Patent Description:
The present invention relates to a tyre.

For example, Patent Document <NUM> below has proposed a tyre provided with first shoulder lateral grooves having tie-bars in which groove bottom surfaces raise locally. The tyre is expected to increase the rigidity of a first shoulder land portion by the tie-bars and improve driving performance on dry road surfaces.

In recent years, with the improvement of vehicle performance, it has been required to further improve steering stability of tyres on dry road surfaces (hereinafter, may be simply referred to as "steering stability"), see for instance <CIT>or <CIT>.

The present invention has been made in view of the above circumstances and has a major object to provide a tyre capable of improving steering stability.

In one aspect of the present invention, a tyre includes a tread portion including a first tread edge, a first shoulder circumferential groove extending in a tyre circumferential direction adjacent to the first tread edge, and a first shoulder land portion demarcated by the first shoulder circumferential groove to include the first tread edge. The first shoulder land portion is provided with a plurality of first shoulder lateral grooves extending from the first shoulder circumferential groove to at least the first tread edge. At least one of the plurality of first shoulder lateral grooves includes a first groove wall and a second groove wall which face each other and extend in a tyre radial direction, and a tie-bar in which a groove bottom portion raises locally. The tie-bar includes an outer surface extending along a ground contact surface of the first shoulder land portion, the outer surface being connected to the first groove wall and the second groove wall. The outer surface includes a first edge connected to the first groove wall, and a second edge connected to the second groove wall, the second edge having a length smaller than a length of the first edge.

Hereinafter, one or more embodiments of the present invention will be described with reference to the drawings.

<FIG> is a development view of a tread portion <NUM> of a tyre <NUM> showing an embodiment of the present invention. The tyre <NUM> according to the present embodiment, for example, is suitably used as a pneumatic tyre for passenger car. However, the present invention is not limited to such an embodiment, and may be applied to a pneumatic tyre for heavy load and a non-pneumatic tyre in which the inside of the tyre is not filled with pressurized air.

As illustrated in <FIG>, the tread portion <NUM> of the tyre <NUM> includes a first tread edge T1, a second tread edge T2, a plurality of circumferential grooves <NUM> extending continuously in the tyre circumferential direction between the first and second tread edges T1 and T2, and a plurality of land portions <NUM> demarcated by the plurality of circumferential grooves <NUM>. The tyre <NUM> according to the present embodiment is a so-called five-land tyre in which the tread portion <NUM> is composed of four circumferential grooves <NUM> and five land portions <NUM>. However, the present invention is not limited to such an aspect. The tyre <NUM> according to another embodiment of the present invention, for example, may be a so-called four-land tyre in which the tread portion <NUM> is composed of three circumferential grooves <NUM> and four land portions <NUM>.

In the present embodiment, the tread portion <NUM> has a designated mounting direction to vehicles. In this embodiment, the first tread edge T1 is intended to be located on the outside of a vehicle when mounted on the vehicle, and the second tread edge T2 is intended to be located on the inside of a vehicle when mounted on the vehicle. However, the present invention is not limited to such an aspect.

The first tread edge T1 and the second tread edge T2 are the axial outermost edges of the ground contacting patch of the tyre <NUM> which occurs under the condition such that the tyre <NUM> under a normal state is grounded on a plane with a standard tyre load at zero camber angles.

As used herein, when a tyre is a pneumatic tyre based on a standard, the "normal state" is such that the tyre <NUM> is mounted onto a standard wheel rim with a standard pressure but loaded with no tyre load. If a tyre is not based on the standards, or if a tyre is a non-pneumatic tyre, the normal state is a standard state of use according to the purpose of use of the tyre and means a state of no load. As used herein, unless otherwise noted, dimensions of portions of the tyre are values measured under the normal state.

As used herein, the "standard pressure" is a standard pressure officially approved for each tyre by standards organizations on which the tyre is based, wherein the standard pressure is the "maximum air pressure" in JATMA, the maximum pressure given in the "Tire Load Limits at Various Cold Inflation Pressures" table in TRA, and the "Inflation Pressure" in ETRTO, for example.

As used herein, when a tyre is a pneumatic tyre based on a standard, the "standard tyre load" is a tyre load officially approved for each tyre by the standards organization in which the tyre is based, wherein the standard tyre load is the "maximum load capacity" in JATMA, the maximum value given in the "Tire Load Limits at Various Cold Inflation Pressures" in TRA, and the "Load Capacity" in ETRTO, for example. For tyres for which various standards have not been established, "standard tyre load" refers to the maximum load applicable to the tyre.

The circumferential grooves <NUM> include a first shoulder circumferential groove <NUM>. The first shoulder circumferential groove <NUM> is arranged adjacent to the first tread edge T1. Further, in the present embodiment, the circumferential grooves <NUM> include a second shoulder circumferential groove <NUM>, a first crown circumferential groove <NUM>, and a second crown circumferential groove <NUM>. The second shoulder circumferential groove <NUM> is arranged adjacent to the second tread edge T2. The first crown circumferential groove <NUM> is arranged between the first shoulder circumferential groove <NUM> and the tyre equator C. The second crown circumferential groove <NUM> is arranged between the second shoulder circumferential groove <NUM> and the tyre equator C.

It is preferable that a distance L1 in the tyre axial direction from the tyre equator C to each of groove centerlines of the first shoulder circumferential groove <NUM> and the second shoulder circumferential groove <NUM>, for example, is of from <NUM>% to <NUM>% of the tread width TW. It is also preferable that a distance L2 in the tyre axial direction from the tyre equator C to each of groove centerlines of the first crown circumferential groove <NUM> and the second crown circumferential groove <NUM>, for example, is of from <NUM>% to <NUM>% of the tread width TW. Note that the tread width TW is the distance in the tyre axial direction from the first tread edge T1 to the second tread edge T2 in the normal state.

In the present embodiment, each of the circumferential grooves <NUM>, for example, extends linearly parallel to the tyre circumferential direction. Each of the grooves <NUM>, for example, may extend in a wavy shape.

A groove width Wa of each of the circumferential grooves <NUM> is preferably at least <NUM>. Further, the groove width Wa of each the circumferential grooves <NUM> is preferably in a range from <NUM>% to <NUM>% of the tread width TW. As a more preferred embodiment, in the present embodiment, the first shoulder circumferential groove <NUM> has the smallest groove width among the plurality of the circumferential grooves <NUM>. However, the present invention is not limited to such an aspect.

The land portions <NUM> includes a first shoulder land portion <NUM>. The first shoulder land portion <NUM> includes the first tread edge T1, and is disposed outwardly in the tyre axial direction of the first shoulder circumferential groove <NUM>. In addition, the land portions <NUM> according to the present embodiment include a second shoulder land portion <NUM>, a first middle land portion <NUM>, a second middle land portion <NUM>, and a crown land portion <NUM>. The second shoulder land portion <NUM> includes the second tread edge T2, and is disposed outwardly in the tyre axial direction of the second shoulder circumferential groove <NUM>. The first middle land portion <NUM> is disposed between the first shoulder circumferential groove <NUM> and the first crown circumferential groove <NUM>. The second middle land portion <NUM> is disposed between the second shoulder circumferential groove <NUM> and the second crown circumferential groove <NUM>. The crown land portion <NUM> is disposed between the first crown circumferential groove <NUM> and the second crown circumferential groove <NUM>.

<FIG> illustrates an enlarged view of the first shoulder land portion <NUM> and the first middle land portion <NUM>. As illustrated in <FIG>, the first shoulder land portion <NUM> is provided with a plurality of first shoulder lateral grooves <NUM> extending from the first shoulder circumferential groove <NUM> to at least the first tread edge T1. In the present embodiment, the first shoulder lateral grooves <NUM> extend beyond the first tread edge T1.

<FIG> illustrates an enlarged perspective view of one of the first shoulder lateral grooves <NUM>. <FIG> illustrates a cross-sectional view taken along the line A-A of <FIG>. As illustrated in <FIG> and <FIG>, at least one of the first shoulder lateral grooves <NUM> includes a first groove wall <NUM> and a second groove wall <NUM> which face each other and extend in the tyre radial direction, and a tie-bar <NUM> in which a groove bottom portion raises locally. In the present embodiment, the first groove wall <NUM> is located on a first side in the tyre circumferential direction of the first shoulder lateral groove <NUM> (e.g., corresponding to the upper side in <FIG>), and the second groove wall <NUM> is located on a second side in the tyre circumferential direction of the first shoulder lateral groove <NUM> (e.g., corresponding to the lower side in <FIG>).

<FIG> illustrates a cross-sectional view taken along the line B-B of <FIG>. As illustrated in <FIG>, the tie-bar <NUM> includes an outer surface <NUM> extending along a ground contact surface of the first shoulder land portion <NUM>, and the outer surface <NUM> is connected to the first groove wall <NUM> and the second groove wall <NUM>. <FIG> illustrates an enlarged plan view of the outer surface <NUM>. As illustrated in <FIG>, the outer surface <NUM> includes a first edge <NUM> connected to the first groove wall <NUM>, and a second edge <NUM> connected to the second groove wall <NUM>. The first edge <NUM> and the second edge <NUM> are boundaries between the outer surface <NUM> and a respective one of the first groove wall <NUM> and the second groove wall <NUM>. When the outer surface <NUM> is connected to the first groove wall <NUM> or the second groove wall <NUM> via a curved surface, the boundary is the intermediate position of the curve constituting the curved surface in a cross section of the first shoulder lateral groove <NUM>.

The second edge <NUM> has a length L4 smaller than a length L3 of the first edge <NUM>. The tyre <NUM> according to the present invention can improve steering stability by adopting the above configuration. The reason can be inferred as follows, for example.

In the present invention, by providing the tie-bar <NUM> in the at least one first shoulder lateral groove <NUM>, the rigidity of the first shoulder land portion <NUM> can be improved, and it is expected that the steering stability can be improved.

As a result of diligent research, the inventors have found that the conventional tie bar could exert the effect of improving the rigidity of the tread land portion, but the ground contact surface of the land portion was slightly distorted around the tie-bar, and the ground pressure around the tie bar became non-uniform.

In order to make the above-mentioned ground pressure uniform, in the present invention, the length L4 of the second edge <NUM> of the outer surface <NUM> of the tie-bar <NUM> is set smaller than the length L3 of the first edge <NUM>. As a result, moderate deformation can be expected on the second groove wall <NUM> side where the second edge <NUM> is connected, and the ground pressure acting around the tie-bar can be made uniform. Thus, a large gripping force can be exhibited in the area around the tie-bar, and further improvement in steering stability can be expected. Such an effect cannot be realized only by adjusting the length of the conventional tie bar, but can be realized by facing the second edge <NUM>, which promotes appropriate deformation, with the first edge <NUM>, which has a high rigidity improving effect. That is, the tyre <NUM> according to the present invention can significantly improve the steering stability as compared with tyres having a conventional tie-bar.

Hereinafter, a more detailed configuration of the present embodiment will be described. Note that each configuration described below shows a specific aspect of the present embodiment. Thus, the present invention can exert the above-mentioned effects even if it does not include the configuration described below. Further, if any one of the configurations described below is applied independently to the tyre of the present invention having the above-mentioned characteristics, the performance improvement according to each additional configuration can be expected. Furthermore, when some of the configurations described below are applied in combination, it is expected that the performance of the additional configurations will be improved.

As illustrated in <FIG>, the first shoulder lateral grooves <NUM> have substantially the same configuration. Further, the first shoulder lateral grooves <NUM>, for example, are inclined at a small angle with respect to the tyre axial direction. The angle of the first shoulder lateral grooves <NUM> with respect to the tyre axial direction, for example, is equal to or less than <NUM> degrees.

As illustrated in <FIG>, the maximum depth d1 of the first shoulder lateral grooves <NUM> is in a range from <NUM>% to <NUM>% of the maximum depth of the first shoulder circumferential groove <NUM> (shown in <FIG>). Such first shoulder lateral grooves <NUM> can exert a good balance between steering stability and wet performance.

As illustrated in <FIG> and <FIG>, it is preferable that each tie-bar <NUM> is arranged inwardly in the tyre axial direction from the center position in the tyre axial direction of the ground contact surface (the surface between the first tread edge T1 and the first shoulder circumferential groove <NUM>) of the first shoulder land portion <NUM>. As a more preferred embodiment, each tie-bar <NUM> of the present embodiment is provided on the end of each first shoulder lateral groove <NUM> on the first shoulder circumferential groove <NUM> side. Such a tie-bar <NUM> can help to improve steering stability.

As illustrated in <FIG>, a depth d2 from the ground contact surface of the first shoulder land portion <NUM> to the outer surface <NUM> of the tie-bar <NUM> is preferably in a range from <NUM>% to <NUM>% of the maximum depth d1 of the first shoulder lateral grooves <NUM> (shown in <FIG>). This can improve steering stability and wet performance in a well-balanced manner.

As illustrated in <FIG>, in a tread plan view, the outer surface <NUM> of each tie-bar <NUM> preferably has a trapezoidal shape. That is, the outer surface <NUM> has a quadrilateral shape surrounded by the first edge <NUM> and the second edge <NUM> which extend parallel to each other, and a third edge <NUM> and a fourth edge <NUM> which extend non-parallel to each other. The third edge <NUM> is located on the first tread edge T1 (shown in <FIG>) side, and the fourth edge <NUM> is located on the first shoulder circumferential groove <NUM> (shown in <FIG>) side. However, the outer surface <NUM> of the present invention is not limited to such an aspect.

The length L3 of the first edge <NUM> and the length L4 of the second edge <NUM> are preferably in a range from <NUM>% to <NUM>% of a width W5 in the tyre axial direction of the ground contact surface of the first shoulder land portion <NUM> (shown in <FIG>). The length L4 of the second edge <NUM> is preferably equal to or more than <NUM>% of the length L3 of the first edge <NUM>, more preferably equal to or more than <NUM>%, but preferably equal to or less than <NUM>%, more preferably equal to or less than <NUM>%. By setting the relationship between the length L3 and the length L4 in this way, the third edge <NUM>, for example, is inclined at an angle of from <NUM> to <NUM> degrees with respect to the tyre axial direction. The fourth edge <NUM> extends along the tyre circumferential direction. The outer surface <NUM> which has the edges defined in this way can improve the stiffness of the first shoulder land portion <NUM> and make the ground pressure uniform, further improving steering stability.

An area of the outer surface <NUM> of each tie-bar <NUM> is preferably equal to or more than <NUM>% of an opening area of each first shoulder lateral groove <NUM> (shown in <FIG>) between the first tread edge T1 and the first shoulder circumferential groove <NUM>, more preferably equal to or more than <NUM>%, but preferably equal to or less than <NUM>%, more preferably equal to or less than <NUM>%. This can improve steering stability and wet performance in a well-balanced manner.

As illustrated in <FIG> and <FIG>, it is preferable that one or more first shoulder lateral grooves <NUM> may include chamfer portions <NUM>. The chamfer portions <NUM> include inclined surfaces formed between the ground contact surface of the first shoulder land portion <NUM> and the groove walls. Such chamfer portions <NUM> can help to further improve the uniformity of the ground pressure.

The inventors have found that the size of the inclined surfaces of the chamfer portions <NUM> were specified according to the lengths of the first edge <NUM> and the second edge <NUM> of the outer surface <NUM>, and the above-mentioned effect could be further improved. Based on such findings, the chamfer portions <NUM> according to the present embodiment include a first inclined surface <NUM> extending from the ground contact surface of the first shoulder land portion <NUM> to the first groove wall <NUM>, and a second inclined surface <NUM> extending from the ground contact surface to the second groove wall <NUM>, and in a tread plan view the maximum width W2 of the second inclined surface <NUM> is greater than the maximum width W1 of the first inclined surface <NUM>. As a result, the second inclined surface <NUM> with a large width is provided on the side of the second groove wall <NUM>, which is easily deformed. Thus, the second inclined surface <NUM> can come into contact with the ground due to the deformation of the second groove wall <NUM>, and the steering stability can further be improved.

The width W1 of the first inclined surface <NUM>, for example, is in a range from <NUM> to <NUM>. The width W2 of the second inclined surface <NUM>, for example, is in a range from <NUM> to <NUM>. When the second inclined surface <NUM> is excessively small, it becomes difficult to obtain the above effects. When the second inclined surface <NUM> is excessively large, the ground contact surface of the first shoulder land portion <NUM> becomes small, which may impair steering stability. From this point of view, the width W2 of the second inclined surface <NUM> is preferably equal to or more than <NUM> times the width W1 of the first inclined surface <NUM>, more preferably equal to or more than <NUM> times, but preferably equal to or less than <NUM> times, more preferably equal to or less than <NUM> times.

An angle θ1 of the first inclined surface <NUM>, for example, is in a range from <NUM> to <NUM> degrees with respect to a tyre normal line. An angle θ2 of the second inclined surface <NUM> with respect to a tyre normal line is greater than the angle θ1. For example, the angle θ2 is in a range from <NUM> to <NUM> degrees. However, the invention is not limited to such an aspect.

As illustrated in <FIG>, at least one of the first shoulder lateral grooves <NUM> is provided with a groove bottom sipe <NUM> opening at the outer surface <NUM>. A depth d3 from the ground contact surface of the first shoulder land portion <NUM> to a bottom of the groove bottom sipe <NUM>, for example, is in a range from <NUM>% to <NUM>% of the maximum depth d1 of the first shoulder lateral groove <NUM> (shown in <FIG>). Such a groove bottom sipe <NUM> can help to maintain the drainage of the first shoulder lateral groove <NUM>. As used herein, "sipe" means an incision having a width of from <NUM> to <NUM>.

As illustrated in <FIG>, the first middle land portion <NUM> is provided with a plurality of first middle shallow grooves <NUM>. The first middle shallow grooves <NUM>, for example, extend from the first shoulder circumferential groove <NUM> and terminate within the first middle land portion <NUM>. Such first middle shallow grooves <NUM> can help to maintain the rigidity of the first middle land portion <NUM> and enhance steering stability.

Preferably, the first middle shallow grooves <NUM> are in communication with the first shoulder circumferential groove <NUM> at positions close to the respective first shoulder lateral grooves <NUM>. In particular, it is preferable that areas where the ends of the respective first shoulder lateral grooves <NUM> on the first shoulder circumferential groove <NUM> side are extended parallel to the tyre axial direction overlap more than <NUM>% of the groove widths of the ends of the respective first middle shallow grooves <NUM> on the first shoulder circumferential groove <NUM> side. Such an arrangement of the first shoulder lateral grooves <NUM> and the first middle shallow grooves <NUM> can help to improve wet performance.

<FIG> illustrates a cross-sectional view taken along the line C-C of <FIG>. As illustrated in <FIG>, in the present embodiment, each first middle shallow groove <NUM> includes a main portion <NUM> and a middle groove-bottom sipe <NUM> extending inwardly in the tyre radial direction from a groove bottom of the main portion <NUM>. A depth d4 of the main portion <NUM>, for example, is smaller than the depth d2 (shown in <FIG>) from the ground contact surface of the first shoulder land portion <NUM> to the outer surface <NUM> of the tie-bar <NUM>. Preferably, the depth d4 is in a range from <NUM>% to <NUM>% of the depth d2, for example. A total depth d5 of the first middle shallow grooves <NUM>, for example, is in a range from <NUM>% to <NUM>% of the maximum depth d1 (shown in <FIG>) of the first shoulder lateral grooves <NUM>. Such first middle shallow grooves <NUM> can help to improve the balance between steering stability and wet performance.

The main portion <NUM> of each first middle shallow groove <NUM>, for example, includes a first shallow groove wall <NUM> and a second shallow groove wall <NUM> which are different in width in a tread plan view. In a tread plan view, a width W4 of the second shallow groove wall <NUM> is greater than a width W3 of the first shallow groove wall <NUM>. Specifically, the width W4 of the second shallow groove wall <NUM> is in a range from <NUM> to <NUM> times the width W3 of the first shallow groove wall <NUM>.

In some preferred embodiments, as illustrated in <FIG>, each first shallow-groove wall <NUM> is located on the first side in the tyre circumferential direction of each first middle shallow groove <NUM>, and each second shallow-groove wall <NUM> is located on the second side in the tyre circumferential direction of each first middle shallow groove <NUM>. As a result, the progress of wear can be made uniform in the first shoulder land portion <NUM> and the first middle land portion <NUM>, and the uneven wear resistance performance can be improved.

Preferably, the first middle land portion <NUM> is provided with one or more connecting sipes <NUM> each extending from either one of the first middle shallow grooves <NUM> to the first crown circumferential groove <NUM>. In the present embodiment, the first middle shallow grooves <NUM> with the connecting sipes <NUM> and the first middle shallow grooves <NUM> without the connecting sipes <NUM> are alternately arranged in the tyre circumferential direction. The connecting sipes <NUM> can provide frictional force during wet driving while maintaining the rigidity of the first middle land portion <NUM>.

<FIG> illustrates an enlarged view of the second shoulder land portion <NUM>, the second middle land portion <NUM> and the crown land portion <NUM>. As illustrated in <FIG>, the second shoulder land portion <NUM> is provided with a plurality of second shoulder lateral grooves <NUM>. The second shoulder lateral grooves <NUM>, for example, extend inwardly from at least the second tread edge T2 and terminate without reaching the second shoulder circumferential groove <NUM>. Such second shoulder lateral grooves <NUM> can improve steering stability and wet performance in a well-balanced manner.

<FIG> illustrates a cross-sectional view taken along the line D-D of <FIG>. As illustrated in <FIG>, one or more second shoulder lateral grooves <NUM> include chamfer portions <NUM>. The chamfer portions <NUM> includes a third inclined surface <NUM> and a fourth inclined surface <NUM>. In a tread plan view, a width of the third inclined surface <NUM> is greater than a width of the fourth inclined surface <NUM>. The configuration of each second inclined surface <NUM> (shown in <FIG>) of the first shoulder lateral grooves <NUM> described above can be applied to each third inclined surface <NUM>. The configuration of each first inclined surface <NUM> (shown in <FIG>) of the first shoulder lateral grooves <NUM> described above can be applied to each fourth inclined surface <NUM>.

As illustrated in <FIG>, each third inclined surface <NUM> is arranged on the first side in the tyre circumferential direction of each second shoulder lateral groove <NUM>, and the fourth inclined surface <NUM> is arranged on the second side in the tyre circumferential direction of each second shoulder lateral groove <NUM>. In other words, the first shoulder lateral grooves <NUM> and the second shoulder lateral grooves <NUM> are opposite in terms of the size relation of the width of the inclined surfaces of the chamfer portions. This can improve traction performance and braking performance on dry roads in a well-balanced manner.

The second middle land portion <NUM> is provided with a plurality of outer second middle shallow grooves <NUM> and a plurality of the inner second middle shallow grooves <NUM>. The outer second middle shallow grooves <NUM> extend from the second crown circumferential groove <NUM> and terminate within the second middle land portion <NUM>. The inner second middle shallow grooves <NUM> extend from the second shoulder circumferential groove <NUM> and terminate within the second middle land portion <NUM>. The outer second middle shallow grooves <NUM> and the inner second middle shallow grooves <NUM> terminate within the second middle land portion <NUM> without crossing the tyre axial center position of the second middle land portion <NUM>. Such outer second middle shallow grooves <NUM> and inner second middle shallow grooves <NUM> can help to improve steering stability and wet performance in a well-balanced manner.

The outer second middle shallow grooves <NUM> and the inner second middle shallow grooves <NUM> each have substantially the same cross-sectional shape as the first middle shallow grooves <NUM> described above. Thus, the configuration of the cross-sectional shape of the first middle shallow grooves <NUM> shown in <FIG> can be applied to the outer second middle shallow grooves <NUM> and the inner second middle shallow grooves <NUM>.

In each outer second middle shallow groove <NUM>, the second shallow-groove wall 56a having a relative greater width is arranged on the second side in the tyre circumferential direction. In each inner second middle shallow groove <NUM>, the second shallow-groove wall 57a having a relative greater width is arranged on the first side in the tyre circumferential direction. As a result, uneven wear of the second middle land portion <NUM> can be suppressed, and traction performance and braking performance on dry road surfaces can be improved in a well-balanced manner.

The crown land portion <NUM> is provided with a plurality of crown shallow grooves <NUM>. The crown shallow grooves <NUM>, for example, extend from the first crown circumferential groove <NUM> and terminate within the crown land portion <NUM>. A length L5 in the tyre axial direction of the crown shallow grooves <NUM>, for example, is in a range from <NUM>% to <NUM>% of a width W6 in the tyre axial direction of the crown land portion <NUM>.

<FIG> illustrates a cross-sectional view taken along the line E-E of <FIG>. As illustrated in <FIG>, the crown shallow grooves <NUM> are not provided with any groove-bottom sipes. Such crown shallow grooves <NUM> can help to maintain the rigidity of the crown land portion <NUM> and provide excellent steering stability.

While the particularly preferable embodiments of the tyre in accordance with the present invention have been described in detail, the present invention is not limited to the illustrated embodiments, but can be modified and carried out in various aspects within the scope of the invention.

Pneumatic tyres, <NUM>/35R19, with the basic tread pattern of <FIG> were prepared based on the specifications in Tables <NUM> to <NUM>. As comparative examples <NUM> to <NUM>, pneumatic tyres in which the first edges and the second edges of the outer surfaces of the tie-bars provided in the first shoulder lateral grooves are the same length were also prepared. The tyres of comparative examples <NUM> to <NUM> are substantially the same as the tyres of the examples except for the above items. In addition, steering stability and wet performance of these test tyres were tested. The common specifications and test methods are as follows.

The steering stability when driving on a test course of a dry road surface with the above test vehicle was evaluated by the driver's sensuality. The test results are indicated using a score with the steering stability of comparative example <NUM> as <NUM>, and the larger the value, the better the steering stability.

The wet performance when driving on a test course of a wet road surface with the above test vehicle was evaluated by the driver's sensuality. The test results are indicated using a score with the wet performance of comparative example <NUM> as <NUM>, and the larger the value, the better the wet performance.

Tables <NUM> and <NUM> show the test results.

Claim 1:
A tyre (<NUM>) comprising:
a tread portion (<NUM>) comprising a first tread edge (T1), a first shoulder circumferential groove (<NUM>) extending in a tyre circumferential direction adjacent to the first tread edge (T1), and a first shoulder land portion (<NUM>) demarcated by the first shoulder circumferential groove (<NUM>) to include the first tread edge (T1), wherein
the first shoulder land portion (<NUM>) is provided with a plurality of first shoulder lateral grooves (<NUM>) extending from the first shoulder circumferential groove (<NUM>) to at least the first tread edge (T1),
at least one of the plurality of first shoulder lateral grooves (<NUM>) comprises a first groove wall (<NUM>) and a second groove wall (<NUM>) which face each other and extend in a tyre radial direction, and a tie-bar (<NUM>) in which a groove bottom portion raises locally,
the tie-bar (<NUM>) comprises an outer surface (<NUM>) extending along a ground contact surface of the first shoulder land portion (<NUM>), the outer surface (<NUM>) being connected to the first groove wall (<NUM>) and the second groove wall (<NUM>),
characterized in that
the outer surface (<NUM>) comprises a first edge (<NUM>) connected to the first groove wall (<NUM>), and a second edge (<NUM>) connected to the second groove wall (<NUM>), the second edge (<NUM>) having a length (L4) smaller than a length (L3) of the first edge (<NUM>).