JP2018034616A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving wet performance while securing the steering stability performance of the tire.SOLUTION: A pneumatic tire 1 in this invention is equipped with three or more circumferential main grooves 21 to 24 extending in a tire circumferential direction, and four rows or more land parts 31 to 35 partitioned by those main grooves 21 to 24. Besides, a second land part 32 in an inside area in a vehicle width direction has a V-shaped lug groove 321 having a V shape. Further, the V-shaped lug groove 321 has a V-shaped apex inside the second land part 32, and opens on the edge part of a tire equator face CL side of the second land part 32 in both ends of the V shape.SELECTED DRAWING: Figure 3

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 the pneumatic tire, there is a problem that the wet performance of the tire should be improved while ensuring the steering stability performance on the dry road surface of the tire. As conventional pneumatic tires related to such problems, techniques described in Patent Documents 1 and 2 are known.

JP 2002-240512 A JP-T-2004-523422 JP 2013-183325 A

  An object of the present invention is to provide a pneumatic tire capable of improving wet performance while ensuring the steering stability performance of the tire.

  In order to achieve the above object, a pneumatic tire according to the present invention includes three or more circumferential main grooves extending in the tire circumferential direction, and four or more rows of land portions defined by the circumferential main grooves. The circumferential main groove at the outermost side in the tire width direction is defined as the outermost circumferential main groove, and the land portion on the outer side in the tire width direction defined by the outermost circumferential main groove Is defined as a shoulder land portion, the land portion on the inner side in the tire width direction defined by the outermost circumferential main groove is defined as a second land portion, and the second land portion has a V-shaped lug groove having a V-shape. And the V-shaped lug groove has the V-shaped top portion inside the second land portion, and at both ends of the V-shape at the edge portion on the tire equatorial plane side of the second land portion. It is characterized by opening.

  In the pneumatic tire, (1) the second land portion includes a V-shaped lug groove having a V shape, thereby draining the tread portion center region (defined as a region between the left and right outermost main grooves). This improves the wet performance of the tire. (2) Since the V-shaped lug groove of the second land portion has a V-shaped top portion inside the second land portion, the rigidity of the edge portion of the second land portion is ensured, and the steering stability performance of the tire is ensured. The Moreover, (3) Since the V-shaped lug groove opens to the edge portion on the tire equatorial plane side of the second land portion at both ends of the V-shape, in particular, the configuration in which the second land portion is in the inner region in the vehicle width direction, A drainage path from the inner region in the vehicle width direction toward the outer region is formed, and drainage performance in the inner region in the vehicle width direction is improved. Thus, there is an advantage that the wet performance of the tire can be improved while ensuring the steering stability performance of the tire.

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 view showing a modification of the V-shaped lug groove shown in FIG. FIG. 6 is an explanatory view showing a modification of the V-shaped lug groove shown in FIG. FIG. 7 is an explanatory view showing a modification of the V-shaped lug groove shown in FIG. FIG. 8 is an explanatory view showing a modification of the V-shaped lug groove shown in FIG. FIG. 9 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. The same figure has shown sectional drawing of the one-side area | region of a 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.

  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 grounding end and the dimension symbol TW is a tread width | variety.

  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 a display requirement of a 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 on the tread surface in an unloaded state in which the tire is mounted on the specified rim and filled with the specified 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. Further, 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 using the center line of the amplitude of the groove wall as a measurement point.

  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 substantially 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).

  Of the two or more circumferential main grooves (including the circumferential main grooves arranged on the tire equator plane CL) arranged in one region with the tire equator plane CL as a boundary, the tire width direction The outermost circumferential main grooves 21 and 24 are defined as outermost circumferential main grooves. The outermost circumferential main grooves are respectively defined in left and right regions with the tire equatorial plane CL as a boundary. Further, the outermost circumferential main groove 21 in the inner region in the vehicle width direction is called an inner outermost main groove, and the outermost main groove 24 in the outer region in the vehicle width direction is called an outer outermost main groove. The distance from the tire equatorial plane CL to the left and right outermost circumferential main grooves 21, 24 (dimension symbols omitted in the figure) is in the range of 20% to 35% of the tire ground contact width TW.

  The tire ground contact width TW is the contact surface between the tire and the flat plate when the tire is mounted on the specified rim to apply 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. It is measured as the maximum linear distance in the tire axial direction.

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

  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 located 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 across the outermost circumferential main grooves 21 and 24. Further, the second land portion 32 in the vehicle width direction inner region is referred to as an inner second land portion, and the second land portion 34 in the vehicle width direction outer region is referred to as an outer second land portion.

  Further, the land portion 33 that is closer to the tire equatorial plane CL than the second land portions 32 and 34 is defined as a center land portion. The center land portion 33 may be disposed on the tire equatorial plane CL (see FIG. 2), or may be disposed at a position off the tire equatorial plane CL (not shown).

  In the configuration of FIG. 2, the left and right second land portions 32 and 34 and the single center land portion 33 are formed. However, in the configuration including five or more circumferential main grooves, two or more rows of center land are provided. A part is formed (not shown). In the configuration including three circumferential main grooves, the second land portion also serves as the center land portion (not shown).

[Inside second land]
3 and 4 are explanatory diagrams showing the tread pattern shown in FIG. In these drawings, FIG. 3 shows three rows of land portions 32, 33, 34 between the left and right outermost circumferential main grooves 21, 24, and FIG. 4 shows the second land portion in the vehicle width direction inner region. An enlarged view of 32 V-shaped lug grooves 321 is shown.

  In the configuration of FIG. 2, as shown in FIG. 3, three rows of land portions including the inner second land portion 32, the center land portion 33, and the outer second land portion 34 are between the left and right outermost circumferential grooves 21, 24. Is formed. Further, the center land portion 33 is on the tire equatorial plane CL.

  As shown in FIG. 3, the inner second land portion 32 includes a plurality of V-shaped lug grooves 321.

  The V-shaped lug groove 321 has a V shape on the tread surface, and is arranged with the top of the V shape facing outward in the tire width direction (in FIG. 3, in the vehicle width direction). Specifically, the V-shaped lug groove 321 has a V-shaped top portion inside the second land portion 32, and the edge of the second land portion 32 on the tire equatorial plane CL side at both ends of the V-shape. Open in the part. Thereby, the triangular block 322 is defined by the V-shaped lug groove 321 and the circumferential main groove 22. A plurality of V-shaped lug grooves 321 are arranged spaced apart from each other in the tire circumferential direction, and are arranged at a predetermined pitch length P1 in the tire circumferential direction.

  The V-shape of the V-shaped lug groove 321 is formed by a pair of groove portions 3211 and 3212 communicating with each other. For example, in the configuration of FIG. 3, the V-shaped lug groove 321 has a structure in which a long groove portion 3211 and a short groove portion 3212 are connected in a V shape. Further, these groove portions 3211 and 3212 communicate with each other inside the second land portion 32 at one end portion, and at the edge portion of the second land portion 32 on the tire equatorial plane CL side at the other end portion. Each is open.

  In the above configuration, (1) since the inner second land portion 32 includes the V-shaped lug groove 321 having a V-shape, it is defined as the tread portion center region (the region between the left and right outermost circumferential main grooves 21 and 24). The drainage performance of the tire is improved, and the wet performance of the tire is improved. (2) Since the V-shaped lug groove 321 of the inner second land portion 32 has a V-shaped top in the inner second land portion 32, the rigidity of the edge portion of the inner second land portion 32 is ensured, and the tire Steering stability performance is ensured. (3) Since the V-shaped lug groove 321 opens at the edge portion on the tire equatorial plane CL side of the inner second land portion 32 at both ends of the V shape, the drainage path from the inner region in the vehicle width direction toward the outer region Is formed, and the drainage of the inner region in the vehicle width direction is improved. Accordingly, the wet performance of the tire can be improved while ensuring the steering stability performance of the tire.

  In FIG. 4, a point A at the top of the V-shaped lug groove 321 and points B and C at both ends are defined. The top point A is defined as the intersection of the groove center lines of the pair of grooves 3211 and 3212 of the V-shaped lug groove 321. The points B and C at both ends are defined as intersections between the edge line of the edge portion of the second land portion 32 and the groove center lines of the groove portions 3211 and 3212. In the configuration in which the second land portion 32 has a notch portion or a chamfered portion at the edge portion, the ridgeline of the edge portion is defined by extending the tread surface of the second land portion 32 and the groove wall surface of the circumferential main groove 22.

  At this time, a straight line AB passing through the point A at the top of the V-shaped lug groove 321 and the point B at one end, and a straight line AC passing through the point A at the top and the point C at the other end, It inclines in the same direction with respect to the tire circumferential direction. For this reason, the point A at the top of the V-shaped lug groove 321 is located on the outer side in the tire circumferential direction with respect to the region between the points B and C at both ends. Thereby, the whole groove length of the V-shaped lug groove 321 increases.

  Further, in FIG. 4, the inclination angles θ1 and θ2 of the groove portions 3211 and 3212 of the V-shaped lug groove 321 at both ends of the V-shaped lug groove 321, that is, the opening with respect to the circumferential main groove 22 are defined. These inclination angles θ1 and θ2 are the intersection angles between the groove center lines of the groove portions 3211 and 3212 of the V-shaped lug groove 321 and the edge portions of the second land portion 32 at the points B and C at both ends of the V-shape. As measured.

  At this time, the inclination angles θ1 and θ2 at both ends of the V-shaped lug groove 321, particularly the smaller inclination angle θ1 is preferably in the range of 15 [deg] or more, and in the range of 20 [deg] or more. Is more preferable. Thereby, the rigidity of the corner | angular part of the triangular block 322 divided by the V-shaped lug groove 321 is ensured. For example, in the configuration of FIG. 4, since the pair of straight lines AB and AC described above are inclined in the same direction with respect to the tire circumferential direction, the inclination angle θ1 of the long groove portion 3211 of the V-shaped lug groove 321 is the other inclination angle. It is smaller than θ2. These inclination angles θ1 and θ2 have a relationship of 15 [deg] ≦ θ1 <θ2 ≦ 80 [deg].

  Similarly, in FIG. 4, the intersection angle φ between the left and right groove portions 3211 and 3212 of the V-shaped lug groove 321 at the top of the V-shaped lug groove 321 is defined. This intersection angle φ is measured as an angle formed by the groove center lines of the left and right groove portions 3211 and 3212 of the V-shaped lug groove 321 at the point A of the V-shaped top portion.

  At this time, the crossing angle φ at the top of the V-shaped lug groove 321 is preferably in the range of 10 [deg] or more, and more preferably in the range of 30 [deg] or more. Thereby, the rigidity of the corner | angular part of the triangular block 322 divided by the V-shaped lug groove 321 is ensured. The upper limit of the intersection angle φ is not particularly limited, but is related to the extended shape of the groove portions 3211 and 3212 of the V-shaped lug groove 321 and the lower limits of the inclination angles θ1 and θ2 at both ends of the V-shaped lug groove 321 described above. Limited.

  For example, in the configuration of FIG. 4, the long groove portion 3211 of the V-shaped lug groove 321 has an arc shape that protrudes toward the tire ground contact end T side. Further, the inclination angle of the groove center line of the long groove portion 3211 with respect to the tire circumferential direction gradually decreases from the opening portion with respect to the circumferential main groove 22 toward the top portion of the V-shaped lug groove 321, and the top portion of the V-shaped lug groove 321. 20 [deg] or less. Thereby, the drainage of the V-shaped lug groove 321 is enhanced, and the rigidity of the triangular block 322 partitioned by the V-shaped lug groove 321 is enhanced.

  In FIG. 4, the distance D1 in the tire width direction from the edge of the second land portion 32 on the tire equatorial plane CL side to the top of the V-shaped lug groove 321 and the width W1 of the second land portion 32 are 0.60. It is preferable to have a relationship of ≦ D1 / W1 ≦ 0.90, and it is more preferable to have a relationship of 0.70 ≦ D1 / W1 ≦ 0.80. Thereby, the extending range of the V-shaped lug groove 321 in the tire width direction is secured, and the distance from the top of the V-shaped lug groove 321 to the edge portion on the outermost circumferential main groove 21 side of the second land portion 32 is secured. Is done.

  The distance D1 of the top of the V-shaped lug groove 321 is the point of the top of the V-shaped lug groove 321 from the left and right edge portions 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. Measured as the distance in the tire width direction up to A.

  The width W1 of the second land portion 32 is measured as a 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. In addition, in a configuration in which the land portion has a notch portion or a chamfered portion in the edge portion, or in a configuration in which the main groove defining the land portion extends in a zigzag shape or a wave shape, the width of the land portion defines the land portion. Measured with reference to the measurement point of the groove width of the main groove.

  For example, in the configuration of FIG. 4, the groove portions 3211 and 3212 of the V-shaped lug groove 321 do not penetrate the second land portion 32 in the tire width direction, and therefore the second land portion 32 is tire-circulated by the V-shaped lug groove 321. Not divided in direction. For this reason, the second land portion 32 is not divided in the tire circumferential direction by grooves or sipes, and is a rib continuous in the tire circumferential direction. Moreover, said ratio D1 / W1 is optimized and the distance W1-D1 between the top part of the V-shaped lug groove 321 and the edge part on the outermost circumferential direction main groove 21 side of the second land part 32 is secured. Further, the edge portion on the outermost circumferential main groove 21 side of the second land portion 32 has a plain structure that is continuous in the tire circumferential direction without being divided by the opening of the lug groove, the opening of the sipe, or the like. . Thereby, the rigidity of the second land portion 32 is ensured.

  Further, the pitch length P1 (see FIG. 3) of the V-shaped lug groove 321 and the distance L1 (see FIG. 4) in the tire circumferential direction between both ends of the V-shape in one V-shaped lug groove 321 are 0.60. It is preferable to have a relationship of ≦ L1 / P1 ≦ 0.80, and it is more preferable to have a relationship of 0.65 ≦ L1 / P1 ≦ 0.75. Thereby, the distance L1 of the both ends of the V-shaped lug groove 321 is optimized.

  The distance L1 is measured as the distance in the tire circumferential direction between points B and C at both ends of the V-shaped lug groove 321.

  Also, the pitch length P1 of the V-shaped lug groove 321, the distance L1 in the tire circumferential direction at both ends of one V-shaped lug groove 321, and the tire from the top of one V-shaped lug groove 321 to the end closer to the tire The circumferential distance L2 preferably has a relationship of 0.50 ≦ L2 / (P1−L1) ≦ 0.90, and has a relationship of 0.65 ≦ L2 / (P1−L1) ≦ 0.75. It is more preferable. Thereby, the position of the top part of the V-shaped lug groove 321 between the V-shaped lug grooves 321 and 321 adjacent in the tire circumferential direction is optimized.

  As shown in FIG. 3, in the configuration in which the pair of groove portions 3211 and 3212 of the V-shaped lug groove 321 is inclined in the same direction with respect to the tire circumferential direction, the above-described 0.60 ≦ L1 / P1 ≦ 0.80 and 0 The ratio L2 / P1 in FIG.4 has a relationship of 0.10 ≦ L2 / P1 ≦ 0.36 under the condition of .50 ≦ L2 / (P1−L1) ≦ 0.90.

  In FIG. 4, the ratio between the maximum value and the minimum value of the groove width Wg in the entire V-shaped lug groove 321 is preferably in the range of 1.00 to 1.05. That is, it is preferable that the V-shaped lug groove 321 has a substantially constant groove width. Further, the groove width Wg of the V-shaped lug groove 321 is preferably in the range of 1.0 [mm] ≦ Wg ≦ 2.5 [mm], and 1.5 [mm] ≦ Wg ≦ 2.0 [mm]. ] Is more preferable. In addition, the lower limit of the groove width Wg of the V-shaped lug groove 321 is set so that the V-shaped lug groove 321 is not blocked when the tire contacts the ground. Thereby, the drainage of the V-shaped lug groove 321 is ensured.

  The groove width Wg of the V-shaped lug groove 321 is measured as the distance between the left and right groove walls on the tread surface 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.

  Further, it is preferable that the groove depth H1 (not shown) of the V-shaped lug groove 321 and the groove depth H0 of the outermost circumferential main groove 21 have a relationship of 0.40 ≦ H1 / H0 ≦ 0.90. , 0.60 ≦ H1 / H0 ≦ 0.80 is more preferable. Thereby, the groove depth H1 of the V-shaped lug groove 321 is ensured, the drainage of the V-shaped lug groove 321 is ensured, and the second is caused by the excessive groove depth H1 of the V-shaped lug groove 321. A decrease in the rigidity of the land portion 32 is suppressed.

  Moreover, as shown in FIG. 4, it is preferable that at least one of a pair of groove parts 3211 and 3212 which comprise V shape of the V-shaped lug groove 321 has a curvilinear shape. Accordingly, the groove length of the V-shaped lug groove 321 is increased and the drainage of the V-shaped lug groove 321 is improved as compared with the configuration in which both the groove portions 3211 and 3212 of the V-shaped lug groove 321 have a linear shape. To do.

  For example, in the configuration of FIG. 4, the long groove portion 3211 of the V-shaped lug groove 321 has an arc shape that protrudes toward the tire contact end side. Further, the maximum protrusion amount D2 of the long groove 3211 with respect to the straight line AB is in the range of 1.5 [mm] ≦ D2. Thereby, the groove length of the long groove part 3211 increases, and the rigidity of the block 322 partitioned into the V-shaped lug groove 321 is enhanced. In addition, a long groove portion 3211 extends from the V-shaped top portion of the V-shaped lug groove 321 in the region on the tire equatorial plane CL side, and protrudes to the outermost circumferential main groove 21 side beyond the V-shaped top portion. Not. Thereby, the rigidity of the edge part by the side of the outermost peripheral direction main groove 22 of the 2nd land part 32 is ensured. Moreover, in the structure of FIG. 4, the short groove part 3212 has a linear shape. However, the present invention is not limited to this, and the short groove portion 3212 may have a curved shape, for example, an arc shape (not shown).

  In the configuration of FIG. 4, the V-shaped lug groove 321 does not intersect with other lug grooves or sipes. Further, the block 322 divided into the V-shaped lug grooves 321 is not divided by other lug grooves or sipes. Thereby, the rigidity of the block 322 is ensured. Further, the long groove portion 3211 of the V-shaped lug groove 321 has an arc shape, and the short groove portion 3212 has a linear shape, so that the block 322 requires one end portion of the V-shaped lug groove 321. It has a shape.

[Modification]
5-8 is explanatory drawing which shows the modification of the V-shaped lug groove described in FIG. In these drawings, the shape of the V-shaped lug groove 321 is schematically shown by the groove center line.

  In the configuration of FIG. 4, as described above, the pair of groove portions 3211 and 3212 of the V-shaped lug groove 321 are inclined in the same direction with respect to the tire circumferential direction, and the long groove portion 3211 is the tire ground contact end T. It has an arc shape that is convex to the side. In such a configuration, the extension length of the V-shaped lug groove 321 is increased, the drainage performance of the V-shaped lug groove 321 is improved, and the rigidity of the block 322 partitioned by the V-shaped lug groove 321 is increased. preferable.

  However, the present invention is not limited to this, and as shown in FIG. 5, both of the pair of grooves 3211 and 3212 of the V-shaped lug groove 321 may have a linear shape, and as shown in FIG. The groove portions 3211 and 3212 may be inclined in directions different from each other with respect to the tire circumferential direction.

  In the configuration of FIG. 4, one of the pair of groove portions 3211 and 3212 of the V-shaped lug groove 321 may extend beyond the point A of the V-shaped top portion. For example, in the modification of FIG. 7, the long groove 3211 of the V-shaped lug groove 321 extends in the tire circumferential direction beyond the vertex A, and in the modification of FIG. 8, the short groove 3212 exceeds the vertex A. Extending in the tire width direction. Such a configuration is preferable in that the draining action of the V-shaped lug groove 321 is improved by increasing the extending length of the V-shaped lug groove 321. On the other hand, also in the configuration of FIGS. 7 and 8, the groove portions 3211 and 3212 of the V-shaped lug groove 321 do not communicate with the circumferential main groove 21 or other V-shaped lug grooves 321, and the interior of the land portion 32. It is necessary to terminate with. Thereby, the rigidity of the land portion 32 is ensured.

[Center land and outer second land]
In FIG. 2, as described above, the pneumatic tire 1 includes the two circumferential main grooves 21 to 24 in the left and right regions with the tire equatorial plane CL as a boundary. Further, between the left and right outermost circumferential main grooves 21, 24, three rows of land portions including an inner second land portion 32, a center land portion 33, and an outer second land portion 34 are partitioned. Further, the center land portion 33 is on the tire equatorial plane CL.

  As shown in FIG. 3, the center land portion 33 includes a plurality of through lug grooves 331 and a plurality of blocks 332 partitioned by these through lug grooves.

  The through lug groove 331 is a lug groove that penetrates the center land portion 33 in the tire width direction, and has a linear shape or a smooth arc shape. A plurality of through lug grooves 331 are arranged at predetermined intervals in the tire circumferential direction. At this time, the through lug groove 331 is disposed on the extended line of the short groove portion 3212 of the V-shaped lug groove 321 of the second land portion 32. Further, the pitch number of the V-shaped lug groove 321 in the second land portion 32 and the pitch number of the through-lug groove 331 in the center land portion 33 are the same, and the V-shaped lug groove 321 and the through-lug groove 331 correspond one-to-one. Arranged. As a result, a drainage path is formed from the V-shaped lug groove 321 of the inner second land portion 32 to the outer region in the vehicle width direction through the through lug groove 331 of the center land portion 33, and the drainage performance of the tread portion center region is improved. To do.

  Further, the through lug groove 331 has a substantially constant groove width (dimension symbol omitted in the figure). Moreover, the groove width of the through lug groove 331 is in a range of 2.5 [mm] or less, and is set to be substantially the same as the groove width of the short groove portion 3212 of the V-shaped lug groove 321 of the second land portion 32. Has been. Specifically, the ratio between the maximum value and the minimum value of the groove width in the short groove portion 3212 of the V-shaped lug groove 321 and the through lug groove 331 of the center land portion 33 is in the range of 1.00 or more and 1.05 or less. is there. Thus, when the through lug groove 331 of the center land portion 33 has a narrow groove width, the rigidity of the center land portion 33 is ensured, and the steering stability performance of the tire is improved.

  For example, in the configuration of FIG. 3, the short groove portion 3212 of the V-shaped lug groove 321 of the second land portion 32 is inclined at a predetermined inclination angle θ2 (see FIG. 4) with respect to the tire circumferential direction. A penetrating lug groove 331 of the center land portion 33 is disposed on the extension line. The through lug groove 331 is inclined in the same direction as the short groove portion 3212 of the V-shaped lug groove 321 with respect to the tire circumferential direction.

  As shown in FIG. 3, the block 332 of the center land portion 33 includes a plurality of non-penetrating lug grooves 333 and a plurality of sipes 334.

  The non-penetrating lug groove 333 terminates inside the block 332 at one end, and opens to the edge of the block 332 outside in the vehicle width direction at the other end. Further, the non-penetrating lug groove 333 extends in the tire width direction while being inclined at a predetermined angle with respect to the tire circumferential direction, and extends in parallel to the through lug groove 331. In the configuration of FIG. 3, the center land portion 33 is on the tire equatorial plane CL, and the non-penetrating lug groove 333 extends beyond the tire equatorial plane CL. Further, the groove width of the non-through lug groove 333 is in a range of 2.5 [mm] or less, has a constant groove width, and is set to be substantially the same as the groove width of the through lug groove 331 Yes. Specifically, the ratio between the maximum value and the minimum value of the groove width in the through lug groove 331 and the non-through lug groove 333 is in the range of 1.00 to 1.05. Thus, since the non-penetrating lug groove 333 has a narrow groove width, the rigidity of the center land portion 33 is ensured, and the steering stability performance of the tire is improved. In addition, one non-through lug groove 333 is disposed between a pair of through lug grooves 331 and 331 adjacent in the tire circumferential direction.

  The sipe 334 terminates inside the block 332 at one end, and opens to the edge of the block 332 outside in the vehicle width direction at the other end. Further, the sipe 334 extends in the tire width direction while being inclined at a predetermined angle with respect to the tire circumferential direction, and extends in parallel to the through lug groove 331. In the configuration of FIG. 3, the block 332 is on the tire equatorial plane CL, and the sipe 334 terminates inside the block 332 without crossing the tire equatorial plane CL. Further, one sipe 334 is disposed in the middle between the through lug groove 331 and the non-through lug groove 333 that are adjacent to each other in the tire circumferential direction.

  Further, as shown in FIG. 3, the edge portion on the inner side in the vehicle width direction of the block 332 has a plain structure that is continuous in the tire circumferential direction without being divided by the opening portion of the lug groove, the opening portion of the sipe, or the like. ing. Thereby, the rigidity of the block 332 is ensured.

  In FIG. 3, the outer second land portion 34 includes a plurality of through lug grooves 341 and a plurality of blocks 342 defined by these through lug grooves 341.

  The through lug groove 341 is a lug groove that penetrates the outer second land portion 34 in the tire width direction, and has a linear shape or a smooth arc shape. A plurality of through lug grooves 341 are arranged at predetermined intervals in the tire circumferential direction. At this time, the through lug groove 341 is disposed on the extension line of the through lug groove 331 of the center land portion 33 and on the extension line of the non-through lug groove 333 of the center land portion 33. Further, the pitch number of the through lug grooves 341 in the outer second land portion 34 is twice the pitch number of the through lug grooves 331 in the center land portion 33. As a result, a drainage path from the through lug groove 331 and the non-through lug groove 333 of the center land portion 33 through the through lug groove 341 of the outer second land portion 34 to the outermost outer peripheral main groove 24 is formed, and the tread portion The drainage of the center area is improved.

  In addition, the chamfered portion that widens the groove opening portion of the through lug groove 341 stepwise and in one direction in the region from the central portion of the outer second land portion 34 to the edge portion on the outer side in the vehicle width direction. (Dimension symbols omitted in the figure). Thereby, the groove volume of the through lug groove 341 is expanded in the region outside in the vehicle width direction, and the drainage performance of the through lug groove 341 is enhanced.

  Further, the groove width of the through lug groove 341 (the dimension symbol is omitted in the drawing) is 2.5 [mm] or less in the region from the edge part on the tire equatorial plane CL side to the center part of the outer second land part 34. It is in the range, and is set to be substantially the same as the groove widths of the through lug groove 331 and the non-through lug groove 333 of the center land portion 33. Specifically, the ratio between the maximum width and the minimum width of the through lug groove 331 and the non-through lug groove 333 in the center land portion 33 and the groove width of the through lug groove 341 in the above region of the outer second land portion 34 is as follows. In the range of 1.00 to 1.05. Thus, the through lug groove 341 has a narrow groove width in the region on the tire equatorial plane CL side of the outer second land portion 34, thereby ensuring the rigidity on the tire equatorial plane CL side of the outer second land portion 34, Improves tire handling stability.

  For example, in the configuration of FIG. 3, the through lug groove 331 and the non-through lug groove 333 of the center land portion 33 are inclined at a predetermined inclination angle with respect to the tire circumferential direction, and the through lug groove 331 and the non-through lug groove 333 are formed. The through lug grooves 341 of the outer second land portion 34 are respectively arranged on the extended line. Further, the through lug groove 341 of the outer second land portion 34 is inclined in the same direction as the through lug groove 331 and the non-through lug groove 333 of the center land portion 33 with respect to the tire circumferential direction.

  As shown in FIG. 3, the block 342 of the outer second land portion 34 includes a plurality of sipes 343.

  The sipe 343 opens at an edge portion on the tire equatorial plane CL side of the outer second land portion 34 at one end portion, and opens at a portion on the outer side in the vehicle width direction of the through lug groove 341 at the other end portion. Further, the sipe 343 is disposed on an extension line of the sipe 334 of the center land portion 33. The sipe 343 extends in parallel to the narrow portion of the through lug groove 341 from the edge portion of the outer second land portion 34 on the tire equatorial plane CL side, and is curved in the tire circumferential direction inside the block 342. The through lug groove 341 opens. Further, the sipe 343 opens into the through lug groove 341 from the opposite side to the chamfered portion of the through lug groove 341. One sipe 334 is arranged in one block 332.

[Inner and outer shoulder land]
As shown in FIG. 2, the pneumatic tire 1 includes an inner shoulder land portion 31 and an outer shoulder land portion 35.

  The inner shoulder land portion 31 includes one circumferential narrow groove 311, a plurality of through lug grooves 312, and a block (reference numerals omitted in the drawing) that are partitioned by these through lug grooves 312.

  The circumferential narrow groove 311 is a linear narrow groove extending in the tire circumferential direction, and has a groove width of 1.0 [mm] to 2.5 [mm]. The circumferential narrow groove 311 increases the groove area in the inner region in the vehicle width direction and improves the drainage performance of the tire.

  The through lug groove 312 is a lug groove that penetrates the inner shoulder land portion 31 in the tire width direction, and has a linear shape or a smooth arc shape on the tire contact surface. The through lug grooves 312 intersect with the circumferential narrow grooves 311 and communicate with each other. Thereby, the drainage property of the inner side shoulder land part 31 is improved. A plurality of through lug grooves 312 are arranged at predetermined intervals in the tire circumferential direction. At this time, the through lug groove 312 is disposed on the extended line of the short groove portion 3212 of the V-shaped lug groove 321 of the inner second land portion 32. Further, the pitch number of the through lug grooves 312 of the inner shoulder land portion 31 is twice the pitch number of the V-shaped lug grooves 321 of the inner second land portion 32. In addition, the groove width of the through lug groove 312 (dimension symbol omitted in the figure) is in the range of 2.5 [mm] or less in the ground contact surface of the shoulder land portion 31, and the inner second land portion 32 The V-shaped lug groove 321 is set to be substantially the same as the groove width of the short groove portion 3212. Specifically, the ratio between the maximum value and the minimum value of the groove width of the short groove portion 3212 of the through lug groove 312 in the ground contact surface of the inner shoulder land portion 31 and the V-shaped lug groove 321 of the inner second land portion 32 is It is in the range of 1.00 or more and 1.05 or less. Thus, the through lug groove 312 has a narrow groove width in the ground contact surface of the inner shoulder land portion 31, so that the rigidity of the inner shoulder land portion 31 is ensured, and the steering stability performance of the tire is improved.

  The outer shoulder land portion 35 includes a plurality of through lug grooves 351 and blocks (reference numerals omitted in the drawing) that are partitioned by these through lug grooves 351.

  The through lug groove 351 is a lug groove that penetrates the outer shoulder land portion 35 in the tire width direction, and has a linear shape or a smooth arc shape on the tire contact surface. A plurality of through lug grooves 351 are arranged at predetermined intervals in the tire circumferential direction. At this time, the through lug groove 351 is disposed on an extension line of the through lug groove 341 of the outer second land portion 34. Further, the pitch number of the through lug grooves 351 of the outer shoulder land portion 35 is the same as the pitch number of the V-shaped lug grooves 321 of the outer second land portion 34. The groove width of the through lug groove 351 (the dimension symbol is omitted in the figure) is in the range of 2.5 [mm] or less at the opening with respect to the outermost circumferential main groove 24, and the outer shoulder land portion 35. The tire is widened in a step-like manner to reach the tire ground contact end T. Thereby, the rigidity of the outer side shoulder land part 35 is ensured, and the drainage of the shoulder land part 35 is improved.

[effect]
As described above, the pneumatic tire 1 includes three or more circumferential main grooves 21 to 24 extending in the tire circumferential direction and four or more rows that are partitioned by the circumferential main grooves 21 to 24. Of land portions 31 to 25 (see FIG. 2). Further, the second land portion 32 in the inner region in the vehicle width direction includes a V-shaped lug groove 321 having a V shape. Further, the V-shaped lug groove 321 has a V-shaped top portion inside the second land portion 32 and opens to the edge portion on the tire equatorial plane CL side of the second land portion 32 at both ends of the V-shape ( (See FIG. 2).

  In such a configuration, (1) the second land portion 32 includes a V-shaped lug groove 321 having a V-shape, thereby defining a tread portion center region (a region between the left and right outermost circumferential main grooves 21 and 24). )) Is improved, and the wet performance of the tire is improved. (2) Since the V-shaped lug groove 321 of the second land portion 32 has a V-shaped top portion inside the second land portion 32, the rigidity of the edge portion of the second land portion 32 is secured, and the steering stability of the tire is ensured. Performance is ensured. In addition, (3) In general, the contact length of the land portion at the time of tire contact is larger as the land portion is closer to the tire equatorial plane CL. In this respect, in the above configuration, the V-shaped lug groove 321 opens at the edge portion on the tire equatorial plane CL side of the second land portion 32 at both ends of the V-shape. Compared with a configuration (not shown) that opens to the outer peripheral main groove side (tire contact end side), the drainage performance of the tread portion center region is improved. Further, in the configuration in which the second land portion 32 is in the vehicle width direction inner region, a drainage path from the vehicle width direction inner region to the outer region is formed, and drainage performance of the vehicle width direction inner region is improved. Thus, there is an advantage that the wet performance of the tire can be improved while ensuring the steering stability performance of the tire.

  The distance D1 in the tire width direction from the edge of the second land portion 32 on the tire equatorial plane CL side to the top of the V-shaped lug groove 321 and the width W1 of the second land portion 32 are 0.60 ≦ D1 / W1. ≦ 0.90 (see FIG. 4). Thereby, there exists an advantage by which the distance D1 of the tire width direction of the V-shaped lug groove 321 is optimized. That is, by satisfying 0.60 ≦ D1 / W1, the extending range of the V-shaped lug groove 321 in the tire width direction is secured, and the drainage of the second land portion 32 is secured. Further, by satisfying D1 / W1 ≦ 0.90, a distance from the top of the V-shaped lug groove 321 and the edge portion on the outermost circumferential main groove 21 side of the second land portion 32 is secured.

  Moreover, in this pneumatic tire 1, the second land portion is a rib continuous in the tire circumferential direction (see FIG. 3). Thereby, there is an advantage that the rigidity of the second land portion 32 is ensured and the steering stability performance of the tire is ensured.

  In this pneumatic tire 1, a plurality of V-shaped lug grooves 321 are arranged in the tire circumferential direction, and the pitch length P <b> 1 of the V-shaped lug grooves 321 (see FIG. 3) and the V in one V-shaped lug groove 321. The distance L1 (see FIG. 4) in the tire circumferential direction between the both ends of the letter shape has a relationship of 0.60 ≦ L1 / P1 ≦ 0.80. Thereby, there exists an advantage by which the distance L1 of the both ends of the V-shaped lug groove 321 is optimized. That is, by satisfying 0.60 ≦ L1 / P1, the extending length of the V-shaped lug groove 321 in the tire circumferential direction is secured, and the drainage action of the V-shaped lug groove 321 is secured. Further, since L1 / P1 ≦ 0.80, the distance between the openings of the V-shaped lug grooves 321 adjacent in the tire circumferential direction is secured, and the rigidity of the second land portion 32 is secured.

  Moreover, in this pneumatic tire 1, the several V-shaped lug groove 321 is mutually spaced apart and arrange | positioned in the tire circumferential direction (refer FIG. 3). Thereby, there exists an advantage by which the rigidity of the 2nd land part 32 is ensured.

  Further, in the pneumatic tire 1, one groove portion 3211 and the other groove portion 3212 of the V-shaped lug groove 321 are inclined in the same direction with respect to the tire circumferential direction (see FIG. 4). Thereby, the extension length of the V-shaped lug groove 321 increases compared with the structure (refer FIG. 6) which each groove part 3211 and 3212 of the V-shaped lug groove 321 inclines in a mutually different direction. Thereby, there exists an advantage which the drainage effect | action of the V-shaped lug groove 321 improves.

  Moreover, in this pneumatic tire 1, the inclination angles θ1 and θ2 (see FIG. 4) of the groove portions of the V-shaped lug groove 321 at both ends of the V-shaped lug groove 321 are in the range of 15 [deg] or more. Thereby, there is an advantage that the intersection angle between the V-shaped lug groove 321 and the edge portion of the second land portion 32 is ensured, and the rigidity of the triangular block 322 partitioned by the V-shaped lug groove 321 is ensured.

  In the pneumatic tire 1, the pitch length P1 of the V-shaped lug groove 321 (see FIG. 3), the distance L1 (see FIG. 4) in the tire circumferential direction at both ends of one V-shaped lug groove 321, and 1 The distance L2 (see FIG. 4) in the tire circumferential direction from the top of the two V-shaped lug grooves 321 to the closer end has a relationship of 0.50 ≦ L2 / (P1−L1) ≦ 0.90. Thereby, there exists an advantage by which the position of the top part of the V-shaped lug groove 321 between the V-shaped lug grooves 321 and 321 adjacent in a tire circumferential direction is optimized. That is, by 0.50 ≦ L2 / (P1-L1), the distance in the tire circumferential direction between the top of the V-shaped lug groove 321 and the end closer to the tire (the tire circumferential direction at points A and C in FIG. 4). Of the short groove portion 3212 of the V-shaped lug groove 321 is ensured. Thereby, the drainage of the V-shaped lug groove 321 is ensured. Further, when L2 / (P1-L1) ≦ 0.90, in particular, as shown in FIG. 3, the pair of groove portions 3211 and 3212 of the V-shaped lug groove 321 are inclined in the same direction with respect to the tire circumferential direction. In the configuration, the V-shaped lug grooves 321 and 321 adjacent to each other in the tire circumferential direction are arranged apart from each other without wrapping in the tire circumferential direction. Specifically, adjacent V-shaped lug grooves 321 and 321 are arranged at a distance of 0.10 <L2 / (P1-L1) in the tire circumferential direction. Thereby, the fall of the rigidity of the second land part 32 resulting from arrangement | positioning of the V-shaped lug groove 321 is suppressed.

  Moreover, in this pneumatic tire 1, the said V-shaped lug groove adjacent to a tire circumferential direction does not mutually wrap in a tire circumferential direction (refer FIG. 3). Thereby, there exists an advantage by which the fall of the rigidity of the 2nd land part 32 resulting from arrangement | positioning of the V-shaped lug groove 321 is suppressed.

  In the pneumatic tire 1, the ratio between the maximum value and the minimum value of the groove width Wg (see FIG. 4) in the entire region of the V-shaped lug groove 321 is in the range of 1.00 to 1.05. In such a configuration, since the groove width Wg of the V-shaped lug groove 321 is substantially constant, there is an advantage that a change in rigidity of the second land portion 32 due to the arrangement of the V-shaped lug groove 321 is reduced.

  Moreover, in this pneumatic tire 1, the groove width Wg of the V-shaped lug groove 321 is in the range of Wg ≦ 2.5 [mm]. In such a configuration, since the V-shaped lug groove 321 is a narrow groove, there is an advantage that a decrease in rigidity of the second land portion 32 due to the arrangement of the V-shaped lug groove 321 is suppressed.

  Further, in this pneumatic tire 1, at least one of the pair of groove portions 3211 and 3212 constituting the V shape of the V-shaped lug groove 321 (the long groove portion 3211 in FIG. 4) is the tire ground contact end T side. It has an arc shape that is convex (see FIG. 4). In such a configuration, the extension length of the groove portion 3211 is increased and the drainage of the V-shaped lug groove 321 is improved as compared with the configuration in which the groove portion 3211 of the V-shaped lug groove 321 has a linear shape (see FIG. 5). There are advantages to doing. In addition, there is an advantage that the drainage performance in the long groove portion 3211 is particularly improved as compared with the configuration in which the groove portion 3211 of the V-shaped lug groove 321 is bent in an L shape (not shown).

  Moreover, in this pneumatic tire 1, two or more circumferential main grooves 21 to 23 and three or more rows of land portions 31 to 33 are arranged in one region (the vehicle width in FIG. 2) with the tire equatorial plane CL as a boundary. (Refer to FIG. 2). Further, the center land portion 33 adjacent to the second land portion 32 includes a through lug groove 331 that penetrates the center land portion 33 in the tire width direction (see FIG. 3). Further, the through lug groove 331 of the center land portion 33 is on an extension line of one groove portion 3212 of the V-shaped lug groove 321 of the second land portion 32. With this configuration, the drainage performance from the groove portion 3212 of the V-shaped lug groove 321 of the second land portion 32 to the through lug groove 331 of the center land portion 33 is improved. Thereby, especially in the configuration in which the second land portion 32 is in the inner region in the vehicle width direction, a drainage path from the inner region in the vehicle width direction toward the outer region is formed, and the drainage performance of the inner region in the vehicle width direction is improved. is there.

  Further, in this pneumatic tire 1, the ratio between the maximum value and the minimum value of the groove width in one groove portion 3212 of the V-shaped lug groove 321 and the through lug groove 331 of the center land portion 33 is 1.00 or more and 1.05. It is in the following range (see FIG. 3). In such a configuration, the groove width of the groove portion 3212 of the V-shaped lug groove 321 of the second land portion 32 and the groove width of the through lug groove 331 of the center land portion 33 are substantially constant, resulting in the arrangement of the lug grooves 321 and 331. There is an advantage that the change in rigidity in the tire width direction of the second land portion 32 and the center land portion 33 is reduced.

  Moreover, in this pneumatic tire 1, the pitch number of the V-shaped lug groove 321 and the pitch number of the penetration lug groove 331 of the center land part 33 are the same (refer FIG. 3). Thereby, the relationship of the pitch number of the V-shaped lug groove 321 of the second land part 32 and the penetration lug groove 331 of the center land part 33 is optimized, and the drainage property of the above-mentioned inner region in the vehicle width direction is ensured. There is.

[Indication of vehicle mounting direction]
The pneumatic tire 1 also includes a mounting direction display unit (not shown) that specifies that the second land portion 32 having the V-shaped lug groove 321 is mounted on the vehicle with the vehicle width direction inside. The mounting direction display part is configured by, for example, marks or irregularities attached to the sidewall part of the tire. For example, ECER30 (European Economic Commission Regulation Article 30) obligates the installation of a mounting direction display section on the side wall that is on the outer side in the vehicle width direction when the vehicle is mounted.

  FIG. 9 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 and (2) dry steering stability performance were performed for a plurality of types of test tires. Further, 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 prescribed load of JATMA are applied to the test tire. The test tire is mounted on all wheels of a 1.6-liter front engine front drive (FF) -driven passenger car, 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 Comparative Example 1 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 Comparative Example 1 as a reference (100), and the larger the value, the better.

  The test tires of Examples 1 to 8, 10, and 11 have the structures described in FIGS. However, in the first embodiment, the center land portion 33 does not include the lug grooves 331 and 333. Further, in the second embodiment, the through lug groove 331 of the center land portion 33 is arranged offset in the tire circumferential direction with respect to the short groove portion 3212 of the V-shaped lug groove 321 of the inner second land portion 32. Moreover, in Example 3, the penetration lug groove 331 of the center land portion 33 does not penetrate the center land portion and has the same structure as the non-through lug groove 333. Moreover, in Example 9, the V-shaped lug groove 321 of the inner side second land portion 32 has a shape shown in FIG. Further, in Examples 1 to 11, the tread width TW = 162 [mm], the groove depth H0 = 7.8 [mm] of the outermost circumferential main groove 21, and the width W1 = 20.0 [mm] of the inner second land portion 32. mm], the pitch length P1 of the V-shaped lug groove 321 = 59.0 [mm], the groove width Wg = 1.5 [mm], and the groove depth H1 = 6.0 [mm].

  In the test tires of Comparative Examples 1 and 2, in the tread pattern of FIG. 2, the V-shaped top portion of the V-shaped lug groove 321 of the inner second land portion 32 faces the tire equatorial plane CL. In Comparative Example 1, the long groove portion 3211 of the V-shaped lug groove 321 opens into the circumferential main groove 21 of the tire ground contact end T, and the short groove portion 3212 terminates inside the second land portion 32. Moreover, the center land part does not have a lug groove. In Comparative Example 2, both of the pair of groove portions 3211 and 3212 of the V-shaped lug groove 321 are open to the circumferential main groove 21 on the tire ground contact end T side. Further, the through lug groove 331 of the center land portion 33 does not penetrate the center land portion, and is offset in the tire circumferential direction with respect to the short groove portion 3212 of the V-shaped lug groove 321 of the inner second land portion 32. Are arranged.

  As the test results show, it can be seen that the test tires of Examples 1 to 11 have both wet steering stability performance and dry steering stability performance.

  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 to 24: circumferential main groove, 31: inner shoulder land portion, 311: circumferential narrow groove, 312: through lug groove, 32: inner second land portion, 321: V-shaped lug groove, 322: block 33: Center land portion, 331: Through lug groove, 332: Block, 333: Non-through lug groove, 334: Sipe, 34: Outer second land portion, 341: Through lug groove, 342: Block, 343: Sipe, 35 : Outer shoulder land portion, 351: Through lug groove, 3211: Groove portion, 3212: Groove portion

Claims (15)

A pneumatic tire comprising three or more circumferential main grooves extending in the tire circumferential direction and four or more rows of land portions defined by the circumferential main grooves,
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, The land portion inside the tire width direction defined in the outermost circumferential direction main groove is defined as a second land portion,
The second land portion includes a V-shaped lug groove having a V-shape, and
The V-shaped lug groove has the V-shaped top portion inside the second land portion, and opens to the edge portion on the tire equatorial plane side of the second land portion at both ends of the V-shape. A featured pneumatic tire.   The distance D1 in the tire width direction from the edge portion on the tire equatorial plane side of the second land portion to the top portion of the V-shaped lug groove and the width W1 of the second land portion are 0.60 ≦ D1 / W1 ≦ 0. The pneumatic tire according to claim 1, having a relationship of .90.   The pneumatic tire according to claim 1 or 2, wherein the second land portion is a rib continuous in the tire circumferential direction. A plurality of the V-shaped lug grooves are arranged in the tire circumferential direction,
The relationship between the pitch length P1 of the V-shaped lug groove and the distance L1 in the tire circumferential direction between the V-shaped end portions of one V-shaped lug groove is 0.60 ≦ L1 / P1 ≦ 0.80. The pneumatic tire according to any one of claims 1 to 3.   The pneumatic tire according to any one of claims 1 to 4, wherein the plurality of V-shaped lug grooves are spaced apart from each other in the tire circumferential direction.   The pneumatic tire according to any one of claims 1 to 5, wherein one groove portion and the other groove portion of the V-shaped lug groove are inclined in the same direction with respect to the tire circumferential direction.   The pneumatic tire according to any one of claims 1 to 6, wherein an inclination angle of the groove portion of the V-shaped lug groove at the both end portions of the V-shaped lug groove is in a range of 15 [deg] or more.   The pitch length P1 of the V-shaped lug groove, the distance L1 in the tire circumferential direction between the two end portions of one V-shaped lug groove, and the end portion closer to the top of the one V-shaped lug groove. The pneumatic tire according to any one of claims 1 to 7, wherein a distance L2 in the tire circumferential direction has a relationship of 0.50 ≦ L2 / (P1-L1) ≦ 0.90.   The pneumatic tire according to any one of claims 1 to 8, wherein the V-shaped lug grooves adjacent in the tire circumferential direction do not wrap in the tire circumferential direction.   The pneumatic tire according to any one of claims 1 to 9, wherein a ratio between a maximum value and a minimum value of the groove width in the entire region of the V-shaped lug groove is in a range of 1.00 to 1.05.   The pneumatic tire according to claim 1, wherein a groove width Wg of the V-shaped lug groove is in a range of Wg ≦ 2.5 [mm].   The pneumatic tire according to any one of claims 1 to 11, wherein at least one of a pair of groove portions constituting the V shape of the V-shaped lug groove has an arc shape. Two or more circumferential main grooves and three or more rows of land portions are arranged in one region having a tire equator plane as a boundary,
Define the land portion on the tire equator side from the second land portion as a center land portion,
The center land portion adjacent to the second land portion includes a through lug groove that penetrates the center land portion in the tire width direction, and
The pneumatic tire according to any one of claims 1 to 12, wherein the through lug groove of the center land portion is on an extension line of one groove portion of the V-shaped lug groove of the second land portion.   The ratio of the maximum value and the minimum value of the groove width in the one lug portion of the V-shaped lug groove and the through lug groove of the center land portion is in a range of 1.00 to 1.05. The described pneumatic tire.   The pneumatic tire according to claim 13 or 14, wherein a pitch number of the V-shaped lug grooves and a pitch number of the through lug grooves in the center land portion are the same.

Images