WO2020179169A1

WO2020179169A1 - Pneumatic tire

Info

Publication number: WO2020179169A1
Application number: PCT/JP2019/048329
Authority: WO
Inventors: 真宜榎本
Original assignee: 横浜ゴム株式会社
Priority date: 2019-03-01
Filing date: 2019-12-10
Publication date: 2020-09-10
Also published as: JP2020138703A; JP7205307B2; CN113597379B; CN113597379A; DE112019006559T5

Abstract

In this pneumatic tire 1, a shoulder land portion 32 is provided with: a circumferential fine groove 23 that extends continuously in a tire circumferential direction; a first shoulder groove 44 of which one end is open on a tire tread end T and another end terminates in the shoulder land portion 32; and a second shoulder groove 45 of which one end is open on a shoulder major groove 22 and another end terminates in the shoulder land portion 32. The first shoulder groove 44 has a groove width Wg4 of at least 1.5 [mm] and no greater than 4.0 [mm] and does not intersect with the circumferential fine groove 23. The second shoulder groove 45 has a groove width Wg5 of at least 0.6 [mm] and no greater than 1.2 [mm] and intersects with the circumferential fine groove 23.

Description

Pneumatic tires

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

　The conventional pneumatic tire has both dry performance and wet performance of the tire because the land part has non-penetrating lug grooves and sipes. As a conventional pneumatic tire adopting such a configuration, the technique described in Patent Document 1 is known.

Japanese Unexamined Patent Publication No. 2017-52327

The purpose of this invention is to provide a pneumatic tire that can achieve both dry performance and wet performance of the tire.

To achieve the above object, a pneumatic tire according to the present invention has a center main groove and a shoulder main groove extending in the tire circumferential direction, and a center land portion and a shoulder defined by the center main groove and the shoulder main groove. A pneumatic tire comprising a land portion, wherein the shoulder land portion has a circumferential narrow groove continuously extending in the tire circumferential direction, and the one end portion opens to the tire ground contact end and the other end. Part has a first shoulder groove that ends in the shoulder land portion, and a second shoulder groove that opens in the shoulder main groove at one end and ends in the shoulder land portion at the other end. The first shoulder groove has a groove width of 1.5 [mm] or more and 4.0 [mm] or less, does not intersect the circumferential narrow groove, and the second shoulder groove is 0. It has a groove width of 6 [mm] or more and 1.2 [mm] or less and intersects with the circumferential narrow groove.

According to the pneumatic tire of the present invention, (1) the shoulder land portion has the circumferential narrow grooves continuously extending in the tire circumferential direction, and therefore the tire circumferential direction has a discontinuous circumferential narrow groove. Compared with, there is an advantage that the wet performance and snow performance of the tire are improved. Further, (2) the first shoulder groove does not intersect the circumferential narrow groove, so that the dry performance of the tire is ensured as compared with the configuration in which the first shoulder groove intersects the circumferential narrow groove. There is. Further, (3) the narrow second shoulder groove intersects the circumferential narrow groove, so that the dry performance of the tire is ensured, and at the same time, the wet performance and the snow performance of the tire are improved.

FIG. 1 is a cross-sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a plan view showing the tread surface of the pneumatic tire shown in FIG. FIG. 3 is an enlarged view showing the tread of the pneumatic tire shown in FIG. FIG. 4 is an enlarged plan view showing the groove unit in the center land portion shown in FIG. FIG. 5 is a sectional view in the groove depth direction showing the groove unit of the center land portion shown in FIG. FIG. 6 is an enlarged plan view showing the groove unit of the shoulder land portion described in FIG. FIG. 7 is a sectional view in the groove depth direction showing the groove unit of the shoulder land portion shown in FIG. FIG. 8 is a chart showing results of performance tests of pneumatic tires according to the embodiment of the present invention. FIG. 9 is an explanatory view showing a test tire of a conventional example. FIG. 10 is an explanatory view showing a test tire of a comparative example.

Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment. Further, the constituent elements of this embodiment include those that can be replaced and are self-evident while maintaining the sameness of the invention. Further, a plurality of modified examples described in this embodiment can be arbitrarily combined within the scope obvious to those skilled in the art.

[Pneumatic tires]
FIG. 1 is a cross-sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment of the present invention. The figure shows a cross-sectional view of one side region in the tire radial direction. Further, 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 the tire rotation axis (not shown). Reference numeral CL is a tire equatorial plane, and refers to a plane that passes through the center point of the tire in the tire rotation axis direction and is perpendicular to the tire rotation axis. The tire 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.

The pneumatic tire 1 has an annular structure centered on the tire rotation axis, and has a pair of

bead cores

11 and 11, a pair of

bead fillers

12 and 12, a carcass layer 13, a belt layer 14, and a tread rubber 15. , 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, 11 are annular members formed by bundling a plurality of bead wires, and form the cores of the left and right bead parts. The pair of

bead fillers

12, 12 are respectively arranged on the outer circumferences of the pair of

bead cores

11, 11 in the tire radial direction to form a bead portion.

The carcass layer 13 has a single-layer structure composed of one 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, 11 to form a skeleton of the tire. Constitute. Further, both ends of the carcass layer 13 are rolled back and locked to the outside in the tire width direction so as to surround 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 the carcass cord. It has a carcass angle of not less than [deg] and not more than 95 [deg] (defined as an inclination angle in the longitudinal direction of the carcass cord 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 arranged around the outer circumference of the carcass layer 13. The pair of

intersecting belts

141 and 142 are formed by coating a plurality of belt cords made of steel or an organic fiber material with coated rubber and rolling the belt cords, and have an absolute value of a belt angle of 20 [deg] or more and 55 [deg] or less. Have. Further, the pair of

crossing belts

141 and 142 have differently signed belt angles (defined as inclination angles in the longitudinal direction of the belt cord with respect to the tire circumferential direction), and the longitudinal directions of the belt cords intersect each other. (So-called cross-ply structure). The belt cover 143 is formed by coating a belt cord made of steel or an organic fiber material with coating rubber, and has a belt angle of 0 [deg] or more and 10 [deg] or less in absolute value. Further, the belt cover 143 is, for example, a strip material formed by coating one or a plurality of belt cords with coated rubber, and the strip material is applied a plurality of times in the tire circumferential direction with respect to the outer peripheral surfaces of the

cross belts

141 and 142. And it is composed by winding it in a spiral shape. Further, the belt cover 143 is arranged so as to cover the entire areas of the

cross belts

141 and 142.

The tread rubber 15 is arranged on the tire radial outer periphery of the carcass layer 13 and the belt layer 14 to form a tread portion of the tire. The pair of

sidewall rubbers

16 and 16 are arranged on the tire width direction outer side of the carcass layer 13 to form left and right sidewall portions. The pair of

rim cushion rubbers

17, 17 are respectively arranged on the tire radial direction inner sides of the rewound portions of the left and

right bead cores

11, 11 and the carcass layer 13 and configure contact surfaces of the left and right bead portions with respect to the rim flange.

[Tread pattern]
FIG. 2 is a plan view showing the tread surface of the pneumatic tire shown in FIG. The figure shows the tread pattern of an all-season tire. In the figure, the tire circumferential direction means the direction around the tire rotation axis. Further, reference numeral T is a tire ground contact end.

As shown in FIG. 2, the pneumatic tire 1 includes a plurality of circumferential

main grooves

21 and 22 extending in the tire circumferential direction, and a plurality of land portions 31 divided into these circumferential

main grooves

21 and 22. 32 is provided on the tread surface.

Here, the left and right circumferential

main grooves

22, 22 on the outermost side in the tire width direction are defined as shoulder main grooves, and the other circumferential main groove 21 between these circumferential

main grooves

22, 22 is defined as the center. Defined as a main groove. Further, the left and

right land portions

32, 32 on the outermost side in the tire width direction are defined as shoulder land portions, and the

other land portions

31, 31 between these

land portions

32, 32 are defined as center land portions. .. Further, an area on the inner side in the tire width direction bounded by the left and right shoulder

main grooves

22, 22 is defined as a center area, and an area on the outer side in the tire width direction is defined as a shoulder area.

The main groove is a groove that is required to display a wear indicator specified in JATMA, and has a groove width of 4.0 [mm] or more and a groove depth of 7.5 [mm] or more.

Groove width is measured as the maximum value of the distance between the left and right groove walls at the groove opening when the tire is mounted on the specified rim and the specified internal pressure is filled up. In the configuration in which the land portion has the cutout portion or the chamfered portion at the edge portion, in the cross-sectional view with the groove length direction as the normal direction, the groove width is based on the intersection point between the tread surface and the extension line of the groove wall. Be measured. Further, in the configuration in which the groove extends in the zigzag shape or the wavy shape in the tire circumferential direction, the groove width is measured with the center line of the amplitude of the groove wall as a reference.

The groove depth is measured as the maximum value of the distance from the tread tread to the groove bottom when the tire is attached to the specified rim and the specified internal pressure is filled and no load is applied. Further, in a configuration in which the groove has a partial uneven portion or a sipe on the groove bottom, the groove depth is measured excluding these.

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

For example, in the configuration of FIG. 2, a single center main groove 21 and a pair of shoulder

main grooves

22, 22 are arranged symmetrically with respect to the tire equatorial plane CL. Further, the center main groove 21 is arranged on the tire equatorial plane CL. The circumferential

main grooves

21 and 22 define four rows of

land portions

31 and 32.

However, the present invention is not limited to this, and four or more circumferential main grooves may be arranged, or the circumferential main grooves may be asymmetrical about the tire equatorial plane CL (not shown). Further, the land portion may be located on the tire equatorial plane CL (not shown) by disposing one circumferential main groove at a position deviated from the tire equatorial plane CL.

Also, in the configuration of FIG. 2, the circumferential

main grooves

21 and 22 have a straight shape. However, the present invention is not limited to this, and the circumferential

main grooves

21 and 22 may have a zigzag shape or a wavy shape having an amplitude in the tire width direction (not shown).

Further, in the configuration of FIG. 2, the pneumatic tire 1 has a tread pattern that is symmetrical with respect to the left and right with a point on the tire equatorial plane CL as the center. However, the pneumatic tire 1 is not limited to this, and may have, for example, a tread pattern that is bilaterally symmetric with respect to the tire equatorial plane CL or a tread pattern that is asymmetrical to the left and right, and the directionality in the tire rotation direction may be set. It may have a tread pattern (not shown).

[Groove unit in the center land area]
FIG. 3 is an enlarged view showing the tread of the pneumatic tire shown in FIG. The figure shows one side region of the tread with the tire equatorial plane CL as a boundary. 4 and 5 are an enlarged plan view (FIG. 4) and a sectional view in the groove depth direction (FIG. 5) showing the groove unit of the center land portion shown in FIG. Further, FIG. 5 shows a sectional view in the groove depth direction along the first center groove 41 and the third center groove 43 of the groove unit 4ce.

As shown in FIG. 3, the center land portion 31 includes a plurality of sets of groove units 4ce. The groove unit 4ce is composed of a first center groove 41, a second center groove 42, and a third center groove 43 as one set. Further, a plurality of sets of groove units 4ce are arranged at predetermined intervals in the tire circumferential direction. The wet performance of the tire is ensured by these center grooves 41 to 43.

Further, as shown in FIG. 4, the first center groove 41, the second center groove 42, and the third center groove 43 are arranged without intersecting each other. That is, the three center grooves 41 to 43 are separated from each other and do not communicate with each other. Therefore, the center land portion 31 is not divided by the center grooves 41 to 43 of the groove unit 4ce and has a tread surface continuous in the tire circumferential direction. As a result, the rigidity of the center land portion 31 is secured, and the steering stability performance of the tire on a dry road surface is improved.

Also, the first center groove 41, the second center groove 42, and the third center groove 43 radially extend at an arrangement interval of 90 [deg] or more and 150 [deg] or less. Specifically, the angle α formed by the first center groove 41 and the second center groove 42, the angle β formed by the second center groove 42 and the third center groove 43, the third center groove 43, and the first center groove 41. Are both in the range of 90 [deg] or more and 150 [deg] or less. Further, it is preferable that the angles α to γ are in the range of 105 [deg] or more and 135 [deg] or less. As described above, the center grooves 41 to 43 of the groove unit 4ce are radially arranged at a predetermined interval, so that the rigidity of the center land portion 31 can be appropriately adjusted as compared with the configuration in which the center grooves 41 to 43 are unevenly distributed. As a result, the dry performance of the tire is efficiently improved.

Other grooves or sipes are arranged in a region (not shown) surrounding the outer periphery of the groove unit 4ce, specifically, in a triangular region connecting the ends of the three center grooves 41 to 43. Instead, the land portion 31 has a continuous tread. As a result, the rigidity of the center land portion 31 is efficiently secured, and the dry performance of the tire is efficiently improved. In addition, the snow performance of the tire is improved.

The angle formed by adjacent grooves is defined as the angle formed by each virtual line connecting both ends of the groove.

The first center groove 41 is a lug groove having a groove width Wg1 (see FIG. 4) of 1.5 [mm] or more and 4.0 [mm] or less, and extends mainly in the tire width direction. The groove width Wg1 of the first center groove 41 is preferably in the range of 1.7 [mm]≦Wg1≦2.5 [mm]. Further, the first center groove 41 is opened at the tire ground contact surface to exert a drainage action and an edge action, thereby enhancing the wet performance and snow performance of the tire. Further, the first center groove 41 has a semi-closed structure which opens at the shoulder main groove 22 at one end and ends in the center land portion 31 at the other end. By opening the first center groove 41 in the shoulder main groove 22, the drainage action and snow performance of the first center groove 41 are improved.

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

The second center groove 42 is a narrow groove or sipe having a groove width of 0.6 [mm] or more and 1.2 [mm] or less, and extends mainly in the tire circumferential direction. Further, it is preferable that the second center groove 42 has a groove width Wg2 of less than 1.0 [mm] and is a sipe that closes at the tire ground contact surface. In addition, the second center groove 42 enhances the wet performance of the tire due to the water absorption effect on the wet road surface. Further, the second center groove 42 increases the adsorbing action on the road surface on snow and the road surface on ice, and improves the snow performance and the on-ice performance of the tire. Further, the second center groove 42 has a closed structure in which the left and right ends terminate in the center land portion 31. Since the second center groove 42 extending in the tire circumferential direction has a groove width narrower than that of the first center groove 41, the rigidity of the center land portion 31 is properly secured and the dryness of the tire is improved. ..

　The narrow groove and sipe are distinguished by the fact that the narrow groove opens at the tire contact surface and the sipe closes at the tire contact surface.

The third center groove 43 is a lug groove, a narrow groove, or a sipe having a groove width Wg3 of 0.6 [mm] or more and 2.0 [mm] or less, and extends mainly in the tire width direction. The third center groove 43 has a semi-closed structure that opens at the center main groove 21 at one end and ends in the center land portion 31 at the other end. Further, the third center groove 43 extends from the inside of the center land portion 31 to a different side with respect to the first center groove 41 and opens to the center main groove 21 on the tire equatorial plane CL side of the center land portion 31. ..

The groove width Wg1 of the first center groove 41, the groove width Wg2 of the second center groove 42, and the groove width Wg3 of the third center groove 43 have a relationship of Wg2<Wg1 and Wg3<Wg1. That is, the groove width Wg1 of the first center groove 41, which is a lug groove, is the widest. As a result, the function of the first center groove 41 as a lug groove is effectively exhibited, and the wet performance of the tire is improved.

On the other hand, the groove width Wg2 of the second center groove 42, and the groove width Wg1 of the first center groove 41 and the groove width Wg3 of the third center groove 43 have a relationship of Wg2<Wg3 and Wg2<Wg1. That is, the groove width Wg2 of the second center groove 42 extending mainly in the tire circumferential direction is the narrowest. Further, it is preferable that the difference between the groove widths Wg1 to Wg3 is 0.1 [mm] or more. As a result, the rigidity of the center land portion 31 is ensured, and the dry performance of the tire is ensured.

For example, in the configuration of FIG. 4, the second center groove 42 and the third center groove 43 are narrow grooves or sipes having groove widths Wg2 and Wg3 of 1.2 [mm] or less, and the grooves of the first center groove 41. The groove widths Wg2 and Wg3 are narrower than the width Wg1. Such a configuration is preferable in that the rigidity of the center land portion 31 is secured and the dry performance of the tire is improved.

Further, in FIG. 4, the inclination angle θ1 of the first center groove 41 with respect to the tire circumferential direction is preferably in the range of 30 [deg]≦θ1≦60 [deg], and 40 [deg]≦θ1≦50 [deg ] Is more preferable. Thereby, the drainage action of the first center groove 41 is improved, and the function of the first center groove 41 as a lug groove is ensured.

The inclination angle θ2 of the second center groove 42 with respect to the tire circumferential direction is preferably in the range of 0 [deg]≦θ2≦30 [deg], and in the range of 0 [deg]≦θ2≦20 [deg]. More preferably. At this time, the second center groove 42 may be inclined toward the first center groove 41 side from the central portion of the groove unit 4ce toward the peripheral portion (see FIG. 4), or conversely, the third center groove 43 side. It may be tilted to (not shown).

The groove inclination angle is an angle formed by each virtual line connecting both ends of the groove and the tire circumferential direction, and is defined in the range of 0 [deg] to 90 [deg].

The inclination angle θ2 of the second center groove 42 with respect to the tire circumferential direction, the inclination angle θ1 of the first center groove 41 with respect to the tire circumferential direction, and the inclination angle θ3 of the third center groove 43 with respect to the tire circumferential direction are θ2<θ1. And, there is a relationship of θ2<θ3. That is, the second center groove 42 extends mainly in the tire circumferential direction, and as a result, the

other grooves

41, 43 mainly extend in the tire width direction due to the restrictions of the arrangement intervals angles α, β, γ. Exists.

For example, in the configuration of FIG. 4, the first center groove 41, the second center groove 42, and the third center groove 43 have their end portions opposed to each other at the central portion of the center land portion 31, and are radially centered around this position. It is postponed. Further, the first center groove 41 is inclined at an inclination angle θ1 with respect to the tire circumferential direction and opens to the shoulder main groove 22 on the outer side in the tire width direction (see FIG. 3 ). Further, the third center groove 43 is inclined in the opposite direction to the first center groove 41 at an inclination angle θ2 and opens to the center main groove 21 on the tire equatorial plane CL side. Therefore, the first center groove 41 and the third center groove 43 are arranged in a V-shape that is convex in the tire circumferential direction. The second center groove 42 extends in the V-shaped convex direction of the first center groove 41 and the third center groove 43 at an inclination angle θ2. As a result, the second center groove 42 extends in the tire circumferential direction at the center of the center land portion 31, and the first center groove 41 and the third center groove 43 extend in the tire width direction with the second center groove 42 as the center. It extends to the left and right.

Further, as shown in FIG. 4, two other second center grooves 42 and third center grooves 43 are arranged close to one first center groove 41. Specifically, the distance Da between the first center groove 41 and the second center groove 42 and the distance Db between the first center groove 41 and the third center groove 43 are 1.0 [mm]≦Da≦5. The relationship is 0.0 [mm] and 1.0 [mm]≦Db≦5.0 [mm]. The range of the distance Dc (dimension symbols omitted in the drawing) between the second center groove 42 and the third center groove 43 is not particularly limited, but is 1.0 [mm] ≦ like the other distances Da and Db. It is preferable that Dc≦5.0 [mm].

The distance between adjacent grooves is measured as the distance between the tread treads.

For example, in the configuration of FIG. 4, as described above, the three center grooves 41 to 43 have their terminations facing each other at the center of the center land portion 31, and extend radially around this position. There is. In addition, the first center groove 41 and the second center groove 42 are arranged apart from each other in the tire circumferential direction and do not overlap each other in the tire circumferential direction. Further, the first center groove 41 and the second center groove 42 are closest to each other at the end portions of the

grooves

41, 42 in the center land portion 31. Therefore, the distance Da between the

adjacent grooves

41 and 42 is measured as the distance between the end portions of the

grooves

41 and 42.

Also, the first center groove 41 and the third center groove 43 are arranged apart from each other in the tire width direction and do not overlap each other in the tire width direction. Further, the first center groove 41 and the third center groove 43 are closest to each other at the end portions of the

grooves

41 and 42 in the center land portion 31. Therefore, the distance Db between the

adjacent center grooves

41 and 43 is measured as the distance between the end portions of the

center grooves

41 and 43. In the above configuration, the first center groove 41 and the second center groove 42 and the third center groove 43 are arranged at mutually different positions in the tire circumferential direction or the tire width direction. It is preferable in that the action can be efficiently obtained.

Also, the second center groove 42 and both the first center groove 41 and the third center groove 43 are separated from each other in the tire circumferential direction and do not overlap in the tire circumferential direction. Further, the third center groove 43 and the first center groove 41 and the second center groove 42 are separated from each other in the tire width direction and do not overlap in the tire width direction. Such a configuration is preferable in that the functions of the second center groove 42 and the third center groove 43 can be efficiently obtained.

Further, the first center groove 41 and the third center groove 43 are inclined in different directions in the tire circumferential direction, and are arranged so as to overlap each other in the tire circumferential direction. As described above, since the angle γ formed by the first center groove 41 and the third center groove 43 is in the range of 90 [deg] or more and 150 [deg] or less, the first center groove 41 is in the tire circumferential direction. By inclining at the predetermined angle θ1, the first center groove 41 and the third center groove 43 necessarily have the above positional relationship.

Further, in the configuration of FIG. 4, the second center groove 42 is inclined toward the first center groove 41, so that the second center groove 42 and the first center groove 41 overlap each other in the tire width direction, while the second center groove 42 and the first center groove 41 overlap each other. The second center groove 42 and the third center groove 43 do not overlap each other in the tire width direction. However, the present invention is not limited to this, and the second center groove 42 and the third center groove 43 may overlap each other in the tire width direction by inclining the second center groove 42 toward the third center groove 43 side. (Not shown).

Further, in FIG. 4, the extending length L1 of the first center groove 41 in the tire width direction and the width Wce of the center land portion 31 may have a relationship of 0.40≦L1/Wce≦0.80. It is preferable to have a relationship of 0.50 ≦ L1 / Wce ≦ 0.70. As a result, the extending length L1 of the first center groove 41 is optimized.

It is preferable that the extension length L2 of the second center groove 42 in the tire circumferential direction and the width Wce of the center land portion 31 have a relationship of 0.20≦L2/Wce≦0.50, and 0.20≦. It is more preferable to have a relationship of L2 / Wce ≦ 0.30. As a result, the extending length L2 of the second center groove 42 is optimized.

The extension length L3 of the third center groove 43 in the tire width direction (reference numeral omitted in the drawing) is not particularly limited, but the extension length L1 of the first center groove 41 and the first center groove described above are not particularly limited. It is restricted by the relationship between the angle γ formed by 41 and the third center groove 43 and the distance Db between the first center groove 41 and the third center groove 43.

The extension lengths L1 and L3 of the first center groove 41 and the third center groove 43 are measured as the distance in the tire width direction between the terminal ends of the

grooves

41 and 43 and the openings for the center main groove 21 and the shoulder main groove 22. Will be done. The extension length L2 of the second center groove 42 is measured as the distance between both ends of the groove 42 in the tire circumferential direction.

The width of the land area is measured as the width of the ground contact area of the land area when the tire is mounted on the specified rim, the specified internal pressure is applied, and there is no load.

In the configuration of FIG. 4, the center grooves 41 to 43 of the groove unit 4ce all have a straight shape. However, the present invention is not limited to this, and each of the center grooves 41 to 43 may have an arc shape, a wave shape, a zigzag shape, etc. (not shown). For example, the second center groove 42 or the third center groove 43 may be a sipe having a zigzag shape.

Further, in FIG. 5, the groove depth Hm of the center main groove 22 and the groove depth H1 of the first center groove 41 have a relationship of 0.50≦H1/Hm≦0.90. Further, the groove depth H1 of the first center groove 41, the groove depth H2 of the second center groove 42, and the groove depth H3 of the third center groove 43 have a relationship of H2<H1 and H3<H1. Therefore, the groove depth H1 of the first center groove 41 is the deepest as compared with the

other grooves

42 and 43. As a result, the groove depth H1 of the first center groove 41 is optimized.

Further, the groove depth Hm of the center main groove 22 and the groove depth H2 of the second center groove 42 have a relationship of 0.20≦H2/Hm≦0.50. Further, the groove depth H2 of the second center groove 42, the groove depth H1 of the first center groove 41, and the groove depth H3 of the third center groove 43 have a relationship of H2 <H3 and H2 <H1. Therefore, the groove depth H2 of the second center groove 42 is the shallowest as compared with the

other grooves

41 and 43. Further, the groove depth H2 of the second center groove 42 is preferably in the range of 1.5 [mm]≦H2. As a result, the shallowest groove depth H2 of the second center groove 42 is properly secured.

[Shoulder land groove unit]
6 and 7 are an enlarged plan view (FIG. 6) and a sectional view in the groove depth direction (FIG. 7) showing the groove unit of the shoulder land portion shown in FIG. Further, FIG. 7 shows a cross-sectional view in the groove depth direction along the first shoulder groove 44 and the second shoulder groove 45.

As shown in FIG. 3, the shoulder land portion 32 includes a circumferential narrow groove 23 and first to third shoulder grooves 44 to 46.

The circumferential narrow groove 23 is a narrow groove continuously extending in the tire circumferential direction, and extends parallel to the tire circumferential direction with respect to the tire circumferential direction. The circumferential narrow groove 23 has a groove width Wgs that is sufficiently narrower than the shoulder main groove 22 (see FIG. 3 ). Further, it is preferable that the groove width Wgs of the circumferential narrow groove 23 has a relationship of 0.10≦Wgs/Wgm≦0.40 with respect to the groove width Wgm of the shoulder main groove 22. Further, it is preferable that the groove width Wgs of the circumferential narrow groove 23 is in the range of 1.0 [mm]≦Wgs≦4.0 [mm]. Further, it is preferable that the groove depth Hs of the circumferential narrow groove 23 (see FIG. 7) has a relationship of 0.30 ≦ Hs / Hm ≦ 0.70 with respect to the groove depth Hm of the shoulder main groove 22. As a result, the groove width Wgs and the groove depth Hs of the circumferential narrow groove 23 are optimized.

Further, in FIG. 6, the distance Ds from the edge portion of the shoulder land portion 32 on the shoulder main groove 22 side to the groove center line of the circumferential narrow groove 23 is 0.10≦Ds with respect to the width Wsh of the shoulder land portion 32. /Wsh≦0.40 is preferable, and 0.15≦Ds/Wsh≦0.30 is more preferable.

In the configuration of FIG. 3, the shoulder land portion 32 does not include any other circumferential narrow groove in the area between the circumferential narrow groove 23 and the tire ground contact end T. Therefore, the shoulder land portion 32 has a wide tread surface continuous in the tire width direction, in which the region between the circumferential narrow groove 23 and the tire ground contact end T is not divided by other circumferential fine grooves. doing. In addition, the other circumferential narrow groove is a narrow groove having an inclination angle of 0 [deg] or more and 20 [deg] or less with respect to the tire circumferential direction and a groove width of 4.0 [mm] or less. Defined.

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

In the above configuration, since the shoulder land portion 32 includes the circumferential narrow groove 23 that continuously extends in the tire circumferential direction, the shoulder land portion 32 includes the circumferential narrow groove that is discontinuous in the tire circumferential direction (see FIG. 9 described later). Compared with, the drainage property of the shoulder land portion 32 and the edge component in the tire width direction are increased. This improves the wet performance and snow performance of the tire.

The first shoulder groove 44 is a lug groove having a semi-closed structure, opens at the tire ground contact end T at one end, extends in the tire width direction, and extends inside the shoulder land portion 32 at the other end. Terminate with. Further, the end portion of the first shoulder groove 44 is in the region between the circumferential narrow groove 23 and the tire ground contact end T, and therefore the first shoulder groove 44 does not intersect the circumferential narrow groove 23.

In the above configuration, since the first shoulder groove 44 does not intersect the circumferential narrow groove 23, a comparison is made with the configuration in which the first shoulder groove 44 intersects the circumferential narrow groove 23 (see FIG. 10 described later). Thus, the rigidity of the shoulder land portion 32 is secured. This ensures the dry performance of the tire.

Further, the first shoulder groove 44 has a groove width Wg4 (see FIG. 6) of 1.5 [mm] or more and 4.0 [mm] or less. Further, the groove depth H4 of the first shoulder groove 44 (see FIG. 7) has a relationship of 0.50 ≦ H4 / Hm ≦ 0.90 with respect to the groove depth Hm of the shoulder main groove 22. Further, as shown in FIG. 7, the groove depth H4 of the first shoulder groove 44 is deeper than the groove depth of the circumferential narrow groove 23.

Further, in FIG. 6, the extending length L4 of the first shoulder groove 44 in the ground contact surface of the shoulder land portion 32 is 0.30≦L4/Wsh≦0.50 with respect to the width Wsh of the shoulder land portion 32. It is preferable to have a relationship, and it is more preferable to have a relationship of 0.35≦L4/Wsh≦0.45. The inclination angle θ4 of the first shoulder groove 44 with respect to the tire circumferential direction is in the range of 50 [deg]≦θ4≦88 [deg].

Further, in FIG. 6, the distance Ds of the circumferential narrow groove 23 and the extension length L4 of the first shoulder groove 44 are 0.40≦(Wsh−Ds−L4)/Wsh with respect to the width Wsh of the shoulder land portion. It is preferable to have a relationship of 0.45≦(Wsh−Ds−L4)/Wsh. Thereby, the distance from the end portion of the first shoulder groove 44 to the circumferential narrow groove 23 is properly secured. The upper limit of the ratio (Wsh-Ds-L4)/Wsh is not particularly limited, but is limited by the range of the distance Ds and the extension length L4.

The width Wce of the center region and the width Wsh of the shoulder land portion 32 are in the range of 20% to 50% with respect to the tire ground contact width TW (see FIG. 2). As a result, the widths Wce and Wsh of the

land portions

31 and 32 are optimized.

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, a specified internal pressure is applied, and the tire is placed vertically on the plate in a stationary state and a load corresponding to the specified load is applied. Is measured as the maximum linear distance in the tire axial direction.

The second shoulder groove 45 is a sipe or a narrow groove having a semi-closed structure, opens at the shoulder main groove 22 at one end, extends in the tire width direction, and has a shoulder land at the other end. It ends in the part 32. In addition, the terminal end portion of the second shoulder groove 45 is in the region between the circumferential narrow groove 23 and the tire ground contact end T, and therefore the second shoulder groove 45 intersects the circumferential narrow groove 23.

In the above configuration, the narrow second shoulder groove 45 intersects the circumferential narrow groove 23 to suppress the decrease in rigidity of the shoulder land portion 32, and the shoulder main groove 22 to the first shoulder groove 44. Drainage and edge components in the tire circumferential direction are ensured in the area up to the end. As a result, the dry performance of the tire is ensured, and at the same time, the wet performance and the snow performance of the tire are improved.

Further, the second shoulder groove 45 has a groove width Wg5 (see FIG. 6) of 0.6 [mm] or more and 1.2 [mm] or less. The groove depth H5 of the second shoulder groove 45 (see FIG. 7) has a relationship of 0.30≦H5/Hm≦0.70 with respect to the groove depth Hm of the shoulder main groove 22. Further, as shown in FIG. 7, the groove depth H5 of the second shoulder groove 45 is deeper than the groove depth of the circumferential narrow groove 23 and shallower than the groove depth H4 of the first shoulder groove 44.

Further, it is preferable that the second shoulder groove 45 is a sipe that closes when the tire touches the ground. As a result, the rigidity of the shoulder land portion 32 when the tire touches the ground, particularly the rigidity of the fine ribs (reference numerals omitted in the drawing) divided into the circumferential narrow groove 23 and the shoulder main groove 22 is ensured.

Further, in the configuration of FIG. 6, the second shoulder groove 45 has a linear shape. However, not limited to this, the second shoulder groove 45 may have a gentle arc shape (not shown).

Further, as shown in FIG. 6, the second shoulder groove 45 is arranged so as to be separated from the first shoulder groove 44 in the tire width direction and not to overlap in the tire width direction. The distance Dc between the second shoulder groove 45 and the first shoulder groove 44 is in the range of 1.0 [mm]≦Dc≦5.0 [mm]. The extension length of the second shoulder groove 45 in the tire width direction (dimension symbols omitted in the drawing) is not particularly limited, but the distance Dc and the extension length L4 of the first shoulder groove 44 are the same. Constrained by relationships.

In the above configuration, since the second shoulder groove 45 is arranged apart from the first shoulder groove 44, a ventilation path in the vulcanization molding process of the tire is secured, and vulcanization failure of the tire is suppressed. .. Further, since the second shoulder groove 45 is arranged close to the first shoulder groove 44, the drainage property of the shoulder land portion 32 is improved.

Further, in FIG. 6, the inclination angle θ5 of the second shoulder groove 45 with respect to the tire circumferential direction is preferably in the range of 30 [deg]≦θ5≦60 [deg], and 40 [deg]≦θ5≦50 [deg ] Is more preferable. Further, the inclination angle θ5 of the second shoulder groove 45 has a relationship of θ5<θ4 with respect to the inclination angle θ4 of the first shoulder groove 44.

Further, as shown in FIG. 6, the first shoulder groove 44 and the second shoulder groove 45 are inclined in directions opposite to each other with respect to the tire circumferential direction. In such a configuration, the steering stability performance (particularly turning performance) of the tire is improved as compared with the configuration in which the first shoulder groove 44 and the second shoulder groove 45 are inclined in the same direction. Further, the angle δ formed by the first shoulder groove 44 and the second shoulder groove 45 is preferably in the range of 120 [deg] ≤ δ ≤ 160 [deg], and 130 [deg] ≤ δ ≤ 150 [deg]. More preferably in the range.

The third shoulder groove 46 is a sipe or narrow groove having a semi-closed structure, which opens to the tire ground contact end T at one end, extends in the tire width direction, and has a shoulder land portion at the other end. Terminate within 32. Further, the end portion of the third shoulder groove 46 is in the region between the circumferential narrow groove 23 and the tire ground contact end T, and therefore the third shoulder groove 46 does not intersect the circumferential narrow groove 23. Further, the third shoulder groove 46 has a groove width of 0.6 [mm] or more and 2.0 [mm] or less (dimension symbols omitted in the drawing). Further, the groove depth of the third shoulder groove 46 (the dimension symbol is omitted in the drawing) is in the range of 30% or more and 60% or less with respect to the groove depth Hm of the shoulder main groove 22.

Further, in FIG. 6, the extension length L6 of the third shoulder groove 46 in the ground contact surface of the shoulder land portion 32 is 0.35≦L6/Wsh≦0.65 with respect to the width Wsh of the shoulder land portion 32. It is preferable to have a relationship, and it is more preferable to have a relationship of 0.40≦L6/Wsh≦0.60. It is preferable that the extension length L6 of the third shoulder groove 46 has a relationship of 1.10≦L6/L4≦1.25 with respect to the extension length L4 of the first shoulder groove 44.

Further, the inclination angle θ6 of the third shoulder groove 46 with respect to the tire circumferential direction is in the range of 50 [deg] ≤ θ6 ≤ 88 [deg]. Further, it is preferable that the inclination angle θ4 of the first shoulder groove 44 is within the range of −10 [deg]≦θ6−θ4≦10 [deg]. Therefore, the third shoulder groove 46 is arranged substantially parallel to the first shoulder groove 44.

Further, in FIG. 3, the first center groove 41 of the center land portion 31 is arranged offset from the first shoulder groove 44 of the shoulder land portion 32 in the tire circumferential direction. Specifically, when the first center groove 41 of the center land portion 31 and the first shoulder groove 44 of the shoulder land portion 32 are projected and viewed in the tire width direction, they are arranged so as not to overlap each other. .. As a result, the pattern noise caused by the arrangement of the relatively

wide grooves

41 and 44 is reduced, and the noise performance of the tire is improved.

Further, as shown in FIG. 3, the second shoulder groove 45 of the shoulder land portion 32 extends along the extension line of the groove center line of the first center groove 41 of the center land portion 31. Specifically, the second shoulder groove 45 is inclined in the same direction with respect to the first center groove 41, and the second shoulder groove 45 is arranged substantially parallel to the first center groove 41. Further, the distance Dp of the second shoulder groove 45 with respect to the extension line of the groove center line of the first center groove 41 is 0≤Dp / Wg1≤2 with respect to the groove width Wg1 (see FIG. 4) of the first center groove 41. It has a relationship of 00. As a result, when the tire rolls, the drainage property from the first center groove 41 of the center land portion 31 to the third center groove 43 of the shoulder land portion 32 is improved, and the wet performance of the tire is improved. In addition, in the configuration of FIG. 3, the first center groove 41 and the second shoulder groove 45 have a linear shape, but not limited to this, they may have an arc shape (not shown).

[effect]
As described above, the pneumatic tire 1 includes the center main groove 21 and the shoulder main groove 22 extending in the tire circumferential direction, and the center land portion 31 and the shoulder defined by the center main groove 21 and the shoulder main groove 22. It is provided with a land portion 32 (see FIG. 2). In addition, the shoulder land portion 32 has a circumferential narrow groove 23 continuously extending in the tire circumferential direction, and the shoulder land portion 32 opens at the tire ground contact end T at one end and inside the shoulder land portion 32 at the other end. And a second shoulder groove 45 that opens into the shoulder main groove 22 at one end and ends in the shoulder land portion 32 at the other end (see FIG. 6). ). The first shoulder groove 44 has a groove width Wg4 of 1.5 [mm] or more and 4.0 [mm] or less and does not intersect the circumferential narrow groove 23. Further, the second shoulder groove 45 has a groove width Wg5 of 0.6 [mm] or more and 1.2 [mm] or less and intersects the circumferential narrow groove 23.

In such a configuration, (1) the shoulder land portion 32 is provided with a circumferential fine groove 23 extending continuously in the tire circumferential direction, and thus is provided with a circumferential fine groove discontinuous in the tire circumferential direction (FIG. 9 described later). Compared with the reference), the drainage property of the shoulder land portion 32 and the edge component in the tire width direction are increased. This has the advantage of improving the wet performance and snow performance of the tire. Further, (2) the first shoulder groove 44 does not intersect with the circumferential narrow groove 23, so that the first shoulder groove 44 intersects with the circumferential narrow groove 23 (see FIG. 10 described later). Thus, the rigidity of the shoulder land portion 32 is secured. This has the advantage of ensuring the dry performance of the tire. Further, (3) the narrow second shoulder groove 45 intersects with the circumferential narrow groove 23, so that the rigidity reduction of the shoulder land portion 32 is suppressed and the shoulder main groove 22 to the first shoulder groove 44 are changed. The drainage property and the edge component in the tire circumferential direction in the region up to the terminal end are secured. As a result, the dry performance of the tire is secured, and at the same time, the wet performance and snow performance of the tire are improved.

Further, in the pneumatic tire 1, the groove width Wgs of the circumferential narrow groove 23 has a relationship of 0.10≦Wgs/Wgm≦0.40 with respect to the groove width Wgm of the shoulder main groove 22 (see FIG. 3). ). The lower limit ensures the function of the circumferential narrow groove 23, and the upper limit ensures the rigidity of the shoulder land portion 32.

Further, in the pneumatic tire 1, the groove depth Hs of the circumferential narrow groove 23 has a relationship of 0.30 ≦ Hs / Hm ≦ 0.70 with respect to the groove depth Hm of the shoulder main groove 22 (FIG. 7). The lower limit ensures the function of the circumferential narrow groove 23, and the upper limit ensures the rigidity of the shoulder land portion 32.

Further, in the pneumatic tire 1, the distance Ds from the edge portion of the shoulder land portion 32 on the shoulder main groove 22 side to the groove center line of the circumferential narrow groove 23 is relative to the width Wsh of the ground contact area of the shoulder land portion 32. 0.10≦Ds/Wsh≦0.40 (see FIG. 6). By the above lower limit, the rigidity of the thin ribs (reference numeral omitted in the figure) partitioned between the circumferential narrow groove 23 and the shoulder main groove 22 is secured, and by the above upper limit, the circumferential narrow groove 23 and the first shoulder groove are secured. There is an advantage that the reduction in rigidity of the shoulder land portion 32 due to the approach of the shoulder land portion 44 is suppressed.

Further, in the pneumatic tire 1, the shoulder land portion 32 does not have any other circumferential narrow groove in the region between the circumferential narrow groove 23 and the tire ground contact end T (see FIG. 3 ). This has the advantage of ensuring the rigidity of the shoulder land portion 32.

Further, in the pneumatic tire 1, the extending length L4 of the first shoulder groove 44 in the ground contact surface of the shoulder land portion 32 is 0.30 ≦ L4 / with respect to the width Wsh of the ground contact region of the shoulder land portion 32. It has a relationship of Wsh≦0.50 (see FIG. 6). The lower limit secures the drainage action of the first shoulder groove 44, and the upper limit has an advantage that the rigidity reduction of the shoulder land portion 32 due to the excessive extension length L4 of the first shoulder groove 44 is suppressed. is there.

Further, in the pneumatic tire 1, the width Wsh of the shoulder land portion 32 has a relationship of 0.15≦Wsh/TW≦0.35 with respect to the tire ground contact width TW (see FIG. 2). This has an advantage that the width Wsh of the shoulder land portion 32 is optimized.

Further, in the pneumatic tire 1, the inclination angle θ4 of the first shoulder groove 44 with respect to the tire circumferential direction is in the range of 50 [deg]≦θ4≦85 [deg] (see FIG. 6). Thereby, there is an advantage that the inclination angle θ4 of the first shoulder groove 44 is optimized.

Further, in the pneumatic tire 1, the second shoulder groove 45 is arranged apart from the first shoulder groove 44 in the tire width direction. With such a configuration, the second shoulder groove 45 is arranged apart from the first shoulder groove 44, so that an air passage is secured in the tire vulcanization molding step, and vulcanization failure of the tire is suppressed. There is.

Further, in the pneumatic tire 1, the distance Dc between the second shoulder groove 45 and the first shoulder groove 44 is in the range of 1.0 [mm]≦Dc≦5.0 [mm]. Thereby, there is an advantage that the distance Dc between the second shoulder groove 45 and the first shoulder groove 44 is optimized. In particular, due to the above upper limit, the second shoulder groove 45 is arranged close to the first shoulder groove 44, so that the drainage property of the shoulder land portion 32 is improved.

Further, in the pneumatic tire 1, the first shoulder groove 44 and the second shoulder groove 45 are inclined in the directions opposite to each other with respect to the tire circumferential direction (see FIG. 6). Such a configuration has an advantage that steering stability performance (particularly turning performance) of the tire is improved as compared with a configuration in which the first shoulder groove 44 and the second shoulder groove 45 are inclined in the same direction.

Further, in the pneumatic tire 1, the inclination angle θ5 of the second shoulder groove 45 with respect to the tire circumferential direction is in the range of 30 [deg]≦θ5≦60 [deg]. This has an advantage that the inclination angle θ5 of the second shoulder groove 45 is optimized.

Further, in the pneumatic tire 1, the angle γ formed by the first shoulder groove 44 and the second shoulder groove 45 is in the range of 90 [deg]≦γ≦150 [deg]. This has the advantage that the angle γ formed by the first shoulder groove 44 and the second shoulder groove 45 is optimized.

Further, in the pneumatic tire 1, the shoulder land portion 32 includes the third shoulder groove 46 arranged between the adjacent first shoulder grooves 44, 44 (see FIG. 6). Further, the extension length L6 of the third shoulder groove 46 in the tire ground contact plane has a relationship of 1.10≦L6/L4≦1.25 with respect to the extension length L4 of the first shoulder groove 44. With such a configuration, the edge component of the shoulder land portion 32 is increased by the third shoulder groove 46, and there is an advantage that the snow performance of the tire is improved.

Further, in the pneumatic tire 1, the center land portion 31 includes a plurality of sets of groove units 4ce each including the first center groove 41, the second center groove 42, and the third center groove 43 as one set (FIG. 2). reference). Further, the first center groove 41, the second center groove 42, and the third center groove 43 are arranged without intersecting each other and are radially arranged at an arrangement interval α, β, γ of 90 [deg] or more and 150 [deg] or less. (See FIG. 4). In addition, the first center groove 41 has a groove width Wg1 of 1.5 [mm] or more and 4.0 [mm] or less, and opens at the shoulder main groove 22 at one end and at the other end. Ends in the center land portion 31.

With such a configuration, (1) the wet performance of the tire is ensured by the groove unit 4ce including a set of three center grooves 41 to 43. Further, (2) since the center grooves 41 to 43 are arranged without intersecting with each other, the rigidity of the center land portion 31 is secured and the dry performance of the tire is secured. Further, (3) since the center grooves 41 to 43 radially extend at the arrangement intervals α, β, γ of 90 [deg] or more and 150 [deg] or less, compared with the configuration in which the center grooves 41 to 43 are unevenly distributed. The rigidity of the center land portion 31 is efficiently ensured, and the dry performance of the tire is efficiently improved. (4) Since the first center groove 41 is a lug groove, the drainage of the

land portions

31 and 32 is ensured, and the wet performance of the tire is ensured. With these, there is an advantage that the wet performance and the dry performance of the tire are compatible with each other.

FIG. 8 is a chart showing the results of a performance test of the pneumatic tire according to the embodiment of the present invention. 9 and 10 are explanatory views showing test tires of a conventional example (FIG. 9) and a comparative example (FIG. 10). These figures show tread plan views of the center land portion and the shoulder land portion in the tire one side region.

In this performance test, several types of test tires were evaluated for (1) dry steering stability performance, (2) wet braking performance, and (3) snow steering stability performance. Further, a test tire with a tire size of 185/60R15 is mounted on a rim with a rim size of 15×6J, and the inner pressure of the front wheels 240 [kPa] and the rear wheels 230 [kPa] and the maximum load specified by JATMA are applied to the test tire.

(1) In the evaluation of dry steering stability performance, the test vehicle runs on a test course on a dry road surface with a flat peripheral circuit at 60 [km/h] to 100 [km/h]. Then, the test driver performs a sensory evaluation on the steerability during lane change and cornering and the stability during straight running. This evaluation is performed by index evaluation using the conventional example as a reference (100), and the larger the value, the more preferable. Further, if the value is 98 or more, it can be said that the dry steering stability performance is properly secured.

(2) In the evaluation of wet braking performance, the test vehicle travels on an asphalt road sprinkled with water at a depth of 1 [mm], and the braking distance from an initial speed of 40 [km / h] is measured. Then, based on the measurement result, index evaluation is performed with the conventional example as a reference (100). The larger the value, the more preferable the evaluation.

(3) In the evaluation on snow steering stability performance, the test vehicle runs on a predetermined handling course on a snowy road at a speed of 40 [km/h], and the test driver performs a sensory evaluation on steering stability. This evaluation is performed by index evaluation using the conventional example as a reference (100), and the larger the value, the more preferable.

The test tire of the embodiment has the configurations shown in FIGS. 1 to 3, has a plurality of sets of groove units 4ce composed of three center grooves 41 to 43 in which the center land portion 31 is radially arranged, and has a shoulder land portion. 32 has a circumferential narrow groove 23 and first to third shoulder grooves 44 to 46. The width Wce of the center land portion 31 is Wce=20 [mm], and the width Wsh of the shoulder land portion 32 is Wsh=30.0 [mm]. Further, the groove width Wgm of the shoulder main groove 22 is 9.3 [mm], and the groove depth Hm is 7.0 [mm]. The groove width Wgs of the circumferential narrow groove 23 is 1.5 [mm], and the groove depth Hs is 3.5 [mm]. Further, the groove width Wg4 of the first shoulder groove 44 is 3.8 [mm], the groove depth H4 is 5.0 [mm], and the inclination angle θ4 is 86 [deg]. The groove width Wg5 of the second shoulder groove 45 is 0.8 [mm], the groove depth H5 is 3.5 [mm], and the inclination angle θ5 is 54 [deg]. Further, the groove width Wg6 of the third shoulder groove 46 is 0.8 [mm], the groove depth H6 is 5.0 [mm], and the inclination angle θ6 is 86 [deg]. Further, the first shoulder groove 44 and the second shoulder groove 45 are separated from each other, and the distance Dc is 1.0 [mm].

The test tire of the conventional example has the configuration of FIG. 9 and differs from the test tire of Example 1 in that the circumferential narrow groove 23 (FIG. 3) is a sipe discontinuous in the tire circumferential direction. .. The test tire of the comparative example has the configuration of FIG. 10, and differs from the test tire of Example 1 in that the circumferential narrow groove 23 intersects the first shoulder groove 44.

As shown in the test results, it can be seen that the test tires of the examples have both wet performance of the tires and snow performance and dry 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 center main groove, 22 Shoulder main groove, 23 circumferential narrow groove, 31 center main groove, 32 shoulder land portion, 4ce groove unit, 41 first center groove, 42 second center groove, 43 third center groove, 44 first shoulder groove, 45th Two shoulder groove, 46 third shoulder groove

Claims

A pneumatic tire comprising a center main groove and a shoulder main groove extending in the tire circumferential direction, and a center land portion and a shoulder land portion defined by the center main groove and the shoulder main groove,
The shoulder land portion is a circumferential narrow groove that extends continuously in the tire circumferential direction, and a first end that opens at the tire ground contact end at one end and terminates in the shoulder land portion at the other end. A shoulder groove and a second shoulder groove that opens at the shoulder main groove at one end and ends in the shoulder land portion at the other end,
The first shoulder groove has a groove width of 1.5 [mm] or more and 4.0 [mm] or less, does not intersect with the circumferential narrow groove, and
The pneumatic tire, wherein the second shoulder groove has a groove width of 0.6 [mm] or more and 1.2 [mm] or less and intersects with the circumferential narrow groove.
The pneumatic tire according to claim 1, wherein the groove width Wgs of the circumferential narrow groove has a relationship of 0.10≦Wgs/Wgm≦0.40 with respect to the groove width Wgm of the shoulder main groove.
The pneumatic tire according to claim 1 or 2, wherein the groove depth Hs of the circumferential narrow groove has a relationship of 0.30 ≦ Hs / Hm ≦ 0.70 with respect to the groove depth Hm of the shoulder main groove. ..
The distance Ds from the edge portion of the shoulder land portion on the shoulder main groove side to the groove center line of the circumferential narrow groove is 0.10 ≦ Ds / Wsh ≦ with respect to the width Wsh of the ground contact region of the shoulder land portion. The pneumatic tire according to any one of claims 1 to 3, which has a relationship of 0.40.
The pneumatic tire according to any one of claims 1 to 4, wherein the shoulder land portion is not provided with another circumferential narrow groove in a region between the circumferential narrow groove and the tire ground contact end.
The extending length L4 of the first shoulder groove in the ground contact surface of the shoulder land portion has a relationship of 0.30 ≦ L4 / Wsh ≦ 0.50 with respect to the width Wsh of the ground contact region of the shoulder land portion. The pneumatic tire according to any one of claims 1 to 5.
7. The pneumatic tire according to claim 1, wherein the width Wsh of the ground contact area of the shoulder land portion has a relationship of 0.15≦Wsh/TW≦0.35 with respect to the tire ground contact width TW. ..
The pneumatic tire according to any one of claims 1 to 7, wherein the inclination angle θ4 of the first shoulder groove with respect to the tire circumferential direction is in the range of 50 [deg] ≤ θ4 ≤ 88 [deg].
The pneumatic tire according to any one of claims 1 to 8, wherein the second shoulder groove is arranged apart from the first shoulder groove in the tire width direction.
The pneumatic tire according to claim 9, wherein a distance Dc between the second shoulder groove and the first shoulder groove is in a range of 1.0 [mm]≦Dc≦5.0 [mm].
The pneumatic tire according to any one of claims 1 to 10, wherein the first shoulder groove and the second shoulder groove are inclined in opposite directions with respect to the tire circumferential direction.
The pneumatic tire according to claim 11, wherein the inclination angle θ5 of the second shoulder groove with respect to the tire circumferential direction is in the range of 30 [deg] ≤ θ5 ≤ 60 [deg].
The pneumatic tire according to any one of claims 1 to 12, wherein the angle γ formed by the first shoulder groove and the second shoulder groove is in the range of 90 [deg] ≤ γ ≤ 150 [deg].
The shoulder land portion includes a third shoulder groove arranged between the adjacent first shoulder grooves, and the extending length L6 of the third shoulder groove in the tire contact patch is the first shoulder. The pneumatic tire according to any one of claims 1 to 13, which has a relationship of 1.10 ≦ L6 / L4 ≦ 1.25 with respect to the extending length L4 of the groove.
The center land portion includes a plurality of sets of groove units composed of a first center groove, a second center groove, and a third center groove.
The first center groove, the second center groove, and the third center groove are arranged without intersecting with each other and extend radially at an arrangement interval of 90 [deg] or more and 150 [deg] or less, and
The first center groove has a groove width of 1.5 [mm] or more and 4.0 [mm] or less, and opens at the shoulder main groove at one end and the center at the other end. The pneumatic tire according to any one of claims 1 to 14, which is terminated in the land portion.