JP2017065625A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of securing stability of a tire and improving wet performance.SOLUTION: A pneumatic tire comprises two or more circumferential main grooves 21-24 arranged on one region out of regions partitioned by a tire equator plane CL, and extending in a tire circumferential direction, and plural land parts 31-35 which are partitioned by circumferential main grooves 21-24. An outside second land part 34 comprises plural circular arc grooves 341 which are formed into a bent or curved shape which is a salient state to the tire equator plane CL and which are continuously arranged in the tire circumferential direction. The circular arc grooves 341 are opened to an outermost circumferential main groove 24 on one ends of the grooves, and are communicated to other circular arm grooves 341 adjacent in the tire circumferential direction on the other ends of the grooves. A maximum value Wg_max of a groove width Wg and a minimum value Wg_min of the groove width Wg of each circular arm groove 341 has a relationship of Wg_max/Wg_min≤1.10.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire capable of improving wet performance while ensuring steering stability performance of the tire.

  In recent pneumatic tires, in order to improve the wet performance of the tire, a configuration including a plurality of arc grooves communicating in the tire circumferential direction is employed. As conventional pneumatic tires employing such a configuration, techniques described in Patent Documents 1 and 2 are known.

JP 2012-131423 A JP 2010-6161 A

  Generally, when the groove area increases, the contact area or rigidity of the land portion decreases, and the steering stability performance of the tire tends to deteriorate.

  Therefore, the present invention has been made in view of the above, and an object of the present invention is to provide a pneumatic tire that can improve wet performance while ensuring steering stability performance of the tire.

  In order to achieve the above object, a pneumatic tire according to the present invention includes two or more circumferential main grooves that are disposed in one region with the tire equatorial plane as a boundary and extend in the tire circumferential direction, and the circumferential direction. A pneumatic tire comprising a plurality of land portions divided into main grooves, wherein the outermost circumferential main groove is defined as the outermost circumferential main groove on the outermost side in the tire width direction, and the outermost circumferential main groove The land portion outside the tire width direction defined in the tire width direction is defined as a shoulder land portion, the land portion inside the tire width direction defined in the outermost circumferential main groove is defined as a second land portion, and the second land portion The land portion on the tire equatorial plane side is defined as a center land portion, and the second land portion has a bent or curved shape that is convex on the tire equatorial plane side and is arranged in a row in the tire circumferential direction. Multiple circles Provided with a groove, and the arc groove opens to the outermost circumferential main groove at one end, communicates with the other arc groove adjacent in the tire circumferential direction at the other end, and The maximum value Wg_max and the minimum value Wg_min of the groove width Wg of the arc groove have a relationship of Wg_max / Wg_min ≦ 1.10.

  In the pneumatic tire according to the present invention, (1) since the plurality of arc grooves open to the outermost circumferential main groove and are arranged in communication with each other in the tire circumferential direction, the drainage performance of the arc grooves is improved. Thereby, there exists an advantage which the wet performance of a tire improves. (2) Since the arc groove has a substantially constant groove width Wg, the ground contact area of the second land portion is ensured as compared with the configuration in which the groove width Wg of the arc groove is widened. Thereby, there exists an advantage by which the steering stability performance of a tire is maintained.

FIG. 1 is a sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a plan view showing a tread surface of the pneumatic tire depicted in FIG. 1. FIG. 3 is an explanatory diagram showing the tread pattern shown in FIG. FIG. 4 is an explanatory diagram showing the tread pattern shown in FIG. FIG. 5 is an explanatory diagram showing the tread pattern shown in FIG. FIG. 6 is an explanatory diagram showing the tread pattern shown in FIG. FIG. 7 is a chart showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Further, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

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

  In the figure, the cross section in the tire meridian direction means a cross section when the tire is cut along a plane including a tire rotation axis (not shown). Reference sign CL denotes a tire equator plane, which is 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. Further, the tire width direction means a direction parallel to the tire rotation axis, and the tire radial direction means a direction perpendicular to the tire rotation axis. Further, the inner side in the vehicle width direction and the outer side in the vehicle width direction are defined as directions with respect to the vehicle width direction when the tire is mounted on the vehicle. Here, of the left and right regions having the tire equator plane as a boundary, a region on the outer side in the vehicle width direction when the tire is mounted on the vehicle is called an outer region, and a region on the inner side in the vehicle width direction is called an inner region.

  In addition, the mounting direction of the tire with respect to the vehicle is configured by, for example, marks or unevenness attached to the sidewall portion of the tire. For example, ECER 30 (European Economic Commission Regulation Article 30) requires that a display portion in the vehicle mounting direction be provided on the side wall portion on the outer side in the vehicle width direction when the vehicle is mounted.

  The pneumatic tire 1 has an annular structure centered on the tire rotation axis, and includes a pair of bead cores 11, 11, a pair of bead fillers 12, 12, a carcass layer 13, a belt layer 14, and a tread rubber 15. And a pair of sidewall rubbers 16 and 16 and a pair of rim cushion rubbers 17 and 17 (see FIG. 1).

  The pair of bead cores 11 and 11 is an annular member formed by bundling a plurality of bead wires, and constitutes the core of the left and right bead portions. The pair of bead fillers 12 and 12 are disposed on the outer circumference in the tire radial direction of the pair of bead cores 11 and 11 to constitute a bead portion.

  The carcass layer 13 has a single layer structure composed of a single carcass ply or a multilayer structure formed by laminating a plurality of carcass plies, and is bridged in a toroidal shape between the left and right bead cores 11 and 11 to form a tire skeleton. Configure. Further, both end portions of the carcass layer 13 are wound and locked outward in the tire width direction so as to wrap the bead core 11 and the bead filler 12. The carcass ply of the carcass layer 13 is formed by coating a plurality of carcass cords made of steel or an organic fiber material (for example, aramid, nylon, polyester, rayon, etc.) with a coat rubber and rolling it, and has an absolute value of 80 A carcass angle (defined as the inclination angle of the carcass cord in the longitudinal direction with respect to the tire circumferential direction) of [deg] or more and 95 [deg] or less.

  The belt layer 14 is formed by laminating a pair of cross belts 141 and 142 and a belt cover 143, and is arranged around the outer periphery of the carcass layer 13. The pair of cross belts 141 and 142 is formed by rolling a plurality of belt cords made of steel or organic fiber material with a coating rubber, and has an absolute value of a belt angle of 20 [deg] or more and 55 [deg] or less. Have. The pair of intersecting belts 141 and 142 have belt angles with different signs (defined as inclination angles in the longitudinal direction of the belt cord with respect to the tire circumferential direction), and intersect the longitudinal directions of the belt cords with each other. (So-called cross-ply structure). The belt cover 143 is configured by covering a belt cord made of steel or an organic fiber material with a coat rubber, and has a belt angle of 0 [deg] or more and 10 [deg] or less in absolute value. The belt cover 143 is, for example, a strip material formed by coating one or a plurality of belt cords with a coat rubber. The strip material is applied to the outer circumferential surface of the cross belts 141 and 142 a plurality of times in the tire circumferential direction. In addition, it is configured to be spirally wound.

  The tread rubber 15 is disposed on the outer circumference in the tire radial direction of the carcass layer 13 and the belt layer 14 to constitute a tread portion of the tire. The pair of side wall rubbers 16 and 16 are respectively arranged on the outer side in the tire width direction of the carcass layer 13 to constitute left and right side wall portions. The pair of rim cushion rubbers 17, 17 are respectively disposed on the inner side in the tire radial direction of the wound portions of the left and right bead cores 11, 11 and the carcass layer 13, and constitute the contact surfaces of the left and right bead portions with respect to the rim flange.

[Tread pattern]
FIG. 2 is a plan view showing a tread surface of the pneumatic tire depicted in FIG. 1. The figure shows a tread pattern of an all-season tire. In the figure, the tire circumferential direction refers to the direction around the tire rotation axis. Moreover, the code | symbol T is a tire ground contact edge and the dimension symbol TW is a tread width.

  As shown in FIG. 2, the pneumatic tire 1 includes a plurality of circumferential main grooves 21 to 24 that extend in the tire circumferential direction, and a plurality of land portions 31 to 11 that are partitioned by the circumferential main grooves 21 to 24. 35 on the tread surface.

  The main groove is a groove having an obligation to display the wear indicator defined in JATMA, and generally has a groove width of 5.0 [mm] or more and a groove depth of 6.5 [mm] or more. Moreover, the lug groove mentioned later is a lateral groove extending in the tire width direction, and generally has a groove width of 1.0 [mm] or more and a groove depth of 3.0 [mm] or more. Further, the sipe described later is a cut formed in the tread surface, and generally has a sipe width of less than 1.0 [mm] and a sipe depth of 2.0 [mm] or more at the tire contact surface. Block.

  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 prescribed rim and filled with the prescribed internal pressure. In the configuration where the land part has a notch part or a chamfered part at the edge part, the groove width is based on the intersection of the tread surface and the extension line of the groove wall in a cross-sectional view in which the groove length direction is a normal direction. Measured. In the configuration in which the groove extends in a zigzag shape or a wave 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 groove depth is measured as the maximum value of the distance from the tread surface to the groove bottom in an unloaded state in which the tire is mounted on the specified rim and filled with the specified internal pressure. Moreover, in the structure which a groove | channel has a partial uneven | corrugated | grooved part and a sipe in a groove bottom, groove depth is measured except these.

  The sipe width is measured as the maximum value of the sipe opening width on the tread of the land portion in a no-load state in which the tire is mounted on the specified rim and filled with the specified internal pressure.

  The tire ground contact surface is applied between the tire and the flat plate when the tire is mounted on the specified rim and applied with the specified internal pressure, and is placed perpendicular to the flat plate in a stationary state and applied with a load corresponding to the specified load. Defined as contact surface.

  The specified rim refers to an “applied rim” defined in JATMA, a “Design Rim” defined in TRA, or a “Measuring Rim” defined in ETRTO. The specified internal pressure means “maximum air pressure” defined by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO. The specified load means the “maximum load capacity” defined by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “LOAD CAPACITY” defined by ETRTO. However, in JATMA, in the case of tires for passenger cars, the specified internal pressure is air pressure 180 [kPa], and the specified load is 88 [%] of the maximum load capacity.

  For example, in the configuration of FIG. 2, the inner region and the outer region in the vehicle width direction have two circumferential main grooves 21, 22; 23, 24. These circumferential main grooves 21 to 24 are arranged symmetrically about the tire equatorial plane CL. Moreover, five rows of land portions 31 to 35 are defined by these circumferential main grooves 21 to 24. Further, one land portion 33 is disposed on the tire equator plane CL.

  However, the present invention is not limited to this, and five or more circumferential main grooves may be arranged, or the circumferential main grooves may be arranged asymmetrically about the tire equatorial plane CL (not shown). Moreover, the land part may be arrange | positioned in the position which remove | deviated from tire equatorial plane CL by arrange | positioning one circumferential main groove | channel on tire equatorial plane CL (illustration omitted).

  Here, among two or more circumferential main grooves arranged in one region (including on the tire equatorial plane CL) with the tire equatorial plane CL as a boundary, the circumferential main groove located on the outermost side in the tire width direction 21 and 24 are defined as the outermost circumferential main grooves. Further, the circumferential main grooves 22 and 23 that are closer to the tire equatorial plane CL than the outermost circumferential main grooves 21 and 24 are defined as center circumferential main grooves.

  Further, the land portions 31 and 35 on the outer side in the tire width direction defined by the outermost circumferential main grooves 21 and 24 are defined as shoulder land portions. The shoulder land portions 31 and 35 are disposed on the tire ground contact edge T. Further, the land portions 32 and 34 on the inner side in the tire width direction defined by the outermost circumferential main grooves 21 and 24 are defined as second land portions. Therefore, the second land portions 32 and 34 are adjacent to the shoulder land portions 31 and 35 with the outermost circumferential main groove 22 interposed therebetween. Further, the land portion 33 on the tire equatorial plane CL side with respect to the second land portions 32 and 34 is referred to as a center land portion.

  In the configuration of FIG. 2, only one center land portion 33 exists, but in a configuration including five or more circumferential main grooves, a plurality of center land portions are defined.

[Outside second land]
3-5 is explanatory drawing which shows the tread pattern described in FIG. In these drawings, FIG. 3 is referred to as a second land portion 34 (hereinafter referred to as an outer second land portion) divided into an outermost peripheral direction main groove 24 (hereinafter referred to as an outermost outermost direction main groove) in the outer region in the vehicle width direction. ) And an enlarged view of a shoulder land portion 35 (hereinafter referred to as an outer shoulder land portion). FIG. 4 shows an enlarged view of the outer second land portion 34. 5 shows a cross-sectional view in the groove depth direction along the arc groove 341 described in FIG.

  In the configuration of FIG. 2, the outer second land portion 34 includes a plurality of arc grooves 341, ribs 342, and a plurality of blocks 343.

  As shown in FIGS. 3 and 4, the arc groove 341 has a bent or curved shape that protrudes toward the tire equatorial plane CL. Therefore, the arc groove 341 does not need to be an accurate arc. A plurality of arc grooves 341 are arranged in a row in the tire circumferential direction. At this time, one arc groove 341 opens to the outermost outer peripheral main groove 24 at one end 3411 (see FIG. 4), and another arc adjacent to the tire circumferential direction at the other end 3412. It communicates with the groove 341.

  The rib 342 is a portion on the tire equatorial plane CL side of the outer second land portion 34 partitioned into a plurality of arc grooves 341, and is continuous in the tire circumferential direction. Therefore, the edge portion on the tire ground contact end T side of the rib 342 is partitioned by the convex wall surface of the arc groove 341 continuous in the tire circumferential direction, and has a wave shape or a zigzag shape. In the configuration of FIG. 3, the circumferential main groove 23 (see FIG. 2) of the tire equatorial plane CL that defines the outer second land portion 34 has a straight shape, so that the edge portion of the rib 342 on the tire equatorial plane CL side is It has a straight shape.

  The plurality of blocks 343 are portions on the tire ground contact end T side of the outer second land portion 34 partitioned into a plurality of arc grooves 341, and are arranged in the tire circumferential direction. Therefore, the edge portion of the block 343 on the tire equatorial plane CL side is partitioned by the concave wall surface of the arc groove 341 and has an arc shape. In the configuration of FIG. 3, the outermost outer circumferential main groove 24 on the tire ground contact end T side that defines the outer second land portion 34 has a straight shape, so that the edge portion on the tire ground contact end T side of the block 343 has a straight shape. have. However, the present invention is not limited to this. For example, the right and left circumferential main grooves 23 and 24 of the outer second land portion 34 have a zigzag shape, so that the edge portions of the ribs 342 and the arcuate grooves 341 on the circumferential main grooves 23 and 24 side. May have a zigzag shape (not shown).

  In the configuration of FIG. 4, the other end 3412 of the arc groove 341 terminates with another arc groove 341 adjacent in the tire circumferential direction. That is, at the communicating portion of the adjacent arc grooves 341 and 341, one arc groove 341 is connected in a T shape to the other arc groove 341 without traversing the other arc groove 341. Thus, the block 343 has an arc-shaped edge portion that continues over the entire arc groove 341.

  In the configuration of FIG. 4, the arc groove 341 has a substantially constant groove width Wg. Specifically, the maximum value Wg_max and the minimum value Wg_min of the groove width Wg of the arc groove 341 have a relationship of Wg_max / Wg_min ≦ 1.10. Further, the ratio Wg_max / Wg_min is preferably in the range of Wg_max / Wg_min ≦ 1.05.

  The groove width Wg of the arc groove 341 is measured as the distance between the left and right groove walls in the groove opening in an unloaded state in which the tire is mounted on the specified rim and filled with the specified internal pressure. Further, the groove width Wg is measured excluding the chamfered part and the notch part formed in the groove opening.

  In the above configuration, (1) since the plurality of arc grooves 341 are opened in the outermost outer peripheral direction main groove 24 and arranged in communication with each other in the tire circumferential direction, the drainage performance of the arc grooves 341 is improved. Thereby, the wet performance of a tire improves. (2) Since the arc groove 341 has a substantially constant groove width Wg, the ground contact area of the outer second land portion 34 is ensured as compared with the configuration in which the groove width Wg of the arc groove 341 is widened. Thereby, the steering stability performance of the tire is maintained. (3) Since the arc groove 341 has a substantially constant groove width Wg, the change in the groove area can be reduced as compared with the configuration in which the groove width Wg of the arc groove 341 is widened. Thereby, the noise performance of the tire is maintained.

  In FIG. 4, the groove width Wg of the arc groove 341 and the width W1 of the outer second land portion 34 preferably have a relationship of 0.04 ≦ Wg / W1 ≦ 0.15, and 0.05 ≦ Wg / It is more preferable to have a relationship of W1 ≦ 0.10. Thereby, the groove width Wg of the circular arc groove 341 is optimized.

  The width W1 of the outer second land portion 34 is measured as the distance in the tire width direction of the left and right edge portions on the tread surface of the land portion in a no-load state in which the tire is mounted on the specified rim and filled with the specified internal pressure. Moreover, in the structure which a land part has a notch part and a chamfering part in an edge part, a land part width | variety is measured on the basis of the intersection of the tread of a land part and the extended line of a groove wall.

  The groove width Wg of the arc groove 341 is preferably in the range of Wg ≦ 2.5 [mm], and more preferably in the range of Wg ≦ 2.0 [mm]. The lower limit of the groove width Wg is defined on the condition that the arc groove 341 is not closed on the tire contact surface, that is, the arc groove 341 is not sipe.

  In FIG. 4, the maximum value Wr_max and the minimum value Wr_min of the width Wr of the rib 342 and the width W1 of the outer second land portion 34 satisfy the relationship of 0.20 ≦ (Wr_max−Wr_min) /W1≦0.50. Preferably, it has a relationship of 0.3 ≦ (Wr_max−Wr_min) /W1≦0.4. The difference Wr_max−Wr_min means the amplitude of the edge portion of the rib 342 on the arc groove 341 side.

  The width Wr of the rib 342 is measured as the distance in the tire width direction of the left and right edge portions on the tread surface of the land portion in a no-load state in which the tire is mounted on the specified rim and filled with the specified internal pressure. Moreover, in the structure which a land part has a notch part and a chamfering part in an edge part, a land part width | variety is measured on the basis of the intersection of the tread of a land part and the extended line of a groove wall. For example, in the configuration of FIG. 4, the width Wr takes the maximum value Wr_max at the communication portion 3412 of the adjacent arc grooves 341 and 341 and takes the minimum value Wr_min at the maximum protrusion position 3413 of the arc groove 341.

  In FIG. 4, the maximum value Wr_max and minimum value Wr_min of the width Wr of the rib 342 and the width W1 of the outer second land portion 34 satisfy 0.2 ≦ {(Wr_max + Wr_min) / 2} /W1≦0.5. It is preferable to have a relationship, and it is more preferable to have a relationship of 0.3 ≦ {(Wr_max + Wr_min) / 2} /W1≦0.4. The ratio {(Wr_max + Wr_min) / 2} / W1 defines the center position of the amplitude of the edge portion of the rib 342 on the arc groove 341 side. Therefore, by optimizing the above ratio, the width Wr of the rib 342 with respect to the width W1 of the outer second land portion 34 is optimized.

  In FIG. 4, the maximum value Wr_max of the width Wr of the rib 342 and the width W1 of the outer second land portion 34 preferably have a relationship of 0.30 ≦ Wr_max / W1 ≦ 0.70, and 0.40 It is more preferable to have a relationship of ≦ Wr_max / W1 ≦ 0.60. The position at which the width Wr of the rib 342 becomes the maximum value Wr_max coincides with the communication portion 3412 of the adjacent arc grooves 341 and 341. Therefore, by optimizing the ratio Wr_max / W1, the position of the communication portion 3412 of the adjacent arc grooves 341 and 341 is optimized.

  Further, as shown in FIG. 4, the block 343 partitioned into the arc groove 341 is connected to the communication portion 3411 between the arc groove 341 and the outermost outer peripheral direction main groove 24 and the communication portion 3412 of the adjacent arc grooves 341 and 341. Chamfered portions 3431 and 3432 are provided. Specifically, as shown in FIG. 5, C chamfering is performed at each position of the block 343.

  In the configuration of FIG. 4, the block 343 has a narrow groove 344 at the edge portion on the outermost outer peripheral direction main groove 24 side. The narrow groove 344 has a semi-closed structure, opens to the outermost circumferential main groove 24 at one end, and terminates in the block 343 at the other end. Further, the narrow groove 344 is inclined with respect to the tire width direction so as to divide the tread surface of the block 343 into two equal parts in the tire circumferential direction. Further, the narrow groove 344 has a chamfered portion 3441 at one edge portion of the groove opening. The chamfered portion 3441 extends in the groove length direction along the groove opening portion of the narrow groove 344 and reaches the edge portion on the outermost outer peripheral direction main groove 24 side of the block 343. The narrow groove 344 has a groove width of 2.0 [mm] or less. The lower limit of the groove width is not particularly limited, provided that the narrow groove 344 is not closed when the tire contacts the ground.

  4, the circumferential length L1 of the edge portion on the outermost outer circumferential direction main groove 24 side of the tread surface of the block 343 and the circumferential direction of the continuous portion of the edge portion of the block 343 divided by the narrow groove 344 are illustrated. The lengths L2a and L2b have a relationship of 0.45 ≦ L2a / L1 ≦ 0.55 and 0.45 ≦ L2b / L1 ≦ 0.55. That is, the narrow groove 344 is disposed at the center portion in the tire circumferential direction of the edge portion on the outermost outer circumferential direction main groove 24 side of the block 343. Thereby, the circumferential length L2a, L2b of the edge part of the block 343 is equalized, and uneven wear of the block 343 is suppressed.

  In FIG. 5, the maximum groove depth H1 of the arc groove 341 and the maximum groove depth H2 of the outermost outer circumferential main groove 24 have a relationship of 0.30 ≦ H1 / H2 ≦ 0.80. Thereby, the maximum groove depth H1 of the circular arc groove 341 is optimized.

  The maximum groove depth H1 of the arc groove 341 is measured as the distance from the tread surface of the block 343 to the maximum depth position of the arc groove 341.

  Further, in FIG. 5, the arc groove 341 has a bottom upper portion 3414 in the opening (communication portion 3411 in FIG. 4) on the circumferential main groove 24 side. Further, the depth H1a of the bottom upper portion 3414 and the maximum groove depth H1 of the arc groove 341 have a relationship of 0.30 ≦ H1a / H1 ≦ 0.80. These bottom upper portions 3414 ensure the rigidity of the outer second land portion 34. On the other hand, the circular arc groove 341 does not have a bottom upper part in the opening with respect to the other adjacent circular arc groove 341. Further, adjacent arc grooves 341 and 341 have the same groove depth and are connected to each other at the communication portion 3412 (see FIG. 4). In FIG. 5, the adjacent arc grooves 341 and 341 are connected to each other at the communication portion 3412 with the maximum groove depth H1. Thereby, the groove bottom of the communication part 3412 of the adjacent circular arc grooves 341 and 341 is formed flush.

  The depth H1a of the bottom upper portion 3414 of the arc groove 341 is measured as the distance from the tread surface of the block 343 to the groove bottom.

[Outer shoulder land]
In the configuration of FIG. 3, the outer shoulder land portion 35 on the outer side in the vehicle width direction includes one circumferential direction narrow groove 351, a plurality of lug grooves 352, a plurality of width direction narrow grooves 353, and a rib 354.

  The circumferential narrow groove 351 has a straight shape extending in the tire circumferential direction, and has a groove width of 2.0 [mm] or less. The lower limit of the groove width is not particularly limited, provided that the circumferential narrow groove 351 is not closed when the tire contacts the ground.

  The lug groove 352 opens at the tread end at one end, extends beyond the tire ground contact end T in the tire width direction, and terminates inside the shoulder land portion 35 at the other end. A plurality of lug grooves 352 are arranged at predetermined intervals in the tire circumferential direction.

  The width direction narrow groove 353 communicates with the terminal portion of the lug groove 352 at one end, extends in the tire width direction and communicates with the circumferential direction narrow groove 351, and the shoulder land portion 35 at the other end. Terminate inside. At this time, the end of the width direction narrow groove 353 on the inner side in the tire width direction may end inside the rib 354 beyond the circumferential direction narrow groove 353 (see FIG. 3), or beyond the circumferential direction narrow groove 353. Instead, it may terminate in the circumferential narrow groove 353 (not shown). One width direction narrow groove 353 is arranged for each of the plurality of lug grooves 352. Further, the groove center line of the width direction narrow groove 353 is on an extension line of the groove center line of the lug groove 352. The width direction narrow groove 353 has a groove width of 2.0 [mm] or less. The lower limit of the groove width is not particularly limited, provided that the width-direction narrow groove 353 is not closed when the tire contacts the ground.

  The rib 354 is partitioned into the outermost outer peripheral main groove 24 and the circumferential narrow groove 351 and extends continuously in the tire circumferential direction. Further, the edge portion of the rib 354 on the outermost outer circumferential direction main groove 24 side has a straight shape along the outermost outermost circumferential direction main groove 24. Further, the edge portion on the circumferential narrow groove 351 side of the rib 354 has a straight shape along the circumferential narrow groove 351, and a plurality of width direction narrow grooves 353 extending the lug groove 352 are formed. And it has a small notch.

  Further, in FIG. 3, the arrangement interval P1 of the arc grooves 341 of the outer second land portion 34 and the arrangement interval P2 of the lug grooves 352 of the shoulder land portion 35 satisfy the relationship of 1.90 ≦ P1 / P2 ≦ 2.10. Have. That is, the arrangement interval P1 of the arc grooves 341 is approximately twice the arrangement interval P2 of the lug grooves 352 of the shoulder land portion 35. Similarly, the arrangement interval P1 of the circular arc grooves 341 is substantially twice the arrangement interval of the width direction narrow grooves 353 of the shoulder land portion 35 (dimensional symbol omitted in the drawing). In addition, the arrangement | positioning space | intervals P1 and P2 of the circular arc groove 341 and the lug groove 352 are periodically fluctuated in the tire circumferential direction when the pneumatic tire 1 has a pitch variation structure.

  Further, in FIG. 3, the inclination angle θ1 with respect to the tire circumferential direction of the outermost secondary land portion 34 on the outermost circumferential main groove 24 side of the circular arc groove 341, and the widthwise narrow groove 353 of the shoulder land portion 35 with respect to the tire circumferential direction. The inclination angle θ2 preferably has a relationship of 20 [deg] ≦ θ2−θ1 ≦ 60 [deg], and more preferably has a relationship of 30 [deg] ≦ θ2−θ1 ≦ 50 [deg]. Therefore, the inclination angle θ1 of the arc groove 341 on the outermost circumferential main groove 24 side is smaller than the inclination angle θ2 of the width direction narrow groove 353.

  The inclination angle θ1 of the arc groove 341 is a straight tire circumference connecting the communication portion 3411 (see FIG. 4) with respect to the outermost circumferential main groove 24 of the arc groove 341 and the maximum protruding position 3413 (see FIG. 4) of the arc groove 341. It is measured as the inclination angle on the acute angle side with respect to the direction.

  The inclination angle θ2 of the width direction narrow groove 353 is an acute angle with respect to a straight tire circumferential direction drawn from the intersection position of the width direction narrow groove 353 and the circumferential direction narrow groove 351 to the intersection position of the width direction narrow groove 353 and the lug groove 352. Measured as side tilt angle.

[Inner second land and center land]
FIG. 6 is an explanatory diagram showing the tread pattern shown in FIG. The figure shows a second land portion 32 (hereinafter referred to as an inner second land portion) divided into an outermost peripheral direction main groove 21 (hereinafter referred to as an inner outermost direction main groove) in the inner region in the vehicle width direction, and an inner side. The enlarged view of the center land part 33 adjacent to the second land part 32 is shown.

  In the configuration of FIG. 6, the inner second land portion 32 includes a plurality of inclined narrow grooves 321 and a plurality of inclined sipes 322.

  The inclined narrow groove 321 opens at the edge portion on the tire equatorial plane CL side of the inner second land portion 32 at one end portion, extends in the tire width direction, and extends to the inner second land portion 32 at the other end portion. Terminate inside. Further, in the configuration of FIG. 6, the inclined narrow groove 321 has a straight shape and is inclined at an inclination angle θ3 with respect to the tire circumferential direction. A plurality of inclined narrow grooves 321 are arranged at predetermined intervals in the tire circumferential direction. Further, the inclined narrow groove 321 has a groove width of 2.0 [mm] or less. The lower limit of the groove width is not particularly limited, provided that the inclined narrow groove 321 is not closed when the tire is grounded.

  The inclined sipe 322 opens at the edge portion on the innermost outer circumferential direction main groove 21 side of the inner side second land portion 32 at one end portion, extends in the tire width direction, and extends toward the inner side second land portion at the other end portion. Terminate inside the part 32. In the configuration of FIG. 6, the inclined sipe 322 has a straight shape and is inclined at an inclination angle θ4 with respect to the tire circumferential direction. A plurality of inclined sipes 322 are arranged at predetermined intervals in the tire circumferential direction.

  In addition, as shown in FIG. 6, the inclined narrow grooves 321 and the inclined sipes 322 are arranged in a staggered manner in the tire circumferential direction. Further, the inclined narrow groove 321 and the inclined sipe 322 are arranged in parallel while being separated from each other. For this reason, the inner second land portion 32 is not divided in the tire circumferential direction by the inclined narrow groove 321 and the inclined sipe 322, and is a rib continuous as a whole in the tire circumferential direction. The left and right edge portions of the inner second land portion 32 have a straight shape along the left and right circumferential main grooves 21 and 22. Adjacent inclined narrow grooves 321 and inclined sipes 322 are disposed so as to wrap in the tire width direction.

  Further, the inclination angle θ3 of the inclined narrow groove 321 with respect to the tire circumferential direction and the inclination angle θ4 of the inclined sipe 322 with respect to the tire circumferential direction are 30 [deg] ≦ θ3 ≦ 60 [deg] and 30 [deg] ≦ θ4 ≦ 60 [deg]. ].

  The inclination angles θ3 and θ4 are measured as angles formed by the center lines of the inclined narrow grooves 321 and the inclined sipes 322 and the tire circumferential direction.

  As shown in FIG. 6, the center land portion 33 adjacent to the inner second land portion 32 includes a plurality of inclined narrow grooves 331.

  The inclined narrow groove 331 opens at the edge portion on the inner second land portion 32 side of the center land portion 33 at one end portion and ends inside the center land portion 33 at the other end portion. Further, the inclined narrow groove 331 is disposed on an extension line of the inclined narrow groove 321 of the inner second land portion 32. A plurality of inclined narrow grooves 331 are arranged at predetermined intervals in the tire circumferential direction. Further, the inclined narrow groove 331 has a groove width of 2.0 [mm] or less. The lower limit of the groove width is not particularly limited, provided that the inclined narrow groove 331 is not closed when the tire contacts the ground.

  In the configuration of FIG. 6, the center land portion 33 is on the tire equator plane CL, and the inclined narrow groove 331 terminates without intersecting the tire equator plane CL. Further, the edge portion on the outer side in the vehicle width direction of the center land portion 33 has a straight shape along the circumferential main groove 23 and has a tread surface continuous in the tire circumferential direction without being divided by the groove or sipe. Yes. For this reason, as shown in FIG. 2, the edge portion on the outer side in the vehicle width direction of the center land portion 33 and the edge portion on the inner side in the vehicle width direction of the outer second land portion 34 have a tread surface that is continuous in the tire circumferential direction. ing. In other words, no groove or sipe is open at the edge of the circumferential main groove 23 that divides the center land portion 33 and the outer second land portion 34.

[effect]
As described above, the pneumatic tire 1 includes two or more circumferential main grooves 21 to 24 that are arranged in one region with the tire equatorial plane CL as a boundary and extend in the tire circumferential direction, and the circumferential direction. And a plurality of land portions 31 to 35 divided into main grooves 21 to 24 (see FIGS. 1 and 2). Further, the second land portion (in FIG. 2, the outer second land portion 34 on the outer side in the vehicle width direction) has a bent or curved shape that protrudes toward the tire equatorial plane CL and is arranged continuously in the tire circumferential direction. A plurality of arc grooves 341 are provided. The arc groove 341 opens to the outermost circumferential main groove 24 at one end, and communicates with another arc groove 341 adjacent in the tire circumferential direction at the other end. Further, the maximum value Wg_max and the minimum value Wg_min of the groove width Wg (see FIG. 4) of the arc groove 341 have a relationship of Wg_max / Wg_min ≦ 1.10.

  In this configuration, (1) the plurality of arc grooves 341 are opened in the outermost circumferential main groove 24 and are arranged in communication with each other in the tire circumferential direction, so that the drainage of the arc grooves 341 is improved. Thereby, there exists an advantage which the wet performance of a tire improves. Further, (2) since the arc groove 341 has a substantially constant groove width Wg, the ground contact area of the second land portion 34 is ensured as compared with the configuration in which the groove width Wg of the arc groove 341 is widened. Thereby, there exists an advantage by which the steering stability performance of a tire is maintained. (3) Since the arc groove 341 has a substantially constant groove width Wg, the change in the groove area can be reduced as compared with the configuration in which the groove width Wg of the arc groove 341 is widened. Thereby, there exists an advantage by which the noise performance of a tire is maintained.

  Further, in the pneumatic tire 1, the groove width Wg of the arc groove 341 and the width W1 of the second land portion 34 have a relationship of 0.04 ≦ Wg / W1 ≦ 0.15 (see FIG. 4). Thereby, there exists an advantage by which the groove width Wg of the circular arc groove 341 is optimized. That is, by satisfying 0.04 ≦ Wg / W1, the groove width Wg of the arc groove 341 is ensured, and the effect of improving the wet performance by the arc groove 341 is appropriately obtained. Further, by satisfying Wg / W1 ≦ 0.15, a decrease in the contact area of the second land portion 34 due to an excessive groove width Wg is avoided, and the steering stability performance of the tire is ensured.

  In this pneumatic tire 1, the groove width Wg of the arc groove 341 is in the range of Wg ≦ 2.5 [mm] (see FIG. 4). Thereby, there is an advantage that the groove width Wg of the arc groove 341 is ensured and the effect of improving the wet performance by the arc groove 341 can be appropriately obtained.

  In the pneumatic tire 1, the other end 3412 of the arc groove 341 terminates in another arc groove 341 adjacent in the tire circumferential direction (see FIG. 4). In such a configuration, compared to a configuration in which adjacent arc grooves intersect in an X shape (not shown), the ground contact area of the block 343 is ensured and the steering stability performance of the tire is ensured.

  Further, in the pneumatic tire 1, a portion on the tire equatorial plane CL side of the second land portion 34 partitioned into a plurality of arc grooves 341 is a rib 342 continuous in the tire circumferential direction (see FIG. 3). Further, the maximum value Wr_max and the minimum value Wr_min of the width Wr of the rib 342 and the width W1 of the second land portion 34 have a relationship of 0.20 ≦ (Wr_max−Wr_min) /W1≦0.50 (see FIG. 4). ). Thereby, there exists an advantage by which the amplitude of the edge part by the side of the circular arc groove 341 of the rib 342 is optimized. That is, by satisfying 0.20 ≦ (Wr_max−Wr_min) / W1, the extension length of the arc groove 341 is ensured, and the effect of improving the wet performance by the arc groove 341 is ensured. In addition, since (Wr_max−Wr_min) /W1≦0.50, a reduction in the contact area of the rib 342 due to an excessive extension of the arc groove 341 is avoided.

  Further, in the pneumatic tire 1, a portion on the tire equatorial plane CL side of the second land portion 34 partitioned into a plurality of arc grooves 341 is a rib 342 continuous in the tire circumferential direction (see FIG. 3). Further, the maximum value Wr_max and the minimum value Wr_min of the width Wr of the rib 342 and the width W1 of the second land portion 34 have a relationship of 0.2 ≦ {(Wr_max + Wr_min) / 2} /W1≦0.5 (FIG. 4). Thereby, the center position of the amplitude of the edge part of the rib 342 on the arc groove 341 side is optimized. That is, by 0.2 ≦ {(Wr_max + Wr_min) / 2} / W1, the extending length of the arc groove 341 is ensured, and the effect of improving the wet performance by the arc groove 341 is ensured. Moreover, since {(Wr_max + Wr_min) / 2} /W1≦0.5, a reduction in the contact area of the rib 342 due to an excessive extension length of the arc groove 341 is avoided.

  Further, the pneumatic tire 1 is a plurality of blocks 343 in which the portion of the second land portion 34 that is partitioned into a plurality of arc grooves 341 on the tire ground contact end T side is arranged in the tire circumferential direction (see FIG. 3). . Further, the block 343 has a chamfered portion 3432 at the communicating portion 3412 of the adjacent arc grooves 341 and 341 (see FIG. 4). Thereby, there exists an advantage which can suppress local cupping and uneven wear.

  Moreover, in this pneumatic tire 1, the portion on the tire ground contact end T side of the second land portion 34 partitioned into a plurality of arc grooves 341 is a plurality of blocks 343 arranged in the tire circumferential direction (see FIG. 2). . Further, the block 343 includes a narrow groove 344 that opens to the outermost circumferential main groove 24 at one end and terminates in the block 343 at the other end. Further, the circumferential length L1 of the edge portion on the outermost circumferential main groove 24 side of the tread surface of the block 343 and the circumferential lengths L2a and L2b of the continuous portion of the edge portion divided by the narrow groove 344 are 0. .45 ≦ L2a / L1 ≦ 0.55 and 0.45 ≦ L2b / L1 ≦ 0.55 (see FIG. 4). Thereby, the circumferential lengths L2a and L2b of the edge portion of the block 343 divided by the narrow groove 344 are made uniform, and there is an advantage that uneven wear of the block 343 is suppressed.

  Moreover, in this pneumatic tire 1, the portion on the tire ground contact end T side of the second land portion 34 partitioned into a plurality of arc grooves 341 is a plurality of blocks 343 arranged in the tire circumferential direction (see FIG. 2). . Also, the block 343 has a groove 344 that opens to the outermost circumferential main groove 24 at one end and terminates in the block 343 at the other end, and a groove along the groove opening of the narrow groove 344. And a chamfered portion 3441 extending in the length direction (see FIG. 4). In such a configuration, there is an advantage that the groove area is increased by the narrow groove 344 and the chamfered portion 3441 and the wet performance of the tire is improved.

  Further, in the pneumatic tire 1, the shoulder land portion 35 includes a plurality of lug grooves 352 that extend in the tire width direction and are arranged at predetermined intervals in the tire circumferential direction (see FIG. 2). Further, the arrangement interval P1 of the arc grooves 341 of the second land portion 34 and the arrangement interval P2 of the lug grooves 352 of the shoulder land portion 35 have a relationship of 1.90 ≦ P1 / P2 ≦ 2.10 (see FIG. 3). ). Thereby, there exists an advantage by which arrangement | positioning space | interval P1 of the circular arc groove 341 is optimized. That is, when 1.90 ≦ P1 / P2, the ground contact area of the second land portion 34 is ensured, and the steering stability performance of the tire is ensured. Further, by satisfying P1 / P2 ≦ 2.10, the total area of the plurality of arc grooves 341 is secured, and the wet performance of the tire is secured.

  In the pneumatic tire 1, the maximum groove depth H1 of the arc groove 341 and the maximum groove depth H2 of the outermost circumferential main groove 24 have a relationship of 0.30 ≦ H1 / H2 ≦ 0.80. (See FIG. 5). Thereby, there exists an advantage by which the maximum groove depth H1 of the circular arc groove 341 is optimized. That is, by satisfying 0.30 ≦ H1 / H2, the maximum groove depth H1 of the arc groove 341 is ensured, and the effect of improving the wet performance by the arc groove 341 is ensured. Further, since H1 / H2 ≦ 0.80, the rigidity of the second land portion 34 is ensured, and the steering stability performance of the tire is ensured.

  Moreover, in this pneumatic tire 1, the circular arc groove 341 has the bottom upper part 3414 formed in the opening part by the outermost peripheral direction main groove 24 side (refer FIG. 5). Further, the depth H1a of the bottom upper portion 3414 and the maximum groove depth H1 of the arc groove 341 have a relationship of 0.30 ≦ H1a / H1 ≦ 0.80. In such a configuration, there is an advantage that the rigidity of the second land portion 34 is ensured by the bottom upper portion 3414 and the steering stability performance of the tire is ensured.

  In the pneumatic tire 1, the shoulder land portion 35 includes a circumferential narrow groove 351 extending in the tire circumferential direction and a plurality of lateral narrow grooves extending in the tire width direction and communicating with the circumferential narrow groove 351. A groove 353, a rib 354 that is partitioned into a circumferential narrow groove 351 and an outermost circumferential main groove 24 and continues in the tire circumferential direction (see FIG. 3). Further, the inclination angle θ1 with respect to the tire circumferential direction of the portion on the outermost circumferential main groove 24 side of the arc groove 341 and the inclination angle θ2 with respect to the tire circumferential direction of the widthwise narrow groove 353 are 20 [deg] ≦ θ2−θ1 ≦. It has a relationship of 60 [deg] (see FIG. 3). In such a configuration, since the inclination angle θ1 of the arc groove 341 of the second land portion 34 and the inclination angle θ2 of the width direction narrow groove 353 of the shoulder land portion 35 have a relationship of θ1 <θ2, the noise performance can be reduced. There is. Further, since the difference θ2−θ1 is optimized, there is an advantage that the noise performance can be reduced while ensuring the wet performance of the tire.

  Further, in the pneumatic tire 1, two or more circumferential main grooves 21, 22 that are arranged in the other region with the tire equatorial plane CL as a boundary and extend in the tire circumferential direction, and the circumferential main groove 21, And a second second land portion 32 divided into 22 (see FIG. 2). The second second land portion 32 has a plurality of inclined narrow grooves 321 and a plurality of inclined sipes 322 that extend while inclining with respect to the tire circumferential direction. Further, the inclined narrow groove 321 opens at one end to the edge portion on the tire equatorial plane CL side of the second second land portion 32 and terminates in the second second land portion 32 at the other end portion. (See FIG. 6). The inclined sipe 322 opens to the edge portion on the outermost circumferential main groove 22 side of the second second land portion 32 at one end portion, and terminates in the second second land portion 32 at the other end portion. Further, the inclined narrow grooves 321 and the inclined sipes 322 are arranged in a staggered manner in the tire circumferential direction. In such a configuration, the second second land portion 32 includes the inclined narrow grooves 321 and the inclined sipes 322 arranged in a staggered manner, so that there is an advantage that the wet performance of the tire is improved. In addition, since the inclined narrow groove 321, the inclined sipe 322, and the semi-closed structure are arranged separately from each other, the second second land portion 32 becomes a rib continuous in the tire circumferential direction. Accordingly, there is an advantage that the rigidity of the second second land portion 32 is ensured and the steering stability performance of the tire is improved.

  In this pneumatic tire 1, the center land portion 33 adjacent to the second second land portion 32 extends along the extended line of the inclined narrow groove 321 of the second second land portion 32. (See FIG. 2). In addition, the inclined narrow groove 331 opens to the edge portion on the second second land portion 32 side of the center land portion 33 at one end portion, and terminates inside the center land portion 33 at the other end portion. (See FIG. 6). In such a configuration, since the center land portion 33 includes the inclined narrow groove 331, there is an advantage that the wet performance of the tire is improved.

  Further, the pneumatic tire 1 includes a display portion that indicates a tire mounting direction with respect to the vehicle, and the arc groove 341 is disposed in a region that is on the outer side in the vehicle width direction when the tire is mounted on the vehicle (see FIG. 2). ). In such a configuration, since the arc groove 341 is disposed in the outer region in the vehicle width direction, there is an advantage that the wet performance of the tire is effectively improved.

  FIG. 7 is a chart showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention.

  In this performance test, evaluations on (1) wet steering stability performance, (2) dry steering stability performance, and (3) noise performance were performed on a plurality of types of test tires. A test tire having a tire size of 215 / 55R17 94W is assembled to a rim having a rim size of 17 × 7 JJ, and an air pressure of 230 [kPa] and a maximum load specified by JATMA are applied to the test tire. The test tire is mounted on all wheels of a passenger car driven by a front engine rear drive (FF) having a displacement of 1.6 L, which is a test vehicle.

  (1) In the evaluation regarding the wet maneuvering stability performance, the test vehicle travels at a speed of 40 [km / h] on an asphalt road sprinkled with a water depth of 1 [mm]. Then, the test driver performs sensory evaluation on the steering performance at the time of race change and cornering and the stability at the time of straight traveling. This evaluation is performed by index evaluation using the conventional example as a reference (100), and the larger the value, the better.

  (2) In the evaluation regarding the dry maneuvering stability performance, the test vehicle travels on a dry road test course having a flat circuit around 60 [km / h] to 100 [km / h]. Then, the test driver performs sensory evaluation on the steering performance at the time of race change and cornering and the stability at the time of straight traveling. This evaluation is performed by index evaluation using the conventional example as a reference (100), and the larger the value, the better.

  (3) In the evaluation relating to the noise performance, the test vehicle runs coasting on a test course having a rough road surface at 10 [km / h] to 20 [km / h], and the test driver performs a sensory evaluation on the in-vehicle noise. This evaluation is performed by index evaluation using the conventional example as a reference (100), and the larger the value, the better.

  The test tires of Examples 1 to 11 have the configurations described in FIGS. 1 and 2, and the outer second land portion 34 that is on the outer side in the vehicle width direction when the tire is mounted on the vehicle includes a plurality of arc grooves 341. Further, the width W1 of the outer second land portion 34 is W1 = 24 [mm].

  In the test tire of Conventional Example 1, in the configuration of Example 1, none of the land portions includes a plurality of arc grooves. In the test tire of Conventional Example 2, in the configuration of Example 1, the outer second land portion 34 includes a plurality of arc grooves.

  As shown in the test results, it can be seen that in the test tires of Examples 1 to 11, the wet steering stability performance, the dry steering stability performance, and the noise performance of the tire are compatible.

  1: pneumatic tire, 11: bead core, 12: bead filler, 13: carcass layer, 14: belt layer, 141, 142: cross belt, 143: belt cover, 15: tread rubber, 16: sidewall rubber, 17: Rim cushion rubber, 21-24: circumferential main groove, 31: inner shoulder land portion, 32: inner second land portion, 321: inclined narrow groove, 322: inclined sipe, 33: center land portion, 331: inclined narrow groove, 34: Outer second land portion, 341: Arc groove, 3411, 3412: Communication portion, 3413: Maximum protruding position, 3414, 3415: Upper bottom portion, 342: Rib, 343: Block, 3431, 3432, 3441: Chamfered portion, 344: narrow groove, 35: outer shoulder land, 351: circumferential narrow groove, 352: lug groove, 353: narrow narrow groove, 354: rib

Claims (16)

A pneumatic system comprising two or more circumferential main grooves disposed in one region with the tire equatorial plane as a boundary and extending in the tire circumferential direction, and a plurality of land portions defined by the circumferential main grooves Tire,
The outer circumferential direction main groove on the outermost side in the tire width direction is defined as the outermost circumferential direction main groove, the land portion on the outer side in the tire width direction defined by the outermost circumferential direction main groove is defined as a shoulder land portion, Define the land portion on the inner side in the tire width direction defined in the outermost circumferential main groove as a second land portion, and define the land portion on the tire equatorial plane side as the center land portion from the second land portion,
The second land portion includes a plurality of arc grooves arranged in a row in the tire circumferential direction and having a bent or curved shape that protrudes toward the tire equatorial plane side,
The arc groove opens to the outermost circumferential main groove at one end, communicates with the other arc groove adjacent in the tire circumferential direction at the other end, and
A pneumatic tire characterized in that the maximum value Wg_max and the minimum value Wg_min of the groove width Wg of the arc groove have a relationship of Wg_max / Wg_min ≦ 1.10.   The pneumatic tire according to claim 1, wherein a groove width Wg of the arc groove and a width W1 of the second land portion have a relationship of 0.04 ≦ Wg / W1 ≦ 0.15.   The pneumatic tire according to claim 1, wherein a groove width Wg of the arc groove is in a range of Wg ≦ 2.5 [mm].   The pneumatic tire according to any one of claims 1 to 3, wherein the other end of the arc groove terminates at the other arc groove adjacent in the tire circumferential direction. A portion on the tire equatorial plane side of the second land portion divided into the plurality of arc grooves is a rib continuous in the tire circumferential direction; and
The maximum value Wr_max and minimum value Wr_min of the rib width Wr and the width W1 of the second land portion have a relationship of 0.20 ≦ (Wr_max−Wr_min) /W1≦0.50. The pneumatic tire according to any one of the above. A portion on the tire equatorial plane side of the second land portion divided into the plurality of arc grooves is a rib continuous in the tire circumferential direction; and
The maximum value Wr_max and the minimum value Wr_min of the rib width Wr and the width W1 of the second land portion have a relationship of 0.2 ≦ {(Wr_max + Wr_min) / 2} /W1≦0.5. The pneumatic tire according to any one of 5. A portion of the second land portion on the tire ground contact end side partitioned by the plurality of arc grooves is a plurality of blocks arranged in the tire circumferential direction; and
The pneumatic tire according to any one of claims 1 to 6, wherein the block has a chamfered portion at a communication portion between adjacent arc grooves. A portion of the second land portion on the tire ground contact side divided into the plurality of arc grooves is a plurality of blocks arranged in the tire circumferential direction,
The block includes a narrow groove that opens in the outermost circumferential main groove at one end and terminates in the block at the other end; and
The circumferential length L1 of the edge portion on the outermost circumferential main groove side of the tread surface of the block and the circumferential lengths L2a and L2b of the continuous portion of the edge portion divided by the narrow groove are 0. The pneumatic tire according to any one of claims 1 to 7, having a relationship of 45≤L2a / L1≤0.55 and 0.45≤L2b / L1≤0.55. A portion of the second land portion on the tire ground contact end side partitioned by the plurality of arc grooves is a plurality of blocks arranged in the tire circumferential direction; and
The block opens in the outermost circumferential main groove at one end and ends in the block at the other end, and the groove length direction along the groove opening of the narrow groove A pneumatic tire according to any one of claims 1 to 8, further comprising a chamfered portion extending to the surface. The shoulder land portion includes a plurality of lug grooves extending in the tire width direction and arranged at predetermined intervals in the tire circumferential direction; and
The pneumatic tire according to any one of claims 1 to 9, wherein an arrangement interval P1 of the arc grooves and an arrangement interval P2 of the lug grooves have a relationship of 1.90 ≦ P1 / P2 ≦ 2.10. .   The maximum groove depth H1 of the circular arc groove and the maximum groove depth H2 of the outermost circumferential main groove have a relationship of 0.30 ≦ H1 / H2 ≦ 0.80. Pneumatic tire described in one. The arc groove has a bottom upper portion formed in an opening on the outermost circumferential direction main groove side; and
The pneumatic according to any one of claims 1 to 11, wherein a depth H1a of the bottom upper portion and a maximum groove depth H1 of the arc groove have a relationship of 0.30 ≦ H1a / H1 ≦ 0.80. tire. The shoulder land portion includes a circumferential narrow groove extending in the tire circumferential direction, a plurality of width narrow grooves extending in the tire width direction and communicating with the circumferential narrow groove, the circumferential narrow groove, and the A rib that is partitioned into an outermost circumferential main groove and continues in the tire circumferential direction; and
An inclination angle θ1 with respect to the tire circumferential direction of the arc groove on the outermost circumferential main groove side and an inclination angle θ2 with respect to the tire circumferential direction of the widthwise narrow groove are 20 [deg] ≦ θ2−θ1 ≦ 60 [. The pneumatic tire according to any one of claims 1 to 12, which has a relationship of deg]. Two or more circumferential main grooves arranged in the other region with the tire equatorial plane as a boundary and extending in the tire circumferential direction, and a second second land portion defined by the circumferential main groove ,
The second second land portion has a plurality of inclined narrow grooves and a plurality of inclined sipes extending while inclining with respect to the tire circumferential direction,
The inclined narrow groove opens to the edge portion on the tire equatorial plane side of the second second land portion at one end portion, and terminates in the second second land portion at the other end portion,
The inclined sipes open at one end to the edge portion on the outermost circumferential main groove side of the second second land portion and terminate in the second second land portion at the other end; and ,
The pneumatic tire according to any one of claims 1 to 13, wherein the inclined narrow grooves and the inclined sipes are arranged in a staggered manner in the tire circumferential direction. The center land portion adjacent to the second second land portion includes an inclined narrow groove extending along an extension line of the inclined narrow groove of the second second land portion, and
The inclined narrow groove opens to an edge portion of the center land portion on the second second land portion side at one end portion, and terminates inside the center land portion at the other end portion. 14. The pneumatic tire according to 14. A display unit indicating a tire mounting direction with respect to the vehicle, and
The pneumatic tire according to any one of claims 1 to 15, wherein the arcuate groove is disposed in a region that is on an outer side in a vehicle width direction when the tire is mounted on the vehicle.

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