A tire has a tread portion 2 including a first land portion 11. The first land portion 11 includes a first circumferential edge 11a, a second circumferential edge 11b, and a tread surface between the first circumferential edge 11a and the second circumferential edge 11b. On the tread surface, a first inclined groove 21 extending from the second circumferential edge 11b to the first circumferential edge 11a side, a second inclined groove 22 extending from the second circumferential edge 11b to the first circumferential edge 11a side so as to be inclined in a direction opposite to that of the first inclined groove 21, and a triangular block 35 demarcated by the first inclined groove 21 and the second inclined groove 22, are formed. A curved groove 15 curved so as to be convex on the second circumferential edge 11b is formed on the triangular block 35.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a tire.

Description of the Background Art

Japanese Laid-Open Patent Publication No. 2015-140047 discloses a tire having improved steering stability on a dry road surface and a wet road surface by improving the arrangement of grooves and sipes.

In recent years, with enhancement of the performance of vehicles, tires having more excellent wet performance have been required. Meanwhile, depending on the arrangement of grooves, steering stability on a dry road surface may be deteriorated with improvement of wet performance.

The present invention has been made in view of the above-described problem, and a main object of the present invention is to provide a tire that can exhibit excellent wet performance while maintaining steering stability on a dry road surface.

SUMMARY OF THE INVENTION

The present invention is directed to a tire having a tread portion, wherein: the tread portion includes a first land portion; the first land portion includes a first circumferential edge, a second circumferential edge, and a tread surface between the first circumferential edge and the second circumferential edge; on the tread surface, a first inclined groove extending from the second circumferential edge to the first circumferential edge side, a second inclined groove extending from the second circumferential edge to the first circumferential edge side so as to be inclined in a direction opposite to that of the first inclined groove, and a triangular block demarcated by the first inclined groove, the second inclined groove, and the second circumferential edge, are formed; and a curved groove curved so as to be convex on the second circumferential edge side is formed on the triangular block.

In the tire according to the present invention, the triangular block is preferably located on a tire equator.

In the tire according to the present invention, the first inclined groove and the second inclined groove preferably communicate with each other.

In the tire according to the present invention, the curved groove preferably communicates with the first inclined groove and the second inclined groove.

In the tire according to the present invention, the curved groove preferably communicates with the first inclined groove and the second inclined groove on the second circumferential edge side with respect to a center position in a tire axial direction of the first land portion.

In the tire according to the present invention, preferably, the triangular block includes an end portion demarcated by the first inclined groove, the second inclined groove, and the curved groove, and a length in the tire axial direction of the end portion is 30% to 70% of a length in the tire axial direction of the triangular block.

In the tire according to the present invention, the first inclined groove is preferably connected to the first circumferential edge.

In the tire according to the present invention, the second inclined groove preferably terminates within the first land portion.

In the tire according to the present invention, the curved groove is preferably curved with a radius of curvature of 15 to 30 mm.

In the tire according to the present invention, a groove width of the curved groove is preferably 2 to 5 mm.

In the tire according to the present invention, preferably, the tire has a designated mounting direction to a vehicle, the tread portion includes a first tread edge located on an outer side of the vehicle when the tire is mounted on the vehicle, a second tread edge located on an inner side of the vehicle when the tire is mounted on the vehicle, a first shoulder main groove continuously extending in the tire circumferential direction between the first tread edge and a tire equator, and a crown main groove adjacent to the second tread edge side of the first shoulder main groove, and the first land portion is demarcated between the first shoulder main groove and the crown main groove.

On the tread surface of the first land portion of the tire according to the present invention, a first inclined groove extending from the second circumferential edge to the first circumferential edge side of the first land portion, a second inclined groove extending from the second circumferential edge to the first circumferential edge side so as to be inclined in a direction opposite to that of the first inclined groove, and a triangular block demarcated by the first inclined groove and the second inclined groove, are formed. In addition, a curved groove curved so as to be convex on the second circumferential edge side is formed on the triangular block.

With the tire according to the present invention, during running on a wet road surface, the first inclined groove and the second inclined groove inclined in different directions, and the curved groove exhibit excellent drainage performance, and the edge of the triangular block provides frictional force in multiple directions. Therefore, the tire according to the present invention can exhibit excellent wet performance.

Moreover, the curved groove inhibits an excessive reduction in the stiffness of a tapered portion of the triangular block between the first inclined groove and the second inclined groove. Therefore, the tire according to the present invention can maintain steering stability on a dry road surface.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.FIG. 1is a development of a tread portion2of a tire1showing the embodiment of the present invention. The tire1according to the present embodiment is suitably used, for example, as a pneumatic tire for a passenger car. However, the present invention is not limited to such a mode, and may be applied to a heavy-duty pneumatic tire and a non-pneumatic tire the interior of which is not filled with pressurized air.

As shown inFIG. 1, the tire1according to the present embodiment has the tread portion2having a designated mounting direction to a vehicle. The tread portion2has a first tread edge Te1located at the outer side of a vehicle when the tire1is mounted on the vehicle, and a second tread edge Te2located at the inner side of the vehicle when the tire1is mounted on the vehicle. The mounting direction to a vehicle is indicated, for example, on a sidewall portion (not shown) by characters or symbols.

In the case of a pneumatic tire, each of the first tread edge Te1and the second tread edge Te2is a ground contact position at the outermost side in the tire axial direction when a normal load is applied to the tire1in a normal state and the tire1is brought into contact with a flat surface at a camber angle of 0°. The normal state is a state where the tire is mounted to a normal rim and inflated to a normal internal pressure and no load is applied to the tire. In the present description, unless otherwise specified, dimensions and the like of components of the tire are values measured in the normal state.

The “normal rim” is a rim that is defined, in a standard system including a standard on which the tire is based, by the standard for each tire, and is, for example, the “standard rim” in the JATMA standard, the “Design Rim” in the TRA standard, or the “Measuring Rim” in the ETRTO standard.

The “normal internal pressure” is an air pressure that is defined, in a standard system including a standard on which the tire is based, by the standard for each tire, and is the “maximum air pressure” in the JATMA standard, the maximum value indicated in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in the TRA standard, or the “INFLATION PRESSURE” in the ETRTO standard.

The “normal load” is a load that is defined, in a standard system including a standard on which the tire is based, by the standard for each tire, and is the “maximum load capacity” in the JATMA standard, the maximum value indicated in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in the TRA standard, or the “LOAD CAPACITY” in the ETRTO standard.

The tread portion2includes a plurality of main grooves3continuously extending in the tire circumferential direction between the first tread edge Te1and the second tread edge Te2, and a plurality of land portions4demarcated by these main grooves3. The tread portion2of the present embodiment includes three main grooves3and four land portions4. However, the tire according to the present invention is not limited to such a mode.

The main grooves3include a first shoulder main groove5provided between the first tread edge Te1and a tire equator C, a second shoulder main groove6provided between the second tread edge Te2and the tire equator C, and a crown main groove7provided between the first shoulder main groove5and the second shoulder main groove6.

The distance La in the tire axial direction from the tire equator C to the groove center line of the first shoulder main groove5or the second shoulder main groove6is, for example, preferably 0.20 to 0.35 times a tread width TW. The distance Lb in the tire axial direction from the tire equator C to the groove center line of the crown main groove7is, for example, preferably not greater than 0.15 times the tread width TW. The tread width TW is the distance in the tire axial direction from the first tread edge Te1to the second tread edge Te2in the normal state.

The crown main groove7of the present embodiment is provided, for example, on the second tread edge Te2side with respect to the tire equator C. However, the position of the crown main groove7is not limited to such a position.

Each main groove3of the present embodiment extends, for example, in a straight manner so as to be parallel to the tire circumferential direction. Each main groove3may extend, for example, in a wavy manner.

The groove width Wa of each main groove3is, for example, preferably 5.0% to 8.0% of the tread width TW. In the present specification, the groove width is the distance between the groove edges in a direction orthogonal to the groove center line. In a preferable mode, the groove width of the second shoulder main groove6is larger than the groove width of the first shoulder main groove5, and the groove width of the crown main groove7is larger than the groove width of the second shoulder main groove6. In the case of a pneumatic tire for a passenger car, the depth of each main groove3is, for example, preferably 5 to 10 mm.

The land portions4include a first land portion11, a second land portion12, a third land portion13, and a fourth land portion14. The first land portion11is demarcated between the first shoulder main groove5and the crown main groove7. The second land portion12is demarcated between the second shoulder main groove6and the crown main groove7. The third land portion13is demarcated between the first shoulder main groove5and the first tread edge Te1. The fourth land portion14is demarcated between the second shoulder main groove6and the second tread edge Te2.

FIG. 2shows an enlarged view of the first land portion11. As shown inFIG. 2, the first land portion11of the present embodiment has a largest width W1in the tire axial direction among the four land portions4. In the tread portion2which includes the four land portions4, a great contact pressure acts on the first land portion11during straight running and during cornering, but, in the present embodiment, the first land portion11has the largest width in the tire axial direction among the four land portions4and has high stiffness. Therefore, steering stability on a dry road surface is improved. The width W1of the first land portion11is, for example, preferably 0.25 to 0.40 times of the tread width TW (shown inFIG. 1, and the same applies below).

The first land portion11includes a first circumferential edge11a, a second circumferential edge11b, and a tread surface11cbetween the first circumferential edge11aand the second circumferential edge11b. The first circumferential edge11ais the circumferential edge on the first shoulder main groove5side of the first land portion11, and the second circumferential edge11bis the circumferential edge on the crown main groove7side of the first land portion11.

On the tread surface11cof the first land portion11, for example, a plurality of first inclined grooves21and a plurality of second inclined grooves22are provided.

Each first inclined groove21extends, for example, so as to be inclined in a first direction (upward toward the right side inFIG. 2) relative to the tire axial direction. The first inclined groove21extends from the second circumferential edge11bto the first circumferential edge11aside. Each first inclined groove21of the present embodiment extends from the second circumferential edge11bto the first circumferential edge11aand traverses the first land portion11. The first inclined groove21is inclined, for example, at an angle θ1of 10 to 60° relative to the tire axial direction. The angle of the first inclined groove21relative to the tire axial direction preferably gradually increases toward the second circumferential edge11bside, for example. Each first inclined groove21of the present embodiment is curved in an arc shape with a radius of curvature of 50 to 150 mm, for example. Such a first inclined groove21can provide frictional force in multiple directions during running on a wet road surface.

Each second inclined groove22is inclined from the second circumferential edge11bto the first circumferential edge11aside in a second direction (downward toward the right side inFIG. 2) opposite to the first direction, and terminates within the first land portion11. The second inclined groove22is inclined, for example, at an angle θ2of 10 to 60° relative to the tire axial direction. The angle of the second inclined groove22relative to the tire axial direction preferably gradually increases toward the first circumferential edge11aside, for example. Each second inclined groove22of the present embodiment is curved in an arc shape with a radius of curvature of 50 to 150 mm, for example.

On the tread surface11cof the first land portion11, triangular blocks35each demarcated by a first inclined groove21, a second inclined groove22, and the second circumferential edge11bare formed. Each triangular block35has a triangular tread surface. The triangular block35is, for example, located on the tire equator C. In the present embodiment, the triangular block35is also located on the center position20in the tire axial direction of the first land portion11. In the triangular block35, 50% or more of the area of the tread surface thereof is preferably located on the second tread edge Te2side with respect to the center position20.

On each triangular block35, a curved groove15curved so as to be convex on the second circumferential edge side is formed. Each curved groove15of the present embodiment extends from a first end15aon the first circumferential edge11aside, terminates at a second end15bwithin the first land portion11, and is curved so as to be convex on the second circumferential edge in a portion that traverses the triangular block35.

With the tire according to the present invention, during running on a wet road surface, the first inclined groove21and the second inclined groove22inclined in different directions, and the curved groove15exhibit excellent drainage performance, and the edge of the triangular block35provides frictional force in multiple directions. Therefore, the tire according to the present invention can exhibit excellent wet performance.

Moreover, the curved groove15inhibits an excessive reduction in the stiffness of a tapered portion of the triangular block35between the first inclined groove21and the second inclined groove22. Therefore, the tire according to the present invention can maintain steering stability on a dry road surface.

Hereinafter, the specific configuration of the tire according to the present embodiment will be described.FIG. 3shows a cross-sectional view of the first inclined groove21taken along a line A-A inFIG. 2. As shown inFIG. 3, the first inclined groove21includes a first tie bar23raised at a groove bottom on the first circumferential edge11a(shown inFIG. 2, and the same applies below) side. The first tie bar23of the present embodiment is provided, for example, in an end portion on the first circumferential edge11aside of the first inclined groove21. The first tie bar23has, for example, a constant depth in the longitudinal direction of the first inclined groove21. The depth d2of the first tie bar23is 45% to 60% of the maximum depth d1of the first inclined groove21. The first inclined groove21including such a first tie bar23can enhance wet performance while inhibiting a reduction in the stiffness of the first land portion11.

As shown inFIG. 2, each second inclined groove22communicates with the first inclined groove21, for example, and preferably intersects the first inclined groove21. Each second inclined groove22of the present embodiment intersects the first inclined groove21on the first circumferential edge11aside with respect to a center position20in the tire axial direction of the first land portion11. In a more preferable mode, the second inclined groove22intersects the first inclined groove21on the second circumferential edge11bside with respect to the first tie bar23(shown inFIG. 3) of the first inclined groove21. Such a second inclined groove22can exhibit excellent drainage performance together with the first inclined groove21.

FIG. 4shows a cross-sectional view of the second inclined groove22taken along a line B-B inFIG. 2. As shown inFIG. 4, the second inclined groove22includes a second tie bar24raised at a groove bottom in an end portion at the first circumferential edge11a. The second tie bar24of the present embodiment has, for example, an inclined bottom surface, and the depth thereof gradually decreases toward the first circumferential edge11aside. The maximum depth d4of the second tie bar24is 60% to 75% of the maximum depth d3of the second inclined groove22, and is preferably larger than the depth d2(shown inFIG. 3) of the first tie bar23. The minimum depth d5of the second tie bar24is 35% to 45% of the maximum depth d3of the second inclined groove22, and is preferably smaller than the depth d2of the first tie bar23. The second inclined groove22including such a second tie bar24serves to enhance steering stability on a dry road surface and wet performance in a well-balanced manner.

As shown inFIG. 2, on the first land portion11, a plurality of curved grooves15are provided in the tire circumferential direction. The curved groove15includes, for example, a first curved portion16on the first end15aside, and a second curved portion17on the second end15bside. The first curved portion16is an arc curve with a radius of curvature having a center on the first curved edge11aside of the curved groove15. The second curved portion17is an arc curve with a radius of curvature having a center on the second circumferential edge11bside of the curved groove15. The edges of the first curved portion16and the second curved portion17of such a curved groove15can provide frictional force in multiple directions and enhance wet performance.

Each curved groove15intersects a curved groove15adjacent thereto in the tire circumferential direction. Each curved groove15of the present embodiment extends from the first end15aand intersects the second inclined groove22. In addition, the curved groove15extends from the second inclined groove22toward the second end15bside and intersects the first inclined groove21that intersects the second inclined groove22. Moreover, the curved groove15extends from the first inclined groove21toward the second end15bside and intersects the curved groove15adjacent thereto in the tire circumferential direction. Furthermore, the second end15bof the curved groove15is located between the first circumferential edge11aand the center position20in the tire axial direction of the first land portion11. In a preferable mode, the second end15bof the curved groove15is located on the second circumferential edge11bside with respect to the terminal end of the second inclined groove22.

The groove width of the curved groove15preferably gradually decreases from the first end15atoward the second end15b. The groove width of the curved groove15is, for example, 2 to 5 mm.

FIG. 5shows an enlarged view of the contour of the curved groove15. InFIG. 5, for ease of understanding the configuration of the curved groove15, other grooves are omitted except portions that intersect the curved groove15. As shown inFIG. 5, the first curved portion16of the curved groove15crosses the center position20in the tire axial direction of the first land portion11, for example. The first curved portion16is, for example, formed between the first end15aand the first inclined groove21and intersects the second inclined groove22. The radius of curvature of the first curved portion16is, for example, 10 to 30 mm.

The first curved portion16includes a first portion26extending from the first end15ato the second inclined groove22, and a second portion27extending from the second inclined groove22to the first inclined groove21. Each of the first portion26and the second portion27is curved. In the present embodiment, the first portion26extends, for example, so as to be inclined in the first direction, and extends along the first inclined groove21. The second portion27traverses the above-described triangular block35and is curved so as to be convex on the second circumferential edge11bside.

The groove width of the second portion27is, for example, 2 to 5 mm. The second portion27is curved, for example, with a radius of curvature of 15 to 30 mm. The radius of curvature of the second portion27is preferably smaller than the radius of curvature of the first portion26. The curved groove15including such a second portion27serves to further enhance wet performance.

The length L2in the tire circumferential direction of the first curved portion16is preferably not less than 30% and more preferably not less than 40%, and is preferably not greater than 70% and more preferably not greater than 60%, of the length L1in the tire circumferential direction of the curved groove15. Each length of the curved groove15is, for example, measured along the groove center line.

FIG. 6shows a cross-sectional view of the first portion26taken along a line C-C inFIG. 5. As shown inFIG. 6, the first portion26is, for example, preferably provided with a third tie bar28raised at a groove bottom on the first end15aside of the curved groove15. The configuration of the first tie bar23of the first inclined groove21can be applied to the third tie bar28of the first portion26. Such a first portion26can enhance wet performance while maintaining steering stability on a dry road surface.

FIG. 7shows a cross-sectional view of the second portion27taken along a line D-D inFIG. 5. As shown inFIG. 7, the second portion27is provided with a fourth tie bar29raised at a groove bottom in a center portion in the longitudinal direction thereof. The depth d7of the fourth tie bar29is 50% to 70% of the maximum depth d6of the second portion27.

FIG. 8shows a cross-sectional view, of the fourth tie bar29, orthogonal to the longitudinal direction of the second portion27. As shown inFIG. 8, the fourth tie bar29preferably has a groove bottom sipe31that is open at the groove bottom and that extends in the longitudinal direction of the second portion27. Such a groove bottom sipe31can enhance the stiffness of the first land portion11while maintaining the drainage performance of the second portion27. In the present specification, the term “sipe” means a slit having a width not greater than 1.5 mm.

As shown inFIG. 5, the second curved portion17of the curved groove15extends, for example, so as to be inclined in the second direction, and extends along the second inclined groove22in the present embodiment. The second curved portion17crosses the center position20in the tire axial direction of the first land portion11, for example. The second curved portion17is, for example, formed between the first inclined groove21and the second end15band intersects the curved groove15adjacent thereto in the tire circumferential direction.

The radius of curvature of the second curved portion17is preferably larger than the radius of curvature of the first curved portion16. The radius of curvature of the second curved portion17is, for example, 30 to 60 mm. Accordingly, during running on a wet road surface, water more easily moves within the second curved portion17, so that wet performance is further improved.

The length L3in the tire circumferential direction of the second curved portion17is smaller than the length L2in the tire circumferential direction of the first curved portion16. The length L3of the second curved portion17is preferably not less than 20% and more preferably not less than 30%, and is preferably not greater than 50% and more preferably not greater than 40%, of the length L1in the tire circumferential direction of the curved groove15.

FIG. 9shows a cross-sectional view of the second curved portion17taken along a line E-E inFIG. 5. As shown inFIG. 9, the second curved portion17is, for example, provided with a fifth tie bar30raised at a groove bottom in an end portion on the first inclined groove21side. The depth d9of the fifth tie bar30is, for example, 50% to 70% of the maximum depth d8of the second curved portion17. The second curved portion17having such a fifth tie bar30serves to enhance steering stability on a dry road surface and wet performance in a well-balanced manner.

An end portion32on the second end15bside of the second curved portion17of the present embodiment has a depth that gradually decreases toward the second end15bside. Accordingly, the end portion32has a bottom surface curved in an arc shape. Therefore, uneven wear is inhibited around the end portion32.

As shown inFIG. 2, the first land portion11is divided into a plurality of blocks by providing the above-described first inclined grooves21, second inclined grooves22, and curved grooves15thereon. The first land portion11of the present embodiment includes a plurality of block elements33each demarcated between two first inclined grooves21.

Each block element33includes, for example, a quadrangular block34having a substantially quadrangular tread surface, and the above-described triangular block35. The quadrangular block34includes a part of the first circumferential edge11aand is demarcated by two first inclined grooves21and a second inclined groove22.

The quadrangular block34has, for example, a plurality of sipes40inclined in the first direction. Each sipe40extends, for example, along the first inclined groove21. The sipes40provided on the quadrangular block34include, for example, a first sipe41, a second sipe42, and a third sipe43. The first sipe41extends from the first circumferential edge11ato the second inclined groove22. The second sipe42extends from the first circumferential edge11ato the second curved portion17of the curved groove15. The third sipe43extends from the second curved portion17to the second inclined groove22. Each of such sipes40can provide frictional force during running on a wet road surface while inhibiting uneven wear of the first land portion11.

FIG. 10shows an enlarged view of the triangular block35. The length L4in the tire axial direction of the triangular block35is, for example, 0.50 to 0.80 times the width W1(shown inFIG. 2) in the tire axial direction of the first land portion11.

The second portion27of the first curved portion16of the curved groove15traverses the triangular block35, for example. In a preferable mode, the curved groove15communicates with the first inclined groove21and the second inclined groove22on the second circumferential edge11bside with respect to the center position20(shown inFIG. 2) in the tire axial direction of the first land portion11and traverses the triangular block35. Accordingly, the triangular block35includes an end portion36demarcated by the first inclined groove21, the second inclined groove22, and the second portion27. The length L5in the tire axial direction of the end portion36is, for example, preferably not less than 30% and more preferably not less than 40%, and is preferably not greater than 70% and more preferably not greater than 60%, of the length L4in the tire axial direction of the triangular block35. Such a triangular block35can ensure stiffness in the tire axial direction and maintain steering stability on a dry road surface.

At the end portion36, an angle θ3between an edge36aon the first inclined groove21side and an edge36bon the second inclined groove22side is, for example, 40 to 80°. Such an end portion36can enhance wet performance while inhibiting chipping of the triangular block35during running. The angle θ3corresponds to the angle between the tangent to the edge36aat a top36cof the end portion36and the tangent to the edge36bat the top36c.

The triangular block35preferably has a fourth sipe44and a fifth sipe45inclined in the second direction. The fourth sipe44and the fifth sipe45extend from the second circumferential edge11band terminate before reaching the second portion27of the first curved portion16. The length in the tire axial direction of the fifth sipe45is larger than the length in the tire axial direction of the fourth sipe44.

FIG. 11shows an enlarged view of the second land portion12and the fourth land portion14. As shown inFIG. 11, each of the width W2in the tire axial direction of the second land portion12and the width W4in the tire axial direction of the fourth land portion14is preferably 0.10 to 0.20 times the tread width TW.

The second land portion12has a plurality of first lateral grooves46and a plurality of termination grooves47. Each first lateral groove46fully traverses the second land portion12, for example. Each termination groove47extends from the second shoulder main groove6and terminates within the second land portion12, for example. Such a first lateral groove46and such a termination groove47serve to enhance steering stability on a dry road surface and wet performance in a well-balanced manner.

In a preferable mode, an end portion on the crown main groove7side of the first lateral groove46preferably overlaps a region obtained by extending an end portion on the second circumferential edge11bside of the first inclined groove21so as to be parallel to the tire axial direction. In addition, the first lateral groove46preferably overlaps a region obtained by extending the second inclined groove22while maintaining the inclination direction and the curvature thereof. Accordingly, the first lateral groove46exhibits excellent drainage performance together with the first inclined groove21and the second inclined groove22, so that wet performance is further enhanced.

The second land portion12of the present embodiment has connection sipes48that extend from the termination grooves47to the crown main groove7, and termination sipes49that extend from the second shoulder main groove6and that terminate within the second land portion12. Such connection sipes48and termination sipes49can provide frictional force during running on a wet road surface while inhibiting uneven wear of the second land portion12.

The fourth land portion14has a plurality of second lateral grooves50and a plurality of first transverse sipes51. Each of the second lateral grooves50and the first transverse sipes51traverses the fourth land portion14.

An end portion on the second shoulder main groove6side of each second lateral groove50preferably overlaps a region obtained by extending an end portion on the second shoulder main groove6side of the first lateral groove46or the termination groove47, which is provided on the second land portion12, so as to be parallel to the tire axial direction. Accordingly, the second lateral groove50and the first lateral groove46or the termination groove47become integrated to exhibit excellent drainage performance during running on a wet road surface.

FIG. 12shows an enlarged view of the third land portion13. As shown inFIG. 12, the width W3in the tire axial direction of the third land portion13is, for example, 0.10 to 0.25 times of the tread width TW. In a preferable mode, the width W3of the third land portion13is larger than the width W2(shown inFIG. 11) in the tire axial direction of the second land portion12and the width W4(shown inFIG. 11) in the tire axial direction of the fourth land portion14.

The third land portion13has a plurality of third lateral grooves53and a plurality of second transverse sipes54. Each of the third lateral grooves53and the second transverse sipes54traverses the third land portion13.

An end portion on the first shoulder main groove5side of each third lateral groove53preferably overlaps a region obtained by extending an end portion on the first shoulder main groove5side of the first inclined groove21or the curved groove15, which is provided on the first land portion11, so as to be parallel to the tire axial direction. Accordingly, the third lateral groove53and the first inclined groove21or the curved groove15become integrated to exhibit excellent drainage performance during running on a wet road surface.

Although the tire according to the embodiment of the present invention has been described in detail above, the present invention is not limited to the above specific embodiment, and various modifications can be made to implement the present invention.

EXAMPLES

Tires with a size of 215/60R16 having the basic pattern inFIG. 1were produced as test tires. As a comparative example, a tire having first land portions a shown inFIG. 13was produced as a test tire. In the tire of the comparative example, a groove c is formed in each triangular block b so as to extend in a straight manner. The tire of the comparative example has substantially the same pattern as shown inFIG. 1, except for the above matters. The respective test tires were tested for steering stability on a dry road surface and wet performance. The common specifications and the test methods for the respective test tires are as follows.

Test vehicle: a front-wheel-drive car having an engine displacement of 2500 cc

Tire mounted position: all wheels

<Steering Stability on Dry Road Surface>

Sensory evaluation was made by a driver for steering stability when the driver drove the above test vehicle on a dry road surface. The results are indicated as scores with the score of the comparative example being regarded as 100. A higher value indicates that the steering stability on a dry road surface is better. As for the scores, 95 points or more is acceptable, and 98 points or more is more preferable.

Sensory evaluation was made by a driver for performance when the driver drove the above test vehicle on a wet road surface. The results are indicated as scores with the score of the comparative example being regarded as 100. A higher value indicates that the wet performance is better. As for the scores, 95 points or more is acceptable, and 98 points or more is more preferable.

The test results are shown in Table 1.

As a result of the tests, it was confirmed that the tire of each Example exhibits excellent wet performance while maintaining steering stability on a dry road surface in a preferable range, and the overall performance of the tire is improved.