Patent Description:
The following Patent Document <NUM> discloses a pneumatic tire in which shoulder blocks are provided with shoulder longitudinal sub-grooves extending in the tire circumferential direction. The shoulder longitudinal sub-grooves reduce lateral rigidity in the tire axial direction of the shoulder blocks. Patent Document <NUM>: <CIT>
Related technologies are also known from <CIT>, <CIT>, <CIT>, <CIT>, and <CIT>.

when blocks in the tread portion are reduced in rigidity, the amount of deformation of the blocks during running becomes large. For this reason, wear energy acting on the blocks is increased, and consequently, there is a tendency that the wear resistance of the blocks is reduced.

The present invention was made in view of the above circumstances, and
a primary object of the present invention is to provide a tire capable of exhibiting excellent ride comfort performance while maintaining wear resistance of blocks.

A tire comprises.

In the present invention, therefore, the tire can exhibit excellent ride comfort performance, while maintaining wear resistance of the block.

The present invention is suitably applied to pneumatic tires for passenger cars, but the present invention may be applied to pneumatic tires for heavy duty vehicles such as trucks and buses, as well as non-pneumatic tires so called airless tire.

Taking a pneumatic tire for a passenger car as an example, an embodiment of the present invention will be described in detail in conjunction with accompanying drawings.

<FIG> is a developed partial view of the tread portion <NUM> of a tire <NUM> as an embodiment of the present invention.

The tire <NUM> comprises a tread portion <NUM> having a first tread edge T1 and a second tread edge T2.

The tread portion <NUM> is provided with circumferential grooves <NUM> disposed between the first tread edge T1 and the second tread edge T2 and extending continuously in the tire circumferential direction.

The tread portion <NUM> comprises land portions <NUM> axially divided by the circumferential grooves <NUM>.

In the present embodiment, the tread portion <NUM> is provided with four circumferential grooves <NUM>, and thereby, divided into five land portions <NUM> as shown in <FIG>.

The present invention is however, not limited to such tread pattern. For example, the tread portion <NUM> may be divided into four land portions <NUM> by three circumferential grooves <NUM>.

In the present embodiment, the tire <NUM> is bidirectional, and not specified which side should be outboard when the tire is attached to a vehicle.

For convenience, in each of the figures herein, the first tread edge T1 is shown as the tread edge on the left side of the tire equator C, and the second tread edge T2 is shown as the tread edge on the right side of the tire equator C.

It is preferable that a half of the tread portion <NUM> between the first tread edge T1 and the tire equator C has substantially the same configuration as a half of the tread portion <NUM> between the second tread edge T2 and the tire equator C.

It is preferable that the tread portion <NUM> has a pointsymmetrical tread pattern.

The first tread edge T1 and the second tread edge T2 correspond to the axially outermost edges of the ground contacting patch of the tire <NUM> when the tire <NUM> under its normal state is loaded by a normal load and the tread portion <NUM> is contacted with a flat horizontal surface at a camber angle of <NUM> degrees.

In the case of a pneumatic tire for which various standards have been established, the "normal state" means a state of the tire which is mounted on a normal rim and inflated to a normal pressure, but loaded with no tire load.

In the case of tires for which no standard is established such as airless tires, the "normal state" means a standard usage state according to the purpose of use of the tire, which is not mounted on the vehicle and loaded with no load.

In the present invention, unless otherwise noted, dimensions, positions and the like of the tire refer to those under the normal state.

The normal rim is a wheel rim officially approved or recommended for the tire by standards organizations, i.e. JATMA (Japan and Asia), T&RA (North America), ETRTO (Europe), TRAA (Australia), STRO (Scandinavia), ALAPA (Latin America), ITTAC (India) and the like which are effective in the area where the tire is manufactured, sold or used.

The normal pressure is the air pressure officially approved or recommended for the tire by standards organizations, i.e. JATMA (Japan and Asia), T&RA (North America), ETRTO (Europe), TRAA (Australia), STRO (Scandinavia), ALAPA (Latin America), ITTAC (India) and the like which are effective in the area where the tire is manufactured, sold or used.

In the case of a pneumatic tire for which various standards have been established, the "normal load" is a load specified for the tire by a standard included in a standardization system on which the tire is based, for example, the "maximum load capacity" in JATMA, maximum value listed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" table in TRA, and "LOAD CAPACITY" in ETRTO.

In the case of tires for which no standard is established, the "normal load" refers to the maximum load applicable to the tire.

In the present embodiment, the circumferential grooves <NUM> are two shoulder circumferential grooves <NUM> and two crown circumferential grooves <NUM>.

The two shoulder circumferential grooves <NUM> are disposed adjacently to the first tread edge T1 and second tread edge T2, respectively.

The two crown circumferential grooves <NUM> are disposed between the shoulder circumferential grooves <NUM>, and one on each side of the tire equator.

The distance L1 in the tire axial direction from the tire equator C to the groove center line of each of the shoulder circumferential grooves <NUM> is preferably set in a range from <NUM>% to <NUM>% of the tread width TW.

The distance L2 in the tire axial direction from the tire equator C to the groove center line of each of the crown circumferential grooves <NUM> is preferably set in a range from <NUM>% to <NUM>% of the tread width TW.

The tread width TW is the distance in the tire axial direction between the first tread edge T1 and the second tread edge T2 in the normal state.

In the present embodiment, each of the circumferential grooves <NUM> is a straight groove extending in parallel with the tire circumferential direction. However, all the circumferential grooves <NUM> or some of them may be non-straight grooves, for example, zigzag or wavy grooves.

It is preferable that the groove width W1 of each of the circumferential grooves <NUM> is at least <NUM>.

Further, it is preferable that the groove width W1 of each of the circumferential grooves <NUM> is set in a range from <NUM>% to <NUM>% of the tread width TW.

The land portions <NUM> include two shoulder land portions <NUM>. The two shoulder land portions <NUM> include the first tread edge T1 and the second tread edge T2, respectively, and are defined on the axially outside of the respective shoulder circumferential grooves <NUM>.

The two shoulder land portions <NUM> have substantially the same configuration.

The land portions <NUM> further include two middle land portions <NUM> and one crown land portion <NUM>.

The two middle land portions <NUM> are positioned adjacently to the respective shoulder land portions <NUM> via the shoulder circumferential grooves <NUM>.

The two middle land portions <NUM> are respectively defined between the crown circumferential groove <NUM> and the respective shoulder circumferential grooves <NUM>.

The two middle land portions <NUM> have substantially the same configuration.

The crown land portion <NUM> is defined between the two crown circumferential grooves <NUM> and positioned on the tire equator C.

<FIG> shows the shoulder land portion <NUM> and the middle land portion <NUM> which are disposed on the first tread edge T1 side of the tire equator C.

As shown in <FIG>, the shoulder land portion <NUM> is provided with lateral grooves <NUM> extending from the shoulder circumferential groove <NUM> to the first tread edge T1. Thereby, the shoulder land portion <NUM> is circumferentially divided into shoulder blocks <NUM> by the shoulder lateral grooves <NUM>.

<FIG> shows three of the shoulder lateral grooves <NUM> and two of the shoulder blocks <NUM>.

As shown, each of the shoulder blocks <NUM> is provided with at least one shoulder sipe <NUM>.

Each shoulder sipe <NUM> extends from one of the shoulder lateral grooves <NUM> and ends within the shoulder block <NUM>.

The term "sipe" means an incision having a small width and having two opposite side walls, the two opposite side walls extend substantially parallel to each other, and the width w2 between the two opposite side walls is <NUM> or less.

Further, the expression "substantially parallel" means that the angle between the two opposite side walls is <NUM> degrees or less. Preferably, the width w2 of the sipe is <NUM> to <NUM>, more preferably <NUM> to <NUM>.

In the present embodiment, the width w2 of the sipe is constant from the opening to the bottom thereof.

However, the present invention is not limited to such constant width. For example, the width of the sipe may be increased near the open top of the sipe by providing a chamfer for the sipe edge or edges.

Further, the width of the sipe may be increased near the bottom of the sipe so as to have a flask-shaped cross sectional shape.

<FIG> shows a cross-sectional view taken along line A-A of <FIG>.

The shoulder lateral grooves <NUM> include a tie-bar-equipped shoulder lateral groove <NUM> which is, as shown in <FIG>, provided with at least one tie bar <NUM> raising from the groove bottom so as to connect between two of the shoulder blocks <NUM> adjacent to each other through the tie-bar-equipped shoulder lateral groove <NUM>. In <FIG>, the tie bars <NUM> are omitted from the shoulder lateral grooves <NUM> for the sake of simplicity.

By adopting the above configuration, the tire <NUM> according to the present invention can exhibit excellent ride comfort performance while maintaining wear resistance of the blocks for the following reasons.

According to the present invention, since the shoulder sipes <NUM> extend from the shoulder lateral grooves <NUM> and end in the shoulder blocks <NUM>, the rigidity in the tire axial direction of the shoulder blocks <NUM> can be relaxed, while maintaining the rigidity in the tire circumferential direction of the shoulder blocks <NUM>. Therefore, it is possible to improve the ride comfort performance while maintaining the wear resistance.

on the other hand, by providing the tie bars <NUM> in the shoulder lateral grooves <NUM>, the deformation of the shoulder land portions <NUM> is appropriately suppressed, and the wear resistance can be further maintained.

In the present invention, therefore, excellent ride comfort performance can be exhibited while maintaining the wear resistance of the blocks.

Hereinafter, the present embodiment will be described in more detail.

Each configuration described below shows a specific example for the present embodiment.

Therefore, even if the tire does not have the configuration described below, the tire will exert the above-mentioned effects of the present invention.

Further, even if any one of the configurations described below is independently applied to the tire having the above-mentioned configurations of the present invention, improvement in performance according to the applied configuration can be expected.

Further, when some of the configurations described below are applied in combination, to the tire having the above-mentioned configurations of the present invention, multiple effect according to the applied configurations on the improvement in performance can be expected.

As shown in <FIG>, the widths w2 in the tire axial direction of the shoulder blocks <NUM> are, for example, set in a range from <NUM>% to <NUM>% of the tread width TW.

Further, the lengths L4 in the tire circumferential direction of the shoulder blocks <NUM> are smaller than the widths w2 of the shoulder blocks <NUM>.

specifically, the lengths L4 in the tire circumferential direction of the shoulder blocks <NUM> are set in a range from <NUM>% to <NUM>% of the widths w2 in the tire axial direction of the shoulder blocks <NUM>. As a result, the ground contacting top surface of each of the shoulder blocks <NUM> is longer in the tire axial direction than in the tire circumferential direction. Further, it is preferable that the ground contacting top surface has a rectangular shape.

The angles of the shoulder lateral grooves <NUM> with respect to the tire axial direction are not more than <NUM> degrees, preferably not more than <NUM> degrees, more preferably not more than <NUM> degrees. Most preferably, the shoulder lateral grooves <NUM> are arranged in parallel with the tire axial direction. Thereby, the wear of the shoulder blocks <NUM> is further suppressed.

Each of the shoulder lateral grooves <NUM> extends from the shoulder circumferential groove <NUM> to the first tread edge T1 while keeping a constant groove width in order to maintain the wear resistance.

Further, it is preferable that the groove widths w4 of the shoulder lateral grooves <NUM> are smaller than the groove widths w3 of the shoulder circumferential grooves <NUM>.

specifically, the groove widths w4 of the shoulder lateral grooves <NUM> are set in a range from <NUM>% to <NUM>% of the groove widths w3 of the shoulder circumferential grooves <NUM>.

In the present embodiment, as shown in <FIG>, the above-said at least one shoulder sipe <NUM> includes a first shoulder sipe <NUM> and a second shoulder sipe <NUM>.

Preferably, each of the shoulder blocks <NUM> is provided with one first shoulder sipe <NUM> and one second shoulder sipe <NUM>.

In each of the shoulder blocks <NUM>, the first shoulder sipe <NUM> is connected to one of the shoulder lateral grooves <NUM> which is positioned on one side of the shoulder block <NUM> in the tire circumferential direction (lower side in <FIG>), and the second shoulder sipe <NUM> is connected to one of the shoulder lateral grooves <NUM> which is positioned on the other side of the shoulder block <NUM> in the tire circumferential direction (upper side in <FIG>). Thereby, the ride comfort performance is further improved.

It is preferable that the first shoulder sipe <NUM> and the second shoulder sipe <NUM> are disposed axially inside the center line 10a of the shoulder block <NUM> in the tire axial direction (in <FIG>, the center line is indicated by alternate long and short dash line).

More specifically, the edges of the first shoulder sipe <NUM> and the edges of the second shoulder sipe <NUM> are completely positioned axially inside the center line 10a.

Therefore, the rigidity of the shoulder block <NUM> is relaxed in its axially inside region, and as a result, the ride comfort performance is further improved.

on the other hand, if the first shoulder sipe <NUM> and the second shoulder sipe <NUM> are disposed excessively close to the shoulder circumferential groove <NUM>, there is a possibility that uneven wear occurs on the shoulder block <NUM>.

Therefore, the axial distance L3 from the connecting position 16a of the first shoulder sipe <NUM> with the shoulder lateral groove <NUM> to the axially inner end of the shoulder lateral groove <NUM> is preferably set in a range from <NUM>% to <NUM>% of the axial width w2 of the ground contacting top surface of the shoulder block <NUM>.

And the axial distance L3 from the connecting position 17a of the second shoulder sipe <NUM> with the shoulder lateral groove <NUM> to the axially inner end of the shoulder lateral groove <NUM> is preferably set in a range from <NUM>% to <NUM>% of the axial width w2 of the ground contacting top surface of the shoulder block <NUM>.

It is preferable that the connecting position 17a of the second shoulder sipe <NUM> with the shoulder lateral groove <NUM> is displaced in the tire axial direction from the connecting position 16a of the first shoulder sipe <NUM> with the shoulder lateral groove <NUM>.

The distance L9 in the tire axial direction between the connecting position 16a and the connecting position 17a is preferably set in a range from <NUM>% to <NUM>% of the axial width w2 of the ground contacting top surface of the shoulder block <NUM>. Thereby, it becomes possible to further improve the wear resistance of the shoulder blocks <NUM>.

In order to further improve the wear resistance of the shoulder blocks <NUM>, it is preferred that the first shoulder sipe <NUM> and the second shoulder sipe <NUM> are inclined in the same direction with respect to the tire circumferential direction.

In the present embodiment, the first shoulder sipe <NUM> and the second shoulder sipe <NUM> are inclined at the same angle with respect to the tire circumferential direction.

Preferably, the angle θ1 between the shoulder lateral groove <NUM> and the shoulder sipe <NUM> is set in a range from <NUM> to <NUM> degrees.

In each of the shoulder blocks <NUM>, the first shoulder sipe <NUM> and the second shoulder sipe <NUM> are arranged such that the first shoulder sipe <NUM> and the second shoulder sipe <NUM> are positioned within a narrow zone <NUM>.

The narrow zone <NUM> is shown in <FIG> by shading with small dots. As shown, the narrow zone <NUM> extends with a constant width and is inclined in the substantially same direction as the first shoulder sipe <NUM> and the second shoulder sipe <NUM> in the top view of the shoulder block <NUM>. The constant width of the narrow zone <NUM> is preferably not more than <NUM>.

In this example, in order to further improve the ride comfort performance, the first shoulder sipe <NUM> and the second shoulder sipe <NUM> are arranged so as to extend substantially on a straight line. In this case, the width of the narrow zone <NUM> can be the substantially same as the width of the sipes <NUM> and <NUM>.

It is preferable that each shoulder sipe <NUM> (<NUM>, <NUM>) ends within the shoulder block <NUM> without crossing the center line 10b of the shoulder block <NUM> in the tire circumferential direction (indicated by the alternate long and short dash line in <FIG>).

It is preferable that the length L5 in the tire circumferential direction of the shoulder sipe <NUM> is set in a range from <NUM>% to <NUM>% of the length L4 in the tire circumferential direction of the shoulder block <NUM>.

such shoulder sipes <NUM> serve for improving the wear resistance and the ride comfort performance in a well-balanced manner.

In the present embodiment, the ground contacting top surface of each of the shoulder blocks <NUM> is not provided with a groove or a sipe except for the first shoulder sipe <NUM> and the second shoulder sipe <NUM>. Thereby, the above described effects are surely exhibited.

The shoulder lateral grooves <NUM> include the tie-bar-equipped shoulder lateral groove <NUM> provided with at least one tie bar <NUM>.

In the embodiment, each of the shoulder lateral grooves <NUM> is formed as the tie-bar-equipped shoulder lateral groove <NUM> provided a plurality of the tie bars <NUM> as shown in <FIG>. Further, each shoulder sipe <NUM> (<NUM>, <NUM>) is connected to the tie-bar-equipped shoulder lateral groove <NUM> at the same position in the groove length direction as one of the tie bars <NUM>. This further improves the wear resistance.

The expression "at the same position as the tie bar <NUM>" means that the shoulder sipe <NUM> is included in a zone, which extends radially outwardly from the radially outer surface of the tie bar <NUM> while keeping a constant width equal to that of the radially outer surface, in the cross section of the tie-bar-equipped shoulder lateral groove <NUM> taken along the length direction of the groove <NUM>. The boundary between the radially outer surface and the other surface of the tie bar <NUM> is lies at the center position of the tie bar <NUM> in the radial height direction.

In this embodiment, as shown in <FIG>, the tie bars <NUM> are an axially inner tie bar <NUM>, an axially outer tie bar <NUM>, and an intermediate tie bar <NUM> therebetween.

The axially inner tie bar <NUM> is disposed axially inside a center position in the tire axial direction of the tie-bar-equipped shoulder lateral groove <NUM>, wherein the center position is that of the center between the axially inner end at the shoulder circumferential groove <NUM> and the axially outer end at the first tread edge.

Preferably, the axially inner tie bar <NUM> is disposed at the axially inner end of the tie-bar-equipped shoulder lateral groove <NUM>. such inner tie bar <NUM> serves for suppressing uneven wear occurring near the axially inner end portion of the tie-bar-equipped shoulder lateral groove <NUM>.

The axially outer tie bar <NUM> is disposed axially outside the above-mentioned center position of the tie-bar-equipped shoulder lateral groove <NUM>.

Preferably, the outer tie bar <NUM> is disposed at the shoulder lateral groove's axially outer end at the first tread edge. specifically, in a cross section of the tie-bar-equipped shoulder lateral groove <NUM> taken along the length direction of the tie-bar-equipped shoulder lateral groove <NUM>, when a zone which extends radially outwardly from the radially outer surface of the outer tie bar <NUM> while keeping a constant width equal to the width of the radially outer surface, is set, the first tread edge T1 is included in this zone.

In other words, the first tread edge T1 is included in the extent of the radially outer surface of the outer tie bar <NUM> in the length direction of the tie-bar-equipped shoulder lateral groove <NUM>.

such outer tie bars <NUM> serve for suppressing uneven wear occurring near the first tread edge T1.

The intermediate tie bar <NUM> is disposed between both ends in the tire axial direction of the shoulder lateral groove <NUM>, and between the axially outer tie bar <NUM> and the axially inner tie bar <NUM>.

such intermediate tie bar <NUM> can effectively suppress the shoulder lateral groove <NUM> from opening excessively, and can further improve the wear resistance.

In the present embodiment, the shoulder sipe <NUM> is connected to the shoulder lateral groove <NUM> at the same position in the groove length direction as the intermediate tie bar <NUM>.

The shoulder lateral groove <NUM> in the present embodiment is provided with only the axially inner tie bar <NUM>, axially outer tie bar <NUM>, and intermediate tie bar <NUM>.

But, the present invention is not limited to such arrangement. For example, the shoulder lateral groove <NUM> may be provided with only one of these tie bars <NUM>, or only two of these tie bars <NUM>.

The axial length L6 of each tie bar <NUM> is preferably set in a range from <NUM>% to <NUM>% of the axial width w2 of the ground contacting top surface of the shoulder block <NUM>.

The total length in the tire axial direction of all the tie bars <NUM> disposed in one shoulder lateral groove <NUM> is preferably set in a range from <NUM>% to <NUM>% of the axial width w2 of the ground contacting top surface of the shoulder block <NUM>.

Here, the axial length of the tie bar <NUM> is measured at the center position in the radial height direction of the tie bar <NUM>. As a result, the wear resistance and the ride comfort performance are improved in a well-balanced manner.

In the present embodiment, the axially inner tie bar <NUM>, axially outer tie bar <NUM>, and intermediate tie bar <NUM> have the same radial height h1.

Preferably, the radial height h1 is set in a range from <NUM>% to <NUM>% of the maximum depth d1 of the shoulder lateral groove <NUM>.

Each of the two middle land portions <NUM> is provided with middle lateral grooves <NUM> as shown in <FIG>.

The middle lateral grooves <NUM> extend across the entire axial width of the middle land portion <NUM>. Thereby, the middle land portion <NUM> is circumferentially divided into middle blocks <NUM>.

It is preferable that the axial width w5 of the ground contacting top surface of the middle block <NUM> is smaller than the axial width w2 of the ground contacting top surface of the shoulder block <NUM>.

It is preferable that the axial width w5 is set in a range from <NUM>% to <NUM>% of the axial width w2.

Thereby, the progress of wear of the shoulder blocks <NUM> and the middle blocks <NUM> becomes uniform, and uneven wear of the shoulder blocks <NUM> and middle blocks <NUM> is suppressed.

The middle lateral grooves <NUM> in this example are inclined with respect to the tire axial direction.

The angle θ2 of the middle lateral groove <NUM> with respect to the tire axial direction is larger than the angle of the shoulder lateral groove <NUM> with respect to the tire axial direction.

For example, the angle θ2 is in a range from <NUM> to <NUM> degrees. In the present embodiment, the angle θ2 of the middle lateral groove <NUM> increases toward the inside in the tire axial direction. Thereby, the middle lateral groove <NUM> is curved convexly toward one side in the tire circumferential direction (lower side in <FIG>).

such middle lateral groove <NUM> can improve the wet performance in addition to the wear resistance and the ride comfort performance.

In the present embodiment, the groove width w6 of the middle lateral groove <NUM> is larger than the groove width w4 of the shoulder lateral groove <NUM>. For example, the groove width w6 of the middle lateral groove <NUM> is set in a range from <NUM>% to <NUM>% of the groove width w4 of the shoulder lateral groove <NUM>. Thereby, the progress of wear of the shoulder land portion <NUM> and the middle land portion <NUM> becomes uniform, and uneven wear of the shoulder land portion <NUM> and the middle land portion <NUM> is suppressed.

<FIG> is a cross-sectional view taken along line B-B of <FIG>.

The middle lateral grooves <NUM> include a tie-bar-equipped middle lateral groove <NUM> which is, as shown in <FIG>, provided with at least one middle tie bar <NUM> raising from the groove bottom so as to connect between two of the middle blocks <NUM> adjacent to each other trough the tie-bar-equipped middle lateral groove <NUM>.

In the present embodiment, each of the middle lateral grooves <NUM> is the tie-bar-equipped middle lateral groove <NUM> provided with only one middle tie bar <NUM>.

The middle tie bar <NUM> serves for increasing the rigidity in the tire circumferential direction of the middle land portion <NUM> and improving the wear resistance.

In the present embodiment, the above-said only one middle tie bar <NUM> is disposed between both ends in the tire axial direction of the tie-bar-equipped middle lateral groove <NUM>. However, the present invention is not limited to such arrangement. For example, a plurality of the middle tie bars <NUM> may be provided in one middle lateral groove <NUM>.

For example, the axial length L7 of the middle tie bar <NUM> is set in a range from <NUM>% to <NUM>% of the axial width w5 of the middle block <NUM>.

The radial height h2 of the middle tie bar <NUM> is set in a range from <NUM>% to <NUM>% of the maximum depth d2 of the middle lateral groove <NUM>.

In the present embodiment, the middle tie bar <NUM> is disposed so as to extend across the center position in the tire axial direction of the tie-bar-equipped middle lateral groove <NUM>. Thereby, the wear resistance and the ride comfort performance are improved in a well-balanced manner.

It is preferable that, when the axial lengths of the tie bars are compared, the middle tie bar <NUM> is larger than any of the axially inner tie bar <NUM>, outer tie bar <NUM> and intermediate tie bar <NUM> provided in the shoulder lateral groove <NUM>.

On the other hand, it is preferable that the axial length L7 of the middle tie bar <NUM> is smaller than the total axial length of the axially inner tie bar <NUM>, outer tie bar <NUM> and intermediate tie bar <NUM>. Thereby, the rigidity distribution of the shoulder land portion <NUM> and the middle land portion <NUM> is optimized, and the wear resistance is further improved.

Each of the middle blocks <NUM> is provided with at least one middle sipe <NUM> as shown in <FIG>.

The middle sipe <NUM> is connected to at least one of the two middle lateral grooves <NUM> located on both sides in the tire circumferential direction of the middle block <NUM>.

In the present embodiment, the middle sipe <NUM> is connected to the two middle lateral grooves <NUM> located on both sides in the tire circumferential direction. That is, the middle sipe <NUM> completely crosses the middle block <NUM> in the tire circumferential direction.

Further, it is preferable that each of the both ends in the tire circumferential direction of the middle sipe <NUM> is connected to a central part of the middle lateral groove <NUM> when divided into three equal parts in the length direction.

such middle sipe <NUM> serves for relaxing the rigidity in the tire axial direction of the middle block <NUM> and improving the ride comfort performance.

The middle sipe <NUM> in this example is inclined with respect to the tire circumferential direction.

It is preferable that the middle sipe <NUM> is inclined in the same direction as the shoulder sipes <NUM>.

The angle θ3 between the middle sipe <NUM> and the middle lateral grooves <NUM> is, for example, set in a range from <NUM> to <NUM> degrees. such middle sipe <NUM> serves for improving the wear resistance and the ride comfort performance in a well-balanced manner.

It is preferable that the middle sipe <NUM> is connected to the middle lateral groove <NUM> at the same position as the middle tie bar <NUM> as shown in <FIG>.

Thereby, the connecting position between the middle lateral groove <NUM> and the middle sipe <NUM> is reinforced by the middle tie bar <NUM>, and uneven wear near the connecting position is suppressed.

In the present embodiment, as shown in <FIG>, each of the middle blocks <NUM> is not provided with a groove or a sipe except for the middle sipe <NUM>. Thereby, the above-mentioned effect can be further enhanced.

<FIG> is a partial top view of the crown land portion <NUM>. As shown in <FIG>, the axial width w7 of the crown land portion <NUM> is, for example, set in a range from <NUM>% to <NUM>% of the tread width Tw.

It is preferable that the axial width w7 of the crown land portion <NUM> is smaller than the axial width w2 of the shoulder blocks <NUM>.

The crown land portion <NUM> is provided with first crown lateral grooves <NUM> and second crown lateral grooves <NUM>.

The first crown lateral grooves <NUM> extend from the crown circumferential groove <NUM> on one side in the tire axial direction (left side in <FIG>) of the crown land portion <NUM> toward the tire equator C, and ends within the crown land portion <NUM>.

The second crown lateral grooves <NUM> extend from the crown circumferential groove <NUM> on the other side in the tire axial direction (right side in <FIG>) of the crown land portion <NUM> toward the tire equator C, and ends within the crown land portion <NUM>.

The first crown lateral grooves <NUM> and the second crown lateral grooves <NUM> can enhance the wet performance, while maintaining the rigidity of the crown land portion <NUM>.

In order to improve the wear resistance and the ride comfort in a well-balanced manner, the axial length L8 of the first crown lateral groove <NUM> and the axial length L8 of the second crown lateral groove <NUM> are preferably set in a range from <NUM>% to <NUM>% of the axial width w7 of the crown land portion <NUM>.

The first crown lateral grooves <NUM> are curved convexly toward one side in the tire circumferential direction (upper side in <FIG>). The second crown lateral grooves <NUM> are curved convexly toward the other side in the tire circumferential direction (lower side in <FIG>). Thereby, uneven wear of the crown land portion <NUM> is further suppressed.

The middle lateral grooves <NUM> adjacent to the first crown lateral grooves <NUM> are curved convexly toward the above-said other side in the tire circumferential direction (lower side in <FIG>).

The middle lateral grooves <NUM> adjacent to the second crown lateral grooves <NUM> are curved convexly toward the above-said one side in the tire circumferential direction (upper side in <FIG>).

By arranging the lateral grooves in such way, the progress of wear in each land portion becomes uniform, and uneven wear in each land portion is suppressed.

while detailed description has been made of a preferable embodiment of the present invention, the present invention can be embodied in various forms without being limited to the illustrated embodiment.

Based on the tread pattern shown in <FIG>, pneumatic tires were experimentally manufactured as working examples Ex. <NUM> according to the present invention.

Further, based on the tread pattern shown in <FIG>, a pneumatic tire was experimentally manufactured as a comparative example Ref. In the comparative example, as shown in <FIG>, the shoulder land portions (a) were provided with no sipes, and the shoulder lateral grooves (b) were provided with no tie bars. Otherwise, the comparative example was substantially the same as the working examples.

Specifications of these test tires are shown in Table <NUM>.

The tire sizes were <NUM>/60R17C (rim size 17x6.0J).

Using a test car (3000cc 4WD car) with the same test tires mounted on all wheels and inflated to <NUM> kPa, the test tires were tested for wear resistance and ride comfort.

After running for <NUM>,<NUM> on general roads and highways with the above test vehicle, the average of the remaining heights of the shoulder blocks (the average of the remaining groove depths of the shoulder lateral grooves) was obtained.

The results are indicated in Table <NUM> by an index based on the comparative example being <NUM>, wherein the larger the value, the better the wear resistance of the shoulder blocks.

when running on general roads and highways with the above test vehicle, the ride comfort was evaluated by the driver. The results are indicated in Table <NUM> by an index based on the comparative example being <NUM>, wherein the larger the value, the better the ride comfort.

Claim 1:
A tire (<NUM>) comprising:
a tread portion (<NUM>) having a first tread edge (T1), and provided with a shoulder circumferential groove (<NUM>) disposed adjacently to the first tread edge (T1) and extending continuously in the tire circumferential direction, so as to define a shoulder land portion (<NUM>) between the shoulder circumferential groove (<NUM>) and the first tread edge (T1), wherein
the shoulder land portion (<NUM>) is provided with shoulder lateral grooves (<NUM>) extending from the shoulder circumferential groove (<NUM>) to the first tread edge (T1), so as to circumferentially divide the shoulder land portion (<NUM>) into shoulder blocks (<NUM>),
each of the shoulder blocks (<NUM>) is provided with a shoulder sipe (<NUM>) which extends from one of the shoulder lateral grooves (<NUM>) and ends within the shoulder block (<NUM>), and
the shoulder lateral grooves (<NUM>) include a tie-bar-equipped shoulder lateral groove (<NUM>) which is provided with at least one tie bar (<NUM>) raising from the groove bottom so as to connect between two of the shoulder blocks (<NUM>) adjacent to the tie-bar-equipped shoulder lateral groove (<NUM>),
characterized in that
said at least one tie bar (<NUM>) includes an axially outer tie bar (<NUM>) positioned axially outside the center position in the tire axial direction of the tie-bar-equipped shoulder lateral groove (<NUM>).