JP7481614B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire that achieves a good balance between dry handling stability (hereinafter sometimes referred to as "dry handling stability") and wet handling stability (hereinafter sometimes referred to as "wet handling stability").

Traditionally, when developing tires for sport utility vehicles, sports sedans, and other vehicles, there has been a demand for improving wet handling while maintaining dry handling.

In response to these demands, tire materials have been designed to contain a relatively large amount of silica in the cap tread rubber, while tire structure has been designed to increase the area of the main grooves, improving drainage.

For example, a known technology for improving wet handling stability while maintaining dry handling stability is a pneumatic tire in which, among the multiple land portions, the land portion adjacent to the outermost peripheral direction main groove on the tire equatorial plane side is an outer second land portion, the land portion adjacent to the outer side in the tire width direction is an outer shoulder land portion, the land portion adjacent to the innermost peripheral direction main groove on the tire equatorial plane side is an inner second land portion, and the land portion adjacent to the outer side in the tire width direction is an inner shoulder land portion, the land portion adjacent to the innermost peripheral direction main groove on the tire equatorial plane side is an inner second land portion, and the land portion adjacent to the outer side in the tire width direction is an inner shoulder land portion, the tire equatorial plane is crossed from the outer shoulder land portion, and a communicating inclined groove extends continuously to the inner second land portion and terminates within the inner second land portion, and the inner second land portion is provided with a secondary groove that passes through the end of the communicating inclined groove and is separated from the innermost peripheral direction main groove (Patent Document 1).

JP 2018-079903 A

The technology disclosed in Patent Document 1 can achieve excellent wet handling stability by forming communicating inclined grooves and sub-grooves to increase the groove area ratio. However, since increasing land rigidity to improve handling stability and improving drainage are in a trade-off relationship, there may be cases where technology aimed at improving drainage does not achieve good dry handling stability.

Therefore, when adopting the technology disclosed in Patent Document 1, there is also room for improvement in dry handling stability. However, in recent years, there has been a high demand for wet handling stability as well, so it is desirable to maintain the same level of drainage as before.

The present invention was made in consideration of the above circumstances, and its purpose is to provide a pneumatic tire that has a good balance between dry and wet handling stability.

The pneumatic tire according to the present invention has a plurality of land portions defined by a plurality of circumferential main grooves, and has an asymmetric pattern with respect to a tire equatorial plane,
A meridian cross section of a tire with normal internal pressure and no load.
The tire has a tire profile including a tire inner profile including a tire equator line between a vehicle-mounted outer ground contact end and a vehicle-mounted inner ground contact end, and two tire outer profiles located on both sides of the tire inner profile in the tire width direction, each of the two tire outer profiles having a dimension that is 20% to 35% of a dimension between both ground contact ends along a virtual tire profile on the assumption that there is no groove between both ground contact ends,
Each of the tire outer profiles is comprised of at least four different shaped curves;
Plan view of the tire
a plurality of first inclined grooves extending toward the outside in the tire width direction at an inclination angle of ±45° or less with respect to the tire width direction in one or both of a vehicle-mounted outer shoulder land portion and a vehicle-mounted inner shoulder land portion located at the outermost side in the tire width direction;
The first inclined groove has a groove width of 2.0 mm or more and 10.0 mm or less;
It is characterized by:

In the pneumatic tire according to the present invention, improvements have been made to the tire outer profile as well as to the inclined grooves formed in the shoulder land portion. As a result, the pneumatic tire according to the present invention can improve the dry handling stability and the wet handling stability in a well-balanced manner.

FIG. 1 is a tire meridian cross-sectional view showing a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a partial plan view of the outer circumferential surface of a pneumatic tire according to one embodiment of the present invention. FIG. 3 is a plan view for explaining the inclination angle of the first inclined groove with respect to the tire width direction in a pneumatic tire according to one embodiment of the present invention.

Below, embodiments of the pneumatic tire according to the present invention (basic form and additional forms 1 to 9 shown below) will be described in detail with reference to the drawings. Note that these embodiments do not limit the present invention. Furthermore, the components of the embodiments include those that are easily replaceable by a person skilled in the art, or those that are substantially the same. Furthermore, the various forms included in the embodiments can be arbitrarily combined within the scope of what is obvious to a person skilled in the art.

Basic form The basic form of the pneumatic tire according to the present invention will be described below. In the following description, the term "tire radial direction (RD)" refers to a direction perpendicular to the rotation axis of the pneumatic tire, the term "tire radial inner side" refers to the side facing the rotation axis in the tire radial direction, and the term "tire radial outer side" refers to the side away from the rotation axis in the tire radial direction. The term "tire circumferential direction (CD)" refers to a circumferential direction with the rotation axis as the central axis. Furthermore, the term "tire width direction (WD)" refers to a direction parallel to the rotation axis, the term "tire width inner side" refers to the proximal side of the tire equatorial plane (or tire equatorial line) in the tire width direction, and the term "tire width outer side" refers to the distal side of the tire equatorial plane in the tire width direction. The term "tire equatorial plane (CL)" refers to a plane perpendicular to the rotation axis of the pneumatic tire and passing through the center of the tire width of the pneumatic tire. The term "tire equatorial line" refers to a line on the tire equatorial plane that runs along the tire circumferential direction of the pneumatic tire 1. In this embodiment, the tire equatorial line is given the same symbol "CL" as the tire equatorial plane. The "pattern asymmetric with respect to the tire equatorial plane" refers to a pattern on each side in the tire width direction based on the tire equatorial line being not symmetric with respect to the tire equatorial line.

Figure 1 is a meridian cross-sectional view of a pneumatic tire according to an embodiment of the present invention. Note that the example shown in Figure 1 shows an unloaded state in which the tire is mounted on a regular rim and has a regular internal pressure, and for the sake of simplicity, the first, second, third, fourth, fifth, and sixth inclined grooves described below are not shown in Figure 1.

Here, "standard rim" refers to the "applicable rim" specified by JATMA, the "design rim" specified by TRA, or the "measuring rim" specified by ETRTO. Furthermore, "standard internal pressure" refers to the "maximum air pressure" specified by JATMA, the maximum value of the "tire load limits at various cold inflation pressures" specified by TRA, or the "inflation pressures" specified by ETRTO.

The tread portion 10 of the pneumatic tire 1 shown in FIG. 1 is made of a rubber material (tread rubber) and is exposed at the outermost part in the tire radial direction of the pneumatic tire 1, and its surface becomes the outline of the pneumatic tire. The surface of the tread portion 10 is formed as a tread surface 12, which is a surface that comes into contact with the road surface when a vehicle (not shown) equipped with the pneumatic tire runs. In the example shown in the figure, five land portions are defined and formed by circumferential main grooves 14, 16, 18, and 20 extending in the tire circumferential direction on both sides of the tire width direction of the tire equatorial plane CL, namely, a vehicle-mounted outer shoulder land portion 22 located on the outer side (OUT) of the vehicle when the pneumatic tire 1 is mounted on the vehicle, a vehicle-mounted inner shoulder land portion 24 located on the inner side (IN) of the vehicle when the pneumatic tire 1 is mounted on the vehicle, a first center land portion 26, a second center land portion 28, and a third center land portion 30. The lower limit value of the groove width of the circumferential main groove is typically 10 mm, and the groove width of the circumferential main groove is preferably 5 to 15 mm. As shown in FIG. 1, shoulder portions 40 are connected to both sides of the tread portion 10 in the tire width direction.

As shown in FIG. 1, the pneumatic tire of this embodiment has a tire profile consisting of a tire inner profile Pi including the tire equator line CL between the vehicle-mounted outer ground contact end E1 and the vehicle-mounted inner ground contact end E2, and two tire outer profiles Po1 and Po2 located on both sides of the tire inner profile Pi in the tire width direction, and each of the two tire outer profiles Po1 and Po2 has a dimension that is 20% to 35% of the dimension between the two ground contact ends along a virtual tire profile when it is assumed that there is no groove between the two ground contact ends E1 and E2.

Under these assumptions, in the pneumatic tire according to the embodiment of the present invention, each of the tire outer profiles Po1 and Po2 is composed of at least four curves of different shapes (10 curves of different shapes as shown in FIG. 1). In contrast, the tire inner profile Pi may be composed of one curve as shown in FIG. 1, or may be composed of multiple curves.

The pneumatic tire according to the present invention further has a plurality of first inclined grooves (grooves indicated by reference numerals 130 and 132 in FIG. 2 described later) extending toward the outside in the tire width direction at an inclination angle of ±45° or less with respect to the tire width direction in one or both of the outer shoulder land portion 22 and the inner shoulder land portion 24 located at the outermost side in the tire width direction in a plan view of the tire, and the first inclined grooves have a groove width of 2.0 mm to 10.0 mm. Here, ±45° means that the absolute value of the angle with respect to the tire width direction is 45°, and for example, when the angle is measured counterclockwise with respect to the tire width direction, it means that it is 0° to 45° or less, or 135° to 180° or less. The inclination angle of the first inclined groove refers to the inclination angle of the groove width direction center line of the groove (a line segment connecting any groove width center points) with respect to the tire width direction. In this specification, the inclination angle of all grooves, not limited to the first inclined groove, means the inclination angle of the groove width direction center line of the groove.

As mentioned above, many pneumatic tires have been developed that improve wet handling stability while maintaining dry handling stability, but in recent years, further improvement of dry handling stability has become an issue along with this development. However, in recent years, there has been a high demand for wet handling stability as well, so we have been actively studying ways to improve dry handling stability while maintaining the same level of drainage as before.

As a result, the inventors focused on improving dry handling stability by reducing the difference in contact pressure between areas of high contact pressure and areas of low contact pressure in the tire width direction by improving the tire outer profile and leveling out the contact pressure in the tire width direction, while maintaining the same level of drainage performance and wet handling stability as before by improving the inclined grooves formed in the shoulder land portion.

That is, for example, when the ground contact pressure of the pneumatic tire disclosed in Patent Document 1 was investigated, there were areas (particularly near the ground contact ends) where the ground contact pressure was clearly higher in the shoulder region (area between the two ground contact ends other than the center region) than in the center region near the tire equatorial plane (a tire inner profile that includes the tire equatorial plane and has a dimension along the tire profile that is 30% to 60% of the dimension between the two ground contact ends along the tire profile (specifically, the profile if there were no grooves)).

This is because, for example, when a lateral force is applied to a tire during lane changes or cornering, stress is concentrated near the contact edge, especially in the shoulder region, causing the contact length in the tire circumferential direction to increase and the contact pressure near the contact edge to increase.

The inventors have come to the realization that by modifying the profile of the shoulder region (especially near the contact edge) to reduce the ground contact pressure in the shoulder region, thereby preventing the occurrence of areas in which the ground contact pressure differs significantly in any of the tire width direction regions when viewed as a whole tire, it is possible to improve dry handling stability even if wet handling stability is maintained by realizing excellent drainage performance by forming inclined grooves in a specific shape in the shoulder land portion, and as a result, it is possible to improve dry handling stability and wet handling stability in a well-balanced manner.

Based on the above findings, in this embodiment, as shown in FIG. 1, the tire outer profile Po1, Po2 corresponding to the shoulder region is composed of at least four curves of different shapes (Po101 to Po110, Po201 to Po210 in FIG. 1).

In this way, by dividing the tire outer profiles Po1 and Po2 into four or more parts and subdividing the profile, it is possible to reduce the contact pressure in areas where the contact pressure was previously locally high. This makes it possible to level out the contact pressure by preventing areas where the contact pressure differs significantly in any tire width direction area when viewed as a whole tire, thereby improving dry handling stability and, as a result, achieving a good balance between dry handling stability and wet handling stability.

If the tire outer profiles Po1, Po2 are divided into only two or three parts, the shape of the profile part improved to reduce the ground pressure when leveling out the ground pressure will be significantly different from the shape of the adjacent profile part. Therefore, in such a case, there is a risk of the so-called buckling (a phenomenon in which the tread surface is curved in a wave shape) occurring. Therefore, in this embodiment, the number of profile parts after dividing the tire outer profiles Po1, Po2 is set to four or more.

In this embodiment, each of the tire outer profiles Po1 and Po2 has a dimension that is 20% to 35% of the dimension between the two ground contact ends E1 and E2 along a virtual tire profile when it is assumed that there is no groove between the two ground contact ends E1 and E2. Hereinafter, the ratio of the dimension of the tire outer profiles Po1 and Po2 along the tire profile may be referred to as the "tire outer profile ratio". By setting the tire outer profile ratio to 20% or more, the tire outer profiles Po1 and Po2 that are the target of the ground pressure reduction can be sufficiently secured. As a result, the number of divisions of the tire outer profiles Po1 and Po2 can be sufficiently secured, and the ground pressure reduction effect can be sufficiently obtained, resulting in excellent dry handling stability. Note that when the tire outer profile ratio is 22% or more, the above effect is achieved at a higher level, which is preferable, and when it is 25% or more, the above effect is achieved at an even higher level, which is extremely preferable.

In contrast, by setting the tire outer profile ratio to 35% or less, the tire inner profile Pi, which is mainly responsible for drainage, can be sufficiently secured, resulting in excellent wet handling stability. Note that if the tire outer profile ratio is set to 33% or less, the above effect is achieved to a higher level, which is preferable, and if it is set to 30%, the above effect is achieved to an even higher level, which is extremely preferable.

The pneumatic tire according to the present invention further has a plurality of first inclined grooves extending outward in the tire width direction at an inclination angle of ±45° or less with respect to the tire width direction in one or both of the vehicle-mounted outer shoulder land portion 22 and the vehicle-mounted inner shoulder land portion 24, which are located at the outermost sides in the tire width direction in a plan view of the tire, thereby improving drainage performance and maintaining wet handling stability at the same level as conventional technology.

2 illustrates an embodiment in which both the outer shoulder land portion 22 and the inner shoulder land portion 24 have a plurality of first inclined grooves 130, 132 extending toward the outside in the tire width direction at an inclination angle of ±45° or less with respect to the tire width direction. As shown in the figure, when the plurality of first inclined grooves 130 provided in the outer shoulder land portion 22 reach at least one of the circumferential main groove 14 and the ground contact end E1, the drainage performance is improved and wet handling stability is improved, but the rigidity of the land portion 22 is reduced and dry handling stability is deteriorated. Therefore, when dry handling stability is to be prioritized over wet handling stability, it is preferable that the plurality of first inclined grooves 130 terminate both tire width direction ends within the land portion and do not reach the ground contact end E1.

Similarly, in the example shown in FIG. 2, when the multiple first inclined grooves 132 provided in the vehicle-mounted inner shoulder land portion 24 reach at least one of the inclined grooves, the circumferential main groove 20, and the ground contact end E2, the drainage performance is improved and wet handling stability is improved, but the rigidity of the land portion 24 is reduced and dry handling stability is deteriorated. Therefore, when dry handling stability is to be prioritized over wet handling stability, it is preferable that the multiple first inclined grooves 132 terminate both ends in the land portion in the tire width direction and do not reach the ground contact end E2.

In the embodiment illustrated in FIG. 2, the first inclined grooves 130, 132 are provided at a constant pitch in the tire circumferential direction (CD) in the vehicle-mounted outer shoulder land portion 22 or the vehicle-mounted inner shoulder land portion 24.

When the inclination angle of the first inclined grooves 130, 132 with respect to the tire width direction exceeds ±45°, assuming that the tire width direction dimensions of the first inclined grooves 130, 132 are constant, the surface area of the first inclined grooves 130, 132 increases. As a result, the rigidity of the land portions 22, 24 decreases, and both dry and wet handling stability decrease. Here, the inclination angle of the first inclined grooves 130, 132 means the angle α formed by the tangent to the center line (C) of the groove width of the first inclined groove at any point on the center line and the tire width direction, as shown in FIG. 3.

Furthermore, by having the plurality of first inclined grooves 130, 132 have a groove width of 2.0 mm or more and 10.0 mm or less, the groove area is sufficiently secured to improve drainage performance, and the rigidity of the land portions 22, 24 is increased without excessively increasing the groove area, thereby achieving further improvement in wet handling stability. The length of the first inclined grooves 130, 132 is preferably independently selected from the range of 40 mm to 80 mm. Here, the length of the first inclined grooves 130, 132 means the length of the center line of the groove width of the first inclined grooves 130, 132. Note that in this specification, the length means the length of the center line of the groove for all grooves, not limited to the first inclined groove.

As described above, the pneumatic tire according to this embodiment can improve the dry handling stability by improving the tire outer profile, and can achieve wet handling stability comparable to that of the conventional tire by improving the inclined grooves formed in the shoulder land portion. As a result, the pneumatic tire according to the present invention can improve the dry handling stability and the wet handling stability in a well-balanced manner. In addition, for at least four differently shaped curves of each tire outer profile (curves Po101 to Po110 and Po201 to Po210 of different shapes in FIG. 1), it is preferable to gradually reduce the radius of curvature from the curve on the inner side in the tire width direction to the curve on the outer side in order to efficiently obtain the effect of leveling the ground contact pressure in the tire width direction.

The pneumatic tire according to the present embodiment shown above has a meridian cross-sectional shape similar to that of a conventional pneumatic tire, although the entire tire is not shown. That is, the pneumatic tire according to the present embodiment has, from the inner side to the outer side in the tire radial direction, a bead portion, a sidewall portion, a shoulder portion, and a tread portion in the tire meridian cross-sectional view. The pneumatic tire has, for example, a carcass layer that extends from the tread portion to the bead portions on both sides in the tire meridian cross-sectional view and is wound around a pair of bead cores, and has a belt layer as described above and, in some cases, a belt cover layer on the tire radial outer side of the carcass layer.

The pneumatic tire according to the present embodiment described above is obtained through each of the usual manufacturing steps, i.e., a tire material mixing step, a tire material processing step, a green tire molding step, a vulcanization step, and a post-vulcanization inspection step. When manufacturing the pneumatic tire according to the present embodiment, for example, convex and concave portions corresponding to the tread pattern shown in FIG. 2 are formed on the inner wall of a vulcanization mold, and vulcanization is performed using this mold.

Additional Embodiments Next, additional embodiments 1 to 9 that can be implemented optionally with respect to the above-described basic embodiment of the pneumatic tire according to the present invention will be described.

Additional Form 1
In the basic form, it is preferable that the first inclined grooves 130, 132 shown in FIG. 2 do not communicate with any of the circumferential main grooves (the circumferential main groove 14 for the inclined groove 130, and the circumferential main groove 20 for the inclined groove 132) (additional form 1).

As described above, multiple first inclined grooves 130 are provided in the vehicle-mounted outer shoulder land portion 22, and when the multiple first inclined grooves 130 are connected to the circumferential main groove 14, wet handling stability is improved while dry handling stability is deteriorated. Therefore, when dry handling stability is to be prioritized over wet handling stability, it is preferable that the multiple first inclined grooves 130 are not connected to the circumferential main groove 14. Similarly, multiple first inclined grooves 132 are provided in the vehicle-mounted inner shoulder land portion 24, and when the first inclined grooves 132 are connected to the circumferential main groove 20, wet handling stability is improved while dry handling stability is deteriorated. Therefore, when dry handling stability is to be prioritized over wet handling stability, it is preferable that the multiple first inclined grooves 132 are not connected to the circumferential main groove 20.

Additional Form 2
In the basic form or the form obtained by adding Additional Form 1 to the basic form, it is preferable that the groove area ratio GR of the ground contact area shown in FIG. 2 is 10% or more and 30% or less, and that the groove area ratio Gri of the ground contact area in the vehicle-mounted inner region from the tire equator line CL and the groove area ratio Gro of the ground contact area in the vehicle-mounted outer region from the tire equator line CL satisfy the relationship Gri>Gro (Additional Form 2).

The outer side of the tread 10 of the pneumatic tire 1 contributes more to dry handling stability than the inner side, so it is preferable not to reduce the rigidity of the land portion on the outer side. However, if the proportion of grooves on the outer side is reduced to improve dry handling stability, wet handling stability will decrease. Therefore, in order to improve wet handling stability when viewed as a whole tire without compromising the rigidity of the land portion on the outer side of the tread, the groove area ratio Gri on the inner side of the tread can be made larger than the groove area ratio Gro on the outer side of the tread, thereby efficiently achieving both dry handling stability and wet handling stability.

Additional Form 3
In the basic form or the basic form plus at least one of additional forms 1 and 2, as illustrated in Fig. 2, a plurality of second inclined grooves 140 communicating with the circumferential main groove 14 are provided in the vehicle-mounted outer shoulder land portion 22, and the second inclined grooves 140 preferably include narrow groove portions 140a each having a width of 50% or less of the first inclined groove 130 and a width of 2.0 mm to 10.0 mm (additional form 3). As illustrated in Fig. 2, the second inclined groove 140 is composed of a narrow groove portion 140a on the outer side in the tire width direction and a wide groove portion 140b communicating with the circumferential main groove 14 on the inner side in the tire width direction relative to the narrow groove portion 140a.

The vehicle-mounted outer shoulder land portion 22 is the portion of the tread surface that contributes greatly to dry handling stability, so it is preferable not to reduce the rigidity of the land portion. However, if the proportion of grooves in the vehicle-mounted outer shoulder land portion 22 is reduced in order to improve dry handling stability, wet handling stability will decrease. Therefore, in order to improve wet handling stability when viewed as a whole tire without compromising the land portion rigidity of the vehicle-mounted outer shoulder land portion 22, it is preferable that the second inclined groove 140 including the narrow groove portion 140a having the specific groove width as described above is provided in the vehicle-mounted outer shoulder land portion 22.

In order to minimize the decrease in the land portion rigidity of the vehicle-mounted outer shoulder land portion 22, it is preferable that at least one end in the tire width direction of the narrow groove portion 140a constituting the second inclined groove 140 terminates within the vehicle-mounted outer shoulder land portion 22. The second inclined groove 140 may be composed of only the narrow groove portion 140a. Alternatively, as illustrated in FIG. 2, the second inclined groove 140 may be composed of a narrow groove portion 140a whose tire width direction outer end terminates and a wide groove portion 140b having a groove width larger than that of the narrow groove 140a, and the narrow groove portion 140a may be connected to the circumferential main groove 14 via the wide groove portion 140b. The wide groove portion 140b may have a groove width of 2.0 mm or more and 10.0 mm or less. The inclination angle of the second inclined groove 140 with respect to the tire width direction is preferably ±45° or less, similar to the inclination angles of the first inclined grooves 130 and 132.

When the second inclined groove 140 is composed only of the narrow groove portion 140a, the length of the narrow groove portion 140a is preferably 10 mm to 20 mm. When the second inclined groove is composed of the narrow groove portion 140a and the wide groove portion 140b, the length of the narrow groove portion 140a is preferably 12 mm to 28 mm, and the length of the wide groove portion 140b is preferably 2 mm to 8 mm.

Additional Form 4
In the basic form or a form in which at least one of Additional Forms 1 to 3 is added to the basic form, at least one circumferential narrow groove 200 communicating with the plurality of first inclined grooves 132 is provided in the vehicle-mounted inner land portion 24 shown in FIG. 2, the circumferential narrow groove 200 is located toward the tire equator line CL from the tire width direction center of the vehicle-mounted inner shoulder land portion 24, and the circumferential narrow groove 200 preferably has a groove width of 1.0 mm or more and 5.0 mm or less (Additional Form 4).

By providing the circumferential narrow grooves 200 extending in the tire circumferential direction in the vehicle-mounted inner shoulder land portion 24, wet handling stability can be further improved. If the groove width of the circumferential narrow grooves 200 is less than 1.0 mm, wet handling stability cannot be significantly improved. If the groove width of the circumferential narrow grooves 200 exceeds 5.0 mm, the rigidity of the land portion 24 decreases, resulting in a decrease in dry handling stability. The upper limit of the groove width of the circumferential narrow grooves 200 is typically 3 mm, and the groove width of the circumferential narrow grooves 200 is preferably 1 to 5 mm.

Additional Form 5
In the basic form or a form obtained by adding at least one of Additional Forms 1 to 4 to the basic form, as shown in FIG. 2, a first center land portion 26, a second center land portion 28, and a third center land portion 30 are defined and formed between the vehicle-mounted outer shoulder land portion 22 and the vehicle-mounted inner shoulder land portion 24 from the vehicle-mounted outer shoulder land portion 22 side toward the vehicle-mounted inner side, and the first center land portion 26 includes a third inclined groove 150 that communicates with the first circumferential main groove 14 and terminates within the land portion 26, and a third inclined groove 150 that communicates with the circumferential main groove 16 and terminates within the land portion 26. The second center land portion 28 is provided with a fourth inclined groove 160 that terminates within the land portion 26, the second center land portion 28 is provided with a fifth inclined groove 170 that communicates with the circumferential main groove 18 and terminates within the land portion 28, and the third center land portion 30 is provided with a sixth inclined groove 180 that communicates with the circumferential main groove 20 and terminates within the land portion 30, and it is preferable that the third inclined groove 150, the fourth inclined groove 160, the fifth inclined groove 170 and the sixth inclined groove 180 each have a groove width of 2.0 mm or more and 10.0 mm or less (Additional Form 5).

In the above-mentioned additional embodiment 4, since the vehicle-mounted inner shoulder land portion 24 is provided with the circumferential narrow groove 200 extending in the tire circumferential direction, the ground contact pressure is higher on the vehicle-mounted outer side than on the vehicle-mounted inner side, and the ground contact pressure of the tire tends to be biased in the tire width direction. Therefore, in order to minimize the bias of the ground contact pressure of the tire in the additional embodiment 4, the first center land portion 26 is provided with a third inclined groove 150 that communicates with the circumferential main groove 14 and terminates within the land portion 26, and a fourth inclined groove 160 that communicates with the circumferential main groove 16 and terminates within the land portion 26, and the second center land portion 28 and the third center land portion 30 are preferably provided with inclined grooves (i.e., the fifth inclined groove 170 and the sixth inclined groove 180) only on the vehicle-mounted inner side. If the groove width of each of the third inclined groove 150, the fourth inclined groove 160, the fifth inclined groove 170, and the sixth inclined groove 180 is less than 2.0 mm, the groove area ratio cannot be increased and wet handling stability cannot be significantly improved. If the groove width of each of the third inclined groove 150, the fourth inclined groove 160, the fifth inclined groove 170, and the sixth inclined groove 180 exceeds 10.0 mm, the rigidity of the land portions 26, 28, and 30 decreases, resulting in a decrease in dry handling stability.

The lengths of the third inclined groove 150, the fourth inclined groove 160, the fifth inclined groove 170, and the sixth inclined groove 180 are preferably independently selected from the range of 2 mm to 8 mm. Here, the inclination angles of the third inclined groove 150, the fourth inclined groove 160, the fifth inclined groove 170, and the sixth inclined groove 180 with respect to the tire width direction are preferably ±45° or less, similar to the inclination angles of the first and second inclined grooves.

Additional Form 6
In a configuration in which at least Additional Configuration 5 is added to the basic configuration, it is preferable that at least one circumferential narrow groove 210 having a groove width of 1.0 mm or more and 5.0 mm or less is provided in the third center land portion 30 as shown in FIG. 2 (Additional Configuration 6).

By providing at least one circumferential narrow groove 210 with a groove width of 1.0 mm or more and 5.0 mm or less in the third center land portion 30, the groove area ratio is increased, and wet handling stability can be further improved. As illustrated in FIG. 2, the circumferential narrow groove 210 provided in the third center land portion 30 may be connected to the sixth inclined groove 180. When the circumferential narrow groove 210 is connected to the sixth inclined groove 180, the sixth inclined groove 180 may be composed of a narrow groove portion and a wide groove portion having a groove width larger than that of the narrow groove portion, as described above with respect to the second inclined groove 140. When the sixth inclined groove 180 is composed of a narrow groove portion and a wide groove portion, the length of the narrow groove portion is preferably 2 mm to 8 mm, and the length of the wide groove portion is preferably 10 mm to 20 mm.

Additional Form 7
In the basic form or a form in which at least one of additional forms 1 to 6 is added to the basic form, it is preferable that the radius of curvature (hereinafter, sometimes referred to as "curvature radius 1") of the innermost curve in the tire width direction among the portions (curves) constituting at least one of the tire outer profiles Po1 and Po2 in Figure 1 (profile portion Po101 and/or profile portion Po201 in the same figure) is 0.40 to 0.60 times the radius of curvature (hereinafter, sometimes referred to as "curvature radius 2") of the outermost curve in the tire width direction among the portions (curves) constituting the tire inner profile Pi (profile Pi itself in the example shown in Figure 1) (additional form 7).

By setting the ratio of curvature radius 1 to curvature radius 2 (curvature radius 1/curvature radius 2) to 0.40 or more, the occurrence of buckling at the connection points between the adjacent curves can be further suppressed without excessively differentiating the shapes of profile portion Po101 and/or profile portion Po201 from the adjacent tire inner profile Pi.

In response to this, by setting the ratio of curvature radius 1 to curvature radius 2 (curvature radius 1/curvature radius 2) to 0.60 or less, the radius of curvature of the tire outer profile Po1 (Po2) corresponding to the shoulder region where the ground contact pressure is relatively high can be made to be further different from the radius of curvature of the tire inner profile Pi corresponding to the center region where the ground contact pressure is relatively low. This further prevents the occurrence of areas where the ground contact pressure is significantly different in any of the tire width direction regions when viewed as a whole tire, thereby further improving dry handling stability and, as a result, achieving a better balance between dry handling stability and wet handling stability.

It is more preferable that the ratio of the radius of curvature 1 to the radius of curvature 2 (radius of curvature 1/radius of curvature 2) is 0.42 or more and 0.58 or less, since the above-mentioned effects are achieved at a higher level, and it is extremely preferable that the ratio is 0.45 or more and 0.55 or less, since the above-mentioned effects are achieved at an even higher level.

Additional Form 8
In the basic form or a form in which at least one of additional forms 1 to 7 is added to the basic form, it is preferable that the radius of curvature (hereinafter sometimes referred to as "radius of curvature 3") of the profile portion Po102 (Po202) that is second from the inside in the tire width direction among the curves that constitute the tire outer profile Po1 (tire outer profile Po2) shown in FIG. 1 is 0.70 to 0.90 times the radius of curvature 1 of the profile portion Po101 (Po201) that is the innermost in the tire width direction among the curves that constitute the tire outer profile Po1 (tire outer profile Po2) (additional form 8).

By setting the ratio of curvature radius 3 to curvature radius 1 (curvature radius 3/curvature radius 1) to 0.70 or more, it is possible to suppress the occurrence of buckling at the contact point between the profile portion Po102 (profile Po202) and the adjacent profile portion Po101 (profile Po201) without excessively differentiating their shapes.

In contrast, by setting the ratio of curvature radius 3 to curvature radius 1 (curvature radius 3/curvature radius 1) to 0.90 or less, the curvature radius 1 of the profile portion Po101 (profile Po201) on the innermost side in the tire width direction, where the ground contact pressure is relatively low, is made to be further different from the curvature radius 3 of the profile Po102 (profile Po202) on the outer side in the tire width direction, where the ground contact pressure is relatively high. This further suppresses the occurrence of areas with significantly different ground contact pressures in any of the tire width direction regions when viewed as a whole shoulder region, thereby further improving dry handling stability, and as a result, it is possible to improve the balance between dry handling stability and wet handling stability.

It is more preferable that the ratio of the radius of curvature 3 to the radius of curvature 1 (radius of curvature 3/radius of curvature 1) is 0.72 or more and 0.88 or less, since the above-mentioned effects are achieved at a higher level, and it is extremely preferable that the ratio is 0.75 or more and 0.85 or less, since the above-mentioned effects are achieved at an even higher level.

Additional Form 9
In the basic form or a form in which at least one of additional forms 1 to 8 is added to the basic form, it is preferable that the dimension along the tire profile of each profile portion Po101 to Po110 (each profile portion Po201 to Po210) constituting the tire outer profile Po1 (Po2) shown in Fig. 1 (hereinafter, sometimes referred to as "the dimension of each curve") is 2.0% to 5.0% of the tread developed width (additional form 9). Here, the tread developed width refers to the tire width direction dimension TDW between the ground contact ends E1 and E2 in Fig. 1.

By making the dimensions of each profile portion 2.0% or more of the tread development width, it is possible to prevent the tire outer profiles Po1 and Po2 from being divided into an excessively large number of profile portions. This prevents an increase in the number of components of the mold used and an increase in the number of steps required to manufacture the tire, thereby reducing tire manufacturing costs.

In addition, by making the dimensions of each profile portion 5.0% or less of the tread development width, the number of divisions into each profile portion of the tire outer profiles Po1 and Po2 can be ensured sufficiently. In order to equalize the ground contact pressure at the tire width direction inner and outer ends of each of the tire outer profiles Po1 and Po2, it is necessary to make the tire radial direction positions significantly different. However, by ensuring a sufficient number of divisions as described above, it is not necessary to make the curvature radius between adjacent profiles extremely different, and thus buckling can be efficiently suppressed at the connection points between adjacent curves.

It is more preferable that the dimensions of each profile portion are between 2.2% and 4.8% of the tread development width, since the above-mentioned effects are achieved to a higher degree, and it is extremely preferable that the dimensions are between 2.5% and 4.5% of the tread development width, since the above-mentioned effects are achieved to an even higher degree.

The tire size was set to 225/50R18 95V (specified by JATMA), and the pneumatic tires of the invention examples 1 to 9 and the conventional example were manufactured with the shape shown in Figure 1. The detailed conditions of these pneumatic tires are as shown in Table 1 below.

In Table 1, the tire outer profile ratio means the ratio of each dimension along the tire profile of the two tire outer profiles to the dimension between both ground contact ends along the tire profile. The number of divisions of the tire outer profile (both) means the number of elements (profile parts) constituting the tire outer profiles Po1 and Po2 shown in FIG. 1. The curvature radius 1 means the curvature radius of the innermost curve in the tire width direction (profile part Po101, profile part Po201) among the curves constituting the tire outer profiles Po1 and Po2 shown in FIG. The curvature radius 2 means the curvature radius of the tire inner profile Pi shown in FIG. The curvature radius 3 means the curvature radius of the second curve from the inner side in the tire width direction (profile part Po102, profile part Po202) among the curves constituting the tire outer profile Po1 (Po2) shown in FIG. 1. The dimensions of each curve refer to the dimensions along the tire profile of each curve (profile portions Po101-Po110, profile portions Po201-Po210) that make up the tire outer profile Po1 (Po2) shown in FIG. 1. Note that the symbols and other information included in each of the above terms conform to the descriptions in this specification.

The pneumatic tire of Example 1 corresponds to the basic form of pneumatic tire described above, and in plan view of the tire, the vehicle-mounted outer shoulder land portion and the vehicle-mounted inner shoulder land portion had a plurality of first inclined grooves that extended outward in the tire width direction at inclination angles of -30° and +30° with respect to the tire width direction, respectively, and were provided at intervals in the tire circumferential direction. Note that the first inclined grooves provided in the vehicle-mounted outer shoulder land portion and the vehicle-mounted inner shoulder land portion did not communicate with any of the circumferential main grooves, and did not extend to the ground contact ends E1 and E2. The groove width of the first inclined grooves was 6.0 mm.

The pneumatic tire of Example 2 has the same configuration as the pneumatic tire of Example 1, except that the groove area ratio GR of the contact area is 25%, and the groove area ratio Gri of the inner tire contact area on the inside of the tire from the tire equator line of the contact area when mounted on the vehicle and the groove area ratio Gro of the outer tire contact area on the outside of the tire from the tire equator line of the contact area when mounted on the vehicle satisfy the relationship Gri>Gro. Table 1 shows the ratio Gri/Gro of Gri to Gro.

The pneumatic tire of Example 3 has the same configuration as the pneumatic tire of Example 2, except that the vehicle-mounted outer shoulder land portion has multiple second inclined grooves with a groove width of 3 mm that communicate with the vehicle-mounted outermost circumferential direction main groove.

The pneumatic tire of Example 4 has a plurality of first inclined grooves in the vehicle-mounted inner shoulder land portion, and has one circumferential narrow groove that communicates with the plurality of first inclined grooves in the vehicle-mounted inner shoulder land portion, and the circumferential narrow groove is located toward the tire equator line from the tire width center of the vehicle-mounted inner shoulder land portion and has a groove width of 3.0 mm, and has the same configuration as the pneumatic tire of Example 3.

In the pneumatic tire of Example 5, a third inclined groove is provided in the first center land portion, the third inclined groove is connected to a first circumferential main groove that defines a vehicle-mounted outer shoulder land portion and a first center land portion, and terminates within the first center land portion, and a fourth inclined groove is provided in the second circumferential main groove that defines the first center land portion and a second center land portion, and terminates within the first center land portion, and the second center land portion defines a second center land portion and a third center land portion. A fifth inclined groove is provided that communicates with the third circumferential main groove and terminates within the second center land portion, and the third center land portion is provided with a sixth inclined groove that communicates with a fourth circumferential main groove that defines the third center land portion and the vehicle-mounted inner shoulder land portion and terminates within the third center land portion. Except for the fact that the third inclined groove, fourth inclined groove, fifth inclined groove, and sixth inclined groove have a groove width of 6.0 mm, this has the same configuration as the pneumatic tire of invention example 4.

The pneumatic tire of Example 6 has the same configuration as the pneumatic tire of Example 5, except that the third center land portion has one circumferential narrow groove with a groove width of 3.0 mm.

The pneumatic tires of Examples 1 to 9 and the conventional pneumatic tire were evaluated for dry handling and wet handling in the following manner.

(Evaluation of dry and wet handling)
The above test tire was mounted on a rim wheel of a JATMA standard rim with a rim size of 7J, the air pressure was adjusted to 230 kPa, and a front-wheel drive vehicle with an engine displacement of 2000 cc was used as the test vehicle, and the test tires were attached to all wheels of the test vehicle and a test run was performed.

Regarding dry handling stability, the test vehicle was driven on a test course with a flat circular circuit and dry road surface at speeds between 10km/h and 180km/h, and the test driver performed a sensory evaluation of steering during lane changes and cornering, and stability while driving straight. Dry handling stability was expressed as a score with the conventional example being given a score of 100, with the higher the score the better. The results are also shown in Table 1.

Regarding wet handling stability, the test vehicle was driven at 40 km/h on an asphalt road with a 1 mm water film, and the test driver performed a sensory evaluation of the steering during lane changes and cornering, and the stability during straight driving. Wet handling stability was expressed as a score with the conventional example being 100, and the higher the score, the better. The results are shown in Table 1.

According to Table 1, it can be seen that the pneumatic tires of Example 1 to Example 4, which fall within the technical scope of the present invention (i.e., the tire profile in the tire meridian cross section is divided into a tire outer profile and a tire inner profile, and improvements are made particularly to the tire outer profile), all have a well-balanced improvement in dry handling stability and wet handling stability compared to the conventional pneumatic tires not falling within the technical scope of the present invention.
Some of the embodiments of the invention related to the present invention are given below.
[Embodiment 1]
A pneumatic tire having a pattern asymmetric with respect to a tire equatorial plane, in which a plurality of land portions are defined by a plurality of circumferential main grooves,
A meridian cross section of a tire with normal internal pressure and no load.
A tire profile is provided between a vehicle-mounted outer ground contact end and a vehicle-mounted inner ground contact end, the tire profile being composed of a tire inner profile including a tire equator line and two tire outer profiles located on both sides of the tire inner profile in the tire width direction, each of the two tire outer profiles having a dimension that is 20% to 35% of a dimension between both ground contact ends along a virtual tire profile on the assumption that there is no groove between the both ground contact ends,
Each of the tire outer profiles is comprised of at least four different shaped curves;
Plan view of the tire
A plurality of first inclined grooves extending toward the outside in the tire width direction at an inclination angle of ±45° or less with respect to the tire width direction are provided in one or both of a vehicle-mounted outer shoulder land portion and a vehicle-mounted inner shoulder land portion located at the outermost side in the tire width direction,
The first inclined groove has a groove width of 2.0 mm or more and 10.0 mm or less;
A pneumatic tire characterized by:
[Embodiment 2]
2. The pneumatic tire according to embodiment 1, wherein the first inclined groove does not communicate with any of the circumferential main grooves.
[Embodiment 3]
The pneumatic tire according to embodiment 1 or 2, wherein a groove area ratio GR of the contact area is 10% or more and 30% or less, and a groove area ratio Gri of the contact area in the tire inner side from the tire equator line of the contact area on the inside of the tire when mounted on a vehicle and a groove area ratio Gro of the contact area in the tire outer side from the tire equator line of the contact area on the outside of the tire when mounted on a vehicle satisfy the relationship Gri > Gro.
[Embodiment 4]
The pneumatic tire according to any one of embodiments 1 to 3, wherein the vehicle-mounted outer shoulder land portion has a plurality of second inclined grooves that communicate with a vehicle-mounted outermost circumferential main groove, the second inclined grooves being 50% or less of the groove width of the first inclined grooves and including narrow groove portions having a groove width of 2.0 mm or more and 10.0 mm or less.
[Embodiment 5]
A pneumatic tire according to any one of embodiments 1 to 4, comprising the vehicle-mounted inner shoulder land portion having the plurality of first inclined grooves, and at least one circumferential narrow groove communicating with the plurality of first inclined grooves of the vehicle-mounted inner shoulder land portion, the circumferential narrow groove being located toward the tire equator line direction from the tire width direction center of the vehicle-mounted inner shoulder land portion, and the circumferential narrow groove having a groove width of 1.0 mm or more and 5.0 mm or less.
[Embodiment 6]
a first center land portion, a second center land portion, and a third center land portion are defined and formed between the vehicle-mounted inner shoulder land portion and the vehicle-mounted outer shoulder land portion, from the vehicle-outer shoulder land portion toward the inner side in the tire width direction,
the first center land portion is provided with a third inclined groove that communicates with a first circumferential main groove that defines the vehicle-mounted outer shoulder land portion and the first center land portion and terminates within the first center land portion, and a fourth inclined groove that communicates with a second circumferential main groove that defines the first center land portion and the second center land portion and terminates within the first center land portion,
a fifth inclined groove is provided in the second center land portion, the fifth inclined groove being connected to a third circumferential main groove that defines the second center land portion and the third center land portion and terminating within the second center land portion;
a sixth inclined groove is provided in the third center land portion, the sixth inclined groove being connected to a fourth circumferential main groove that defines and partitions the third center land portion and the vehicle-mounted inner shoulder land portion, and terminating within the third center land portion;
The third inclined groove, the fourth inclined groove, the fifth inclined groove, and the sixth inclined groove each have a groove width of 2.0 mm or more and 10.0 mm or less.
A pneumatic tire according to embodiment 5.
[Embodiment 7]
The pneumatic tire according to embodiment 6, wherein at least one circumferential narrow groove having a groove width of 1.0 mm or more and 5.0 mm or less is provided in the third center land portion.
[Embodiment 8]
The pneumatic tire according to any one of embodiments 1 to 7, wherein the radius of curvature of the innermost curve in the tire width direction among the curves constituting the tire outer profile is 0.40 times or more and 0.60 times or less the radius of curvature of the outermost curve in the tire width direction among the curves constituting the tire inner profile.
[Embodiment 9]
A pneumatic tire according to any one of embodiments 1 to 8, wherein the radius of curvature of the second curve from the inner side in the tire width direction among the curves constituting the tire outer profile is 0.70 to 0.90 times the radius of curvature of the innermost curve in the tire width direction among the curves constituting the tire outer profile.
[Embodiment 10]
10. The pneumatic tire according to any one of embodiments 1 to 9, wherein a dimension along the tire profile of each curve constituting the tire outer profile is 2.0% or more and 5.0% or less of the tread developed width.

Reference Signs List 1 Pneumatic tire 10 Tread portion 12 Tread surface 14, 16, 18, 20 Circumferential main groove 22, 24, 26, 28, 30 Land portion 40 Shoulder portion 130, 132 First inclined groove 140 Second inclined groove 140a Narrow groove portion 140b Wide groove portion 150 Third inclined groove 160 Fourth inclined groove 170 Fifth inclined groove 180 Sixth inclined groove 200, 210 Circumferential narrow groove CL Tire equatorial plane, tire equatorial line E1, E2 Ground contact edge Pi Tire inner profile Po1, Po2 Tire outer profile TDW Tread developed width

Claims (22)

A pneumatic tire having a pattern asymmetric with respect to a tire equatorial plane, in which a plurality of land portions are defined by a plurality of circumferential main grooves,
A meridian cross section of a tire with normal internal pressure and no load.
A tire profile is provided between a vehicle-mounted outer ground contact end and a vehicle-mounted inner ground contact end, the tire profile being composed of a tire inner profile including a tire equator line and two tire outer profiles located on both sides of the tire inner profile in the tire width direction, each of the two tire outer profiles having a dimension that is 20% to 35% of a dimension between both ground contact ends along a virtual tire profile on the assumption that there is no groove between the both ground contact ends,
Each of the tire outer profiles is comprised of at least four different shaped curves;
Plan view of the tire
A plurality of first inclined grooves extending toward the outside in the tire width direction at an inclination angle of ±45° or less with respect to the tire width direction are provided in one or both of a vehicle-mounted outer shoulder land portion and a vehicle-mounted inner shoulder land portion located at the outermost side in the tire width direction,
The first inclined groove has a groove width of 2.0 mm or more and 10.0 mm or less,
the first inclined groove does not communicate with any of the circumferential main grooves;
A pneumatic tire characterized by: 2. The pneumatic tire according to claim 1, wherein a groove area ratio GR of the ground contact region is 10% or more and 30% or less, and a groove area ratio Gri of the inner ground contact region of the tire on the inner side of the ground contact region when mounted on a vehicle from the tire equator line of the ground contact region and a groove area ratio Gro of the outer ground contact region of the tire on the outer side of the ground contact region when mounted on a vehicle satisfy a relationship Gri > Gro . 3. The pneumatic tire according to claim 1, wherein the vehicle-mounted outer shoulder land portion has a plurality of second inclined grooves that communicate with a vehicle-mounted outermost circumferential main groove, the second inclined grooves having a groove width of 50% or less of the first inclined grooves and including narrow groove portions having a groove width of 2.0 mm or more and 10.0 mm or less. 4. The pneumatic tire according to claim 1, wherein the vehicle-mounted inner shoulder land portion has the plurality of first inclined grooves, and the vehicle-mounted inner shoulder land portion has at least one circumferential narrow groove communicating with the plurality of first inclined grooves, the circumferential narrow groove being located toward the tire equator line direction from the tire width direction center of the vehicle-mounted inner shoulder land portion, and the circumferential narrow groove has a groove width of 1.0 mm or more and 5.0 mm or less. a first center land portion, a second center land portion, and a third center land portion are defined and formed between the vehicle-mounted inner shoulder land portion and the vehicle-mounted outer shoulder land portion, from the vehicle-outer shoulder land portion toward the inner side in the tire width direction,
the first center land portion is provided with a third inclined groove that communicates with a first circumferential main groove that defines the vehicle-mounted outer shoulder land portion and the first center land portion and terminates within the first center land portion, and a fourth inclined groove that communicates with a second circumferential main groove that defines the first center land portion and the second center land portion and terminates within the first center land portion,
a fifth inclined groove is provided in the second center land portion, the fifth inclined groove being connected to a third circumferential main groove that defines the second center land portion and the third center land portion and terminating within the second center land portion;
a sixth inclined groove is provided in the third center land portion, the sixth inclined groove being connected to a fourth circumferential main groove that defines and partitions the third center land portion and the vehicle-mounted inner shoulder land portion, and terminating within the third center land portion;
The third inclined groove, the fourth inclined groove, the fifth inclined groove, and the sixth inclined groove each have a groove width of 2.0 mm or more and 10.0 mm or less.
The pneumatic tire according to claim 4 . The pneumatic tire according to claim 5 , wherein at least one circumferential narrow groove having a groove width of 1.0 mm or more and 5.0 mm or less is provided in the third center land portion. 7. The pneumatic tire according to claim 1, wherein a radius of curvature of an innermost curve in the tire width direction among the curves constituting the tire outer profile is 0.40 to 0.60 times a radius of curvature of an outermost curve in the tire width direction among the curves constituting the tire inner profile. 8. The pneumatic tire according to claim 1, wherein a radius of curvature of a second curve from the inside in the tire width direction among the curves constituting the tire outer profile is 0.70 to 0.90 times a radius of curvature of an innermost curve in the tire width direction among the curves constituting the tire outer profile. The pneumatic tire according to any one of claims 1 to 8 , wherein a dimension along the tire profile of each curve constituting the tire outer profile is 2.0% to 5.0% of the tread developed width. A pneumatic tire having a pattern asymmetric with respect to a tire equatorial plane, in which a plurality of land portions are defined by a plurality of circumferential main grooves,
A meridian cross section of a tire with normal internal pressure and no load.
A tire profile is provided between a vehicle-mounted outer ground contact end and a vehicle-mounted inner ground contact end, the tire profile being composed of a tire inner profile including a tire equator line and two tire outer profiles located on both sides of the tire inner profile in the tire width direction, each of the two tire outer profiles having a dimension that is 20% to 35% of a dimension between both ground contact ends along a virtual tire profile on the assumption that there is no groove between the both ground contact ends,
Each of the tire outer profiles is comprised of at least four different shaped curves;
Plan view of the tire
A plurality of first inclined grooves extending toward the outside in the tire width direction at an inclination angle of ±45° or less with respect to the tire width direction are provided in one or both of a vehicle-mounted outer shoulder land portion and a vehicle-mounted inner shoulder land portion located at the outermost side in the tire width direction,
The first inclined groove has a groove width of 2.0 mm or more and 10.0 mm or less,
the vehicle-mounted outer shoulder land portion has a plurality of second inclined grooves communicating with the vehicle-mounted outermost circumferential main groove, the second inclined grooves being 50% or less of the groove width of the first inclined grooves and including narrow groove portions having a groove width of 2.0 mm or more and 10.0 mm or less;
A pneumatic tire characterized by: 11. The pneumatic tire according to claim 10, wherein a groove area ratio GR of the ground contact region is 10% or more and 30% or less, and a groove area ratio Gri of the ground contact region in the tire inner side from the tire equator line of the ground contact region on the inside when mounted on a vehicle and a groove area ratio Gro of the ground contact region in the tire outer side from the tire equator line of the ground contact region on the outside when mounted on a vehicle satisfy a relationship Gri > Gro. 12. The pneumatic tire according to claim 10, wherein the vehicle-mounted inner shoulder land portion has the plurality of first inclined grooves, and the vehicle-mounted inner shoulder land portion has at least one circumferential narrow groove communicating with the plurality of first inclined grooves, the circumferential narrow groove being located toward the tire equator line direction from the tire width direction center of the vehicle-mounted inner shoulder land portion, and the circumferential narrow groove has a groove width of 1.0 mm or more and 5.0 mm or less. a first center land portion, a second center land portion, and a third center land portion are defined and formed between the vehicle-mounted inner shoulder land portion and the vehicle-mounted outer shoulder land portion, from the vehicle-outer shoulder land portion toward the inner side in the tire width direction,
the first center land portion is provided with a third inclined groove that communicates with a first circumferential main groove that defines the vehicle-mounted outer shoulder land portion and the first center land portion and terminates within the first center land portion, and a fourth inclined groove that communicates with a second circumferential main groove that defines the first center land portion and the second center land portion and terminates within the first center land portion,
a fifth inclined groove is provided in the second center land portion, the fifth inclined groove being connected to a third circumferential main groove that defines the second center land portion and the third center land portion and terminating within the second center land portion;
a sixth inclined groove is provided in the third center land portion, the sixth inclined groove being connected to a fourth circumferential main groove that defines and partitions the third center land portion and the vehicle-mounted inner shoulder land portion, and terminating within the third center land portion;
The third inclined groove, the fourth inclined groove, the fifth inclined groove, and the sixth inclined groove each have a groove width of 2.0 mm or more and 10.0 mm or less.
The pneumatic tire of claim 12. The pneumatic tire according to claim 13 , wherein at least one circumferential narrow groove having a groove width of 1.0 mm or more and 5.0 mm or less is provided in the third center land portion. The pneumatic tire according to any one of claims 10 to 14, wherein the radius of curvature of the innermost curve in the tire width direction among the curves constituting the tire outer profile is 0.40 times or more and 0.60 times or less of the radius of curvature of the outermost curve in the tire width direction among the curves constituting the tire inner profile. The pneumatic tire according to any one of claims 10 to 15, wherein the radius of curvature of the second curve from the inner side in the tire width direction among the curves constituting the tire outer profile is 0.70 times or more and 0.90 times or less of the radius of curvature of the innermost curve in the tire width direction among the curves constituting the tire outer profile. The pneumatic tire according to any one of claims 10 to 16, wherein a dimension along the tire profile of each curve constituting the tire outer profile is 2.0% or more and 5.0% or less of the tread developed width. A pneumatic tire having a pattern asymmetric with respect to a tire equatorial plane, in which a plurality of land portions are defined by a plurality of circumferential main grooves,
A meridian cross section of a tire with normal internal pressure and no load.
A tire profile is provided between a vehicle-mounted outer ground contact end and a vehicle-mounted inner ground contact end, the tire profile being composed of a tire inner profile including a tire equator line and two tire outer profiles located on both sides of the tire inner profile in the tire width direction, each of the two tire outer profiles having a dimension that is 20% to 35% of a dimension between both ground contact ends along a virtual tire profile on the assumption that there is no groove between the both ground contact ends,
Each of the tire outer profiles is comprised of at least four different shaped curves;
Plan view of the tire
A plurality of first inclined grooves extending toward the outside in the tire width direction at an inclination angle of ±45° or less with respect to the tire width direction are provided in one or both of a vehicle-mounted outer shoulder land portion and a vehicle-mounted inner shoulder land portion located at the outermost side in the tire width direction,
The first inclined groove has a groove width of 2.0 mm or more and 10.0 mm or less,
the vehicle-mounted inner shoulder land portion has the plurality of first inclined grooves, and the vehicle-mounted inner shoulder land portion has at least one circumferential narrow groove communicating with the plurality of first inclined grooves, the circumferential narrow groove being located toward the tire equator line direction from the tire width direction center of the vehicle-mounted inner shoulder land portion, and the circumferential narrow groove has a groove width of 1.0 mm or more and 5.0 mm or less;
a first center land portion, a second center land portion, and a third center land portion are defined and formed between the vehicle-mounted inner shoulder land portion and the vehicle-mounted outer shoulder land portion, from the vehicle-outer shoulder land portion toward the inner side in the tire width direction,
the first center land portion is provided with a third inclined groove that communicates with a first circumferential main groove that defines the vehicle-mounted outer shoulder land portion and the first center land portion and terminates within the first center land portion, and a fourth inclined groove that communicates with a second circumferential main groove that defines the first center land portion and the second center land portion and terminates within the first center land portion,
a fifth inclined groove is provided in the second center land portion, the fifth inclined groove being connected to a third circumferential main groove that defines the second center land portion and the third center land portion and terminating within the second center land portion;
a sixth inclined groove is provided in the third center land portion, the sixth inclined groove being connected to a fourth circumferential main groove that defines and partitions the third center land portion and the vehicle-mounted inner shoulder land portion, and terminating within the third center land portion;
the third inclined groove, the fourth inclined groove, the fifth inclined groove, and the sixth inclined groove each have a groove width of 2.0 mm or more and 10.0 mm or less;
A pneumatic tire characterized by: The pneumatic tire according to claim 18 , wherein at least one circumferential narrow groove having a groove width of 1.0 mm or more and 5.0 mm or less is provided in the third center land portion. 20. The pneumatic tire according to claim 18 or 19, wherein the radius of curvature of the innermost curve in the tire width direction among the curves constituting the tire outer profile is 0.40 to 0.60 times the radius of curvature of the outermost curve in the tire width direction among the curves constituting the tire inner profile. The pneumatic tire according to any one of claims 18 to 20, wherein the radius of curvature of the second curve from the inner side in the tire width direction among the curves constituting the tire outer profile is 0.70 times or more and 0.90 times or less of the radius of curvature of the innermost curve in the tire width direction among the curves constituting the tire outer profile. The pneumatic tire according to any one of claims 18 to 21, wherein a dimension along the tire profile of each curve constituting the tire outer profile is 2.0% or more and 5.0% or less of the tread developed width.

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