes provided between the adjacent lug grooves to the circumferential main groove on the inner side in the tire width direction is Ls1, Ls2, ..., Lsn (n is Natural number of 3 or more)
The distances in the tire circumferential direction between the convex portions of the connection portions of the plurality of sipes provided between the adjacent lug grooves to the circumferential main groove on the outer side in the tire width direction are Lz1, Lz2, ..., Lzn (n). The pneumatic tire according to claim 13 or 14, wherein Ls1 <Lz1 and Lsn> Lzn in the case of (a natural number of 3 or more).

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