JP2020006728A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire which can achieve both of dry performance and wet performance.SOLUTION: This pneumatic tire comprises a circumferential groove 24 which extends in a tire circumferential direction, and plural penetration grooves 41 which extend in a tire width direction and penetrate the circumferential groove 24, and of which both end parts terminate in a land part. In an area on at least one side in a tire width direction of the circumferential groove 24, a groove width Wg_min of the narrowest penetration groove 41A and a groove width Wg_max of the widest penetration groove 41B of the plural penetration grooves 41 have a relationship of 1.50≤Wg_max/Wg_min≤20.0. Further, in the case that the groove width of the penetration groove 41 is 1.5 mm or more, both have a relationship of 1.50≤Wg_max/Wg_min≤3.00.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire capable of achieving both dry performance and wet performance of the tire.

  With recent pneumatic tires, there is a demand for improving sports performance not only in circuit running but also in running on city streets and highways. Therefore, in order to achieve both dry performance and wet performance of the tire, two circumferential main grooves are provided in the vehicle width direction inner region bounded by the tire equatorial plane, and a single circumferential direction is provided in the vehicle width direction outer region. A configuration having a main groove and a single circumferential narrow groove is employed. As a conventional pneumatic tire adopting such a configuration, a technique described in Patent Literature 1 is known.

  Patent Document 2 discloses a conventional pneumatic tire adopting a configuration in which a sipe penetrating a circumferential groove and a narrow groove penetrating the circumferential groove and having one end terminating in a land portion are alternately arranged. Are known.

JP-A-2006-74386 JP 2013-49407 A

  An object of the present invention is to provide a pneumatic tire that can achieve both dry performance and wet performance of a tire.

  To achieve the above object, a pneumatic tire according to an aspect of the present invention includes a circumferential groove extending in a tire circumferential direction, a tire extending in a tire width direction, penetrating the circumferential groove, and having both ends. A plurality of through-grooves terminating in the land portion, and in at least one region in the tire width direction of the circumferential groove, among the plurality of through-grooves, a groove width Wg_min of the narrowest through-groove and a widest width. The groove width Wg_max of the through groove has a relationship of 1.50 ≦ Wg_max / Wg_min ≦ 20.0. In at least one region of the circumferential groove in the tire width direction, the groove width of the plurality of through grooves is 1.5 mm or more, and the narrowest one of the plurality of through grooves. The groove width Wg_min of the groove and the groove width Wg_max of the widest through groove have a relationship of 1.50 ≦ Wg_max / Wg_min ≦ 3.00.

  In the pneumatic tire according to the present invention, (1) the through-groove penetrates the circumferential narrow groove, so that drainability near the circumferential narrow groove is improved, and the wet performance of the tire is improved. At the same time, since the through groove does not open to the circumferential main groove and the tire ground contact end, the rigidity of the left and right land portions defined by the circumferential narrow groove is secured. As a result, there is an advantage that the wet performance and the dry performance of the tire are compatible with each other efficiently. (2) Since a plurality of types of through-grooves having mutually different groove widths are arranged at predetermined intervals in the tire circumferential direction, a comparison is made with a configuration in which the plurality of types of through-grooves 41 all have the same width and the same length. Then, a through groove having a wide groove width is arranged on the tread of one land portion. Thereby, there is an advantage that the dry performance and the wet performance of the tire can be improved in a well-balanced manner.

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 illustrating a tread surface of the pneumatic tire illustrated in FIG. 1. FIG. 3 is an enlarged view illustrating a main part of an outer region in a vehicle width direction of the pneumatic tire illustrated in FIG. 2. FIG. 4 is an explanatory diagram illustrating a through groove of the pneumatic tire illustrated in FIG. 3. FIG. 5 is an explanatory view showing a modification of the through groove shown in FIG. FIG. 6 is an explanatory view showing a modification of the through groove shown in FIG. FIG. 7 is an explanatory view showing a modification of the through groove shown in FIG. FIG. 8 is an explanatory view showing a modification of the through groove shown in FIG. FIG. 9 is an explanatory view showing a modification of the through groove shown in FIG. FIG. 10 is an explanatory view showing a modification of the through groove shown in FIG. FIG. 11 is a diagram illustrating a case where both the inside in the vehicle width direction and the outside in the vehicle width direction of the circumferential narrow groove are sipes. FIG. 12 is a diagram illustrating a case where both the inside in the vehicle width direction and the outside in the vehicle width direction of the circumferential narrow groove are sipes. FIG. 13 is a diagram illustrating a case where both the inside in the vehicle width direction and the outside in the vehicle width direction of the circumferential narrow groove are sipes. FIG. 14 is a chart showing the results of performance tests of the pneumatic tire according to the embodiment of the present invention. FIG. 15 is a table showing results of performance tests of the pneumatic tire according to the embodiment of the present invention. FIG. 16 is a chart showing the results of performance tests of the pneumatic tire according to the embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description of each embodiment, the same or equivalent components as those of the other embodiments are denoted by the same reference numerals, and description thereof will be simplified or omitted. The present invention is not limited by each embodiment. The components of each embodiment include components that can be easily replaced by those skilled in the art, or components that are substantially the same. Further, the configurations described below can be appropriately combined. The configuration may be omitted, replaced, or changed without departing from the spirit of the invention.

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

  In FIG. 1, the cross section in the tire meridian direction refers to a cross section when the tire is cut along a plane including a tire rotation axis (not shown). Reference symbol CL denotes a tire equatorial plane, which is a plane passing through the center point of the tire in the tire rotation axis direction and perpendicular to the tire rotation axis. The tire width direction refers to a direction parallel to the tire rotation axis, and the tire radial direction refers to a direction perpendicular to the tire rotation axis.

  The inside in the vehicle width direction and the outside in the vehicle width direction are defined as directions with respect to the vehicle width direction when the tire is mounted on the vehicle. Further, left and right regions bounded by the tire equatorial plane are defined as a vehicle width direction outer region and a vehicle width direction inner region, respectively. Further, the pneumatic tire includes a mounting direction indicator (not shown) that indicates a mounting direction of the tire with respect to the vehicle. The mounting direction display section is constituted by, for example, marks and irregularities provided on the sidewall portion of the tire. For example, ECER30 (Article 30 of the Regulations of the European Economic Commission) mandates that a vehicle mounting direction indicator be provided on a side wall portion that is outward in the vehicle width direction when the vehicle is mounted.

  The pneumatic tire 10 has an annular structure about the tire rotation axis, and includes a pair of bead cores 11, a pair of bead fillers 12, 12, a carcass layer 13, a belt layer 14, and a tread rubber 15. , A pair of sidewall rubbers 16, 16 and a pair of rim cushion rubbers 17, 17 (see FIG. 1).

  The pair of bead cores 11 and 11 are formed by winding one or more bead wires made of steel in an annular and multiple manner, and are embedded in the bead portions to form the cores of the right and left bead portions. The pair of bead fillers 12, 12 are arranged on the tire radial outer periphery of the pair of bead cores 11, 11 to reinforce the bead portion.

  The carcass layer 13 has a single-layer structure made up of one carcass ply or a multilayer structure made up of a plurality of carcass plies, and is bridged between the left and right bead cores 11 in a toroidal manner to form a tire skeleton. Is configured. Further, both end portions of the carcass layer 13 are wrapped around the bead core 11 and the bead filler 12 to be wrapped outward in the tire width direction and locked. The carcass ply of the carcass layer 13 is formed by rolling a plurality of carcass cords made of steel or an organic fiber material (for example, aramid, nylon, polyester, rayon, etc.) with a coating rubber, and forming an absolute value of 80. It has a carcass angle of not less than [deg] and not more than 90 [deg] (defined as the inclination angle of the carcass cord in the longitudinal direction with respect to the tire circumferential direction).

  The belt layer 14 is formed by laminating a pair of cross belts 141 and 142 and a belt cover 143, and is disposed so as to be looped around the outer periphery of the carcass layer 13. The pair of crossed belts 141 and 142 are formed by coating a plurality of belt cords made of steel or organic fiber material with a coating rubber and rolling the belt cords, and have a belt angle of 20 [deg] or more and 55 [deg] or less in absolute value. Have. Further, the pair of crossed belts 141 and 142 have mutually different belt angles (defined as the inclination angle of the belt cord in the longitudinal direction with respect to the tire circumferential direction), and cross the belt cords in the longitudinal direction. (So-called cross-ply structure). The belt cover 143 is formed by coating a belt cover cord made of steel or an organic fiber material with 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 in which one or a plurality of belt cover cords are coated with coat rubber. It can be configured to be wound spirally.

  The tread rubber 15 is arranged on the outer periphery of the carcass layer 13 and the belt layer 14 in the tire radial direction, and forms a tread portion of the tire. The pair of sidewall rubbers 16 and 16 are respectively disposed outside the carcass layer 13 in the tire width direction to form left and right sidewall portions. The pair of rim cushion rubbers 17, 17 are respectively arranged on the inner side in the tire radial direction of the rewinding portions of the left and right bead cores 11, 11 and the carcass layer 13, and constitute the rim fitting surfaces 20 of the bead portions.

[Tread pattern]
FIG. 2 is a plan view showing a tread surface of the pneumatic tire 10 shown in FIG. FIG. 2 shows a tread pattern of the all-season tire. In FIG. 2, the tire circumferential direction refers to a direction around the tire rotation axis. The symbol T is a tire contact end, and the dimension symbol TW is a tire contact width.

  As shown in FIG. 2, the pneumatic tire 10 includes a plurality of circumferential main grooves 21 to 23 and a circumferential narrow groove 24 extending in a tire circumferential direction, and a plurality of circumferential grooves 21 to 24 partitioned into the circumferential grooves 21 to 24. Are provided on the tread surface.

  The main groove is a groove that is required to display a wear indicator specified by JATMA, and generally has a groove width of 3.0 [mm] or more and a groove depth of 6.0 [mm] or more. Further, the through groove is a lateral groove extending in the tire width direction. The through groove includes a lug groove and a sipe described later. The lug groove is open when the tire is in contact with the ground and functions as a groove. The groove width of the lug is, for example, 1.5 [mm] or more. The sipe is a cut formed in the tread tread and is distinguished from the lug groove in that the sipe closes when the tire is in contact with the ground.

  The circumferential narrow groove 24 will be described later.

  The groove width is measured as the maximum value of the distance between the left and right groove walls at the groove opening in a no-load state in which the tire is mounted on the specified rim and the specified internal pressure is filled. In the configuration in which the land has a notch or chamfer at the edge, the groove width is taken as the measurement point at the intersection of the tread surface and the extension of the groove wall in a sectional view with the groove length direction as the normal direction. Is measured. In a configuration in which the groove extends in a zigzag or wavy 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 a no-load state in which the tire is mounted on a specified rim and the specified internal pressure is filled. In a configuration in which the groove has a partially uneven portion or a sipe at the groove bottom, the groove depth is measured excluding these.

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

  For example, in the configuration of FIG. 2, the pneumatic tire 10 has a tread pattern that is asymmetrical about the tire equatorial plane CL. Further, an inner region in the vehicle width direction bounded by the tire equatorial plane CL has two circumferential main grooves 21 and 22, and an outer region in the vehicle width direction has one circumferential main groove 23 and one circumferential direction. And a narrow groove 24. These circumferential grooves 21, 22; 23, 24 are arranged symmetrically with respect to the tire equatorial plane CL. Further, land portions 31 to 35 in five rows are defined by these circumferential grooves 21 to 24. One land portion 33 is arranged on the tire equatorial plane CL.

  Further, land portions 31 and 35 on the outer side in the tire width direction defined by the outermost circumferential main groove 21 in the vehicle width direction inner region or the circumferential narrow groove 24 in the vehicle width direction outer region are defined as shoulder land portions. The shoulder land portions 31 and 35 are outermost land portions in the tire width direction, and are located on the tire contact end T. Further, land portions 32 and 34 on the inner side in the tire width direction defined by the outermost circumferential main groove 21 or the circumferential narrow groove 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 grooves 21 and 24 interposed therebetween. The land portion 33 located on the tire equatorial plane CL side with respect to the second land portions 32 and 34 is defined as a center land portion.

[Outside area in the vehicle width direction]
In the configuration of FIG. 2, the outer region in the vehicle width direction bounded by the tire equatorial plane CL is a single circumferential main groove 23, and a single outer circumferential groove is disposed outside the circumferential main groove 23. And a circumferential narrow groove 24. Further, a shoulder land portion 35 and a second land portion 34 are defined by these circumferential grooves 23 and 24.

  For example, in the configuration of FIG. 2, the circumferential main groove 23 and the circumferential narrow groove 24 have a straight shape having a constant groove width. Further, the distance Dm from the tire equatorial plane CL to the groove center line of the circumferential main groove 23 is in the range of 8% to 12% with respect to the tire contact width TW. The distance Dn from the tire equatorial plane CL to the groove center line of the circumferential narrow groove 24 is in the range of 26% to 32% with respect to the tire contact width TW.

  The groove center line of the circumferential main groove is defined as a straight line that passes through the midpoint of the measurement points on the left and right of the groove width of the circumferential main groove and is parallel to the tire circumferential direction.

  Tire contact width TW is the contact surface between the tire and the flat plate when the tire is mounted on a specified rim to apply a specified internal pressure and is placed perpendicular to the flat plate in a stationary state and a load corresponding to a specified load is applied. Is measured as the maximum linear distance in the tire axial direction at.

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

  The groove width of the circumferential main groove 23 is in the range of 5.0 mm or more and 25.0 mm or less, and the groove depth is in the range of 5.0 mm or more and 12.0 mm or less. (Dimension symbols are omitted in the figure). Further, the groove width Ws (see FIG. 4 described later) of the circumferential narrow groove 24 is in the range of not less than 3.0 [mm] and not more than 7.0 [mm], and the groove depth is not less than 3.0 [mm] and not more than 7 [mm]. 0.0 [mm] or less (dimension symbols omitted in the figure).

  Further, in the configuration of FIG. 2, the edges of the left and right land portions 33 and 34 defined by the circumferential main groove 23 in the vehicle width direction outer region on the circumferential main groove 23 side also have openings of the sipes and grooves. By having a flat plane structure, it extends continuously in the tire circumferential direction. Thereby, the noise performance of the tire is enhanced.

[Thru-groove in outer area in vehicle width direction]
FIG. 3 is an enlarged view illustrating a main part of an outer region in a vehicle width direction of the pneumatic tire illustrated in FIG. 2. FIG. 4 is an explanatory diagram illustrating a through groove of the pneumatic tire illustrated in FIG. 3. In these figures, FIG. 3 shows the second land portion 34 and the shoulder land portion 35 in the outer region in the vehicle width direction, and FIG. 4 shows an enlarged view in which the circumferential narrow groove 24 and the plurality of through grooves 41 are extracted. I have.

  As shown in FIG. 2, the pneumatic tire 10 includes the above-described narrow circumferential groove 24 and a plurality of through grooves 41 (41 </ b> A, 41 </ b> B) in a vehicle width direction outer region.

  The through groove 41 extends in the tire width direction and penetrates the circumferential narrow groove 24, and is opened in the second land portion 34 and the shoulder land portion 35 without opening to the circumferential main groove 23 and the tire contact end T. Terminate. For this reason, the through groove 41 branches off from the circumferential narrow groove 24 in a branch shape in the tire width direction and terminates inside the left and right land portions 34 and 35. Here, the end portion of the through groove 41 on the inner side in the tire width direction is simply referred to as “inner end portion”, and the outer end portion on the outer side in the tire width direction is simply referred to as “outside end portion”. The plurality of through grooves 41 (41A, 41B) are arranged at predetermined intervals in the tire circumferential direction.

  In the above-described configuration, since the through groove 41 penetrates the circumferential narrow groove 24, drainage near the circumferential narrow groove 24 is improved, and the wet performance of the tire is improved. At the same time, since the through groove 41 does not open to the circumferential main groove 23 and the tire ground contact end T, the rigidity of the left and right land portions 34 and 35 defined by the circumferential narrow groove 24 is secured. As a result, the wet performance and the dry performance of the tire are efficiently compatible.

  Further, as shown in FIG. 3, a plurality of types of through-grooves 41 (41A, 41B) having different extending lengths are arranged in a mixed manner. Further, among the plurality of types of through grooves 41, the extension length L1_min of the shortest through groove 41A and the extension length L1_max of the longest through groove 41B are 1.10 ≦ L1_max / L1_min ≦ 3. 0.001 and more preferably 1.20 ≦ L1_max / L1_min ≦ 1.60. The relationship between the groove width Wg1 of the shortest through groove 41A and the groove width Wg2 of the longest through groove 41B is Wg2> Wg1. The range of the extension length L1 of the through groove 41 is not particularly limited, but is limited by the range of the distance Di, Do (see FIG. 4) of the terminal end of the through groove 41 in each of the land portions 34, 35 described later. .

  The extension length L1 of the through groove is a distance in the tire width direction from the inner end portion to the outer end portion of the through groove when the tire is mounted on a specified rim to apply a specified internal pressure and to be in a no-load state. Defined. Further, in a configuration including three or more types of through grooves having different extension lengths, the extension length L1_min of the shortest first through groove and the extension of the longest second through groove are different. The length L1_max is measured respectively.

  For example, in the configuration of FIG. 3, a plurality of through grooves 41 (41A and 41B) are arranged at predetermined intervals in the tire circumferential direction. In addition, these through grooves 41A and 41B intersect only the circumferential narrow groove 24 and are not connected to other grooves or sipes. Further, the second land portion 34 and the shoulder land portion 35 are not divided in the tire circumferential direction by lug grooves or sipes, and have treads that are continuous in the tire circumferential direction. The first and second through-grooves 41A and 41B are arranged in parallel with each other by inclining their longitudinal directions in the same direction and at the same inclination angle with respect to the tire circumferential direction. However, the inclination angles θ of the plurality of through grooves 41A and 41B may be different within a range described later.

  Further, in FIG. 3, it is preferable that the contact widths W1 and W2 of the second land portion 34 and the shoulder land portion 35 have a relationship of 1.00 ≦ W2 / W1 ≦ 2.00, and 1.20 ≦ W2 / W1 ≦ It is more preferable to have a relationship of 1.40. Further, it is preferable that the contact width W1 of the second land portion 34 has a relationship of 0 ≦ W1 / TW ≦ 0.30 with respect to the tire contact width TW. Thereby, the ground contact widths W1 and W2 of the left and right land portions 34 and 35 defined by the circumferential main groove 23 and the circumferential narrow groove 24 are optimized.

  The contact width of the land is determined by contacting the tire with the flat plate when the tire is mounted on the specified rim and the specified internal pressure is applied, and the tire is placed perpendicular to the flat plate at rest and a load corresponding to the specified load is applied. It is measured as the maximum linear distance in the tire axial direction on the surface.

  In addition, the plurality of through-grooves 41 (41A, 41B) are arranged with at least one end portion mutually offset in the tire width direction. At this time, the terminal end of the through groove 41 may be offset on the second land portion 34 side (see FIG. 3), or as described later, on the shoulder land portion 35 side, or on the second land portion 34 side and the shoulder land portion. The offset may be performed on both sides. In addition, a plurality of types of through grooves 41A and 41B having mutually different groove widths are arranged in a predetermined order in the tire circumferential direction. At this time, as shown in FIGS. 3 and 4, two types of through-grooves 41A and 41B having a groove width may be alternately arranged in the tire circumferential direction, or three or more types of through-grooves 41 may be provided as described later. They may be arranged. The case where the through grooves 41A and 41B having two types of groove widths are alternately arranged in the tire circumferential direction means that each of the plurality of through grooves is narrower than the groove width of another through groove adjacent in the tire circumferential direction. Has a width. When the through-grooves 41A and 41B having two kinds of groove widths are alternately arranged in the tire circumferential direction, each of the plurality of through-grooves has a groove width wider than the groove width of another through-groove adjacent in the tire circumferential direction. Means to have.

[Length of penetration groove]
In FIG. 4, the distance Di (including the minimum value Di_min and the maximum value Di_max in FIG. 4) from the circumferential narrow groove 24 to the inner end portion of the through groove 41 (41 </ b> A, 41 </ b> B), and the second land portion 34. The contact width W1 (see FIG. 3) preferably has a relationship of 0.10 ≦ Di / W1 ≦ 0.80, and more preferably has a relationship of 0.20 ≦ Di / W1 ≦ 0.40. Thereby, the extension length Di of the through groove 41 in the second land portion 34 in the tire width direction is optimized.

  Also, in FIG. 4, the distance Do (including the minimum value Do_min and the maximum value Do_max in FIG. 4) from the circumferential narrow groove 24 to the outer end of the through groove 41 (41A, 41B) and the shoulder land portion 35 are shown. The ground width W2 (see FIG. 3) preferably has a relationship of 0.10 ≦ Do / W2 ≦ 0.60, and more preferably has a relationship of 0.20 ≦ Do / W2 ≦ 0.40. Thereby, the extending length of the through groove 41 in the shoulder land portion 35 in the tire width direction is optimized.

  The distances Di and Do to the end of the through groove are determined from the measurement points of the contact width W1 and W2 of the land portion when the tire is mounted on the specified rim and the specified internal pressure is applied and no load is applied. It is measured as the distance to the terminal end in the tire width direction. In a configuration in which three or more types of distances Di and Do having mutually different numerical values exist, it is necessary that the distance Di; the maximum value Di_max; Do_max of the Do; and the minimum value Di_min; Do_min satisfy the above conditions, respectively.

  In FIG. 4, the minimum value Di_min and the maximum value Di_max of the distance Di between the inner end portions of the plurality of through grooves 41 (41A, 41B) have a relationship of 1.10 ≦ Di_max / Di_min ≦ 3.00. And more preferably 1.20 ≦ Di_max / Di_min ≦ 1.60. In addition, the offset amount ΔDi in the tire width direction of the inner end portion of the through groove 41 has a relationship of 0.10 ≦ ΔDi / W1 ≦ 0.60 with respect to the contact width W1 of the second land portion 34 (see FIG. 3). It is preferable to have a relationship of 0.20 ≦ ΔDi / W1 ≦ 0.40. Therefore, in the second land portion 34, the end portions of the through grooves 41A and 41B are arranged offset from each other in the tire width direction. Thereby, the positions of the inner end portions of the through grooves 41A and 41B in the second land portion 34 are optimized, and the wet performance and the dry performance of the tire are compatible. In particular, since the second land portion 34 greatly contributes to the wet performance, the above configuration efficiently improves the wet performance of the tire.

  On the other hand, it is preferable that the minimum value Do_min and the maximum value Do_max of the distance Do of the outer end portions of the plurality of through grooves 41 (41A, 41B) have a relationship of 0.90 ≦ Do_max / Do_min ≦ 1.10. More preferably, the relationship 0.95 ≦ Do_max / Do_min ≦ 1.05 is satisfied. Further, the offset amount ΔDo in the tire width direction of the outer end portion of the through groove 41 has a relationship of 0 ≦ ΔDo / W2 ≦ 0.10 with respect to the contact width W2 of the shoulder land portion 35 (see FIG. 3). It is more preferable that the relation of 0 ≦ ΔDo / W2 ≦ 0.05 is satisfied. Therefore, in the shoulder land portion 35, the end portions of the through grooves 41A and 41B are arranged with their positions aligned in the tire width direction. Thereby, the rigidity of the shoulder land portion 35 can be properly secured, and the dry braking performance of the tire is improved.

  The offset amount ΔDi; ΔDo at the end of the through groove is calculated as a difference between the maximum value Di_max; Do_max and the minimum value Di_min; Do_min of the distance Di; Do from the circumferential narrow groove to the end.

  As shown in FIG. 4, a plurality of through-grooves 41 (41A, 41B) are arranged so that their longitudinal directions are inclined in the same direction with respect to the tire circumferential direction. The inclination angle θ of the through groove 41 with respect to the tire circumferential direction is preferably in the range of 50 [deg] ≦ θ ≦ 80 [deg], and is preferably in the range of 55 [deg] ≦ θ ≦ 75 [deg]. Is more preferred. Thereby, the drainage of the through groove 41 is improved, and the pattern noise of the tire caused by the through groove 41 is reduced.

  The inclination angle θ of the through groove is measured as an angle between a straight line connecting both ends of the groove center line of the through groove and the tire circumferential direction.

  The inclination angle θ1 of the through groove 41 having the smallest inclination angle θ and the inclination angle θ2 of the through groove 41 having the largest inclination angle θ have a relationship of 0 [deg] ≦ θ2−θ1 ≦ 10 [deg]. It is preferable to have a relationship of 0 [deg] ≦ θ2−θ1 ≦ 5 [deg]. That is, it is preferable that the inclination angle θ of the through groove 41 is substantially constant. Thereby, the rigidity of the land portion can be appropriately secured, and uneven wear is suppressed.

[Groove width of through groove]
Further, the ratio of the groove width Wg of the through groove 41 to the groove width Ws of the circumferential narrow groove 24, that is, the ratio Wg / Ws of the groove width of each through groove to the groove width of the circumferential narrow groove 24 is as follows. It preferably has a relationship of 0.30 ≦ Wg / Ws ≦ 1.30, and more preferably has a relationship of 0.60 ≦ Wg / Ws ≦ 1.00. Thereby, the drainage action of the through groove 41 is properly secured.

  Further, in at least one region of the circumferential narrow groove 24 in the tire width direction, the groove width Wg_min of the narrowest through groove and the groove width Wg_max of the widest through groove 41B among the plurality of through grooves 41 are: It is preferable to have a relationship of 1.50 ≦ Wg_max / Wg_min ≦ 20.0. By satisfying this condition, dry performance and wet performance can be improved in a well-balanced manner.

  In a case where the groove width of the plurality of through grooves 41 is 1.5 mm or more in at least one side of the circumferential narrow groove 24 in the tire width direction, the narrowest through hole of the plurality of through grooves 41 is provided. It is preferable that the groove width Wg_min of the groove 41A and the groove width Wg_max of the widest through groove 41B have a relationship of 1.50 ≦ Wg_max / Wg_min ≦ 3.00. By satisfying this condition, dry performance and wet performance can be improved in a well-balanced manner.

  Here, in the configuration of FIG. 4, the through groove 41 has a straight shape having a constant groove width as a whole, and has a tapered shape in which the groove width is narrowed at the end. The right and left end portions of the through groove 41 narrow the groove width in the same direction in the tire circumferential direction, so that the entire through groove 41 has a trapezoidal shape having an upper bottom and a lower bottom in the tire circumferential direction. . In addition, a plurality of through grooves 41A and 41B are arranged so as to be aligned in the tire circumferential direction. However, the present invention is not limited to this, and the terminal end of the through groove 41 may have a rectangular shape or an arc shape (not shown). Further, the entire through groove 41 may have a rectangular shape or a parallelogram shape (not shown).

[Shoulder lug groove on the outside area in the vehicle width direction]
As shown in FIG. 2, the shoulder land portion 35 in the vehicle width direction outside region includes a plurality of shoulder lug grooves 42 in the vehicle width direction outside region.

  The shoulder lug groove 42 has one end portion in the shoulder land portion 35, extends in the tire width direction, and opens to the tire contact end T. In addition, the shoulder lug groove 42 does not communicate with the circumferential narrow groove 24 and the through groove 41, and does not overlap in the tire width direction. Further, a plurality of shoulder lug grooves 42 are arranged at predetermined intervals in the tire circumferential direction.

  Further, as shown in FIG. 3, the long through groove 41 </ b> B is on an extension of the groove center line of the shoulder lug groove 42. Specifically, the groove center line of the shoulder lug groove 42 has a gentle arc shape, and the through groove 41B extends including an extension of the groove center line of the shoulder lug groove 42. In such a configuration, drainage from the second land portion 34 to the shoulder land portion 35 is improved by the shoulder lug groove 42 extending along the extension of the through groove 41B. The present invention is not limited to the above, and the short through groove 41A may be on an extension of the groove center line of the shoulder lug groove 42 (not shown).

  Also, as shown in FIG. 3, the shoulder of the through-groove 41 (41A, 41B) is not overlapped in the tire circumferential direction with the groove centerline of the shoulder lug groove 42 in the ground contact plane. The positional relationship between the lug groove 42 and the through groove 41 in the tire circumferential direction is set. Specifically, the distances D1A and D1B in the tire circumferential direction between the ends of the groove center lines of the through grooves 41A and 41B in FIG. 3 and the ends of the groove center lines of the shoulder lug grooves 42 are 0 ≦ D1A and 0 ≦. It is set in the range of D1B. As a result, the pattern noise caused by the overlap between the grooves is reduced, and the quietness (noise performance) of the tire is improved.

  The end of the groove center line of the through groove is defined as the intersection of the terminal end of the opening of the through groove and the groove center line of the through groove on the tread of the land portion.

  As shown in FIG. 3, the terminal end of the shoulder lug groove 42 and the outer terminal end of the through groove 41 </ b> B facing the shoulder lug groove 42 are separated from each other in the tire width direction. Further, the shoulder lug groove 42 and the through groove 41B are not connected by another groove or sipes. Also, the distance D2 in the tire width direction from the end of the shoulder lug groove 42 to the outer end of the through groove 41B and the contact width W2 of the shoulder land 35 are 0.10 ≦ D2 / W2 ≦ 0.60. It is preferable to have a relationship, more preferably 0.30 ≦ D2 / W2 ≦ 0.50. Thereby, both wet performance and dry performance of the tire are compatible. That is, the rigidity of the shoulder land portion 35 and the ground contact area are secured by the lower limit, and the dry performance of the tire is secured. Further, by the upper limit, the extending length of the through groove 41 and the shoulder lug groove 42 in the tire width direction is secured, and the wet performance of the tire is secured.

  Further, in the configuration of FIG. 3, the shoulder land portion 35 is divided into grooves or sipes in a region between the end portions of all the shoulder lug grooves 42 and the outer end portions of all the through grooves 41 (41A, 41B). Instead, it has a plain tread that is continuous in the tire circumferential direction. That is, the shoulder lug groove 42 and the through groove 41 do not overlap each other in the tire width direction. Thereby, the dry performance of the tire is further improved.

  In FIG. 3, the arrangement interval P1 of the through grooves 41 and the arrangement interval P2 of the shoulder lug grooves 42 in the tire circumferential direction preferably have a relationship of 0.30 ≦ P1 / P2 ≦ 0.70. More preferably, the relationship of 40 ≦ P1 / P2 ≦ 0.60 is satisfied. Thereby, the arrangement intervals P1 and P2 of the through groove 41 and the shoulder lug groove 42 are optimized. In the configuration of FIG. 3, a pair of short and long through holes 41 </ b> A and 41 </ b> B and a single shoulder lug groove 42 are arranged in the tire circumferential direction with the same pitch length.

  The arrangement intervals P1 and P2 of the through groove 41 and the shoulder lug groove 42 are measured using an intersection point between the groove center line of each groove and the circumferential center line of the groove or the tire grounding end as a measurement point.

[Modification]
5 to 10 are explanatory diagrams showing modified examples of the through groove shown in FIG. In these drawings, the same components as those shown in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted.

  As shown in FIGS. 5 to 8, the narrow through-grooves 41A and the wide through-grooves 41B do not have to be alternately arranged in the tire circumferential direction. FIGS. 5 to 8 show a case where the groove width of the plurality of through-grooves 41 is 1.5 [mm] or more in at least one side of the circumferential groove 24 in the tire width direction. In FIG. 5, the condition that the groove width Wg_min of the narrowest through groove 41A and the groove width Wg_max of the widest through groove 41B have a relationship of 1.50 ≦ Wg_max / Wg_min ≦ 3.00 is satisfied. For example, the minimum value Di_min and the minimum value Do_min may be substantially the same, and the maximum value Di_max may be larger than the maximum value Do_max. In FIG. 6, if the groove width Wg_min of the narrowest through groove 41A and the groove width Wg_max of the widest through groove 41B satisfy the condition of 1.50 ≦ Wg_max / Wg_min ≦ 3.00, the maximum is obtained. The value Do_max and the maximum value Di_max may be substantially the same, and the minimum value Di_min and the minimum value Do_min may be substantially the same. Furthermore, in FIG. 7, if the groove width Wg_min of the narrowest through groove 41A and the groove width Wg_max of the widest through groove 41B satisfy the condition of 1.50 ≦ Wg_max / Wg_min ≦ 3.00, the minimum is obtained. The minimum value Di_min may be smaller than the value Do_min, and the maximum value Di_max may be larger than the maximum value Do_max. In FIG. 8, if the groove width Wg_min of the narrowest through groove 41A and the groove width Wg_max of the widest through groove 41B satisfy the condition of 1.50 ≦ Wg_max / Wg_min ≦ 3.00, The minimum value Di_min due to the narrow through groove 41A and the minimum value Do_min due to the widest through groove 41B are almost the same, and the maximum value Di_max due to the widest through groove 41B and the maximum value Do_max due to the narrowest through groove 41A are May be substantially the same.

  By the way, the groove width of the through groove 41 may be different on both sides of the circumferential narrow groove 24 in the tire width direction. That is, as shown in FIG. 9, the groove width of the through groove 41 </ b> B is constant, and the groove width is the same between the inside of the circumferential narrow groove 24 in the vehicle width direction and the outside in the vehicle width direction. On the other hand, the groove width of the through groove 41C and the through groove 41D changes in the middle of the extending direction, and the groove width is different between the inside of the circumferential narrow groove 24 in the vehicle width direction and the outside in the vehicle width direction. As shown in FIG. 9, the through groove 41 </ b> C has a smaller groove width on the outside in the vehicle width direction than the groove width on the inner side in the vehicle width direction. As shown in FIG. 9, the through groove 41 </ b> D has a wider groove width on the outside in the vehicle width direction than the groove width on the inner side in the vehicle width direction. On the outer side in the vehicle width direction of the circumferential narrow groove 24, the condition that the groove width Wg_min of the narrowest through groove 41C and the groove width Wg_max of the widest through groove 41B are 1.50 ≦ Wg_max / Wg_min ≦ 3.00 is satisfied. Meets On the inner side in the vehicle width direction of the circumferential narrow groove 24, the groove width Wg_min of the narrowest through groove 41D and the groove width Wg_max of the widest through groove 41B satisfy 1.50 ≦ Wg_max / Wg_min ≦ 3.00. The conditions are met. It is sufficient that at least one side of the circumferential narrow groove 24 in the tire width direction satisfies this condition. In FIG. 9, three or more types of through grooves 41B, 41C and 41D are arranged. In FIG. 9, the minimum value Di_min may be smaller than the minimum value Do_min, and the maximum value Di_max may be larger than the maximum value Do_max.

  Further, when the groove width of the through groove 41 is different on both sides of the circumferential narrow groove 24 in the tire width direction, the groove width of the narrow groove width of the through groove is less than 1.5 [mm]. There may be. FIG. 10 is a diagram illustrating an example in which the groove width changes in the middle of the extending direction of the through groove 41 and the through groove having a narrow groove width is a sipe. As shown in FIG. 10, the through groove 41 </ b> E and the through groove 41 </ b> F have a sipe 41 </ b> S outside the circumferential narrow groove 24 in the vehicle width direction. In FIG. 10, the lengths of the sipes 41S in the tire width direction are all the same. For this reason, in the through groove 41E and the through groove 41F, the groove width on the outer side in the vehicle width direction of the circumferential narrow groove 24 is smaller than the groove width on the inner side in the vehicle width direction of the circumferential narrow groove 24. On the inner side in the vehicle width direction of the circumferential narrow groove 24, the condition that the groove width Wg_min of the narrowest through groove 41E and the groove width Wg_max of the widest through groove 41F are 1.50 ≦ Wg_max / Wg_min ≦ 3.00 is satisfied. Meets In FIG. 10, the minimum value Di_min may be smaller than the minimum value Do_min (same as the maximum value Do_max), and the maximum value Di_max may be larger than the maximum value Do_max.

  In FIG. 10, the groove width (not shown) of the sipe 41S may be different outside the circumferential narrow groove 24 in the vehicle width direction. And regarding the sipe 41S, the groove width Wg_min of the narrowest sipe 41S and the groove width Wg_max of the widest sipe 41S may satisfy the condition of 1.50 ≦ Wg_max / Wg_min ≦ 20.0.

  Regarding the through groove 41, both the inside in the vehicle width direction and the outside in the vehicle width direction of the circumferential narrow groove 24 may be sipes. FIGS. 11 to 13 are diagrams showing a case in which both the inner side in the vehicle width direction and the outer side in the vehicle width direction of the circumferential narrow groove 24 are sipes. That is, in FIGS. 11 to 13, the through grooves 41 of the circumferential narrow groove 24 are all sipes.

  In FIG. 11, the groove width of the sipe 41S of the through groove 41G and the groove width of the sipe 41S of the through groove 41H are different, and the narrowest penetration is made inside the circumferential narrow groove 24 in the vehicle width direction or outside in the vehicle width direction. The groove width Wg_min (not shown) of the groove 41G and the groove width Wg_max (not shown) of the widest through groove 41G satisfy the condition of 1.50 ≦ Wg_max / Wg_min ≦ 20.0. In FIG. 11, through-grooves 41G and 41H having two types of groove widths are alternately arranged in the tire circumferential direction. This means that each of the plurality of through-grooves 41 has a narrower groove width than the width of the other through-grooves 41 adjacent in the tire circumferential direction. This means that each of the plurality of through grooves 41 has a groove width wider than the groove width of the other through grooves 41 adjacent in the tire circumferential direction. In FIG. 11, the minimum value Do_min (same as the maximum value Do_max) and the minimum value Di_min (same as the maximum value Di_max) may be the same.

  In FIG. 12, the groove width of the sipe 41S of the through groove 41G and the groove width of the sipe 41S of the through groove 41I are different, and the narrowest penetration is made inside or outside the vehicle width direction of the circumferential narrow groove 24. The groove width Wg_min (not shown) of the groove 41G and the groove width Wg_max (not shown) of the widest through groove 41I satisfy the condition of 1.50 ≦ Wg_max / Wg_min ≦ 20.0. In FIG. 12, through-grooves 41G and 41I having two kinds of groove widths are alternately arranged in the tire circumferential direction. This means that each of the plurality of through-grooves 41 has a narrower groove width than the width of the other through-grooves 41 adjacent in the tire circumferential direction. This means that each of the plurality of through grooves 41 has a groove width wider than the groove width of the other through grooves 41 adjacent in the tire circumferential direction. In FIG. 12, the minimum value Di_min (same as the maximum value Di_max) and the minimum value Do_min may be the same, and the maximum value Do_max may be larger than the maximum value Di_max.

  In FIG. 13, the groove width of the sipe 41S of the through groove 41G is different from the groove width of the sipe 41S of the through groove 41I, and the narrowest penetration is made inside the circumferential narrow groove 24 in the vehicle width direction or outside in the vehicle width direction. The groove width Wg_min (not shown) of the groove 41G and the groove width Wg_max (not shown) of the widest through groove 4IG satisfy the condition of 1.50 ≦ Wg_max / Wg_min ≦ 20.0. In FIG. 13, through-grooves 41G and 41I having two kinds of groove widths are alternately arranged in the tire circumferential direction. This means that each of the plurality of through-grooves 41 has a narrower groove width than the width of the other through-grooves 41 adjacent in the tire circumferential direction. This means that each of the plurality of through grooves 41 has a groove width wider than the groove width of the other through grooves 41 adjacent in the tire circumferential direction. In FIG. 13, the minimum value Di_min (same as the maximum value Di_max) and the minimum value Do_min may be the same, and the maximum value Do_max may be larger than the maximum value Di_max.

[effect]
As described above, the pneumatic tire 10 has the circumferential narrow groove 24 extending in the tire circumferential direction, the tire circumferential direction extending through the circumferential narrow groove 24, and both ends in the land portion. A plurality of terminally extending through-grooves 41 are provided, and in at least one region in the tire width direction of the circumferential narrow groove 24, among the plurality of through-grooves 41, the width of the narrowest through-groove Wg_min and the widest through-groove The groove width Wg_max of the groove has a relationship of 1.50 ≦ Wg_max / Wg_min ≦ 20.0. In at least one area of the circumferential narrow groove 24 in the tire width direction, the groove width of the plurality of through grooves 41 is 1.5 [mm] or more, and the width of the plurality of through grooves 41 is the largest. The groove width Wg_min of the narrow through groove and the groove width Wg_max of the widest through groove have a relationship of 1.50 ≦ Wg_max / Wg_min ≦ 3.00.

  A circumferential main groove 23 disposed in one region (in the vehicle width direction outer region in FIG. 2) having the tire equatorial plane CL as a boundary, and a circumferential narrow groove disposed outside the circumferential main groove 23 in the tire width direction. The groove 24 includes a shoulder land portion 35 and a second land portion 34 defined by the circumferential main groove 23 and the circumferential narrow groove 24 (see FIG. 2). The pneumatic tire 10 extends in the tire width direction, penetrates the circumferential narrow groove 24, has an inner terminal portion in the tire width direction in the second land portion 34, and has an outer terminal portion in the shoulder land portion 35. (See FIG. 3). Further, the groove width Wg_min of the narrowest through groove and the groove width Wg_max of the widest through groove have a relationship of 1.50 ≦ Wg_max / Wg_min ≦ 20.0. When the groove width of the plurality of through-grooves is 1.5 mm or more, there is a relationship of 1.50 ≦ Wg_max / Wg_min ≦ 3.00.

  In such a configuration, (1) the through-groove 41 penetrates the circumferential narrow groove 24, so that the drainage near the circumferential narrow groove 24 is improved, and the wet performance of the tire is improved. At the same time, since the through groove 41 does not open to the circumferential main groove 23 and the tire ground contact end T, the rigidity of the left and right land portions 34 and 35 defined by the circumferential narrow groove 24 is secured. As a result, there is an advantage that the wet performance and the dry performance of the tire are compatible with each other efficiently. (2) Since a plurality of types of through-grooves 41 (41A to 41I) having mutually different groove widths are arranged at predetermined intervals in the tire circumferential direction, all of the plurality of types of through-grooves 41 have the same width and the same length. As compared with a configuration having a notch (not shown), a through groove having a wider groove width is arranged on the tread of one land portion (the land portions 34 and 35 in FIG. 3). Thereby, there is an advantage that the dry performance and the wet performance of the tire can be improved in a well-balanced manner.

  Further, in the pneumatic tire 10, among the plurality of through grooves 41, the length L1_min of the shortest through groove in the tire width direction and the length L1_max of the longest through groove in the tire width direction are 1.10 ≦ L1_max / L1_min ≦ 3.00, and the width Wg1 of the shortest through groove and the width Wg2 of the longest through groove have a relationship of Wg2> Wg1. Accordingly, the positions of the inner end portions of the through grooves 41A and 41B in the second land portion 34 are optimized, and there is an advantage that the dry performance and the wet performance of the tire are compatible.

  Further, in the pneumatic tire 10, it is preferable that a pair of through grooves 41A and 41B having mutually different groove widths are alternately arranged in the tire circumferential direction (see FIGS. 3 and 4). Thereby, each of the plurality of through grooves 41 has a groove width smaller than the groove width of another through groove adjacent in the tire circumferential direction. Each of the plurality of through grooves has a groove width wider than the groove width of another through groove adjacent in the tire circumferential direction. Thereby, the dry performance and the wet performance of the tire can be improved in a well-balanced manner.

  Further, in the pneumatic tire 10, the shoulder land portion 35 has a shoulder lug groove 42 having one end portion in the shoulder land portion 35 and extending in the tire width direction to open to the tire grounding end T ( (See FIG. 2). Further, the through groove 41 (a long through groove 41B in FIG. 2) is on an extension of the groove center line of the shoulder lug groove. Thereby, there is an advantage that the drainability of the shoulder land portion 35 is improved.

  Further, in the pneumatic tire 10, the inclination angle θ of the through groove 41 with respect to the tire circumferential direction is preferably in the range of 50 [deg] ≦ θ ≦ 80 [deg]. Thereby, the dry performance and the wet performance of the tire can be improved in a well-balanced manner.

  Further, in the pneumatic tire 10, the ratio of the groove width of each of the plurality of through grooves 41 to the groove width of the circumferential narrow groove 24 is preferably 0.30 or more and 1.30 or less. Thereby, the dry performance and the wet performance of the tire can be improved in a well-balanced manner.

  Further, in the pneumatic tire 10, the shoulder land portion 35 has a shoulder lug groove 42 having one end portion in the shoulder land portion 35 and extending in the tire width direction to open to the tire grounding end T ( (See FIG. 2). Further, the groove center line of the through groove 41 does not overlap with the groove center line of the shoulder lug groove 42 in the tire circumferential direction. Thereby, there is an advantage that the pattern noise caused by the overlap of the through grooves is reduced, and the quietness (noise performance) of the tire is improved.

  Further, in the pneumatic tire 10, a distance D2 in the tire width direction from an end portion of the shoulder lug groove 42 to an outer end portion of the through groove 41 facing the shoulder lug groove 42, and a contact width W2 of the shoulder land portion 35. Have a relationship of 0.10 ≦ D2 / W2 ≦ 0.60 (see FIG. 3). Thereby, there is an advantage that the dry performance and the wet performance of the tire are compatible. That is, the rigidity of the shoulder land portion 35 and the ground contact area are secured by the lower limit, and the dry performance of the tire is secured. Further, by the upper limit, the extending length of the through groove 41 and the shoulder lug groove 42 in the tire width direction is secured, and the wet performance of the tire is secured.

  Further, in the pneumatic tire 10, the arrangement interval P1 of the through grooves 41 and the arrangement interval P2 of the shoulder lug grooves 42 in the tire circumferential direction have a relationship of 0.30 ≦ P1 / P2 ≦ 0.70. Thereby, there is an advantage that the arrangement intervals P1 and P2 of the through groove 41 and the shoulder lug groove 42 are optimized.

  Further, the pneumatic tire 10 includes a mounting direction indicator (not shown) for designating that one of the regions (the outer region in the vehicle width direction in FIG. 2) is to be mounted on the vehicle in the vehicle width direction. By arranging the circumferential narrow groove and the through groove in the outer region in the vehicle width direction, the dry performance, the wet performance, and the noise performance can be improved in a well-balanced manner.

  FIGS. 14 to 16 are tables showing the results of performance tests of the pneumatic tire according to the embodiment of the present invention.

  In this performance test, evaluations of (1) dry steering stability, (2) wet steering stability, and (3) noise performance were performed on a plurality of types of test tires. A test tire having a tire size of 245 / 40R18 97Y is mounted on a rim having a rim size of 18 × 8.5 J, and an internal pressure of 230 [kPa] and a specified load of JATMA are applied to the test tire. Also, test tires are mounted on all wheels of a test vehicle, a passenger car.

  (1) In the evaluation relating to dry steering stability performance, a test vehicle travels on a dry road surface test course having a flat peripheral circuit at a speed of 60 [km / h] to 100 [km / h]. Then, the test driver performs a sensory evaluation of the steering performance at the time of a race change and cornering and the stability at the time of straight running. This evaluation is performed by index evaluation using the conventional example as a reference (100), and the larger the numerical value, the more preferable.

  (2) In the evaluation of the wet steering stability performance, the test vehicle travels on a predetermined test course under rainy conditions, and the lap time is measured. Then, an index evaluation is performed based on the measurement result. This evaluation is performed by index evaluation using the conventional example as a reference (100), and the larger the numerical value, the better.

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

  The test tires of Examples 1 to 29 have the configurations shown in FIGS. 1 to 3, and have a circumferential main groove 23 and a circumferential narrow groove 24 and two types of long and short through grooves 41A and 41B. And a shoulder lug groove 42 are provided in the outer region in the vehicle width direction. Further, in the test tires of Examples 1 to 29, among the plurality of through grooves, the groove width Wg_min of the narrowest through groove and the groove width Wg_max of the widest through groove are 1.50 ≦ Wg_max / Wg_min ≦ 20.0. When the groove width of the through grooves 41A and 41B is 1.5 mm or more, the groove width Wg_min of the narrowest through groove and the groove width Wg_max of the widest through groove among the plurality of through grooves are 1.50. ≤ Wg_max / Wg_min ≤ 3.00.

  In the test tire of the conventional example, the groove width of the through groove is 5.0 [mm], and the groove width and the length of the through groove are all equal. The conventional test tire does not have the shoulder lug groove 42.

  As shown in the test results, in the test tires of Examples 1 to 29, it is understood that the wet steering stability, the dry steering stability, and the noise performance of the tire are improved.

  Reference Signs List 10 pneumatic tire; 11 bead core; 12 bead filler; 13 carcass layer; 14 belt layer; 15 tread rubber; 16 sidewall rubber; 17 rim cushion rubber; 20 rim fitting surface; 21 to 23 circumferential main groove; Direction narrow groove; 31-35 Land portion; 41, 41A-41I Penetration groove; 41S sipes; 42 Shoulder lug groove; 141, 142 Cross belt; 143 Belt cover; CL Tire equatorial plane;

Claims (13)

  A circumferential groove extending in the tire circumferential direction, a plurality of through grooves extending in the tire width direction, penetrating the circumferential groove, and having both ends terminated in the land portion; In at least one region in the tire width direction, the groove width Wg_min of the narrowest through groove and the groove width Wg_max of the widest through groove among the plurality of through grooves are 1.50 ≦ Wg_max / Wg_min. A pneumatic tire having a relationship of ≦ 20.0.   In at least one region in the tire width direction of the circumferential groove, the groove width of the plurality of through grooves is 1.5 mm or more, and among the plurality of through grooves, the narrowest of the through grooves. The pneumatic tire according to claim 1, wherein a groove width Wg_min and a groove width Wg_max of the widest through groove have a relationship of 1.50 ≦ Wg_max / Wg_min ≦ 3.00.   Among the plurality of through grooves, the length L1_min of the shortest through groove in the tire width direction and the length L1_max of the longest through groove in the tire width direction satisfy a relationship of 1.10 ≦ L1_max / L1_min ≦ 3.00. 3. The pneumatic tire according to claim 1, wherein the width Wg1 of the shortest through groove and the width Wg2 of the longest through groove have a relationship of Wg2> Wg1.   The pneumatic tire according to any one of claims 1 to 3, wherein a pair of the through grooves having mutually different groove widths are alternately arranged in a tire circumferential direction.   The pneumatic tire according to claim 4, wherein each of the plurality of through grooves has a groove width smaller than a groove width of another through groove adjacent in the tire circumferential direction.   The pneumatic tire according to claim 4, wherein each of the plurality of through grooves has a groove width wider than a groove width of another through groove adjacent in the tire circumferential direction.   The pneumatic tire according to any one of claims 1 to 6, wherein an inclination angle θ of the through groove with respect to the tire circumferential direction is in a range of 50 [deg] ≦ θ ≦ 80 [deg].   The pneumatic device according to any one of claims 1 to 7, wherein a ratio of a width of each of the plurality of through grooves to a width of the circumferential narrow groove is not less than 0.30 and not more than 1.30. tire. The shoulder land portion partitioned into the circumferential narrow groove has a shoulder lug groove having one end portion in the shoulder land portion and extending in the tire width direction and opening to the tire grounding end, and
The pneumatic tire according to any one of claims 1 to 8, wherein the through groove is on an extension of a center line of the shoulder lug groove. The shoulder land portion partitioned into the circumferential narrow groove has a shoulder lug groove having one end portion in the shoulder land portion and extending in the tire width direction and opening to the tire grounding end, and
The pneumatic tire according to any one of claims 1 to 9, wherein a groove centerline of the through groove does not overlap with a groove centerline of the shoulder lug groove in a tire circumferential direction.   The distance D2 in the tire width direction from the terminal end of the shoulder lug groove to the outer terminal end of the through groove facing the shoulder lug groove, and the contact width W2 of the shoulder land portion are 0.10 ≦ D2 / The pneumatic tire according to claim 9, wherein W2 ≦ 0.60.   The arrangement interval P1 of the through groove and the arrangement interval P2 of the shoulder lug groove in the tire circumferential direction have a relationship of 0.30 ≦ P1 / P2 ≦ 0.70. A pneumatic tire according to claim 1.   The pneumatic tire according to any one of claims 1 to 12, further comprising: a mounting direction display unit that specifies that the vehicle should be mounted on a vehicle with the one side region being set outward in the vehicle width direction.

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