JP2015209169A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire that is excellent in abrasion resistance performance on a dry road surface and balance between wet turning performance and on-snow controllability/stability performance.SOLUTION: A tread pattern of a pneumatic tire includes: two outer circumferential main grooves arranged outside in a tire width direction; two inner circumferential main grooves sandwiched between the outer circumferential main grooves; a plurality of lug grooves crossing two regions of intermediate land parts partitioned by the outer circumferential main grooves and the inner circumferential main grooves; and circumferential shallow grooves, whose groove depths are shallower than the groove depths of the circumferential main grooves, which are provided respectively at the regions of the intermediate land parts and partition a land part block into an inner intermediate land part block and an outer intermediate land part block. In the region of the inner intermediate land part block are provided three-dimentional shape inner sipes extending inside in the tire width direction from the circumferential shallow grooves. In the region of the outer intermediate land part block are provided planar-shape outer sipes extending outside in the tire width direction from the circumferential shallow grooves.

Description

  The present invention relates to a pneumatic tire provided with a tread pattern.

  All-season tires used throughout the year: four circumferential main grooves, inner land area defined by two inner circumferential main grooves, outer circumferential main groove and inner circumferential direction A tire having two intermediate land areas defined by a main groove is conventionally known (see Patent Document 1). In the tire of Patent Document 1, lug grooves are provided in the region of the inner land portion and the region of the intermediate land portion, and the lug grooves in the two intermediate land portions extend inclining in the same direction with respect to the tire circumferential direction. At the same time, the lug groove in the region of the inner land portion extends in a different direction from the lug groove in the region of the intermediate land portion in a tire circumferential direction. According to the tire of Patent Document 1, the dry performance can be improved while maintaining the snow performance.

JP 2010-168006 A

The all-season tire is desirably provided with tire performance that can cope with various road surface conditions such as dry, wet, and snow. However, in the tire of Patent Document 1, the balance between the wear resistance performance on the dry road surface, the wet performance and the snow performance is not sufficient. Specifically, if the wet turning performance and the snow handling stability performance are to be improved, the wear resistance performance on the dry road surface is lowered.
The present invention provides a pneumatic tire that improves wet turning performance and snow handling stability performance while maintaining at least wear resistance performance on a dry road surface.

One embodiment of the present invention is a pneumatic tire including a bead, a sidewall, a belt layer, a carcass layer, and a tread portion having a tread pattern.
The tread pattern is
Four circumferential main grooves parallel to the tire circumferential direction, including two outer circumferential main grooves and two inner circumferential main grooves sandwiched between the outer circumferential main grooves, A circumferential main groove group in which the tire center line passes between the inner circumferential main grooves,
A region of a central land portion defined by the two inner circumferential main grooves and through which the tire center line passes, and two intermediate lands defined by the outer circumferential main groove and the inner circumferential main groove A plurality of lug grooves that form a plurality of land blocks in the region of the central land and the intermediate land,
Provided in each of the regions of the intermediate land portion and extending in the tire circumferential direction, the intermediate land portion block of the intermediate land portion is located on the inner side in the tire width direction and the outer intermediate portion located on the outer side in the tire width direction. A circumferential shallow groove having a groove depth shallower than the circumferential main groove, which is divided into land blocks.
The lug grooves provided in each of the regions of the intermediate land portion, when proceeding from the outer side in the tire width direction to the inner side in the tire width direction, the inclination of the lug groove approaches the tire circumferential direction at a position intersecting with the shallow circumferential groove. Has a bent portion bent to
The direction of the lug groove that crosses the region of the central land portion from the outer side in the tire width direction toward the inner side in the tire width direction of the lug groove, and the region of the intermediate land portion of the lug groove The direction in which the lug groove that crosses the tire from the outer side in the tire width direction toward the inner side in the tire width direction is opposite to each other with respect to the direction in the tire width direction.
An inner sipe extending inward in the tire width direction from the circumferential shallow groove is provided in the area of the inner middle land block, and an outer side in the tire width direction from the circumferential shallow groove in the area of the outer intermediate land block. An outer sipe is provided that extends to.
The inner sipe satisfies zigzag from the tread surface to the inside of the tread or in a direction inclined with respect to the tire radial direction, and extends zigzag on the tread surface;
The outer sipe satisfies at least one of linearly extending along the tire radial direction from the tread surface to the inside of the tread and linearly extending on the tread surface.

Another embodiment of the present invention is a pneumatic tire including a bead, a sidewall, a belt layer, a carcass layer, and a tread portion having a tread pattern.
The tread pattern is
Four circumferential main grooves parallel to the tire circumferential direction, including two outer circumferential main grooves and two inner circumferential main grooves sandwiched between the outer circumferential main grooves, A circumferential main groove group in which the tire center line passes between the inner circumferential main grooves,
A region of a central land portion defined by the two inner circumferential main grooves and through which the tire center line passes, and two intermediate lands defined by the outer circumferential main groove and the inner circumferential main groove A plurality of lug grooves that form a plurality of land blocks in the region of the central land and the intermediate land,
Provided in each of the regions of the intermediate land portion and extending in the tire circumferential direction, the intermediate land portion block of the intermediate land portion is located on the inner side in the tire width direction and the outer intermediate portion located on the outer side in the tire width direction. A circumferential shallow groove having a groove depth shallower than the circumferential main groove, which is divided into land blocks.
The lug grooves provided in each of the regions of the intermediate land portion, when proceeding from the outer side in the tire width direction to the inner side in the tire width direction, the inclination of the lug groove approaches the tire circumferential direction at a position intersecting with the shallow circumferential groove. Has a bent portion bent to
The direction of the lug groove that crosses the region of the central land portion from the outer side in the tire width direction toward the inner side in the tire width direction of the lug groove, and the region of the intermediate land portion of the lug groove The direction in which the lug groove that crosses the tire from the outer side in the tire width direction toward the inner side in the tire width direction is opposite to each other with respect to the direction in the tire width direction.
An inner sipe extending inward in the tire width direction from the circumferential shallow groove is provided in the area of the inner middle land block, and an outer side in the tire width direction from the circumferential shallow groove in the area of the outer intermediate land block. An outer sipe is provided that extends to.
The inner sipe extends linearly along the tire radial direction from the tread surface to the inside of the tread, and satisfies a zigzag shape extending on the tread surface;
The outer sipe satisfies linearly extending along the tire radial direction from the tread surface to the inside of the tread and linearly extending on the tread surface.

The groove bottom of the lug groove in the peripheral region of the lug groove including the crossing portion of the lug groove intersecting the circumferential shallow groove has a groove depth compared to the groove bottom of the region deviated from the peripheral region of the intersection. Forming a shallow raised bottom,
Of the raised portion of the lug groove, the length along the lug groove of the portion extending inward in the tire width direction from the intersecting portion is the length of the portion of the raised portion extending outward in the tire width direction from the intersecting portion. It is preferable that the length is longer than the length along the lug groove.

Yet another embodiment of the present invention is a pneumatic tire including a bead, a sidewall, a belt layer, a carcass layer, and a tread portion having a tread pattern.
The tread pattern is
Four circumferential main grooves parallel to the tire circumferential direction, including two outer circumferential main grooves and two inner circumferential main grooves sandwiched between the outer circumferential main grooves, A circumferential main groove group in which the tire center line passes between the inner circumferential main grooves,
A region of a central land portion defined by the two inner circumferential main grooves and through which the tire center line passes, and two intermediate lands defined by the outer circumferential main groove and the inner circumferential main groove A plurality of lug grooves that form a plurality of land blocks in the region of the central land and the intermediate land,
Provided in each of the regions of the intermediate land portion and extending in the tire circumferential direction, the intermediate land portion block of the intermediate land portion is located on the inner side in the tire width direction and the outer intermediate portion located on the outer side in the tire width direction. A circumferential shallow groove having a groove depth shallower than the circumferential main groove, which is divided into land blocks.
The lug grooves provided in each of the intermediate land regions are bent so that the groove inclination approaches the tire circumferential direction at a position intersecting with the circumferential shallow groove when proceeding from the tire width direction outer side to the tire width direction inner side. Have a bend,
The direction of the lug groove that crosses the region of the central land portion from the outer side in the tire width direction toward the inner side in the tire width direction of the lug groove, and the region of the intermediate land portion of the lug groove The direction in which the lug groove that crosses the tire from the outer side in the tire width direction toward the inner side in the tire width direction is opposite to each other with respect to the direction in the tire width direction.
The groove bottom of the crossing peripheral region of the lug groove including the crossing portion of the lug groove intersecting the circumferential shallow groove and the region before and after the crossing portion is compared with the groove bottom of the region deviating from the crossing peripheral region. A raised bottom is formed.
Of the raised portion of the lug groove, the length along the lug groove of the portion extending inward in the tire width direction from the intersecting portion is the length of the portion of the raised portion extending outward in the tire width direction from the intersecting portion. Longer than the length along the lug groove.

  At the position where the lug groove intersects the inner circumferential main groove, the inner intermediate land block has an acute angle corner portion formed at an acute angle by the lug groove and the inner circumferential main groove. And it is preferable that the width | variety in the tire width direction of the said inner middle land part block becomes large as it approaches the said acute angle corner | angular part in a tire circumferential direction.

  The center position in the tire width direction of the circumferential shallow groove is from the edge in contact with the inner intermediate land portion of the inner circumferential main groove by a distance of 40 to 60% of the maximum width in the tire width direction of the intermediate land portion. It is preferable that it exists in a distant position.

In the outer intermediate land block, the obtuse angle portion formed at an obtuse angle by the lug groove and the outer circumferential main groove at the position where the lug groove intersects the outer circumferential main groove, Has an outer middle land block,
A chamfer extending in the tire circumferential direction from the obtuse angle corner is provided at an edge where the outer intermediate land block contacts the outer circumferential main groove, and the chamfer is chamfered as the distance from the obtuse angle corner increases in the tire circumferential direction. It is preferable that the width is reduced, and the end is made on the way to the corner on the opposite side of the obtuse corner of the edge in the tire circumferential direction.

  A shoulder land portion is provided on the outer side in the tire width direction of the outer circumferential main groove, and the outer circumferential direction main groove extends from the tire width direction outer side to the tire width direction inner side in the region of the shoulder land portion. It is preferable that a shoulder lug groove which is closed without being connected to is provided.

  The width of the shoulder lug groove is preferably wider than the maximum groove width of the lug groove.

  According to the above-described tire, it is possible to improve wet turning performance and on-snow maneuvering stability performance while maintaining at least wear resistance performance on a dry road surface.

1 is an external view illustrating an entire tire according to an embodiment of the present invention. FIG. 2 is a half sectional view showing a part of the tire of FIG. 1. It is the figure which carried out the plane development view so that the tread pattern of the tire of an embodiment was easy to understand. It is a figure which expands and shows the tread pattern shown in FIG. 3 paying attention to a central land part and a middle land part. It is a figure which expands and shows the intermediate land part shown in FIG. It is a figure explaining an example of the sipe used for the middle land part shown in FIG. It is a figure explaining the other example of the sipe used for the middle land part shown in FIG. It is a figure explaining the other example of the sipe used for the middle land part shown in FIG. It is a figure explaining the other example of the sipe used for the middle land part shown in FIG.

Hereinafter, the pneumatic tire of the present invention will be described in detail.
In FIG. 1, the external appearance of the pneumatic tire 1 which is one Embodiment of this invention is shown.
A pneumatic tire (hereinafter referred to as a tire) 1 is a tire for a passenger car.
As the structure and rubber member of the tire 1 of the present invention, known ones may be used, or new ones may be used, and there is no particular limitation in the present invention.

As shown in FIG. 2, the tire 1 includes a tread portion 2, sidewalls 3, beads 4, a carcass layer 5, and a belt layer 6. FIG. 2 is a half sectional view showing a part of the tire 1. In addition, although not shown, the tire 1 has an inner liner layer and the like. The sidewall 3 and the bead 4 are disposed on both sides in the tire width direction so as to sandwich the tread portion 2 and form a pair.
As the tread portion 2, the bead 4, the belt layer 6, the inner liner layer and the like, known ones may be used, or new ones may be used, and there is no particular limitation in the present invention.

  As shown in FIG. 3, the tire 1 of the present invention has a tread pattern 10 that is a feature of the present invention formed in a tread portion. FIG. 3 is a plan development view of the tread pattern 10 of the tire 1 of the present invention in an easy-to-understand manner. The tire 1 having the tread pattern 10 can be suitably used for a passenger car tire. The dimensions of the circumferential main groove, lug groove, sipe, ground contact width, chamfer, circumferential direction shallow groove, shoulder lug groove, and land block, which will be described later, are numerical examples of passenger car tires.

  In the tire 1 of the present invention, the mounting direction of the tire to be mounted toward the outside of the vehicle is predetermined. In FIG. 3, the symbol CL indicates a tire center line (tire equator line). In the tire 1, the region of the tread pattern 10 on the left side in FIG. 3 from the tire equator line CL is mounted on the vehicle inner side, and the region of the tread pattern 10 on the right side in FIG. However, conversely, the vehicle inner side and the vehicle outer side may be reversed and attached to the vehicle.

The tread pattern 10 contacts the road surface in a tire width direction region indicated by a contact width 11w in a state where the tire 1 is mounted on the vehicle. In addition, the area | region shown with a diagonal line in the tread pattern 10 is an area | region outside a tire peripheral direction from a contact end.
Here, the grounding end is determined as follows. The tire width direction end portion of the contact surface when the tire 10 is assembled to a normal rim, filled with a normal internal pressure of 180 kPa, and brought into contact with a horizontal plane under the condition that the load is 88% of the normal load. The regular rim here refers to an “applied rim” defined in JATMA, a “Design Rim” defined in TRA, or a “Measuring Rim” defined in ETRTO. In addition, the normal internal pressure means “maximum air pressure” prescribed by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” prescribed by TRA, or “INFLATION PRESSURES” prescribed by ETRTO. 180 kPa when the tire is for a passenger car. The normal load means “maximum load capacity” defined in JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined in TRA, or “LOAD CAPACITY” defined in ETRTO.

In the present invention, the tire width direction refers to the rotation center axis direction of the tire 1, and the tire circumferential direction refers to the rotation direction of the rotation surface of the tread surface formed when the tire 1 is rotated around the tire rotation center axis. Say. The outer side in the tire width direction refers to the side away from the tire center line CL with respect to a certain position for comparison, and the inner side in the tire width direction refers to the side closer to the tire center line CL with respect to the position for comparison. FIG. 3 shows these directions. In the tread pattern 10 of the present invention, the rotation direction of the tire is not particularly limited.
The tire 1 of the present invention may be one in which pitches having the same dimensions in the tire circumferential direction are aligned with the tread pattern 10 shown in FIG. 3 in the tire circumferential direction. May be a plurality of pitches having different dimensions in the tire circumferential direction arranged in the tire circumferential direction.

  The tread pattern 10 includes a circumferential main groove group including four circumferential main grooves 11, 13, 15, 17 parallel to the tire circumferential direction, lug grooves 31, 33, 35, and circumferential shallow grooves 41, 43. And.

(Circumferential groove group)
The circumferential main groove group includes two outer circumferential main grooves 11 and 13 and two inner circumferential main grooves 15 and 17. The outer circumferential main grooves 11 and 13 are arranged on the outer side in the tire width direction with respect to the inner circumferential main grooves 15 and 17. The two inner circumferential main grooves 15 and 17 are disposed between the outer circumferential main grooves 11 and 13. A tire center line CL passes between the inner circumferential main groove 15 and the inner circumferential main groove 17 in the tire width direction. The groove depths of the outer circumferential main grooves 11 and 13 and the inner circumferential main grooves 15 and 17 are equal to each other, but may be different in other embodiments. The total amount of the groove widths of the outer circumferential main grooves 11 and 13 and the inner circumferential main grooves 15 and 17 is preferably 15 to 25% of the ground contact width 11w in terms of wet performance.

(Lug groove)
The lug grooves 31, 33, and 35 are grooves that cross the region of the central land portion 21 and the regions of the intermediate land portions 23 and 25, and a plurality of lug grooves are provided at intervals in the tire circumferential direction. Each of the lug groove 31 and the lug grooves 33 and 35 may extend linearly or may be curved and extended gently. The groove widths 31w, 33w, and 35w of the lug grooves 31, 33, and 35 are all equal in the tire width direction, and are, for example, 2 to 7 mm.

Here, the central land portion 21 and the intermediate land portions 23 and 25 will be described.
The central land portion 21 is a portion formed by being defined by the two inner circumferential main grooves 15 and 17. The tire center line CL passes through the region of the central land portion 21. The lug groove 31 forms a plurality of land portion blocks 22 in the tire circumferential direction in the region of the central land portion 21. As shown in FIG. 4, the lug groove 31 extends at an inclination angle θce with respect to the X2 direction in the tire circumferential direction. FIG. 4 is a partially enlarged view of the tread pattern 10. The inclination angle θce is, for example, 60 to 85 degrees. Thus, the lug groove 31 has an inclination angle closer to the tire width direction than the tire circumferential direction, so that high block rigidity of the land block 22 is ensured and a small rudder during vehicle travel is provided. Wet turning performance at corners and snow handling stability are improved. When the lug groove 31 is gently curved and extends, the inclination angle θce is determined in the width direction of the lug groove 31 at a portion where the lug groove 31 is connected to the inner circumferential main groove 15 and the inner circumferential main groove 17 respectively. The inclination with respect to the X2 direction of the straight line which connects two points in the center position of a connection is represented.

  The intermediate land portion 23 is a portion formed by the outer circumferential main groove 11 and the inner circumferential main groove 15. The lug grooves 33 form a plurality of land portion blocks 24 in the tire circumferential direction in the region of the intermediate land portion 23. Further, the intermediate land portion 25 is defined by the outer circumferential main groove 13 and the inner circumferential main groove 17, and is a portion formed between the outer circumferential main groove 13 and the inner circumferential main groove 17. is there. The lug grooves 35 form a plurality of land portion blocks 26 in the tire circumferential direction in the region of the intermediate land portion 25.

The direction of the groove inclination that inclines with respect to the X1 direction of the lug groove 33 that proceeds inward from the outer side in the tire width direction is the direction of the groove inclination that inclines with respect to the X2 direction of the lug groove 35 that proceeds inward from the outer side in the tire width direction. Is the same. In other words, the lug groove 33 and the lug groove 35 are inclined in the same direction with respect to the X1 direction or the X2 direction in the tire circumferential direction. The groove inclination direction is in the range of −90 degrees (90 degrees counterclockwise) to 90 degrees (90 degrees clockwise) with respect to the X1 direction or X2 direction of the tire circumferential direction. Represents the distinction between tilting in the range of 90 to 0 degrees or tilting in the range of 0 to 90 degrees, and grooves tilting in the same range have the same and different groove tilt directions. The grooves inclined in the angle range have different groove inclination directions.
On the other hand, when the lug groove 31 crosses the region of the central land portion 21 from the outer side in the tire width direction toward the inner side in the tire width direction, the lug groove 31 and the lug grooves 33 and 35 are inclined with respect to the tire width direction. When the tire crosses the region of the intermediate land portions 23 and 25 from the outer side in the tire width direction to the inner side, the direction in which the lug grooves 33 and 35 are inclined with respect to the tire width direction is opposite to the tire width direction. It is. Such a tilting direction of the groove ensures the steering performance when turning left and right.

  When the lug groove 33 further proceeds from the outer side in the tire width direction to the inner side in the tire width direction, the same direction in the tire circumferential direction (X1 direction) in the outer region in the tire width direction and the inner region in the tire width direction than the circumferential shallow groove 41. The lug groove 33 has a bent portion that bends so that the inclination of the groove approaches the tire circumferential direction at a position P (see FIG. 4) where the lug groove 33 intersects the circumferential shallow groove 41. Specifically, as shown in FIG. 4, the lug groove 33 is inclined at the inclination angle θm1 with respect to the X2 direction at the outer side in the tire width direction from the position P, and is inclined at the inclination angle θm2 with respect to the X1 direction at the inner side in the tire width direction from the position P. Inclined. The inclination angle θm2 is smaller than the inclination angle θm1. Thereby, the lug groove 33 is bent so that the groove inclination approaches the tire circumferential direction (X1 direction) when viewed from the outer side in the tire width direction toward the inner side in the tire width direction. The inclination angle θm1 of the groove inclination is, for example, 60 to 85 degrees. The inclination angle θm2 is, for example, 30 to 50 degrees. Thus, the lug groove 33 has two kinds of inclination angles, so that the turning is excellent even when turning from a small rudder angle to a medium rudder angle while the vehicle is traveling on a dry road surface, a wet road surface, and a snowy road surface. Performance and stable performance are obtained. When the inner portion of the lug groove 33 from the circumferential shallow groove 41 is gently curved and extends, the inclination angle θm1 is a portion where the lug groove 33 is connected to the outer circumferential main groove 11 and the circumferential shallow groove 41, respectively. The inclination with respect to the tire circumferential direction of the straight line which connects the two points in the center position of the groove width direction of the lug groove 33 is represented. In addition, when the lug groove 33 is gently curved and extends, the inclination angle θm2 is set in the groove width direction of the lug groove 33 at the portion where the lug groove 33 is connected to each of the inner circumferential main groove 15 and the circumferential shallow groove 41. The inclination with respect to the tire circumferential direction of a straight line connecting two points at the center position is represented.

  When the lug groove 35 further advances from the outer side in the tire width direction to the inner side in the tire width direction, the lug groove 35 is arranged in the tire circumferential direction in the region outside the tire width direction and the region inside the tire width direction from the circumferential shallow groove 43. While extending in the same direction (X2 direction), the lug groove 35 has a bent portion that bends so that the groove slope approaches the tire circumferential direction at a position Q (see FIG. 4) where the lug groove 35 intersects the circumferential shallow groove 43. Specifically, as shown in FIG. 4, the lug groove 35 is inclined at the inclination angle θm1 with respect to the X1 direction on the outer side in the tire width direction from the position Q, and is inclined with respect to the X2 direction at the inner side in the tire width direction from the position Q. The angle θm2 is inclined. Thereby, the lug groove 35 is bent so that the groove inclination approaches the tire circumferential direction (X2 direction) when viewed from the tire width direction outer side toward the tire width direction inner side. In addition, the inclination angle θm1 when the inner portion of the lug groove 35 from the circumferential shallow groove 43 extends while being gently curved is connected to each of the inner circumferential main groove 17 and the circumferential shallow groove 43 with the lug groove 35. The inclination with respect to the tire circumferential direction of the straight line which connects two points in the center position of the groove width direction of the partial lug groove 35 is represented. In addition, when the lug groove 35 is gently curved and extends, the inclination angle θm2 is set in the groove width direction of the lug groove 35 where the lug groove 35 is connected to each of the inner circumferential main groove 17 and the circumferential shallow groove 43. The inclination with respect to the tire circumferential direction of a straight line connecting two points at the center position is represented. In another embodiment of the lug groove 35, the inclination angle on the outer side in the tire width direction from the position Q may be larger than the inclination angle on the inner side in the tire width direction from the position Q, and the inclination angle on the inner side in the tire width direction from the position Q. May be smaller than the inclination angle outside the position Q in the tire width direction.

  From the viewpoint of securing block rigidity, a region on the inner land portion 23 on the inner side in the tire width direction with respect to the circumferential shallow groove 41 described later is compared with a region on the outer side in the tire width direction with respect to the circumferential shallow groove 41 described later. And preferably wide in the tire width direction. From the same point of view, a region on the inner land portion 25 on the inner side in the tire width direction with respect to the circumferential shallow groove 43 described later is a tire width compared to a region on the outer side in the tire width direction with respect to the circumferential shallow groove 43 described later. Wide in the direction is preferred.

(Circumferential shallow groove)
The circumferential shallow grooves 41 and 43 are provided in the regions of the intermediate land portions 23 and 25, respectively, and extend in the tire circumferential direction. The circumferential shallow grooves 41 and 43 divide the intermediate land portions 23 and 25 into inner intermediate land portions 23i and 25i and outer intermediate land portions 23o and 25o. The land blocks of the intermediate land portions 23 and 25 are divided into tire widths. The inner intermediate land blocks 24a and 26a located on the inner side in the direction and the outer intermediate land blocks 24b and 26b located on the outer side in the tire width direction are divided.
The circumferential shallow grooves 41, 43 are raised to a shallower depth than the circumferential main grooves 11, 13, 15, 17 and the lug grooves 33, 35. Thereby, the wet turning performance is improved while ensuring the block rigidity in the intermediate land portions 23 and 25 and the wear resistance on the dry road surface.
The groove depth of the circumferential shallow grooves 41, 43 is preferably 70% or less of the groove depth of the circumferential main grooves 11, 13, 15, 17 from the viewpoint of ensuring wear resistance. % Is preferred.
Moreover, it is preferable that the groove width of the circumferential shallow grooves 41 and 43 is 5 to 15% of the length in the tire width direction of the intermediate land portions 23 and 25, respectively. The length in the tire width direction of the intermediate land portions 23 and 25 indicates the maximum length in the tire width direction of the land portion blocks 22 and 24 on the tread surface.

Moreover, the center position of the circumferential shallow grooves 41 and 43 in the tire width direction is the middle of the inner circumferential main grooves 15 and 17 by a distance of 40 to 60% of the maximum width of the intermediate land portions 23 and 25 in the tire width direction. From the viewpoint of improving wear resistance, it is preferable that the position is away from the edge in contact with the land portions 23, 25, and more preferably, the center position in the tire width direction of the circumferential shallow grooves 41, 43 is the intermediate land portion. The inner circumferential main grooves 15 and 17 are separated from the edges in contact with the intermediate land portions 23 and 25 by a distance of more than 50% of the maximum width in the tire width direction of 23 and 25 and 60%. That is, in the intermediate land portions 23 and 25, the width of the land portion in the inner region in the tire width direction with respect to the circumferential shallow grooves 41 and 43 is the circumferential shallow groove 41 and 43 in the intermediate land portions 23 and 25. On the other hand, it is preferable that it is wider than the width of the land portion in the outer region in the tire width direction.
In addition, it is preferable that the circumferential direction shallow groove | channel is not provided in the area | region of the central land part 21, and the area | region of the shoulder land parts 51 and 53 mentioned later. These land portions 21, 51, and 53 contribute greatly to wet turning performance during braking and driving stability on snow, and providing a shallow circumferential groove provides both wet turning performance and wear resistance on dry road surfaces. This is because it cannot be achieved.

As described above, the circumferential shallow grooves 41 and 43 divide the land blocks 24 and 26 into the inner intermediate land blocks 24a and 26a and the outer intermediate land blocks 24b and 26b, while the lug grooves 33 and 35 The bent portion intersects with the circumferential shallow grooves 41 and 43, and the inclined direction is closer to the tire circumferential direction on the inner side in the tire width direction than the bent portion on the inner side in the tire width direction. For this reason, the inner intermediate land block 24a, 26a is provided with the sharpest acute angle portion among the corner portions in the land block 24, 26. For this reason, when the land blocks 24 and 26 do not have sipes described later, the inner intermediate land blocks 24a and 26a having the corners have lower block rigidity than the outer intermediate land blocks 24b and 26b. This point will be described later.

The groove depths of the circumferential shallow grooves 41 and 43 are shallower than the groove depths of the lug grooves 33 and 35 as described above. For this reason, the groove bottoms of the lug grooves 33 and 35 in the intersecting peripheral region including the portions where the lug grooves 33 and 35 intersect the circumferential shallow grooves 41 and 43 are compared with the groove bottoms in the region deviated from the intersecting peripheral region. A bottom raised portion having a shallow groove depth is formed. In the example shown in FIG. 5, a bottom raised portion 33 a of the lug groove 33 is shown. Among the raised portions of the lug grooves 33 and 35, the length along the lug grooves 33 and 35 of the portion extending inward in the tire width direction from the intersecting portion is the portion extending from the intersecting portion outward in the tire width direction in the raised portion. It is longer than the length along the lug grooves 33, 35. In the example of the lug groove 33 shown in FIG. 5, the length W _m1 along the lug grooves 33 and 35 of the portion 33 d extending from the intersecting portion 33 b to the inside in the tire width direction of the bottom raised portion 33 a of the lug groove 33 is the intersecting portion. It is longer than the length W _m2 along the lug grooves 33 and 35 of the portion 33e extending outward in the tire width direction from 33b.

  Thus, regarding the length of the bottom raised portion of the groove bottom of the lug grooves 33 and 35, the length of the bottom raised portion on the inner side in the tire width direction with respect to the intersecting portion is set to the length of the bottom raised portion with respect to the intersecting portion of the tire. The inner intermediate land block 24a, which has a lower block rigidity by providing the sharpest corners in the land blocks 24 and 26, is longer than the length of the outer portion in the width direction. , 26a is made close to the block rigidity of the outer intermediate land block 24b, 26b. As a result, the block rigidity of the inner intermediate land blocks 24a and 26a and the block rigidity of the outer intermediate land blocks 24b and 26b can be made close to each other, maintaining at least wear resistance and maintaining wet turning performance and snow handling stability. Performance can be improved.

(Sipe)
The tread pattern 10 further includes sipes 34a, 34b, 36a, 36b in the intermediate land portions 23, 25. FIG. 5 is an enlarged view of the intermediate land portion 23 shown in FIG.
In this specification, a sipe is one having a width of less than 1.5 mm and a groove depth of less than 5 mm. The lug groove refers to a groove having a groove width of 1.5 mm or more and a groove depth of 5 mm or more.
The sipes 34a, 34b, 36a, 36b are grooves extending so as to be parallel to the lug grooves 33, 35 in the respective intermediate land areas. Two sipes 34a are provided in the region of the inner intermediate land portion 23i, extend from the circumferential shallow groove 41 toward the inner circumferential main groove 15 and are closed in the region of the inner intermediate land portion 23i. . Two sipes 34b are provided in the region of the outer intermediate land portion 23o, and extend from the circumferential shallow groove 41 toward the outer circumferential main groove 11 to be connected to the outer circumferential main groove 11. Two sipes 36a are provided in the region of the inner intermediate land portion 25i, extend from the circumferential shallow groove 43 toward the inner circumferential main groove 17 side, and are closed in the region of the inner intermediate land portion 25i. . Two sipes 36b are provided in the region of the outer intermediate land portion 25o, and extend from the circumferential shallow groove 43 toward the outer circumferential main groove 13 to be connected to the outer circumferential main groove 13. Since the sipe 34a and the sipe 36a are provided in the inner intermediate land blocks 24a and 26a, they are referred to as inner sipe, and hereinafter referred to as inner sipe 34a and 36a. Since the sipe 34b and the sipe 36b are provided in the outer intermediate land blocks 24b and 26b, they are referred to as outer sipes, and hereinafter referred to as outer sipes 34b and 36b. In another embodiment, the number of sipes in one inner middle land block 24a, 26a and outer middle land block 24b, 26b may be one, or three or more.

The inner sipes 34a and 36a are respectively wave-shaped (zigzag) while being displaced in a direction orthogonal to the extending direction of the inner sipes 34a and 36a in the tire width direction inner region with respect to the circumferential shallow grooves 41 and 43, respectively. And extends in a wave shape (zigzag shape) at the bottom while being displaced in a direction from the tread surface toward the sipe bottom, that is, a direction orthogonal to the tire radial direction. That is, the inner sipes 34a and 36a extend in a wave shape from the tread surface to the inside of the tread, and extend in a wave shape on the tread surface. The sipe having such a shape of the inner sipes 34a and 36a is hereinafter also referred to as a three-dimensional shape.
On the other hand, the outer sipes 34b and 36b extend linearly along the tire radial direction from the tread surface to the inside of the tread, and extend linearly on the tread surface.

  The reason why the inner sipes 34a and 36a are three-dimensional sipes with respect to the outer sipes 34b and 36b is as follows. The innermost land blocks 24a and 26a are formed by innermost circumferential main grooves 15 and 17 and lug grooves 33 and 35, and the innermost land blocks 24 and 26 have innermost corners 23c and 25c. The block rigidity of the intermediate land block 24a, 26a is lowered. For this reason, in order to suppress the degree of further decrease by the inner sipes 34a and 36a, the inner sipes 34a and 36a are used with three-dimensional sipes that can suppress the decrease in block rigidity compared to the outer sipes 34b and 36b. That is, the inner intermediate land blocks 24a and 26a on the inner side in the tire width direction with respect to the circumferential shallow grooves 41 and 43 of the land blocks 24 and 26 are on the outer side in the tire width direction with respect to the circumferential shallow grooves 41 and 43. Compared to the outer intermediate land blocks 24b and 26b, the inclination angle of the lug grooves 33 and 35 with respect to the tire circumferential direction is small, and the block rigidity is low. For this reason, by making the inner sipes 34a and 36a into the above-mentioned three-dimensional shape, the block rigidity of the inner intermediate land blocks 24a and 26a that affect the wet turning performance and the on-snow maneuvering stability performance is appropriately maintained. As a result, the block rigidity of the inner intermediate land blocks 24a and 26a and the block rigidity of the outer intermediate land blocks 24b and 26b can be made close to each other, maintaining at least wear resistance and maintaining wet turning performance and snow handling stability. Performance can be improved.

  Such inner sipes 34a and 36a are not necessarily limited to three-dimensional sipes. The inner sipes 34a and 36a are designed so that the block rigidity of the inner intermediate land blocks 24a and 26a, which is reduced by having at least the sharp corners 23c and 25c, approaches the block rigidity of the outer intermediate land blocks 24b and 26b. The form may be determined according to the form of the outer sipes 34b and 36b.

As one form of the combination of the inner sipes 34a, 36a and the outer sipes 34b, 36b, the inner sipes 34a, 36a extend from the tread surface into the tread in a wave shape or in a direction inclined with respect to the tire radial direction, and The outer sipe 34b, 36b is linearly extended along the tire radial direction from the tread surface to the inside of the tread and is extended linearly on the tread surface. A form A that satisfies at least one of them is mentioned.
As another form of the combination of the inner sipes 34a and 36a and the outer sipes 34b and 36b, the inner sipes 34a and 36a extend linearly along the tire radial direction from the tread surface to the inside of the tread, and the tread. The outer sipe 34b, 36b is satisfied to extend linearly along the tire radial direction from the tread surface to the inside of the tread, and is satisfied to extend linearly on the tread surface. B is mentioned.

6 to 8 are diagrams showing examples of various sipes S. FIG. A sipe S shown in FIG. 6 is a three-dimensional sipe that extends in a wave shape from the tread surface to the inside of the tread and also extends in the wave shape on the tread surface. The sipe S shown in FIG. 7 is a sipe that extends linearly from the tread surface into the tread along the tire radial direction and also extends linearly on the tread surface.
The sipe S shown in FIG. 8 is a sipe that extends linearly along the tire radial direction from the tread surface to the inside of the tread and extends in a wave shape on the tread surface. A sipe S shown in FIG. 9 is a sipe that extends in a direction inclined with respect to the tire radial direction from the tread surface to the inside of the tread and extends in a wave shape on the tread surface, and is a three-dimensional sipe.
The sipe is closed so that there is no gap due to the force received from the road surface during braking, driving, or turning of the tire, and the wall surfaces inside the tread of the sipe are in contact with each other. If the surface irregularities that engage each other are formed on the wall surface at the time of this contact, when the sipe is closed, the tread rubber part that has been divided by the sipe is against the force received from the road surface as if there is no division. Drag is generated and block rigidity is maintained. This is also true for sipes that have a wave shape on the tread surface. Therefore, in the sipe S shown in FIGS. 6 to 9, the order of suppressing the decrease in the block rigidity due to the sipe is the sipe S shown in FIG. 6 and the sipe S shown in FIG. 9, and then the sipe S shown in FIG. 8. Finally, the sipe S shown in FIG. 7 is obtained.

Therefore, in the combination form A, for example, the sipe S shown in FIG. 6 or 9 is used for the inner sipes 34a and 36a, and the sipe S shown in FIG. 7 or 8 is used for the outer sipes 34b and 36b. it can.
In the combination form B, for example, the sipe S shown in FIG. 8 can be used for the inner sipes 34a and 36a, and the sipe S shown in FIG. 7 can be used for the outer sipes 34b and 36b.

  Thus, by applying the sipe shape that can suppress the decrease in the block rigidity to the inner sipe 34a, 36a as compared with the sipe shape of the outer sipe 32b, 34b, The balance of block rigidity of 23o and 25o is appropriate. Thereby, wet turning performance and on-snow maneuvering stability performance can be improved while maintaining at least wear resistance performance.

The tread pattern 10 further has a sipe 32.
The sipe 32 is a groove extending so as to be parallel to the lug groove 31 in the region of the central land portion 21. Two sipes 32 are provided for each land block 22. In other embodiments, one land block 22 or three or more may be provided per land block 22. The sipe 32 has a three-dimensional shape, which reinforces the block rigidity of the central land portion 21 during braking / driving. The sipe 32 is connected to the inner circumferential main grooves 15 and 17. In another embodiment, the sipe 32 may have a two-dimensional shape, and may be closed within the central land portion 21 without being connected to the inner circumferential main grooves 15 and 17.

As described above, the inner intermediate land blocks 24a and 26a are configured such that the lug grooves 33 and 35 and the inner circumferential main grooves 15 and 35 are located at positions where the lug grooves 33 and 35 intersect the inner circumferential main grooves 15 and 17, respectively. 17 and acute angle corner portions 23c and 25c having tips formed at an acute angle. At this time, the width in the tire width direction of the inner intermediate land block 24a, 26a becomes wider as it approaches the acute angle portions 23c, 25c in the tire circumferential direction. FIG. 5 shows an example of the inner intermediate land block 24a. That is, the width in the tire width direction of the inner intermediate land block 24a becomes wider from the minimum width w _min toward the acute angle portion 23c, and the maximum width w _max is reached at the acute angle portion 23c. Here, the minimum width w _min and the maximum width w _max are preferably set such that the block width change rate (w _max −w _min ) / w _max is 0.05 to 0.2. If the block width change rate (w _max −w _min ) / w _max exceeds 0.2, the balance of the block rigidity of the inner intermediate land blocks 24a and 26a and the outer intermediate land blocks 24b and 26b is not preferable. If the block width change rate (w _max −w _min ) / w _max is less than 0.05, the difference in block stiffness between the area around the acute corner of the inner intermediate land blocks 24a and 26a and the other areas is When spreading, braking, driving, or turning, the area around the sharp corners of the inner intermediate land blocks 24a, 26a is greatly deformed, maintaining wet resistance and at least maintaining wet-resistant performance and snow handling stability It is not preferable in terms of performance.

(Shoulder land)
The tread pattern 10 further has a shoulder land portion 51 in a region outside the outer circumferential main groove 11 in the tire width direction. Further, a shoulder land portion 53 is provided in a region on the outer side in the tire width direction of the outer circumferential main groove 13.
In the regions of the shoulder land portions 51 and 53, shoulder lug grooves 61 and 63 extending from the outer side in the tire width direction toward the outer circumferential main grooves 11 and 13, respectively, are provided. The shoulder lug grooves 61 and 63 are closed on the way without being connected to the outer circumferential main grooves 11 and 13, respectively. Thereby, the shoulder land parts 51 and 53 form the continuous land part extended continuously in a tire peripheral direction. Since the shoulder land portions 51 and 53 have a high contribution to the braking performance and the turning performance, by forming such a continuous land portion, a decrease in the block rigidity of the shoulder land portions 51 and 53 can be suppressed, and dryness can be achieved. Wear resistance performance on the road surface is improved. The shoulder land portions 51 and 53 preferably form continuous land portions on the side in contact with the outer circumferential main grooves 11 and 13 in terms of securing wet turning performance and snow handling stability performance.
In the region of the shoulder land portion 51, the distance between the end of the shoulder lug groove 61 and the outer circumferential main groove 11, that is, the width of the portion that connects two blocks adjacent in the tire circumferential direction to form a continuous land portion ( The connection width) is preferably 5 to 20% of the length in the tire width direction between the outer circumferential main groove 11 and the ground contact end. In this embodiment, it is 15%, for example. Similarly, in the region of the shoulder land portion 53, the distance (connection width) between the end of the shoulder lug groove 63 and the outer circumferential main groove 13 is the length of the tire width direction length between the outer circumferential main groove 13 and the ground contact end. It is preferable that it is 5 to 20%.

The shoulder lug grooves 61 and 63 are formed in a tapered shape at the inner end in the tire width direction. The maximum groove widths 61w, 62w of the shoulder lug grooves 61, 63 are wider than the groove widths (maximum groove widths) 31w, 33w, 35w of the lug grooves 31, 33, 35, for example, 4 to 8 mm. As described above, the wide width of the shoulder land portions 51 and 53 having a high contribution during braking and driving improves wet turning performance and on-snow handling stability. The maximum groove width 61w of the shoulder lug groove 61 and the maximum groove width 63w of the shoulder lug groove 63 may be the same or different.
The shoulder lug groove 61 extends with an inclination of θsh, for example, 75 to 90 degrees with respect to the X1 direction in the tire circumferential direction. Further, the shoulder lug groove 63 extends with an inclination of θsh, for example, 75 to 90 degrees with respect to the X2 direction of the tire circumferential direction. Thus, by setting the inclination angle so that the direction of the shoulder lug grooves 61 and 63 approaches the tire width direction as compared with the tire circumferential direction, high block rigidity in the shoulder land portions 51 and 53 is ensured, and small The wet turning performance at the rudder angle and the steering stability performance on snow are improved. As shown in FIG. 4, the inclination angle θsh of the shoulder lug grooves 61 and 63 corresponds to the point of the middle position of the width of the shoulder lug groove 61 and the shoulder lug groove 63 in the tire circumferential direction at the contact end and the outer circumferential main groove. This is represented by the inclination of the straight line connecting the intermediate position points in the tire circumferential direction at the end portions on the 11 and 13 sides with respect to the tire circumferential direction. Note that the inclination angles of the shoulder lug grooves 61 and 63 may be the same or different.

Further, sipes 62 and 64 are provided in the regions of the shoulder land portions 51 and 53, respectively. Two sipes 62 and 64 are provided between two shoulder lug grooves 61 and 63 adjacent in the tire circumferential direction. In another embodiment, the number of sipes 62 and 64 provided in the shoulder land portions 51 and 53 between the two adjacent shoulder lug grooves 61 and 63 may be one or three or more. The sipes 62 and 64 preferably have a three-dimensional shape on the inner side in the tire width direction from the ground contact end, and have a two-dimensional shape on the outer side in the tire width direction from the ground contact end. Since the sipes 62 and 64 have a three-dimensional shape on the inner side in the tire width direction from the ground contact end, the rigidity at the time of braking / driving of the shoulder land portions 51 and 53 can be increased.
Alternatively, the sipes 62 and 64 extend linearly in the extending direction of the sipes 62 and 64, and extend in a planar shape in the sipe depth direction from the tread surface of the sipes 62 and 64 toward the bottom of the sipes 62 and 64. A two-dimensionally shaped portion (first portion) and a zigzag extending while displacing in a direction orthogonal to the extending direction of the sipes 62 and 64, and the sipes 62 and 64 from the tread surface of the sipes 62 and 64. And a three-dimensional portion (second portion) extending in a zigzag shape while displacing in a direction orthogonal to the sipe depth direction toward the bottom of the sipe 62, 64, When proceeding from the outer side in the direction toward the outer circumferential main grooves 11 and 13, it is preferable that the two-dimensional shape part is changed to a three-dimensional shape part and the process ends. Since the sipes 62 and 64 have a three-dimensional shape on the side close to the outer circumferential main grooves 11 and 13, the rigidity during braking / driving of the shoulder land portions 51 and 53 can be increased.

(chamfer)
The tread pattern 10 further includes chamfers 21a, 23a, 25a, 51a, and 53a.
As shown in FIG. 4, a chamfer 21 a is applied to a part of the edge portion in contact with the inner circumferential main grooves 15, 17 of the central land portion 21. Thereby, the edge amount of the central land portion 21 is increased, and the wet turning performance and the snow handling stability performance are improved. On the other hand, by providing the chamfer 21a, the wear resistance on the dry road surface is ensured without excessively reducing the block rigidity.
The chamfers 21a are provided on both sides of each land block 22 in the tire width direction, and are processed so that the chamfering depth becomes larger toward the both sides in the tire circumferential direction. The depth of the chamfer 21a is preferably within 50% of the groove depth of the inner circumferential main grooves 15 and 17 and more preferably 10 to 30% for reasons of wear resistance.

As shown in FIG. 4, a chamfer 23 a is applied to a part of the edge in contact with the outer circumferential main groove 11 of the outer intermediate land portion 23 o. Further, a chamfer 25a is applied to a part of the edge portion in contact with the outer circumferential main groove 13 of the outer intermediate land portion 25o.
Of the outer intermediate land blocks 24b and 26b, at the positions where the lug grooves 33 and 35 are connected to the outer circumferential main grooves 11 and 13, the lug grooves 33 and 35 and the outer circumferential main grooves 11 and 13 form an obtuse angle. The outer intermediate land blocks 24b and 26b have obtuse corners 23d and 25d (see FIG. 4) formed in the above. At this time, the chamfers 23a and 25a extend from the obtuse angle portions 23d and 25d in the tire circumferential direction. The chamfers 23a and 25a have a chamfer width that decreases with distance from the obtuse corners 23d and 25d in the tire circumferential direction, and the chamfers 23a and 25a are on the way to sharp corners opposite to the obtuse corners 23d and 25d at both ends in the tire circumferential direction. It is preferable to end with. FIG. 5 shows a chamfer 23a that ends in the middle of the outer intermediate land block 24b while proceeding to an acute corner opposite to the obtuse corner 23d. Due to the chamfers 23a and 25a, a decrease in block rigidity due to chamfering is suppressed in a region around the acute angle corners opposite to the obtuse angle corners 23d and 25d. Thereby, the abrasion resistance performance of the area | region around an acute corner | angular part can be improved. On the other hand, in the chamfered portions starting from the obtuse corner portions 23d and 25d, the block edge components increase in the outer intermediate land blocks 24b and 26b due to the chamfering, thereby improving wet turning performance and snow handling stability performance. be able to. The chamfering depth is 50% or less of the groove depth of the outer circumferential main grooves 11 and 13 and is preferably 10 to 30 of the groove depth of the outer circumferential main grooves 11 and 13 for reasons of wear resistance. %. Since chamfering 23a and 25a is performed on a part of the edge portion, the block rigidity is not excessively reduced, and the wear resistance can be maintained. The edge portion in contact with the inner circumferential main groove 15 of the intermediate land portion 23 may be chamfered. Further, chamfering may also be performed on an edge portion in contact with the inner circumferential main groove 17 of the intermediate land portion 25.

  As shown in FIG. 4, chamfers 51 a and 53 a are formed on part of the edges of the shoulder land portions 51 and 53 that contact the outer circumferential main grooves 11 and 13. Thereby, the edge amounts of the shoulder land portions 51 and 53 are increased, and the wet turning performance and the snow handling stability performance are improved. Further, since chamfering 51a and 53a is performed on a part of the edge portion, the block rigidity is not excessively reduced, and wear resistance on the dry road surface is ensured. The depth of the chamfers 51a and 53a is preferably within 50% of the groove depth of the outer circumferential main grooves 11 and 13, and is preferably 10 to 30%.

The groove depths of the outer circumferential main grooves 11, 13, 15, 17 may be equal to or different from each other.
The maximum depth of the chamfers 21a, 23a, 25a, 51a, 53a may be equal or different from each other.
The groove depths of the circumferential shallow grooves 41 and 43 may be equal to or different from each other.
The maximum widths of the land blocks 24, 26 may be equal or different from each other.

In the pneumatic tire 1 described above, the inner sipes 34a and 36a provided in the region of the inner intermediate land blocks 24a and 26a extend from the tread surface into the tread in a wave shape or in a direction inclined with respect to the tire radial direction. The outer sipes 34b and 36b provided in the region of the outer intermediate land blocks 24b and 26b are linearly formed along the tire radial direction from the tread surface to the inside of the tread. At least one of extending and extending linearly on the tread surface is satisfied.
Further, the inner sipes 34a and 36a provided in the region of the inner intermediate land blocks 24a and 26a extend linearly along the tire radial direction from the tread surface to the inside of the tread, and extend in a wave shape on the tread surface. The outer sipe 34b, 36b provided in the region of the outer intermediate land block 24b, 26b extends linearly along the tire radial direction from the tread surface to the inside of the tread, and linearly on the tread surface. Satisfied to extend.
When the inner sipe 34a, 36a and the outer sipe 34b, 36b are not provided, the inner intermediate land block 24a, 26a has the sharpest acute angle portion of the intermediate land portions 23, 25. Therefore, the inner intermediate land block 24a , 26a, the block rigidity is likely to decrease. However, as described above, the inner sipe 34a, 36a uses the sipe shape that suppresses the decrease in the block rigidity as compared with the outer intermediate land blocks 24b, 26b, thereby increasing the block rigidity of the inner intermediate land blocks 24a, 26a. The block rigidity of the outer intermediate land blocks 24b and 26b can be approached. For this reason, it is possible to improve wet turning performance and snow handling stability performance while maintaining at least wear resistance performance.

  Further, in the pneumatic tire 1, the bottom of the lug groove in the crossing peripheral region of the lug grooves 33, 35 including the crossing portion of the lug grooves 33, 35 crossing the circumferential shallow grooves 41, 43 deviates from the crossing peripheral region. A raised bottom portion having a groove depth shallower than the groove bottom in the region is formed. At this time, of the bottom raised portions of the lug grooves 33, 35, the length along the lug grooves 33, 35 of the portion extending inward in the tire width direction from the intersection with the circumferential shallow grooves 41, 43 is the bottom raised portion. The length extending from the intersection with the circumferential shallow grooves 41 and 43 to the outer side in the tire width direction is longer than the length along the lug grooves 33 and 35. As a result, the block rigidity of the inner intermediate land blocks 24a and 26a can be made closer to the block rigidity of the outer intermediate land blocks 24b and 26b. For this reason, it is possible to improve wet turning performance and snow handling stability performance while maintaining at least wear resistance performance.

(Other embodiments)
The inner sipes 34a and 36a and the outer sipes 34b and 36b may not be parallel to the lug grooves 33 and 35. Further, the inner sipes 34a and 36a may be closed within the region of the inner intermediate land portions 23i and 25i without being connected to the inner circumferential main grooves 15 and 17.
The shoulder lug grooves 61 and 63 may be connected to the outer circumferential main grooves 11 and 13, and a plurality of land blocks may be formed in the tire circumferential direction. The tread pattern 10 may not have the shoulder land portions 61 and 63.
The width of the shoulder lug grooves 61, 63 may be equal to or smaller than the width of the lug grooves 31, 33, 35.
The number of circumferential main grooves is not limited to four, and may be five or more. In this case, three or more inner circumferential main grooves may be included.

(Example)
In order to investigate the effect of the tread pattern 10 of the tire 1 of the present invention, a tire was manufactured as a prototype.
The tire size was P265 / 70R17 113T. The rim was 17 × 7.5 J, and a tire provided with a tread pattern having the specifications shown in the following table was produced. In order to examine the tire performance, an FF vehicle having an engine displacement of 2 liters was used as a test vehicle. The internal pressure condition was 210 (kPa) for both the front and rear wheels.
As tire performance of the prototype tire, wet turning performance, snow handling stability performance, and wear resistance performance were evaluated as follows.

For wet turning performance, on a wet road surface with a water film with a water depth of 1 mm at an outdoor tire test site, the test vehicle was run on a turning circuit of R30 (radius 30 m) at the limit speed for 5 laps, and the average lateral acceleration at that time was It was measured. Evaluation was shown by the index | exponent which makes the reciprocal number of the measured value of the tire of a prior art example 100. The larger the index value, the better the wet turning performance.
Regarding the snow handling stability performance, the tire was evaluated by running on the snow road surface instead of the wet road surface having a water film having a water depth of 1 mm and sensory evaluation by the driver. Evaluation was shown by the index | index which makes the tire of a conventional example 100. The larger the index value, the better the steering stability performance on snow.
As for the wear resistance, the amount of wear was measured after traveling 2000 km on a public road. The evaluation was performed by using the reciprocal of the measured value, and indicated by an index with the reciprocal of the measured value of the conventional tire as 100. The larger the index value, the better the wear resistance performance.

The specification of the Example of evaluation, a comparative example, and a prior art example, and its evaluation result are shown to the following Tables 1-4.
"The shape of the inner sipe of the intermediate land portion" and "the shape of the outer sipe of the intermediate land portion" shown in Tables 1 and 2 represent the shapes of the inner sipe 34a, 36a and the outer sipe 34b, 36b. Further, “length of the raised portion Wm1 (%): Wm2 (%)” is the length of the raised portion shown in FIG. 5 with respect to the maximum width in the tire width direction of the intermediate land portions 23 and 25 of the lug grooves 33 and 35. It is a percentage display of the ratio of Wm1 and Wm2.
In Tables 3 and 4, items for “inner middle land block width change rate (%)”, “circumferential shallow groove position (%)”, and “shoulder lug groove width” relative to Tables 1 and 2 Has been added. “Change rate (%) of inner middle land block width” is a percentage of (w _max −w _min ) / w _max obtained from the maximum width w _max and the minimum width w _{min of the} inner middle land block shown in FIG. It is a display. “Position (%) of circumferential shallow groove” refers to the distance in the tire width direction from the edge in contact with the inner circumferential main grooves 15, 17 of the inner intermediate land portions 23 i, 25 i to the center position of the circumferential shallow grooves 41, 43. It is a percentage display of the ratio with respect to the maximum width | variety of the tire width direction of middle land part 23,25. When this percentage is larger than 50%, it indicates that the center positions of the circumferential shallow grooves 41 and 43 are located on the outer side in the tire width direction with respect to the centers of the intermediate land portions 23 and 25 in the tire width direction.
In Examples 1 to 4 and Comparative Examples 1 to 3, “the position of the circumferential shallow groove (%)” was set to 35%, and “the width of the shoulder lug groove” was set to 5 mm. In Examples 1 to 4 and Comparative Examples 1 to 3, the “inside intermediate land block width change rate (%)” was set to 0%. That is, the inner middle land block width does not change.

As can be seen from Tables 1 and 2, the inner sipes 34a and 36a satisfy a zigzag shape (wave shape) extending from the tread surface into the tread and a zigzag shape (wave shape) on the tread surface, The outer sipes 34b and 36b satisfy at least one of linearly extending along the tire radial direction from the tread surface to the inside of the tread and linearly extending on the tread surface, or the inner sipes 34a and 36a. Satisfies the fact that it extends linearly along the tire radial direction from the tread surface to the inside of the tread, and extends in a zigzag shape (wave shape) on the tread surface, and the outer sipes 34b and 36b extend from the tread surface to the inside of the tread. Extending linearly along the tire radial direction and straight on the tread surface By satisfying to extend, the wear resistance on a dry road surface while conventional contrast enhancing (102 or more index), it is possible to improve the wet turning performance and on-snow steering stability.
Further, as can be seen from Tables 1 and 2, the inner sipes 34a and 36a satisfy the linear extension along the tire radial direction from the tread surface to the inside of the tread, and the corrugated shape extends on the tread surface. The outer sipe 34b, 36b extends from the tread surface to the inside of the tread in a straight line along the tire radial direction, and satisfies the linear extension on the tread surface. It is possible to improve wet turning performance and on-snow maneuvering stability performance while improving the comparison with the example (index is 102 or more).

  From Table 3, by increasing the length Wm1 of the bottom raised portion of the lug grooves 33, 35 with respect to the length Wm2, while improving the wear resistance performance on the dry road surface compared with the conventional example (index 102 or more), Wet turning performance and snow maneuvering stability performance can be improved.

As can be seen from a comparison between Example 5 in Table 3 and Example 1 in Table 1, the width of the inner intermediate land blocks 24a and 26a in the tire width direction can be increased as the tire approaches the acute angle portion in the tire circumferential direction. It can be seen that this is preferable in terms of wear resistance on dry road surfaces, wet turning performance and snow handling stability.
As can be seen from a comparison between Example 1 in Table 1 and Example 8 in Table 4, the center position of the circumferential shallow grooves 41 and 43 in the tire width direction is the maximum width of the intermediate land portions 23 and 25 in the tire width direction. It is determined that the distance between the inner circumferential land portions 23i and 25i of the inner circumferential main grooves 15 and 17 is away from the edge in contact with the inner intermediate land portions 23i and 25i by a distance of 40 to 60%. It turns out that it is preferable at the point of stability performance.
As can be seen from the comparison of Examples 8 and 9 in Table 4, the provision of chamfers 23a and 25a on the outer intermediate land blocks 24b and 26b improves the wear resistance performance on the dry road surface, wet turning performance and snow handling stability performance. It turns out that it is preferable at a point.
As can be seen from the comparison between Example 1 in Table 1 and Example 10 in Table 4, the width of the shoulder lug grooves 61, 63 is wider than the maximum groove width of the lug grooves 31, 33, 35. It can be seen that it is preferable in terms of wear resistance performance on a dry road surface, wet turning performance and snow handling stability performance.
As can be seen from the comparison between Example 5 in Table 3 and Example 11 in Table 4, the shoulder lug grooves 61 and 63 are blocked without being connected to the outer circumferential main groove, and wear resistance performance on a dry road surface. It can be seen that it is preferable in terms of wet turning performance and snow handling stability performance.

  As mentioned above, although the pneumatic tire of this invention was demonstrated in detail, this invention is not limited to the said embodiment, Of course, in the range which does not deviate from the main point of this invention, you may make a various improvement and change. is there.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 10 Tread pattern 11, 13 Outer circumferential direction main groove 15, 17 Inner circumferential direction main groove 21 Central land part 21a, 23a, 25a, 51a, 53a Chamfer 23,25 Middle land part 23i, 25i Inside Intermediate land portion 23o, 25o Outer intermediate land portion 23c, 25c Acute angle portion 23d, 25d Obtuse angle portion 22, 24, 26 Land block 24a, 26a Inner intermediate land block 24b, 26b Outer intermediate land block 31, 33, 35 lug groove 33a bottom raising portion 31w, 33w, 35w maximum groove width 34, 36 sipe 34a, 36a inner sipe 34b, 36b outer sipe 41, 43 circumferential shallow groove 51, 53 shoulder land portion 61, 63 shoulder lug groove 61w, 62w Shoulder lug groove maximum groove width θm1, θm2 Lug groove inclination CL Center Line P, Q Position X1 where the lug groove intersects with the circumferential shallow groove X1 First direction X2 in the tire circumferential direction Second direction in the tire circumferential direction

Claims (9)

A pneumatic tire including a bead, a sidewall, a belt layer, a carcass layer, and a tread portion having a tread pattern,
The tread pattern is
Four circumferential main grooves parallel to the tire circumferential direction, two outer circumferential main grooves arranged on the outer side in the tire width direction, and two inner sides sandwiched between the outer circumferential main grooves A circumferential main groove, a tire center line passes between the inner circumferential main grooves, and a circumferential main groove group;
A region of a central land portion defined by the two inner circumferential main grooves and through which the tire center line passes, and two intermediate lands defined by the outer circumferential main groove and the inner circumferential main groove A plurality of lug grooves that form a plurality of land blocks in the region of the central land and the intermediate land,
Provided in each of the regions of the intermediate land portion and extending in the tire circumferential direction, the intermediate land portion block of the intermediate land portion is located on the inner side in the tire width direction and the outer intermediate portion located on the outer side in the tire width direction. A circumferential shallow groove having a groove depth shallower than the circumferential main groove, which is divided into land blocks,
The lug grooves provided in each of the regions of the intermediate land portion, when proceeding from the outer side in the tire width direction to the inner side in the tire width direction, the inclination of the lug groove approaches the tire circumferential direction at a position intersecting with the shallow circumferential groove. Has a bent portion bent to
The direction of the lug groove that crosses the region of the central land portion from the outer side in the tire width direction toward the inner side in the tire width direction of the lug groove, and the region of the intermediate land portion of the lug groove The direction of inclining with respect to the tire width direction of the lug groove that crosses from the outer side in the tire width direction toward the inner side in the tire width direction is opposite to each other with respect to the direction of the tire width direction,
An inner sipe extending inward in the tire width direction from the circumferential shallow groove is provided in the area of the inner middle land block, and an outer side in the tire width direction from the circumferential shallow groove in the area of the outer intermediate land block. An outer sipe extending to
The inner sipe satisfies zigzag from the tread surface to the inside of the tread or in a direction inclined with respect to the tire radial direction, and extends zigzag on the tread surface;
The pneumatic tire according to claim 1, wherein the outer sipe satisfies at least one of linearly extending along a tire radial direction from the tread surface to the inside of the tread and linearly extending on the tread surface. A pneumatic tire including a bead, a sidewall, a belt layer, a carcass layer, and a tread portion having a tread pattern,
The tread pattern is
Four circumferential main grooves parallel to the tire circumferential direction, two outer circumferential main grooves arranged on the outer side in the tire width direction, and two inner sides sandwiched between the outer circumferential main grooves A circumferential main groove, a tire center line passes between the inner circumferential main grooves, and a circumferential main groove group;
A region of a central land portion defined by the two inner circumferential main grooves and through which the tire center line passes, and two intermediate lands defined by the outer circumferential main groove and the inner circumferential main groove A plurality of lug grooves that form a plurality of land blocks in the region of the central land and the intermediate land,
Provided in each of the regions of the intermediate land portion and extending in the tire circumferential direction, the intermediate land portion block of the intermediate land portion is located on the inner side in the tire width direction and the outer intermediate portion located on the outer side in the tire width direction. A circumferential shallow groove having a groove depth shallower than the circumferential main groove, which is divided into land blocks,
The lug grooves provided in each of the regions of the intermediate land portion, when proceeding from the outer side in the tire width direction to the inner side in the tire width direction, the inclination of the lug groove approaches the tire circumferential direction at a position intersecting with the shallow circumferential groove. Has a bent portion bent to
The direction of the lug groove that crosses the region of the central land portion from the outer side in the tire width direction toward the inner side in the tire width direction of the lug groove, and the region of the intermediate land portion of the lug groove The direction of inclining with respect to the tire width direction of the lug groove that crosses from the outer side in the tire width direction toward the inner side in the tire width direction is opposite to each other with respect to the direction of the tire width direction,
An inner sipe extending inward in the tire width direction from the circumferential shallow groove is provided in the area of the inner middle land block, and an outer side in the tire width direction from the circumferential shallow groove in the area of the outer intermediate land block. An outer sipe extending to
The inner sipe extends linearly along the tire radial direction from the tread surface to the inside of the tread, and satisfies a zigzag shape extending on the tread surface;
2. The pneumatic tire according to claim 1, wherein the outer sipe satisfies linear extension along the tire radial direction from the tread surface to the inside of the tread and linear extension on the tread surface. The groove bottom of the lug groove in the peripheral region of the lug groove including the crossing portion of the lug groove intersecting the circumferential shallow groove has a groove depth compared to the groove bottom of the region deviated from the peripheral region of the intersection. Forming a shallow raised bottom,
Of the raised portion of the lug groove, the length along the lug groove of the portion extending inward in the tire width direction from the intersecting portion is the length of the portion of the raised portion extending outward in the tire width direction from the intersecting portion. The pneumatic tire according to claim 1, wherein the pneumatic tire is longer than a length along the lug groove. A pneumatic tire including a bead, a sidewall, a belt layer, a carcass layer, and a tread portion having a tread pattern,
The tread pattern is
Four circumferential main grooves parallel to the tire circumferential direction, two outer circumferential main grooves arranged on the outer side in the tire width direction, and two inner sides sandwiched between the outer circumferential main grooves A circumferential main groove, a tire center line passes between the inner circumferential main grooves, and a circumferential main groove group;
A region of a central land portion defined by the two inner circumferential main grooves and through which the tire center line passes, and two intermediate lands defined by the outer circumferential main groove and the inner circumferential main groove A plurality of lug grooves that form a plurality of land blocks in the region of the central land and the intermediate land,
Provided in each of the regions of the intermediate land portion and extending in the tire circumferential direction, the intermediate land portion block of the intermediate land portion is located on the inner side in the tire width direction and the outer intermediate portion located on the outer side in the tire width direction. A circumferential shallow groove having a groove depth shallower than the circumferential main groove, which is divided into land blocks,
The lug grooves provided in each of the intermediate land regions are bent so that the groove inclination approaches the tire circumferential direction at a position intersecting with the circumferential shallow groove when proceeding from the tire width direction outer side to the tire width direction inner side. Have a bend,
The direction of the lug groove that crosses the region of the central land portion from the outer side in the tire width direction toward the inner side in the tire width direction of the lug groove, and the region of the intermediate land portion of the lug groove The direction of inclining with respect to the tire width direction of the lug groove that crosses from the outer side in the tire width direction toward the inner side in the tire width direction is opposite to each other with respect to the direction of the tire width direction,
The groove bottom of the crossing peripheral region of the lug groove including the crossing portion of the lug groove intersecting the circumferential shallow groove and the region before and after the crossing portion is compared with the groove bottom of the region deviating from the crossing peripheral region. Forming a raised bottom,
Of the raised portion of the lug groove, the length along the lug groove of the portion extending inward in the tire width direction from the intersecting portion is the length of the portion of the raised portion extending outward in the tire width direction from the intersecting portion. A pneumatic tire characterized by being longer than a length along the lug groove.   At the position where the lug groove intersects the inner circumferential main groove, the inner intermediate land block has an acute angle corner portion formed at an acute angle by the lug groove and the inner circumferential main groove. And the width | variety in the tire width direction of the said inner side intermediate land block is a pneumatic tire of any one of Claims 1-4 widened as the said acute angle part is approached in a tire circumferential direction.   The center position in the tire width direction of the circumferential shallow groove is from the edge in contact with the inner intermediate land portion of the inner circumferential main groove by a distance of 40 to 60% of the maximum width in the tire width direction of the intermediate land portion. The pneumatic tire according to any one of claims 1 to 5, which is located at a distant position. In the outer intermediate land block, the obtuse angle portion formed at an obtuse angle by the lug groove and the outer circumferential main groove at the position where the lug groove intersects the outer circumferential main groove, Has an outer middle land block,
A chamfer extending in the tire circumferential direction from the obtuse angle corner is provided at an edge where the outer intermediate land block contacts the outer circumferential main groove, and the chamfer is chamfered as the distance from the obtuse angle corner increases in the tire circumferential direction. The pneumatic tire according to any one of claims 1 to 6, wherein the pneumatic tire ends in the middle of proceeding to a corner opposite to the obtuse angle corner among both ends of the edge in the tire circumferential direction of the edge.   A shoulder land portion is provided on the outer side in the tire width direction of the outer circumferential main groove, and the outer circumferential direction main groove extends from the tire width direction outer side to the tire width direction inner side in the region of the shoulder land portion. The pneumatic tire according to any one of claims 1 to 7, wherein a shoulder lug groove that is closed without being connected to the tire is provided.   The pneumatic tire according to claim 8, wherein a groove width of the shoulder lug groove is wider than a maximum groove width of the lug groove.

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