阅读说明：本技术 二轮车用轮胎 (Tire for two-wheeled vehicle ) 是由 大庭裕史 槙冈稔晃 宫里彰 于 2019-11-15 设计创作，主要内容包括：本发明提供一种二轮车用轮胎,其通过胎面花纹的改良来提高排水性,从而在不损害干燥路面上的行驶性能的前提下进一步提高潮湿路面上的行驶性能。二轮车用轮胎(10)具备形成为环状的胎面部。在胎面部(11)设有多个主槽(21～23)和多个刀槽花纹(31～35),多个刀槽花纹中的至少一部分与主槽连通,与刀槽花纹连通的带刀槽花纹的主槽的宽度为2mm以上且12mm以下,其长度为15mm以上且200mm以下,与带刀槽花纹的主槽连通的连通刀槽花纹的深度为2.0mm以上,而且连通刀槽花纹中的至少一部分具有车辆直行时的轮胎接地宽度的1倍以上且3倍以下的长度。(The invention provides a tire for a two-wheeled vehicle, which improves the drainage performance through the improvement of the tread pattern, thereby further improving the running performance on a wet road surface without damaging the running performance on a dry road surface. A tire (10) for a two-wheeled vehicle is provided with a tread portion formed in an annular shape. A tread portion (11) is provided with a plurality of main grooves (21-23) and a plurality of sipes (31-35), at least a part of the sipes are communicated with the main grooves, the width of the main grooves of the sipes communicated with the main grooves is more than 2mm and less than 12mm, the length of the main grooves is more than 15mm and less than 200mm, the depth of the communicated sipes communicated with the main grooves of the sipes is more than 2.0mm, and at least a part of the communicated sipes has the length which is more than 1 time and less than 3 times of the tire grounding width when a vehicle runs straight.)

1. A tire for a two-wheeled vehicle, comprising a tread portion formed in an annular shape,

a plurality of main grooves and a plurality of sipes are provided in the tread portion, at least a part of the plurality of sipes communicating with the main grooves,

the width of the main groove of the sipe with the knife groove is more than 2mm and less than 12mm, the length is more than 15mm and less than 200mm,

the communicating sipes communicating with the main grooves of the sipe have a depth of 2.0mm or more, and at least a part of the communicating sipes have a length of 1 to 3 times as long as a tire contact width when the vehicle travels straight.

2. The tire for a two-wheeled vehicle according to claim 1,

the proportion of the communicating sipes is more than 50% of the total sipes.

3. Tire for a two-wheeled vehicle according to claim 1 or 2,

the number of sipes is 20% to 200% of the number of main grooves.

4. A tire for a motorcycle according to any one of claims 1 to 3,

the communicating sipe comprises a sipe having a bend.

5. A tire for a motorcycle according to any one of claims 1 to 4,

the groove area ratio is 15% or less.

Technical Field

The present invention relates to a tire for a two-wheeled vehicle (hereinafter also simply referred to as "tire"), and more particularly, to a pneumatic tire for a two-wheeled vehicle relating to improvement of a tread pattern provided on a ground contact surface portion of the tire.

Background

Since a motorcycle has a characteristic that it turns by tilting a vehicle body, unlike a four-wheeled vehicle such as a car, a truck, and a bus, a tire for a two-wheeled vehicle has a tire shape with a smaller radius of curvature of a crown portion than that of a tire for a four-wheeled vehicle and a relatively circular cross section. That is, in the pneumatic tire for a two-wheeled vehicle, the center portion of the tread is mainly grounded during straight running of the vehicle, and the shoulder portion of the tread is mainly grounded during cornering.

As a conventional technique relating to such a tire for a two-wheeled vehicle, for example, patent document 1 discloses a tire for an electric two-wheeled vehicle, in which: the tire has a tire-shaped reinforcing structure body formed of reinforcing elements and anchored to a tire bead on each side of the tire, wherein a base portion of the tire bead is attached to a rim plate, a sidewall portion is provided as an extension portion radially outward of each tire bead, the sidewall portion is joined to a tread provided with a slit radially outward, the length of the slit is less than 1.2 times the width of the surface of a contact patch, and at least one slit has at least one end terminating in a crack having a width of more than 2.5mm and a length of 2.5mm to 10mm and provided in the tread. The purpose of this technique is to improve the grip characteristics of a wetted surface.

Documents of the prior art

Patent document

Patent document 1: japanese Kohyo publication (Kohyo publication) No. 2013-519563

Disclosure of Invention

Problems to be solved by the invention

However, the technique disclosed in patent document 1 is not sufficient in terms of securing the water drainage performance, and a technique for further improving the running performance on a wet road surface without impairing the running performance on a dry road surface has been demanded.

Accordingly, an object of the present invention is to provide a tire for a two-wheeled vehicle, which improves water drainage by improving a tread pattern, and further improves running performance on a wet road surface without impairing running performance on a dry road surface.

Means for solving the problems

The present inventors have conducted extensive studies and as a result, have found that the above problems can be solved by disposing a sipe of a predetermined size communicating with a main groove of a predetermined size in a tread portion, and have completed the present invention.

That is, the tire for a two-wheeled vehicle of the present invention includes a tread portion formed in a ring shape,

a plurality of main grooves and a plurality of sipes are provided in the tread portion, at least a part of the plurality of sipes communicating with the main grooves,

the width of the main groove of the sipe with the knife groove is more than 2mm and less than 12mm, the length is more than 15mm and less than 200mm,

the communicating sipes communicating with the main grooves of the sipe have a depth of 2.0mm or more, and at least a part of the communicating sipes have a length of 1 to 3 times as long as a tire contact width when the vehicle travels straight.

In the tire of the present invention, it is preferable that the proportion of the communicating sipes is 50% or more of the total sipes. In the tire of the present invention, it is preferable that the number of sipes is 20% or more and 200% or less of the number of main grooves.

Further, in the tire of the present invention, it is preferable that the communicating sipe includes a sipe having a curved portion. In the tire of the present invention, the groove area ratio is preferably 15% or less.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, the above configuration can realize a tire for a two-wheel vehicle, comprising: the water drainage is improved by improving the tread pattern, so that the running performance on a wet road surface is further improved on the premise of not damaging the running performance on a dry road surface.

Drawings

Fig. 1 is a partially developed view of a front tire showing an example of a tire for a two-wheel vehicle according to the present invention.

Fig. 2 is a cross-sectional view in the width direction of a front tire showing an example of a tire for a two-wheel vehicle according to the present invention.

Fig. 3 is a partially developed view showing a rear tire of another example of the tire for a two-wheel vehicle according to the present invention.

Fig. 4 is a cross-sectional view in the width direction of a rear tire showing another example of the tire for a two-wheel vehicle according to the present invention.

Fig. 5 is a partially developed view showing a front tire used in comparative example 1.

Fig. 6 is a partially developed view showing a rear tire used in comparative example 1.

Fig. 7A is a graph showing the magnitude of the lateral force (CF) generated with respect to the Slip Angle (SA) in the case where CA is 0 ° for the front tire in example 1 and comparative example 1.

Fig. 7B is a graph showing the magnitude of the lateral force (CF) generated with respect to the Slip Angle (SA) in the case where CA is 15 ° for the front tire in example 1 and comparative example 1.

Fig. 7C is a graph showing the magnitude of the lateral force (CF) generated with respect to the Slip Angle (SA) in the case where CA is 30 ° in the front tire in example 1 and comparative example 1.

Fig. 8A is a graph showing the magnitude of the lateral force (CF) generated with respect to the Slip Angle (SA) in the case where CA is 0 ° in the rear tire of example 1 and comparative example 1.

Fig. 8B is a graph showing the magnitude of the lateral force (CF) generated with respect to the Slip Angle (SA) in the case where CA is 15 ° in the rear tire of example 1 and comparative example 1.

Fig. 8C is a graph showing the magnitude of the lateral force (CF) generated with respect to the Slip Angle (SA) in the case where CA is 30 ° in the rear tire of example 1 and comparative example 1.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Fig. 1 is a partially developed view of a front tire of an example of a tire for a two-wheel vehicle according to the present invention. Fig. 2 is a cross-sectional view in the width direction of a front tire of an example of a tire for a two-wheel vehicle according to the present invention.

As shown in the figure, the tire 10 for a two-wheel vehicle of the invention is provided with a tread part 11 formed in a ring shape, and a tread pattern comprising a plurality of main grooves 21-23 and a plurality of sipes 31-35 is formed on the tread part 11. The main grooves 21 to 23 and the sipes 31 to 35 are arranged so as not to cross the tire equatorial plane CL, and both ends thereof terminate on one side of the tire ground contact surface portion, and in the illustrated front wheel tire, are arranged obliquely so as to extend from the inner side to the outer side in the tire width direction toward the tire rotation direction. The tread pattern shown in the drawings is a so-called directional pattern that specifies the rotational direction when mounted on a vehicle. The arrows in the figure indicate the direction of rotation of the tire.

In the tire 10 for a two-wheeled vehicle of the present invention, at least a part of the plurality of sipes 31 to 35 communicates with the main grooves 21 to 23, and specifically, in the illustrated example, the sipes 31 to 34 communicate with the main grooves 21 to 23. In the present invention, it is important that the width and length of the main grooves 21 to 23 of the sipe communicating with each other and the depth and length of the communicating sipes 31 to 34 communicating with the main grooves 21 to 23 of the sipe satisfy predetermined conditions. According to the present invention, since the sipe having a depth and a length equal to or greater than a predetermined value and both ends terminating at one side of the tire ground contact surface portion communicates with the main groove having a length and a volume equal to or greater than a predetermined value and both ends terminating at one side of the tire ground contact surface portion, the main groove and the sipe as a whole extend from the inside to the outside of the ground contact surface portion, and therefore, drainage performance can be improved and running performance on a wet road surface can be improved. On the other hand, in the present invention, the drainage is improved by providing the sipe instead of the groove, and therefore, the running performance on a dry road surface is not impaired. Thus, a tire for a two-wheeled vehicle can be realized in which the running performance on a wet road surface is further improved without impairing the running performance on a dry road surface.

In the present invention, the width of the main grooves 21 to 23 with the sipe is required to be 2mm or more and 12mm or less, and preferably 3mm or more and 8mm or less. The lengths of the main grooves 21 to 23 with the sipe are required to be 15mm to 200mm, and preferably 18mm to 150 mm. If the width or length of the main grooves 21 to 23 with a sipe pattern is less than the above range, sufficient drainage performance is not obtained, and running performance on a wet road surface becomes insufficient. On the other hand, if the width or length of the main grooves 21 to 23 with a sipe pattern is larger than the above range, the rigidity is lowered, and the running performance on a dry road surface becomes insufficient.

In the present invention, the lengths of the main grooves 21 to 23 having the sipe pattern are lengths of line segments connecting the tire circumferential ends of the grooves to each other. The width of the main grooves 21 to 23 having a sipe is a value obtained by dividing the groove area of each groove by the length of the groove, and the area of each groove is the surface area of the opening of each groove.

In the present invention, the depth of the communicating sipes 31 to 34 needs to be 2.0mm or more, and preferably 2.5mm or more and 6.0mm or less. By setting the depth of the communicating sipes 31 to 34 within the above range, drainage performance and rigidity of the tread portion can be ensured in a well-balanced manner. Here, the depth of the sipe means the maximum depth from the opening portion of the sipe to the bottom portion of the sipe, measured in a direction perpendicular to the tire surface.

In the present invention, at least a part of the communicating sipes 31 to 34 need to have a length of 1 to 3 times of the tire contact width when the vehicle travels straight. If the length of the communicating sipes 31 to 34 is less than the above range, sufficient drainage performance cannot be obtained, and running performance on a wet road surface becomes insufficient. On the other hand, if the length of the communicating sipes 31 to 34 is longer than the above range, the rigidity is lowered, and the running performance on a dry road surface becomes insufficient. The length of the sipe is preferably 1.3 times or more and 2.6 times or less. Here, the length of the sipe refers to a length between both ends of the sipe measured along the sipe on the tire surface.

Here, in the present invention, the tire contact surface width when the vehicle travels straight is the maximum width of the tire contact surface when the tire is mounted on the application rim, the tire is filled with a predetermined air pressure, and a load corresponding to 60% of the maximum load capacity is applied. The applied Rim is a standard Rim (or an "Approved Rim") and a "Recommended Rim") having an applied size described in the following standard, and the predetermined air pressure is an air pressure corresponding to a maximum load (maximum load capacity) of a single wheel having an applied size described in the following standard. The standard is a standard determined by an industrial standard effective in a region where a tire is produced or used, and is defined, for example, in "Year Book of the association of tires and rims" in the united states of america, "Standards Manual of the european organization for tire and rim technology" in europe, and "JATMA Year Book" in japan.

In the present invention, at least a part of the communicating sipes 31 to 34 need to have the predetermined length, and specifically, the number of communicating sipes of preferably 20% or more, more preferably 40% or more, of the communicating sipes 31 to 34 in the whole has the predetermined length. If the number of communicating sipes having the above-described predetermined length is too small, the desired effects of the present invention may not be obtained.

In the present invention, the communicating sipes 31 to 34 may have a depth and a length satisfying the above-described conditions, but the following configuration is preferable.

The width of the communicating sipes 31 to 34 is preferably 0.5mm or more and 2mm or less, and more preferably 0.7mm or more and 1.5mm or less. By setting the width of the communicating sipes 31 to 34 within the above range, drainage performance and rigidity of the tread portion can be preferably secured in a balanced manner. Here, the width of the sipe means an opening width measured at a sipe opening portion in a direction perpendicular to an extending direction of the sipe.

The communicating sipes 31 to 34 may be linear or have a curved portion. The linear shape is preferable from the viewpoint of ensuring drainage, but the rigidity can be supplemented by providing a sipe having a curved portion, for example, a wave shape or a zigzag shape. For example, in the illustrated example, the communicating sipe 31 has a curved portion. When the sipe has a bend, the angle α of the bend is preferably 90 ° or more and 170 ° or less, and more preferably 100 ° or more and 160 ° or less. Here, the angle α of the curved portion of the sipe means an angle formed by intersection points of two tangent lines drawn at both ends of the curved portion.

In the present invention, the ratio of the communicating sipes 31 to 34 is preferably 50% or more, and more preferably 70% or more, of all sipes including sipes not communicating with the main grooves (hereinafter also referred to as "individual sipes"). The ratio of the communicating sipes 31 to 34 is preferably set in the above range because the drainage performance can be further improved.

In the present invention, the number of all sipes 31 to 35 is preferably 20% to 200%, more preferably 40% to 180%, of the number of all main grooves 21 to 23. Setting the number of sipes to the above range is preferable because the drainage performance and the rigidity of the tread portion can be ensured.

In the present invention, the communication mode between the main groove with sipe and the communicating sipe is not particularly limited. Particularly preferably, the communicating sipes include 30% or more of the number of the main grooves of the sipe and have an angular deviation of 40 ° or less between the extending direction of the communicating sipe and the extending direction of the main groove of the sipe. For example, in the illustrated example, the angular deviations between the extending direction of the communicating sipes 31 and 32 and the extending direction of the main groove 21 of the sipe, between the extending direction of the communicating sipe 33 and the extending direction of the main groove 22 of the sipe, and between the extending direction of the communicating sipe 34 and the extending direction of the main groove 23 of the sipe are within 40 °. Such an arrangement is preferable because the effect of improving the drainage performance by the arrangement of the communicating sipes can be more reliably obtained.

In the present invention, the extending direction of the main groove of the sipe is a direction in which a line segment connecting the ends of each groove in the tire circumferential direction extends, and the extending direction of the communicating sipe is a direction in which a line segment connecting the ends of the communicating sipe to each other extends.

Specifically, in the illustrated example, the communicating sipe 31 is disposed along the outer contour line of the main sipe groove 21, and communicates with the main sipe groove 21 at the outer end in the tire width direction. The communicating sipe 32 is substantially provided on an extension line of the extending direction of the tire width direction inner end portion of the main sipe 21, and the tire width direction inner end portion of the main sipe 21 communicates with the main sipe 21. The communicating sipe 33 is substantially provided on an extension line of the extending direction of the tire width direction outer side end portion of the main sipe 22, and the tire width direction outer side end portion of the main sipe 22 communicates with the main sipe 22. The communicating sipe 34 is provided substantially on an extension line of the extending direction of the tire width direction outer side end portion of the main sipe 23, and the tire width direction outer side end portion of the main sipe 23 communicates with the main sipe 23.

In the present invention, in addition to the communicating sipes 31 to 34, another sipe not communicating with the main groove may be provided. The dimensions and the like of the other sipes are not particularly limited, but similarly to the communicating sipe and the like, the communicating sipe may be disposed so as to be inclined so as to extend from the inner side to the outer side in the tire width direction toward the tire rotation direction.

In the present invention, the main grooves 21 to 23 with a sipe pattern may have a width and a length satisfying the above conditions, but the following configuration is preferable.

The depth of the main grooves 21-23 having a sipe pattern is preferably 2.5mm to 10mm, and more preferably 2.5mm to 6 mm. This is preferable because the drainage performance and the rigidity of the tread portion can be secured in a balanced manner. Here, the depth of the main groove refers to the maximum depth from the opening of the groove to the groove bottom, measured in a direction perpendicular to the tire surface.

The main grooves 21 to 23 having a sipe pattern may have a shape in which the outer contour line is formed of 3 or more curved lines and/or straight lines. The communicating sipes 31 to 34 may extend from the corners of the main grooves 21 to 23 constituting the sipe, where the curved lines and/or straight lines intersect. In the illustrated front wheel tire, the main grooves 21 to 23 with the sipe pattern may extend so that the inclination angle with respect to the tire circumferential direction increases toward the tire rotational direction.

In the present invention, other main grooves not communicating with the sipe may be provided in addition to the main grooves 21 to 23 having the sipe. The size and the like of the other main grooves are not particularly limited, but they may be arranged obliquely so as to extend from the inner side to the outer side in the tire width direction toward the tire rotation direction, similarly to the main grooves of the sipe, and the like.

The main grooves and sipes of the present invention can be arranged axisymmetrically about a tire equatorial plane CL, and are alternately arranged at intervals of, for example, 1/2 to 1/3 on one side and the other side of a tread ground contact surface portion across the tire equatorial plane CL.

In the tire of the present invention, the groove area ratio is preferably 15% or less, more preferably 1% or more and 15% or less, and further preferably 1% or more and 9% or less. By setting the groove area ratio in the above range, the rigidity of the tread portion can be favorably ensured, which is preferable. Here, the groove area ratio refers to a ratio of the groove portion excluding the sipe to the area of the tread ground contact surface portion. The present invention has an advantage that the water drainage performance can be improved while securing rigidity by suppressing the groove area ratio to be low.

In the tire of the present invention, the tread pattern of the tire contact surface portion may satisfy the above conditions, and the tire structure and the details of the material used are not particularly limited, but may be configured as follows, for example.

As shown in fig. 2, for example, in the tire 10 of the present invention, a pair of sidewall portions 12 and bead portions 13 are arranged in this order on the inner side in the tire radial direction of a tread portion 11 formed in a ring shape. In the tire 10 of the present invention, at least 1 carcass ply 1 is used as a carcass, and at least 1 belt layer 2 is arranged on the outer side of the carcass ply 1 in the tire radial direction from the tread portion 11.

The carcass ply 1 is formed by arranging relatively high-elasticity textile cords in parallel with each other. The number of the carcass ply 1 may be 1, 2, or 3 or more. Both ends of the carcass cord 1 may be folded and locked from the inner side to the outer side of the tire around the bead core 3 embedded in the bead portion 13 at the bead portion 13, or may be clamped and locked from both sides by a bead wire, and any fixing method may be used.

The belt layer 2 can be, for example, a spiral belt made of a rubber-coated cord wound spirally in the tire circumferential direction. Further, the belt member may be composed of two or more oblique belt layers in which the cord directions are alternately arranged between the layers. Examples of the reinforcing material constituting the belt layer include nylon fibers, aramid (trade name: Kevlar), and steel. Among them, aromatic polyamide and steel are reinforcing materials that do not elongate at high temperatures and can suppress expansion of the tread portion.

In the tire of the present invention, the bead apex 4 may be disposed on the outer side of the bead core 3 in the tire radial direction, and an inner liner, not shown, may be disposed on the innermost layer of the tire.

Fig. 3 is a partially developed view of a rear tire of another example of the tire for a two-wheel vehicle according to the present invention. Fig. 4 is a cross-sectional view of a rear tire of another example of the tire for a two-wheeled vehicle according to the present invention in the width direction. In the illustrated tire 40 for a motorcycle, it is important only that the tread portion 41 is provided with the main grooves 51 to 54 having the sipe with the predetermined width and length and the communicating sipes 61 to 66 communicating with the main grooves 51 to 54 having the sipe with the predetermined depth and length conditions, whereby the desired effects of the present invention can be obtained, and there is no particular limitation in other aspects.

A tire 40 for a two-wheeled vehicle of the present invention is shown in the figure and comprises a tread portion 41 formed in an annular shape, and a tread pattern including a plurality of main grooves 51 to 54 and a plurality of sipes 61 to 67 is formed on the tread portion 41. The main grooves 51 to 54 and the sipes 61 to 67 are arranged so as not to cross the tire equatorial plane CL, and both ends thereof terminate on one side of the tire ground contact surface portion, and in the rear wheel tire shown in the figure, are arranged obliquely so as to extend from the inner side to the outer side in the tire width direction in the direction opposite to the tire rotation direction. The tread pattern shown in the drawings is a so-called directional pattern that specifies the rotational direction when mounted on a vehicle. The arrows in the figure indicate the direction of rotation of the tire.

In the tire 40 for a two-wheeled vehicle of the present invention, at least a part of the plurality of sipes 61 to 67, specifically, the communicating sipes 61 to 66 communicate with the main grooves 51 to 54 having the sipe. In this case, the main grooves including the main grooves 51 to 54 with sipes and the sipes including the communicating sipes 61 to 66 can be configured and preferred conditions similar to those of the main grooves 21 to 23 with sipes and the communicating sipes 31 to 34, and therefore, the description thereof will be omitted.

Specifically, in the illustrated example, the communicating sipe 61 is provided substantially on an extension line of the extending direction of the tire width direction inner end portion of the main groove 51 with the sipe, and the tire width direction inner end portion of the main groove 51 with the sipe communicates with the main groove 51 with the sipe. The communicating sipe 62 is disposed along the outer contour line of the main sipe 51, and communicates with the main sipe 51 at the outer end of the main sipe 51 in the tire width direction. The communicating sipe 63 is substantially provided on an extension line of the extending direction of the tire width direction inner end portion of the main sipe 52, and the tire width direction inner end portion of the main sipe 52 communicates with the main sipe 52. The communicating sipe 64 is substantially provided on an extension line of the extending direction of the tire width direction inner end portion of the main sipe 53, and the tire width direction inner end portion of the main sipe 53 communicates with the main sipe 53. The communicating sipe 65 is substantially provided on an extension line of the extending direction of the tire width direction inner end portion of the main sipe 54, and the tire width direction inner end portion of the main sipe 54 communicates with the main sipe 54. The communicating sipe 66 is disposed along the outer contour line of the main sipe 54, and communicates with the main sipe 54 at the outer end of the main sipe 54 in the tire width direction.

In the rear wheel tire shown in fig. 3, when another main groove or another sipe is provided, the main groove or the communicating sipe may be arranged to be inclined so as to extend from the inner side to the outer side in the tire width direction in the opposite direction to the tire rotation direction, similarly to the main groove or the communicating sipe with a sipe.

As shown in fig. 4, for example, in a tire 40 of the present invention, a pair of sidewall portions 42 and a bead portion 43 are arranged in this order on the inner side in the tire radial direction of a tread portion 41 formed in a ring shape. In the tire 40 of the present invention, at least 1 carcass ply 5 is used as a carcass, and at least 1 belt layer 6 is disposed on the outer side of the carcass ply 5 in the tire radial direction from the tread portion 41. The structure and preferred conditions of the carcass ply 5, belt 6, and the like can be the same as those of the tire 10, and therefore, are omitted here.

In the tire of the present invention, bead apex 8 can be disposed on the outer side in the tire radial direction of bead core 7 embedded in bead portion 43, and an inner liner, not shown, can be disposed on the innermost layer of the tire.

The tire of the present invention can be applied to either a front tire or a rear tire of a motorcycle, and can also be applied to a tire having either a radial structure or a bias structure.

Examples

The present invention will be described in more detail below with reference to examples.

(example 1)

A front tire having a tire gauge of 120/70ZR17M/C with the tread pattern shown in fig. 1 and a rear tire having a tire gauge of 190/55ZR17M/C with the tread pattern shown in fig. 3 were evaluated.

The front tire of example 1 satisfies the following conditions.

Main sipe-provided groove 21: width 4mm, length 74mm, depth 3.5 mm.

Main sipe groove 22: width 4mm, length 18mm, depth 3 mm.

Main groove with sipe 23: 3mm in width, 37mm in length and 4mm in depth.

Communicating sipe 31: the length is 2.6 times of the tire grounding width when the vehicle travels straight, the width is 1mm, and the depth is 3.5 mm.

Communicating sipe 32: the length is 0.6 times of the tire ground contact width when the vehicle travels straight, the width is 1mm, and the depth is 3.5 mm.

Communicating sipe 33: the length is 0.7 times of the tire grounding width when the vehicle travels straight, the width is 1mm, and the depth is 3 mm.

Communicating sipe 34: the length is 0.8 times of the tire grounding width when the vehicle travels straight, the width is 1mm, and the depth is 4 mm.

Individual sipes 35: the length is 0.9 times of the tire ground contact width when the vehicle travels straight, the width is 1mm, and the depth is 2.5 mm.

Ratio of communicating sipes: 80 percent.

Number of sipes: 167% of the number of main grooves.

Groove area ratio: 5 percent.

The rear tire of example 1 satisfies the following conditions.

Main groove with sipe 51: 5mm in width, 147mm in length and 5mm in depth.

Main siped groove 52: width 4mm, length 60mm, depth 4.5 mm.

Main sipe-provided groove 53: 5mm in width, 85mm in length and 6mm in depth.

Main siped groove 54: width 4mm, length 78mm, depth 4 mm.

Communicating sipe 61: the length is 0.7 times of the tire grounding width when the vehicle travels straight, the width is 1mm, and the depth is 5 mm.

Communicating sipe 62: the length is 2.6 times of the tire grounding width when the vehicle travels straight, the width is 1mm, and the depth is 5 mm.

Communicating sipe 63: the length is 0.6 times of the tire ground contact width when the vehicle travels straight, the width is 1mm, and the depth is 4.5 mm.

Communicating sipe 64: the length is 1.2 times of the tire grounding width, the width is 1mm, and the depth is 6mm when the vehicle runs straight.

Communicating sipe 65: the length is 0.4 times of the tire grounding width when the vehicle travels straight, the width is 1mm, and the depth is 4 mm.

Communicating sipe 66: the length is 1.4 times of the tire grounding width, the width is 1mm, and the depth is 4mm when the vehicle runs straight.

Individual sipes 67: the length is 0.7 times of the tire ground contact width when the vehicle travels straight, the width is 1mm, and the depth is 3.5 mm.

Ratio of communicating sipes: 86 percent.

Number of sipes: 175% of the number of main grooves.

Groove area ratio: 5 percent.

Comparative example 1

The tire of comparative example 1 used a front tire 110 having a tire specification 120/70ZR17M/C with a tread pattern shown in fig. 5 in a tread portion 111 and a rear tire 140 having a tire specification 190/55ZR17M/C with a tread pattern shown in fig. 6 in a tread portion 141.

The front tire of comparative example 1 satisfies the following conditions.

Main groove 121: width 4mm, length 74mm, depth 3.5 mm.

Main groove 122: 3mm in width, 33mm in length and 2.5mm in depth.

Main groove 123: 4mm in width, 46mm in length and 3mm in depth.

Main groove 124: width 4mm, length 71mm, depth 4 mm.

Communicating sipe 131: the length is 2.7 times of the tire grounding width when the vehicle travels straight, the width is 1mm, and the depth is 0.3 mm.

Ratio of communicating sipes: 100 percent.

Number of sipes: 25% of the number of main grooves.

Groove area ratio: 8 percent.

The rear tire of comparative example 1 satisfies the following conditions.

Main groove 151: 5mm in width, 151mm in length and 5mm in depth.

Main groove 152: width 4mm, length 105mm, depth 4.5 mm.

Main groove 153: 5mm in width, 170mm in length and 6mm in depth.

Main groove 154: width 4mm, length 77mm, depth 4 mm.

Main groove 155: 3mm in width, 42mm in length and 3.5mm in depth.

Communicating sipe 161: the length is 3.0 times of the tire grounding width, the width is 1mm, and the depth is 0.3mm when the vehicle runs straight.

Communicating sipe 162: the length is 1.6 times of the tire grounding width, the width is 1mm, and the depth is 0.3mm when the vehicle runs straight.

Ratio of communicating sipes: 100 percent.

Number of sipes: 40% of the number of main grooves.

Groove area ratio: 7 percent.

The front and rear tires of example 1 and comparative example 1 were mounted on a vehicle, and the ride comfort performance on a dry road surface and the braking performance on a wet road surface were evaluated sensorially by a test driver. The results are expressed by an index with reference to comparative example 1 as 100, and the higher the value is, the better the running performance is. The results are shown in table 1 below.

[ Table 1]

As shown in the above table, it is apparent that, in the case of the tire of the example in which the sipe satisfying the conditions of the predetermined depth and length communicates with the main groove having the predetermined width and length, the running performance on a wet road surface and the running performance on a dry road surface can be obtained in a well balanced manner as compared with the tire of the comparative example in which the conditions are not satisfied.

The front tires (internal pressure 250kPa, load 1.3kN) and the rear tires (internal pressure 290kPa, load 2kN) of example 1 and comparative example 1 were evaluated for the handling properties by the indoor test. Specifically, the magnitude of the lateral force (CF) generated with respect to the Slip Angle (SA) under the conditions that the Camber Angle (CA) is 0 °, 15 °, and 30 ° is measured. The results are shown in fig. 7A to 8C. That is, fig. 7A shows the result in the case where CA of the front tire is 0 °, fig. 7B shows the result in the case where CA of the front tire is 15 °, and fig. 7C shows the result in the case where CA of the front tire is 30 °. Fig. 8A shows the results when CA of the rear tire is 0 °, fig. 8B shows the results when CA of the rear tire is 15 °, and fig. 8C shows the results when CA of the rear tire is 30 °.

As is clear from the results of fig. 7A to 8C, the magnitude of the lateral force (CF) generated with respect to the Slip Angle (SA) in example 1 is improved as compared with comparative example 1 under any of the conditions of the Camber Angle (CA) of 0 °, 15 °, and 30 °. It is found that a sufficient lateral force can be obtained particularly when the camber angle is small.

Description of the reference numerals

1.5, carcass ply; 2.6, a belt ply; 3. 7, a bead core; 4. 8, triangular adhesive tape; 10. 40, 110, 140, a tire for a motorcycle; 11. 41, 111, 141, a tread portion; 12. 42, a sidewall portion; 13. 43, bead portion; 21-23, 51-54, main grooves with knife groove patterns; 31 to 34, 61 to 66, communicating sipes; 35. 67, individual sipes; 121-124, 151-155, main groove; 131. 161-162 and communicating sipes.