Tire

Abstract

To improve wet traction performance while maintaining low rolling resistance performance.SOLUTION: Provided is a tire having: a pair of circumferential main grooves 21 extending in a tire circumferential direction; a single center land part 31 defined on an inner side in a tire width direction of each circumferential main groove; a pair of shoulder land parts 32 defined on an outer side in the tire width direction of each circumferential main groove; at least one circumferential narrow groove 22, 23 with opening edges thereof which extend in the tire circumferential direction in the center land part, and in which cut-off portions 22c, 23c are formed respectively; and a plurality of width direction narrow grooves 42 which extend in the tire width direction in the center land part, and are each provided with a notch 42c in the opening edge, and formed in the tire circumferential direction. When subjected to a load in an inflated state, at least 20% of the opposing groove walls of the circumferential narrow grooves and width direction narrow grooves, excluding the groove bottoms and notches, come into contact to be open in a tread surface 15A.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This invention relates to a tire.

Background Art

[0002] For example, Patent Document 1 describes a tire having excellent fuel consumption performance and drainage performance.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, for example, in the case of a heavy-duty tire, in order to reduce rolling resistance, a pattern with a narrow groove width in the center part is increasingly adopted for the purpose of increasing block rigidity. However, such a tire is concerned about deterioration of wet traction performance due to a decrease in groove area.

[0005] An object of this invention is to provide a tire capable of improving wet traction performance while maintaining low rolling resistance performance.

Means for Solving the Problems

[0006] To achieve the above object, a tire according to one aspect of the present invention includes a pair of circumferential main grooves extending in the tire circumferential direction, a single center land portion partitioned inside the tire width direction of each of the circumferential main grooves, a pair of shoulder land portions partitioned outside the tire width direction of each of the circumferential main grooves, at least one circumferential narrow groove formed with a notch at an opening edge portion extending in the tire circumferential direction at the center land portion, and a plurality of width direction narrow grooves formed extending in the tire width direction at the center land portion with a notch provided at an opening edge portion and formed in the tire circumferential direction. The circumferential narrow groove and the width direction narrow groove are such that, in an inflated state when a load is applied, at least 20[%] of the opposing groove walls excluding the groove bottom and the notch are in contact and open at the tread surface.

Advantages of the Invention

[0007] According to this invention, while maintaining low rolling resistance performance, wet traction performance can be improved.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

Figure 23

Figure 24

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited by these embodiments. Also, the components of this embodiment include those that are replaceable and self-evidently replaceable while maintaining the identity of the invention. Further, a plurality of modifications described in this embodiment can be arbitrarily combined within the scope self-evident to those skilled in the art.

[0010] In the following description, the tire radial direction refers to the direction orthogonal to the tire rotation axis (not shown) which is the rotation axis of the pneumatic tire 1 of the embodiment, the inner side in the tire radial direction refers to the side facing the tire rotation axis in the tire radial direction, and the outer side in the tire radial direction refers to the side away from the tire rotation axis in the tire radial direction. Also, the tire circumferential direction refers to the circumferential direction around the tire rotation axis as the central axis. Further, the tire width direction refers to the direction parallel to the tire rotation axis, the inner side in the tire width direction refers to the side facing the tire equatorial plane (tire equator line) CL in the tire width direction, and the outer side in the tire width direction refers to the side away from the tire equatorial plane CL in the tire width direction. The tire equatorial plane CL is a plane that is orthogonal to the tire rotation axis and passes through the center of the tire width of the pneumatic tire 1, and the tire equatorial plane CL coincides with the center line in the tire width direction which is the central position in the tire width direction of the pneumatic tire 1. The tire equator line refers to a line on the tire equatorial plane CL along the tire circumferential direction of the pneumatic tire 1. Also, the cross-section in the tire meridian direction (meridian sectional view) refers to the cross-section when the tire is cut by a plane including the tire rotation axis.

[0011] FIG. 1 shows a meridian cross-section of the pneumatic tire 1 of the embodiment, showing a cross-section of a region on one side of the tire rotation axis in the tire radial direction. In the present embodiment, as an example, a pneumatic radial tire for heavy loads mounted on heavy-duty vehicles such as trucks and buses will be described. The pneumatic tire 1 of the present embodiment is particularly suitable for all-season tires.

[0012] The pneumatic tire 1 of the embodiment has an annular structure centered on the tire rotation axis. As shown in FIG. 1, it includes a pair of bead cores 11, 11, a pair of bead fillers 12, 12, a carcass layer 13, a belt layer 14, a tread rubber 15, a pair of sidewall rubbers 16, 16, and a pair of rim cushion rubbers 17, 17.

[0013] The pair of bead cores 11, 11 are formed by winding one or a plurality of bead wires made of steel in an annular and multiple manner, and are embedded in the bead portions to form the cores of the bead portions on both sides in the tire width direction.

[0014] The pair of bead fillers 12, 12 are composed of a lower filler 121 and an upper filler 122, and are respectively arranged on the outer circumference in the tire radial direction of the pair of bead cores 11, 11 to reinforce the bead portions.

[0015] The carcass layer 13 has a single-layer structure composed of a single carcass ply or a multi-layer structure formed by laminating a plurality of carcass plies. The carcass layer 13 is bridged in a toroidal shape between the two bead cores 11, 11 to form the skeleton of the tire. Also, both ends of the carcass layer 13 are wound back and locked outward in the tire width direction so as to wrap the bead core 11 and the bead filler 12. Further, the carcass layer 13 is formed by covering a plurality of carcass cords made of steel with a coat rubber and performing rolling processing. If it is a radial tire, it has a cord angle (defined as the inclination angle of the longitudinal direction of the carcass cord with respect to the tire circumferential direction) of 80° or more and 90° or less in absolute value, and if it is a bias tire, it has a cord angle of 30° or more and 45° or less.

[0016] The belt layer 14 is formed by laminating a plurality of belt plies 141 to 144, and is wound around the outer periphery of the carcass layer 13. These belt plies 141 to 144 include a high-angle belt 141, a pair of cross belts 142 and 143, and a belt cover 144. The high-angle belt 141 is formed by coating a plurality of steel belt cords with cover rubber and subjecting them to rolling processing, and has a cord angle (defined as the inclination angle of the longitudinal direction of the belt cord with respect to the tire circumferential direction) of 45° or more and 70° or less in absolute value. The pair of cross belts 142 and 143 are formed by coating a plurality of steel belt cords with cover rubber and subjecting them to rolling processing, and have a cord angle of 10° or more and 55° or less in absolute value. Also, the pair of cross belts 142 and 143 have cord angles of opposite signs to each other, and are laminated with the longitudinal directions of the belt cords crossing each other (having a so-called cross-ply structure). The belt cover 144 is formed by coating a plurality of belt cover cords made of steel or organic fiber material with cover rubber and subjecting them to rolling processing, and has a cord angle of 10° or more and 55° or less in absolute value.

[0017] The tread rubber 15 is disposed on the outer periphery in the tire radial direction of the carcass layer 13 and the belt layer 14, and constitutes the tread portion of the pneumatic tire 1. The tread rubber 15 has a tread surface (tread face) 15A on the outer peripheral surface that contacts the road surface during running. The outer end of the tread surface 15A in the tire width direction becomes the grounding end T. Also, the tread rubber 15 has a buttress portion 15B that does not contact the road surface during running on both outer side portions in the tire width direction with respect to the grounding end T of the tread surface 15A. The buttress portion 15B is provided in the tread rubber 15 from the grounding end T outward in the tire width direction and inward in the tire radial direction up to the sidewall rubber 16. In the pneumatic tire 1 of the embodiment, the buttress portion 15B is provided in the range from the grounding end T outward in the tire width direction and inward in the tire radial direction to the buttress end (indicator) B that is continuous in the tire circumferential direction, as shown in FIG. 1.

[0018] A pair of sidewall rubbers 16, 16 are respectively disposed on the outer sides in the tire width direction of the carcass layer 13 to constitute the sidewall portions on both sides in the tire width direction.

[0019] A pair of rim cushion rubbers 17, 17 extend from the inner sides in the tire diameter direction to the outer sides in the tire width direction of the respective bead cores 11, 11 and the turned-up portions of the carcass layer 13 to constitute the rim fitting surfaces of the bead portions.

[0020] The pneumatic tire 1 of the embodiment has the above-described form as a basic configuration, and a tread pattern is provided on the tread surface 15A of the tread portion. Hereinafter, the details of the tread pattern will be described.

[0021] As shown in FIG. 2, the pneumatic tire 1 of the embodiment includes a pair (two) of circumferential main grooves 21 provided with the tire equatorial plane CL as a boundary on the tread surface 15A, and three rows of land portions 31, 32, 32 partitioned by the circumferential main grooves 21.

[0022] The circumferential main groove 21 extends along the tire circumferential direction and has an annular structure that linearly and continuously extends over the entire tire circumference. The circumferential main groove 21 is defined as a groove having an obligation to display a wear indicator defined by JATMA. The circumferential main groove 21 has a groove width W0 (see FIG. 17) of 3 [mm] or more and 10 [mm] or less, and a groove depth D1 (see FIG. 17) of 5 [mm] or more and 20 [mm] or less, excluding notches, in a straight groove portion.

[0023] The groove width is measured as the maximum value of the distance between the opposing groove walls or edges at the opening edge portion on the tread surface in a no-load state where the tire is mounted on a specified rim and filled with a specified internal pressure.

[0024] The groove depth is measured as the maximum value of the distance from the tread surface to the groove bottom in a no-load state where the tire is mounted on a specified rim and filled with a specified internal pressure. Further, in a configuration having partial uneven portions or sipes at the groove bottom, the groove depth is measured excluding these.

[0025] The specified rim refers to the "Standard Rim" defined by JATMA, the "Design Rim" defined by TRA, or the "MEASURING RIM" defined by ETRTO. Also, the specified internal pressure refers to the "Maximum Air Pressure" defined by JATMA, the maximum value of "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" defined by TRA, or the "INFLATION PRESSURES" defined by ETRTO. Note that the state where the tire is mounted on the specified rim and filled with the specified internal pressure is called the inflated state.

[0026] In the embodiment, the land portions 31, 32, 32 of the tread are composed of a single row of center land portion 31 and a pair (two rows) of shoulder land portions 32, 32. These land portions 31, 32, 32 extend over the entire circumference of the tire to form an annular tread surface. The shoulder land portions 32, 32 are land portions partitioned outside the tire width direction of the circumferential main grooves 21, 21, respectively. The shoulder land portions 32, 32 are arranged in regions on both outer sides in the tire width direction with the tire equatorial plane CL as a boundary. The shoulder land portions 32, 32 have a grounding end T at the outer end in the tire width direction of their tread surface 15A, and have a buttress portion 15B outside the tire width direction from the grounding end T. The center land portion 31 is a land portion between the pair of shoulder land portions 32, 32. The center land portion 31 is partitioned on the tire equatorial plane CL between the two circumferential main grooves 21, 21.

[0027] The grounding end T is defined as the maximum width position in the tire axial direction at the contact surface between the tire and the flat plate when a load corresponding to the specified load is applied perpendicularly to the flat plate in a stationary state in the inflated state. The specified load refers to the "Maximum Load Capacity" defined by JATMA, the maximum value of "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" defined by TRA, or the "LOAD CAPACITY" defined by ETRTO. In the case of the pneumatic tire 1 of the embodiment, the specified load is 88[%] of the maximum load capacity at the specified internal pressure.

[0028] The pneumatic tire 1 of the embodiment is configured such that one side and the other side on the outer side in the tire width direction are symmetric with respect to the tire equatorial plane CL.

[0029] As shown in FIG. 2, the center land portion 31 is provided with circumferential grooves 22, 23, 23 and a widthwise groove 42.

[0030] As shown in FIG. 2, the circumferential grooves 22, 23, 23 extend along the tire circumferential direction and have an annular structure that continuously extends over the entire tire circumference. At least one circumferential groove 22, 23, 23 may be provided. In the pneumatic tire 1 of the embodiment, a center circumferential groove (first circumferential groove) 22 provided along the tire equatorial plane CL and middle circumferential grooves (second circumferential grooves) 23, 23 provided one on each outer side in the tire width direction of the center circumferential groove 22 are configured to be three in total.

[0031] Due to these circumferential grooves 22, 23, 23, as shown in FIG. 2, a center central land portion 311 is formed between the center circumferential groove 22 and each middle circumferential groove 23 in the center land portion 31. The center central land portion 311 extends along the tire circumferential direction over the entire tire circumference to form an annular tread surface. Further, as shown in FIG. 2, a center intermediate land portion 312 is formed between the middle circumferential groove 23 and the circumferential main groove 21 in the center land portion 31. The center intermediate land portion 312 extends along the tire circumferential direction over the entire tire circumference to form an annular tread surface.

[0032] As shown in FIGS. 3 to 7, the center circumferential direction groove 22 is configured such that from the groove bottom 22a to midway of opening to the tread surface 15A is mainly formed as the groove 22b, and a notch 22c is formed at the opening edge portion opening to the tread surface 15A. As shown in FIG. 2, the groove 22b is formed in a zigzag shape so as to meander in the tire width direction along the tire circumferential direction. The groove 22b is formed continuously in the tire circumferential direction with a constant groove width W3a. The notch 22c is formed in a tapered shape so as to spread in the tire radial direction from the groove 22b toward the tread surface 15A. The notch 22c is provided only on one side in the tire width direction of the groove 22b in accordance with the zigzag shape of the groove 22b at each cross-sectional position in the tire circumferential direction of the center circumferential direction groove 22, as shown in FIGS. 3, 5, and 6, and includes a form provided on both sides in the tire width direction of the groove 22b, as shown in FIGS. 4 and 7. As shown in FIG. 2, the notch 22c is alternately provided on one side and the other side in the tire width direction of the groove 22b in accordance with the zigzag shape of the groove 22b along the tire circumferential direction. For this reason, in the center circumferential direction groove 22, depending on the form of the notch 22c, the groove width W3 including the notch 22c changes in the tire circumferential direction. As shown in FIG. 2, in the center circumferential direction groove 22, the groove width W3 including the notch 22c is formed to form a wide portion 22w (see FIG. 7) at the bent portion of the groove 22b and a narrow portion 22s (see FIG. 4) at the non-bent portion of the groove 22b in accordance with the zigzag shape of the groove 22b along the tire circumferential direction. Under the same measurement conditions as the circumferential main groove 21, as shown in FIGS. 3 to 7, in the center circumferential direction groove 22, the groove width W3 including the notch 22c is larger than the groove width W3a, 10 [mm] or less, the groove width W3a of the groove 22b excluding the notch 22c is 0.5 [mm] or more and 3 [mm] or less, and the groove depth d3 is 5 [mm] or more and 20 [mm] or less. In the center circumferential direction groove 22, the groove depth at the notch 22c is 4 [mm] or less, and as shown in FIG. 13, the notch 22c disappears due to wear of the tread surface 15A by that amount, leaving only the groove 22b.

[0033] As shown in FIG. 8, the middle circumferential-direction groove 23 is configured such that from the groove bottom 23a to midway through the opening to the tread surface 15A, it is mainly formed as a groove 23b, and a notch 23c is formed at the opening edge portion that opens to the tread surface 15A. As shown in FIG. 2, the groove 23b is formed in a zigzag shape so as to meander in the tire width direction along the tire circumferential direction. The groove 23b is formed continuously in the tire circumferential direction with a constant groove width W4a. The notch 23c is formed in a tapered shape so as to expand in the tire diameter direction from the groove 23b toward the tread surface 15A. The notch 23c is provided only on one side of the groove 23b in the tire width direction. In the middle circumferential-direction groove 23, the groove width W4 including the notch 23c is formed to change in the tire circumferential direction. As shown in FIG. 2, in the middle circumferential-direction groove 23, the groove width W4 including the notch 23c is formed to be narrower to wider between the bent portions of the groove 23b in accordance with the zigzag shape of the groove 22b along the tire circumferential direction. Under the same measurement conditions as the circumferential-direction main groove 21, as shown in FIG. 8, in the middle circumferential-direction groove 23, the groove width W4 including the notch 23c is larger than the groove width W4a and is 10 [mm] or less, the groove width W4a of the groove 23b excluding the notch 23c is 0.5 [mm] or more and 3 [mm] or less, and the groove depth d4 is formed to be 5 [mm] or more and 20 [mm] or less. In the middle circumferential-direction groove 23, the groove depth at the notch 23c is 4 [mm] or less, and as a result of the tread surface 15A wearing by that amount, as shown in FIG. 13, the notch 23c disappears and only the groove 23b remains.

[0034] The width-direction grooves 42 extend along the tire width direction and are provided in a plurality arranged in the tire circumferential direction as shown in FIG. 2. One end of the width-direction groove 42 communicates with the bent portion of the middle circumferential-direction groove (circumferential-direction groove) 23, and the other end communicates with the circumferential-direction main groove 21. As shown in FIG. 9, the width-direction groove 42 is configured mainly as a sipe 42b from the groove bottom 42a to midway through the opening to the tread surface 15A, and a notch 42c is formed at the opening edge portion opening to the tread surface 15A. The width-direction groove 42 is formed in a cross-sectional spherical shape in which the groove bottom 42a has a wider groove width than the sipe 42b. The sipe 42b of the width-direction groove 42 communicates with the groove 23b of the middle circumferential-direction groove 23. The sipe 42b is formed in an arc shape that curves in the tire circumferential direction as shown in FIG. 2. The sipe 42b is formed continuously in the tire width direction with a constant groove width W5a. The notch 42c is provided on both sides of the sipe 42b in the tire circumferential direction. On one side of the sipe 42b in the tire circumferential direction, the notch 42c is formed in a tapered shape so as to spread in the tire circumferential direction from the sipe 42b toward the tread surface 15A, and on the other side of the sipe 42b in the tire circumferential direction, the notch 42c is formed in a concave groove shape so as to spread in the tire circumferential direction from the sipe 42b toward the tread surface 15A. Under the same measurement conditions as the circumferential-direction main groove 21, as shown in FIG. 9, the groove width W5 including the notch 42c of the width-direction groove 42 is larger than the groove width W5a, 10 [mm] or less, the groove width W5a of the sipe 42b excluding the notch 42c is 1 [mm] or less, and the groove depth d5 is formed to be 5 [mm] or more and 20 [mm] or less. The depth of the groove in the notch 42c of the width-direction groove 42 is 4 [mm] or less, and due to the wear of the tread surface 15A by that amount, the notch 42c disappears and only the sipe 42b remains as shown in FIG. 13.

[0035] As shown in FIG. 2, each center center land portion 311 formed between the center circumferential direction groove 22 and each middle circumferential direction groove 23 has a center sipe 41 formed on the tread surface 15A. The center sipe 41 includes a first center sipe 41a and a second center sipe 41b. The first center sipe 41a is formed linearly by connecting the bent portion of the groove 22b of the center circumferential direction groove 22 and the bent portion of the groove 23b of the middle circumferential direction groove 23. The second center sipe 41b is formed in an S shape by connecting the straight portion of the groove 22b of the center circumferential direction groove 22 and the straight portion of the groove 23b of the middle circumferential direction groove 23. The first center sipe 41a and the second center sipe 41b are alternately provided in the tire circumferential direction. Each center center land portion 311 is divided into center blocks 311a divided in the tire circumferential direction by a plurality of center sipes 41. The center sipe 41 is formed with a groove width of 1 [mm] or less and a groove depth of 5 [mm] or more and 20 [mm] or less under the same measurement conditions as the circumferential main groove 21. Hereinafter, a groove with a groove width of 1 [mm] or less is defined as a sipe.

[0036] As shown in FIG. 2, each center intermediate land portion 312 formed between each middle circumferential direction groove 23 and each circumferential main groove 21 has the above-described width direction groove 42 and a middle sipe 43 formed therein. The middle sipe 43 is formed in an S shape by connecting the middle circumferential direction groove 23 and the circumferential main groove 21 between the width direction grooves 42. The middle sipe 43 is provided in a plurality (two in the embodiment) in the tire circumferential direction between the width direction grooves 42. Each center intermediate land portion 312 is divided into intermediate blocks 312a divided in the tire circumferential direction by a plurality of width direction grooves 42 and middle sipes 43. The middle sipe 43 is formed with a groove width of 1 [mm] or less and a groove depth of 5 [mm] or more and 20 [mm] or less under the same measurement conditions as the circumferential main groove 21.

[0037] Here, as described above, the center land portion 311 is divided into a plurality of central blocks 311a at each center side 41, and the center intermediate land portion 312 adjacent to the center land portion 311 in the tire width direction is divided into a plurality of intermediate blocks 312a by each width direction groove 42 and each middle side 43. In the pneumatic tire 1 of the embodiment, the number of blocks P1 in the tire circumferential direction of the central block 311a and the number of blocks P2 in the tire circumferential direction of the intermediate block 312a satisfy the relationship of P1 ≤ P2. Specifically, in the pneumatic tire 1 of the embodiment, the number of blocks P1 in the tire circumferential direction of the central block 311a and the number of blocks P2 in the tire circumferential direction of the intermediate block 312a satisfy the relationship of 1.2 ≤ P2 / P1 ≤ 2, and preferably satisfy the relationship of P2 / P1 = 1.5.

[0038] As shown in FIG. 2, the shoulder land portion 32 is provided with a shoulder circumferential groove 24, a first one-sided open side 46, and a second one-sided open side 47.

[0039] The shoulder circumferential groove 24 is provided on the tread surface 15A side or the buttress portion 15B side in the shoulder land portion 32. In the pneumatic tire 1 of the embodiment, the shoulder circumferential groove 24 is provided in the buttress portion 15B. The shoulder circumferential groove 24 extends along the tire circumferential direction and has an annular structure that continuously extends linearly over the entire tire circumference. The shoulder circumferential groove 24 is formed with a groove width W6 of 0.5 [mm] or more and 6 [mm] or less and a groove depth d6 of 4 [mm] or more and 20 [mm] or less as shown in FIG. 10 under the same measurement conditions as the circumferential main groove 21.

[0040] The first one-sided open sipes 46 are provided on the shoulder land portion 32 on the tread surface 15A side or the battless portion 15B side. In the pneumatic tire 1 of the embodiment, the first one-sided open sipes 46 are provided in the battless portion 15B. The first one-sided open sipes 46 extend in the tire width direction and are arranged in a plurality in the tire circumferential direction. As shown in FIG. 2, the first one-sided open sipes 46 are arranged at intervals y1 of 4 [mm] or more and 15 [mm] or less in the tire circumferential direction. One end of the first one-sided open sipes 46 terminates within the shoulder land portion 32, and the other end communicates with the shoulder circumferential groove 24 to be formed. In the pneumatic tire 1 of the embodiment, the first one-sided open sipes 46 are arranged inside the tire width direction of the shoulder circumferential groove 24, one end terminates at the grounding end T, and the other end communicates with the shoulder circumferential groove 24 to be formed. The first one-sided open sipes 46 are formed with a groove width W7 of 1 [mm] or more and 1.0 [mm] or less and a groove depth d7 of 0.5 [mm] or more and 3.0 [mm] or less under the same measurement conditions as the circumferential main groove 21, as shown in FIG. 11.

[0041] The second one-sided open sipes 47 are provided on the tread surface 15A at the shoulder land portion 32. The second one-sided open sipes 47 extend in the tire width direction and are arranged in a plurality in the tire circumferential direction. As shown in FIG. 2, the second one-sided open sipes 47 are arranged at intervals y2 of 4 [mm] or more and 15 [mm] or less in the tire circumferential direction. One end of the second one-sided open sipes 47 communicates with the circumferential main groove 21, and the other end terminates within the shoulder land portion 32 to be formed. The second one-sided open sipes 47 are formed with a groove width W8 of 1 [mm] or less and a groove depth d8 of 0.5 [mm] or more and 20 [mm] or less under the same measurement conditions as the circumferential main groove 21, as shown in FIG. 12.

[0042] Also, in the pneumatic tire 1 of the embodiment, as shown in FIG. 14, the shoulder land portion 32 may be provided with a shoulder lug groove 44 and a shoulder sipe 45.

[0043] The shoulder lug grooves 44 extend in the tire width direction and are provided in a plurality side by side in the tire circumferential direction. One end of the shoulder lug groove 44 communicates with the circumferential main groove 21, and the other end extends outward in the tire width direction. In the pneumatic tire 1 of the embodiment, the other end of the shoulder lug groove 44 extends beyond the grounding end T to the buttress portion 15B and communicates with the shoulder circumferential direction fine groove 24. The shoulder lug groove 44 is formed in an arc shape curved in the tire circumferential direction from one end to the other end. The shoulder land portion 32 is divided into shoulder blocks 32a divided in the tire circumferential direction by a plurality of shoulder lug grooves 44. The shoulder lug groove 44 is formed such that, under the same measurement conditions as the circumferential main groove 21, as shown in FIG. 15, the groove width W1 is 5 [mm] or more and 15 [mm] or less, and the groove depth d1 is 1 [mm] or more and 5 [mm] or less.

[0044] The shoulder sipes 45 extend in the tire width direction and are provided in the shoulder blocks 32a sandwiched between the shoulder lug grooves 44. One end of the shoulder sipe 45 communicates with the circumferential main groove 21, and the other end communicates with the shoulder circumferential direction fine groove 24. The shoulder sipe 45 is formed in an arc shape curved in the tire circumferential direction from one end to the other end, similar to the shoulder lug groove 44. The shoulder sipe 45 is formed such that, under the same measurement conditions as the circumferential main groove 21, as shown in FIG. 16, the groove width W2 is 1 [mm] or less, and the groove depth d2 is 1 [mm] or more and 15 [mm] or less.

[0045] The circumferential main groove 21, where one end of the shoulder lug groove 44 and the shoulder sip 45 communicate with each other, has a groove wall opening to the tread surface 15A formed in an arc shape. The circumferential main groove 21 has a groove wall at the portion where the shoulder sip 45 communicates in the shoulder block 32a sandwiched between the shoulder lug grooves 44 on the shoulder land portion 32 side formed as a single first arc 21a. The circumferential main groove 21 has a groove wall at the portion facing the first arc 21a on the center land portion 31 side formed as a plurality of second arcs 21b arranged in the tire circumferential direction. In the pneumatic tire 1 of the embodiment, three second arcs 21b are arranged in the tire circumferential direction at the portion facing the first arc 21a. The first arc 21a and each second arc 21b are formed as arcs convex toward the tire equatorial plane CL side. Although not shown in the figure, the first arc 21a and each second arc 21b may be formed as arcs concave toward the tire equatorial plane CL side.

[0046] Further, as shown in FIGS. 2 and 17, in the circumferential main groove 21, a range from the groove bottom 21d to a line DL at 50% or less of the groove depth D1 is formed in a straight shape along the tire circumferential direction. That is, in the groove wall of the circumferential main groove 21 from the line DL toward the opening edge portion, it is formed as the above-described first arc 21a and second arcs 21b, and from the line DL to the groove bottom 21d, it is formed in a straight shape having no first arc 21a and second arcs 21b.

[0047] The pneumatic tire 1 of the above-described embodiment is characterized in that it includes a pair of circumferential main grooves 21 extending in the tire circumferential direction, a single center land portion 31 partitioned inside the tire width direction of each circumferential main groove 21, a pair of shoulder land portions 32 partitioned outside the tire width direction of each circumferential main groove 21, at least one circumferential narrow groove 22, 23 formed with notches 22c, 23c at the opening edge portion extending in the tire circumferential direction at the center land portion 31, and a plurality of widthwise narrow grooves 42 formed extending in the tire width direction at the center land portion 31 with notches 42c provided at the opening edge portion. As illustrated in FIG. 18, in the inflated state when a load is applied, at least 20% of the opposing groove walls of the narrow grooves 22b, 23b and the sipes 42b come into contact with each other excluding the groove bottoms 22a, 23a, 42a and the notches 22c, 23c, 42c and open at the tread surface 15A.

[0048] Here, the time of load application means the time when a load of 88% of the maximum load capacity is applied.

[0049] According to this pneumatic tire 1, when the tread surface 15A comes into contact with the ground G, at least 20% of the opposing groove walls of the narrow grooves 22b, 23b and the sipes 42b come into contact with each other, so that the rigidity of the center land portion 31 can be ensured and the rolling resistance performance can be maintained. Further, according to this pneumatic tire 1, when the tread surface 15A comes into contact with the ground G, the groove bottoms 22a, 23a, 42a and the notches 22c, 23c, 42c are not blocked and open at the tread surface 15A, so that the groove area can be ensured to improve the drainage performance and the wet traction performance can be improved. In the pneumatic tire 1 of the embodiment, it is preferable for ensuring the rolling resistance performance that in the inflated state when a load is applied, at least 50% of the opposing groove walls of the narrow grooves 22b, 23b and the sipes 42b come into contact with each other within the range of 10% to 90% from the groove bottoms 22a, 23a, 42a.

[0050] In addition, in the pneumatic tire 1 of the embodiment, when the tread surface 15A comes into contact with the ground, the groove widths W3a, W4a, and W5a of the narrow grooves 22b and 23b where the opposing groove walls come into contact and the sipes 42b are in the range of 1 [mm] or more and 3 [mm] or less. According to this pneumatic tire 1, the above range of the groove widths W3a, W4a, and W5a of the narrow grooves 22b and 23b and the sipes 42b is preferable for ensuring the rigidity of the center land portion 31 and maintaining the rolling resistance performance.

[0051] In addition, in the pneumatic tire 1 of the embodiment, the groove widths W3 and W4 of the circumferential narrow grooves 22 and 23 and the groove width W0 of the circumferential main groove 21 satisfy the relationships of 0.3 ≤ W3 / W0 ≤ 0.6 and 0.3 ≤ W4 / W0 ≤ 0.6. According to this pneumatic tire 1, by appropriately setting the groove widths W3 and W4 of the circumferential narrow grooves 22 and 23 with respect to the groove width W0 of the circumferential main groove 21, drainage and rigidity can be maintained.

[0052] In addition, in the pneumatic tire 1 of the embodiment, the groove width W5 of the widthwise narrow groove 42 and the groove width W0 of the circumferential main groove 21 satisfy the relationship of 0.25 ≤ W5 / W0 ≤ 0.75. According to this pneumatic tire 1, by appropriately setting the groove width W5 of the widthwise narrow groove 42 with respect to the groove width W0 of the circumferential main groove 21, drainage and rigidity can be maintained.

[0053] Further, in the pneumatic tire 1 of the embodiment, the shoulder land portion 32 includes a buttress portion 15B and has a shoulder circumferential narrow groove 24 formed to extend in the tire circumferential direction at the shoulder land portion 32.

[0054] According to this pneumatic tire 1, by arranging the shoulder circumferential narrow groove 24 in the shoulder land portion 32, the groove area can be increased, drainage can be improved, and wet traction performance can be improved.

[0055] Further, in the pneumatic tire 1 of the embodiment, the shoulder land portion 32 has a plurality of first one-sided open sipes 46 formed in the tire circumferential direction, one end of which terminates within the shoulder land portion 32 and the other end of which communicates with the shoulder circumferential narrow groove 24.

[0056] According to this pneumatic tire 1, by arranging the first one-sided open sipes 46, the groove area can be increased, the drainage performance can be improved, and the wet traction performance can be improved.

[0057] Moreover, in the pneumatic tire 1 of the embodiment, the groove depth d7 of the first one-sided open sipes 46 and the groove depth D1 of the circumferential main groove 21 satisfy the relationship of 0.05 ≤ d7 / D1 ≤ 0.8.

[0058] According to this pneumatic tire 1, while having the first one-sided open sipes 46, it is possible to maintain the rigidity of the shoulder land portion 32, and both the wet traction performance and the low rolling resistance performance can be achieved.

[0059] In the pneumatic tire 1 of the embodiment, the interval y1 in the tire circumferential direction of the first one-sided open sipes 46 is in the range of 4 [mm] ≤ y1 ≤ 15 [mm]. According to this pneumatic tire 1, by appropriately setting the interval y1 of the first one-sided open sipes 46, the drainage performance can be improved, and the wet traction performance can be improved.

[0060] Moreover, in the pneumatic tire 1 of the embodiment, the second one-sided open sipes 47 are formed in plurality in the tire circumferential direction, with one end communicating with the circumferential main groove 21 and the other end terminating within the shoulder land portion 32 at the shoulder land portion 32.

[0061] According to this pneumatic tire 1, by arranging the second one-sided open sipes 47, the groove area can be increased, the drainage performance can be improved, and the wet traction performance can be improved.

[0062] Moreover, in the pneumatic tire 1 of the embodiment, the groove depth d8 of the second one-sided open sipes 47 and the groove depth D1 of the circumferential main groove 21 satisfy the relationship of 0.6 ≤ d8 / D1 ≤ 0.8.

[0063] According to this pneumatic tire 1, while having the second one-sided open sipes 47, it is possible to maintain the rigidity of the shoulder land portion 32, and both the wet traction performance and the low rolling resistance performance can be achieved.

[0064] In the pneumatic tire 1 of the embodiment, the circumferential interval y2 of the second single-sided open groove 47 is in the range of 4 [mm] ≤ y2 ≤ 15 [mm]. According to this pneumatic tire 1, by appropriately setting the interval y2 of the second single-sided open groove 47, the drainage performance can be improved and the wet traction performance can be improved.

[0065] In the pneumatic tire 1 of the embodiment, as shown in FIG. 2, the length L1 of the second single-sided open groove 47 is in the range of 3 [mm] ≤ L1 ≤ 10 [mm]. According to this pneumatic tire 1, by appropriately setting the length L1 of the second single-sided open groove 47, it is possible to prevent a decrease in the rigidity of the shoulder land portion 32 while ensuring the drainage performance. By setting the length L1 of the second single-sided open groove 47 in the range of 3 [mm] ≤ L1 ≤ 5 [mm], it is possible to remarkably obtain the effect of preventing a decrease in the rigidity of the shoulder land portion 32 while ensuring the drainage performance.

[0066] Further, in the pneumatic tire 1 of the embodiment, in at least one circumferential groove 22, a wide portion 22w and a narrow portion 22s are alternately provided in the tire circumferential direction at the opening edge portion opening to the tread surface 15A, and notches 22c change from one side to both sides in the tire width direction as the groove width becomes narrower, constituting a first circumferential groove (center circumferential groove) 22.

[0067] According to this pneumatic tire 1, by alternately repeating the wide portion 22w and the narrow portion 22s, it is possible to achieve both the maintenance of the rigidity of the center land portion 31 and the groove area, and to achieve both the low rolling resistance performance and the wet traction performance.

[0068] Further, in the pneumatic tire 1 of the embodiment, at least one circumferential groove 23 forms a second circumferential groove (middle circumferential groove) 23 formed in a zigzag shape while changing the groove width W3 of the opening edge portion opening to the tread surface 15A.

[0069] According to this pneumatic tire 1, by having the second circumferential direction narrow grooves 23 arranged while changing the groove width W3, it is possible to achieve both the rigidity of the center land portion 31 and the maintenance of the groove area, and also to achieve both low rolling resistance performance and wet traction performance.

[0070] Further, in the pneumatic tire 1 of the embodiment, the width direction narrow groove 42 connects the circumferential direction main groove 21 and the second circumferential direction narrow groove 23 adjacent in the tire width direction, and a groove width W5 that opens to the tread surface 15A becomes narrower as it approaches the tire equatorial plane CL.

[0071] According to this pneumatic tire 1, by having the width direction narrow groove 42 that changes the groove width W5, it is possible to achieve both the rigidity of the center land portion 31 and the maintenance of the groove area, and also to achieve both low rolling resistance performance and wet traction performance.

[0072] Further, in the pneumatic tire 1 of the embodiment, the width direction narrow groove 42 connects the circumferential direction main groove 21 and the second circumferential direction narrow groove 23 adjacent in the tire width direction, and in the block partitioned by the circumferential direction main groove 21, the second circumferential direction narrow groove 23, and the width direction narrow groove 42, there are middle sipes 43 that connect the circumferential direction main groove 21 and the second circumferential direction narrow groove 23 and are formed in a plurality in the tire circumferential direction.

[0073] According to this pneumatic tire 1, by arranging the middle sipes 43 in the block partitioned by the circumferential direction main groove 21, the second circumferential direction narrow groove 23, and the width direction narrow groove 42, it is possible to achieve both the rigidity of the center land portion 31 and the maintenance of the groove area, and also to achieve both low rolling resistance performance and wet traction performance. In particular, by alternately arranging the width direction narrow groove 42 and the plurality of middle sipes 43 in the tire circumferential direction, the effect of achieving both the rigidity of the center land portion 31 and the maintenance of the groove area, and also achieving both low rolling resistance performance and wet traction performance can be remarkably obtained.

[0074] Further, in the pneumatic tire 1 of the embodiment, there are center sipes 41 that connect the first circumferential direction narrow groove 22 and the second circumferential direction narrow groove 23 adjacent in the tire width direction and are formed in a plurality in the tire circumferential direction.

[0075] According to this pneumatic tire 1, by disposing the center sipe 41 on the land portion between the first circumferential direction narrow groove 22 and the second circumferential direction narrow groove 23 adjacent in the tire width direction, it is possible to achieve both the rigidity of the center land portion 31 and the maintenance of the groove area, and it is possible to achieve both low rolling resistance performance and wet traction performance.

[0076] Further, in the pneumatic tire 1 of the embodiment, the number of blocks P1 in the tire circumferential direction of the central block 311a partitioned by the first circumferential direction narrow groove 22, the second circumferential direction narrow groove 23, and each center sipe 41, and the number of blocks P2 in the tire circumferential direction of the intermediate block 312a partitioned by the circumferential direction main groove 21, the second circumferential direction narrow groove 23, each width direction narrow groove 42, and each middle sipe 43 satisfy the relationship of 1.2 ≦ P2 / P1 ≦ 2.

[0077] According to this pneumatic tire 1, since the number of blocks P1 on the inner side in the tire width direction of the center land portion 31 is smaller than the number of blocks P2 on the outer side in the tire width direction in the center land portion 31, the distortion of the center land portion 31 can be reduced, the drainage performance can be improved, and the wet traction performance can be improved.

[0078] Further, in the pneumatic tire 1 of the embodiment, the shoulder land portion 32 is formed in a rib shape continuous in the tire circumferential direction.

[0079] According to this pneumatic tire 1, by forming the shoulder land portion 32 in a rib shape, the groove area can be reduced, the land portion rigidity can be increased, and the low rolling resistance performance can be improved.

[0080] Further, in the pneumatic tire 1 of the embodiment, the shoulder land portion 32 includes a buttress portion 15B, and has a shoulder circumferential direction narrow groove 24 formed to extend in the tire circumferential direction at the buttress portion 15B, a shoulder lug groove 44 having one end communicating with the circumferential direction main groove 21 at the shoulder land portion 32 and the other end extending outward in the tire width direction and formed in a plurality in the tire circumferential direction to partition the shoulder block 32a, and a shoulder sipe 45 formed with one end communicating with the circumferential direction main groove 21 and the other end communicating with the shoulder circumferential direction narrow groove 24 at the shoulder block 32a.

[0081] According to this pneumatic tire 1, by disposing the shoulder lug grooves 44 and the shoulder sipes 45 in the shoulder land portion 32, the groove area of the shoulder land portion 32 can be increased, drainage performance can be improved, and wet traction performance can be improved. In this pneumatic tire 1, it is preferable for improving wet traction performance that the groove width W1 of the shoulder lug groove 44 and the groove width W2 of the shoulder sipe 45 satisfy the relationship of 6 ≦ W1 / W2 ≦ 12. Further, it is preferable for maintaining the rigidity of the shoulder block 32a and the groove area and maintaining low rolling resistance performance and wet traction performance that the groove depth d1 of the shoulder lug groove 44 and the groove depth D1 of the circumferential main groove 21 satisfy the relationship of 0.1 ≦ d1 / D1 ≦ 0.3.

[0082] Incidentally, in the present embodiment, as described above, the pneumatic tire 1 has been described as an example of a tire. This pneumatic tire 1 can be filled with air, an inert gas such as nitrogen, and other gases. However, the configuration of the tread pattern of the pneumatic tire 1 described in the present embodiment can be arbitrarily applied to other tires within the scope obvious to those skilled in the art. Examples of other tires include airless tires and solid tires.

Example

[0083] Figs. 19 to 24 are charts showing the results of performance tests of the pneumatic tire according to the embodiment. Hereinafter, performance evaluation tests conducted on a conventional pneumatic tire, a comparative pneumatic tire, and an example pneumatic tire according to the embodiment will be described. The performance evaluation test was a test on low rolling resistance performance and wet traction performance.

[0084] The evaluation test of the low rolling resistance performance was carried out by measuring the average rolling resistance of an inflated tire with a tire size of 295 / 80R22.5 (rim 22.5×9.00) during forward and reverse rotation at 80 km / h and 85% of the specified load in accordance with ECE R117-02 (ECE Regulation No.117 Revision 2), and then indexing it. This evaluation was performed by an index evaluation based on the conventional example (100), indicating that the larger the numerical value, the higher the low rolling resistance performance.

[0085] The evaluation test of the wet traction performance was carried out by mounting an inflated tire of the above tire size on the above test vehicle, measuring the deceleration from 60 km / h to the final speed of 20 km / h during ABS (Anti-lock Breake System) braking on a wet road surface in accordance with ECE R117-02 (ECE Regulation No.117 Revision 2), and then indexing it. This evaluation was performed by an index evaluation based on the conventional example (100), indicating that the larger the numerical value, the higher the wet traction performance.

[0086] The conventional inflated tire mainly has two circumferential main grooves, partitioning a single center land portion and a pair of shoulder land portions.

[0087] The inflated tire of the example mainly has two circumferential main grooves, partitioning a single center land portion and a pair of shoulder land portions, and has one circumferential narrow groove formed with a notch at the opening edge extending in the tire circumferential direction at the center land portion, and a plurality of widthwise narrow grooves formed with notches at the opening edges extending in the tire width direction at the center land portion and formed in the tire circumferential direction. When the circumferential narrow groove and the widthwise narrow groove are in an inflated state and under a load, at least 20[%] of the opposing groove walls excluding the groove bottom and the notch are in contact and open on the tread surface.

[0088] And as shown in the test results, it can be seen that the inflated tire of this example has improved low rolling resistance performance and wet traction performance compared to the conventional example.

[0089] The present disclosure includes the following inventions. [Invention 1] A pair of circumferential main grooves extending in the tire circumferential direction, A single center land section partitioned inside the tire width direction of each of the circumferential main grooves, A pair of shoulder land sections partitioned outside the tire width direction of each of the circumferential main grooves, At least one circumferential narrow groove in which a notch is formed at an opening edge extending in the tire circumferential direction at the center land section, Width direction narrow grooves extending in the tire width direction at the center land section, provided with notches at the opening edges, and formed in a plurality in the tire circumferential direction, having When under load in an inflated state, at least 20[%] of the opposing groove walls excluding the groove bottom and the notch of the circumferential narrow groove and the width direction narrow groove are in contact and open at the tread surface, a tire. [Invention 2] The shoulder land section includes a buttress section and has a shoulder circumferential narrow groove formed by extending in the tire circumferential direction at the shoulder land section, The tire according to Invention 1. [Invention 3] The shoulder land section has a plurality of first one-sided open sipes formed in the tire circumferential direction, one end of which terminates inside the shoulder land section and the other end of which communicates with the shoulder circumferential narrow groove, The tire according to Invention 2. [Invention 4] The groove depth d7 of the first one-sided open sipes and the groove depth D1 of the circumferential main grooves satisfy the relationship of 0.05 ≦ d7 / D1 ≦ 0.8, The tire according to Invention 3. [Invention 5] The shoulder land section has a plurality of second one-sided open sipes formed in the tire circumferential direction, one end of which communicates with the circumferential main groove and the other end of which terminates inside the shoulder land section, The tire according to any one of Inventions 1 to 4. [Invention 6] The groove depth d8 of the second side open type groove and the groove depth D1 of the circumferential main groove satisfy the relationship of 0.6 ≦ d8 / D1 ≦ 0.8. The tire according to Invention 5. [Invention 7] In at least one of the circumferential narrow grooves, a wide portion and a narrow portion are alternately provided in the tire circumferential direction at the opening edge portion opening to the tread surface, and the notches change from one side to both sides in the tire width direction as the groove width becomes narrower, constituting a first circumferential narrow groove. The tire according to any one of Inventions 1 to 6. [Invention 8] At least one of the circumferential narrow grooves forms a second circumferential narrow groove formed in a zigzag shape while changing the groove width at the opening edge portion opening to the tread surface. The tire according to any one of Inventions 1 to 7. [Invention 9] The width direction narrow groove connects the circumferential main groove and the second circumferential narrow groove adjacent in the tire width direction, and the groove width opening to the tread surface is formed narrower as it approaches the tire equatorial plane. The tire according to Invention 8. [Invention 10] At least one of the circumferential narrow grooves forms a second circumferential narrow groove formed in a zigzag shape while changing the groove width at the opening edge portion opening to the tread surface, the width direction narrow groove connects the circumferential main groove and the second circumferential narrow groove adjacent in the tire width direction, inside the partition formed by the circumferential main groove, the second circumferential narrow groove, and the width direction narrow groove, there are middle-sized ones formed in plurality in the tire circumferential direction connecting the circumferential main groove and the second circumferential narrow groove. The tire according to any one of Inventions 1 to 9. [Invention 11] In at least one of the circumferential narrow grooves, a wide portion and a narrow portion are alternately provided in the tire circumferential direction at the opening edge portion opening to the tread surface, and the notches change from one side to both sides in the tire width direction as the groove width becomes narrower, constituting a first circumferential narrow groove. At least one of the circumferential fine grooves forms a second circumferential fine groove formed in a zigzag shape while changing the groove width of the opening edge portion that opens to the tread surface. It has a center sipe formed by connecting the first circumferential fine groove and the second circumferential fine groove and formed in a plurality in the tire circumferential direction. The tire according to any one of Inventions 1 to 10. [Invention 12] The number of blocks P1 in the tire circumferential direction of the central block partitioned by the first circumferential fine groove, the second circumferential fine groove, and each center sipe, and the number of blocks P2 in the tire circumferential direction of the intermediate block partitioned by the circumferential main groove, the second circumferential fine groove, each widthwise fine groove, and each middle sipe satisfy the relationship of 1.2 ≦ P2 / P1 ≦ 2. The tire according to Inventions 10 and 11. [Invention 13] The shoulder land portion is formed in a rib shape continuous in the tire circumferential direction. The tire according to any one of Inventions 1 to 12. [Invention 14] The shoulder land portion includes a buttress portion, and a shoulder circumferential fine groove formed to extend in the tire circumferential direction at the buttress portion, A shoulder lug groove formed at the shoulder land portion, having one end communicating with the circumferential main groove and the other end extending outward in the tire width direction and formed in a plurality in the tire circumferential direction to partition shoulder blocks, A shoulder sipe formed at the shoulder block, having one end communicating with the circumferential main groove and the other end communicating with the shoulder circumferential fine groove. It has. The tire according to any one of Inventions 1 to 12.

Explanation of Signs

[0090] 1 Pneumatic tire (tire) 15A Tread surface 15B Buttress portion 21 Circumferential main groove 22 Center circumferential fine groove (first circumferential fine groove) 22a Groove bottom 22b Groove 22c Notch 22s Narrow part 22w Wide part 23 Middle circumferential groove (second circumferential groove) 23a Groove bottom 23b Groove 23c Notch 24 Shoulder circumferential groove 31 Center land 32 Shoulder land 32a Shoulder block 41 Center sipe 42 Widthwise groove 42a Groove bottom 42b Sipe 42c Notch 43 Middle sipe 44 Shoulder lug groove 45 Shoulder sipe 46 First side open sipe 47 Second side open sipe 311a Central block 312a Intermediate block CL Tire equatorial plane T Ground contact end

Claims

1. A pair of circumferential main grooves extending in the tire circumferential direction, A single center land portion partitioned inside the tire width direction of each of the circumferential main grooves, A pair of shoulder land portions partitioned outside the tire width direction of each of the circumferential main grooves, At least one circumferential narrow groove in which a notch is formed at an opening edge portion extending in the tire circumferential direction at the center land portion, Width direction narrow grooves that extend in the tire width direction at the center land portion, are provided with notches at the opening edge portions, and are formed in a plurality in the tire circumferential direction, having, In the inflated state during load application, at least 20 [%] of the opposing groove walls excluding the groove bottom and the notch are in contact and open at the tread surface for the circumferential narrow groove and the width direction narrow groove, a tire.

2. The shoulder land portion includes a buttress portion and has a shoulder circumferential narrow groove formed by extending in the tire circumferential direction at the shoulder land portion, The tire according to Claim 1.

3. The shoulder land portion has a plurality of first one-sided open sipes formed in the tire circumferential direction, with one end terminating inside the shoulder land portion and the other end communicating with the shoulder circumferential narrow groove, The tire according to Claim 2.

4. The groove depth d7 of the first one-sided open sipe and the groove depth D1 of the circumferential main groove satisfy the relationship of 0.05 ≦ d7 / D1 ≦ 0.8, The tire according to Claim 3.

5. The shoulder land portion has a plurality of second one-sided open sipes formed in the tire circumferential direction, with one end communicating with the circumferential main groove and the other end terminating inside the shoulder land portion, The tire according to Claim 1.

6. The groove depth d8 of the second one-sided open sipe and the groove depth D1 of the circumferential main groove satisfy the relationship of 0.6 ≦ d8 / D1 ≦ 0.8, The tire according to Claim 5.

7. At least one of the circumferential narrow grooves constitutes a first circumferential narrow groove in which a wide portion and a narrow portion are alternately provided in the tire circumferential direction at the opening edge portion opening to the tread surface, and the notch changes from one side to both sides in the tire width direction as the groove width narrows, The tire according to Claim 1.

8. At least one of the circumferential narrow grooves forms a second circumferential narrow groove formed in a zigzag shape while changing the groove width of the opening edge portion opening to the tread surface, The tire according to Claim 7.

9. The width direction narrow grooves connect the circumferential main groove and the second circumferential narrow groove adjacent in the tire width direction, and the groove width opening to the tread surface is formed narrower as it approaches the tire equatorial plane, The tire according to claim 8.

10. The widthwise narrow groove connects the circumferential main groove and the second circumferential narrow groove adjacent in the tire width direction, Within the sections formed by the circumferential main groove, the second circumferential narrow groove, and the widthwise narrow groove, there are a plurality of middle sipes formed in the tire circumferential direction that connect the circumferential main groove and the second circumferential narrow groove. The tire according to claim 8.

11. There are a plurality of center sipes formed in the tire circumferential direction that connect the first circumferential narrow groove and the second circumferential narrow groove adjacent in the tire width direction. The tire according to claim 10.

12. The number of blocks P1 in the tire circumferential direction of the central block partitioned by the first circumferential narrow groove, the second circumferential narrow groove, and each center sipe, and the number of blocks P2 in the tire circumferential direction of the intermediate block partitioned by the circumferential main groove, the second circumferential narrow groove, each widthwise narrow groove, and each middle sipe satisfy the relationship 1.2 ≤ P2 / P1 ≤ 2. The tire according to claim 11.

13. The shoulder land portion is formed in a rib shape continuous in the tire circumferential direction. The tire according to any one of claims 1 to 12.

14. The shoulder land portion includes a buttress portion, a shoulder circumferential narrow groove formed to extend in the tire circumferential direction at the buttress portion, Shoulder lug grooves formed at the shoulder land portion, each having one end communicating with the circumferential main groove and the other end extending outward in the tire width direction, and partitioning shoulder blocks in the tire circumferential direction, Shoulder sipes formed at the shoulder blocks, each having one end communicating with the circumferential main groove and the other end communicating with the shoulder circumferential narrow groove. It has. The tire according to any one of claims 1 to 12.

Images