JPH05229310A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE:To improve operational stability including hydroplaning resistance and on-snow performance by forming zigzag peripheral direction grooves in an outer side region and specifying the pitch and width direction amplitude of them. CONSTITUTION:The following grooves are formed: first oblique width direction grooves 2, communicated with a main groove 1a on the most, inner side and extending in a tread width direction to cross a main groove 1b and the outermost main groove 1c to be terminated on the inner side of a tread end To in a mounted attitude, and second width direction grooves 3 in a reverse direction. Zigzag peripheral direction grooves 4 are formed in a tread outer side region with these first and second width direction grooves 2 and 3, and pitch and width direction amplitude to tread grounding width are made 10-30% and 5-20% respectively. Consequently operational stability, including hydroplaing resistance, and on-snow performance on snow road surfaces can be improved to provide user-oriented appearance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire for automobiles, and more particularly to a radial tire for passenger cars that exhibits desirable performance throughout the four seasons.
The present invention relates to a so-called high-performance all-season radial tire that simultaneously satisfies the performance required for both summer tires and winter tires (snow tires) with the same tire and significantly improves these performances. ..

[0002]

2. Description of the Related Art Conventionally, many techniques have been disclosed for radial tires for all season (hereinafter referred to as all season tires). Among these conventional techniques, the recent technique is to combine the tread rubber and the tread pattern as appropriate to achieve both the steering stability in the non-snow season and the snow performance in the snow season. That is, on the other hand, by combining a tread rubber-like rubber with a relatively low elastic modulus that maintains a high friction coefficient at low temperatures, and a pattern in which a large number of sipes are arranged on the basis of a zigzag circumferential groove, An all-season tire that reduces the rigidity of the tread to further improve snow performance.

On the other hand, a rubber tread rubber having a relatively high elastic modulus is used, and the pattern construction in which the number of sipes to be arranged is further reduced to further increase the rigidity of the tread as compared with the above-mentioned tire. In other words, it is an all-season tire that emphasizes steering stability during non-snowy seasons.

[0004]

However, among the above-mentioned prior arts, the all-season tire, which relatively emphasizes snow performance, can certainly improve the snow performance.
Due to the low rigidity of the tread, there was a problem in handling stability on dry roads during non-snow seasons. This problem becomes more serious as the vehicle speed increases, and in addition, the zigzag circumferential main groove has a problem in hydroplaning resistance on a wet road surface. Further, there is a general tendency for passenger car tires to require even higher performance, and it is generally recognized that high-performance tires have a relatively simple tread mainly composed of straight main grooves. However, there is a problem that the above-mentioned conventional all-season tire is not suitable in terms of not only steering stability but also appearance.

Further, in the all-season tire of the above-mentioned prior art, which has been relatively weighted in terms of steering stability, the tread has too high rigidity, resulting in a tire whose snow performance is greatly deteriorated. There was a problem that could not exert the function of.

As described above, the all-season tire according to the prior art has the most important steering stability performance as a summer tire or the snow performance such as traction performance, braking performance and slip resistance performance on snow as a winter tire. home,
The tire has a problem that the performance of at least one of them is sacrificed. Attempts were also made to balance the characteristics of both steering stability and on-snow performance, but there was the problem of unsatisfactory performance. As described above, in the prior art, there is no tire that simultaneously satisfies the performances of both the summer tire and the winter tire.

The present invention has been made to solve the above problems in a tread pattern. That is, the object of the present invention is not only dry road surfaces, but also exhibits excellent steering stability performance including hydroplaning resistance not only on wet road surfaces, but also on snowy road surfaces only on the snow performance of conventional tires for snow roads. It is to propose a high-performance all-season radial tire for automobiles, which has a performance close to that of a vehicle and has an appearance desired by the user.

[0008]

According to the present invention, first, in order to advantageously solve the above-mentioned problems, a plurality of main grooves extending substantially in the circumferential direction of the tread, and a mounting attitude of the main grooves to a vehicle are provided. Of the tire of No. 1, which extends in the tread width direction from the main groove located on the innermost side of the vehicle, inclining in the same direction with respect to the circumferential direction of the tread, and across the main groove located on the outermost side of the vehicle.
A plurality of width-direction grooves and a plurality of second width-direction grooves that extend in the width direction from the outer tread end of the vehicle and incline in a direction opposite to the first width-direction groove with respect to the tread circumferential direction. In the asymmetric pattern pneumatic radial tire each of which comprises a plurality of main grooves and a plurality of the first widthwise grooves to form a substantially rhombic block, and the outermost main groove, Within the outer region defined by the outer tread edge, each one of the first widthwise grooves intersects at least two adjacent second widthwise grooves, and
At least one of the first widthwise grooves intersects at least two of the first widthwise grooves adjacent to each other, and the first and second widthwise grooves thereof cause at least one in the outer region. Zigzag circumferential groove is formed, and the pitch of the zigzag circumferential groove is set to 10% or more and 30% or less of the tread contact width, and the widthwise amplitude of this groove is set to 5% or more and 20% or less of the tread contact width. It is based on a pneumatic radial tire characterized by the following.

As a preferred embodiment of the present invention, a main groove located on the innermost side and a circumferential groove extending on a tread side wall surface radially inward of the inner tread end are provided with respect to the tread circumferential direction. It is preferable that a plurality of width direction grooves that are inclined in the opposite direction to the first width direction groove be communicated with each other.

Further, as an embodiment of the present invention, the second widthwise groove has an end portion in the outer region, the end portion is inclined in substantially the same direction as the second widthwise groove, and Forming a third widthwise groove having a groove width narrower than that of the second widthwise groove, and extending the third widthwise groove across all of the main grooves to form the substantially diamond-shaped block; Is preferably divided substantially on its diagonal to form substantially triangular sub-blocks.

Further, as an embodiment of the present invention, the average inclination angle of the first widthwise groove with respect to the circumferential direction of the tread is set to be equal to or smaller than the average inclination angle of the second widthwise groove with respect to the circumferential direction of the tread. Is desirable.

Further, as an embodiment of the present invention, it is desirable that the width of each main groove is equal to or larger than the width of each of the first width direction groove and the second width direction groove.

Furthermore, as an embodiment of the present invention, a notch is formed in each of the substantially rhombic blocks, the notch extending from each substantially rhombic obtuse angle forming part toward the other obtuse angle forming part and ending inside each of the blocks. It is desirable to provide a section.

The present invention will be described more specifically with reference to the embodiment shown in FIG. FIG. 1 is a view showing a horizontally developed asymmetric tread pattern of an embodiment of the pneumatic tire for all seasons of the present invention. In FIG. 1, XX is a line at which the tire equatorial plane cuts the surface of the tread, and To and Ti indicate tread edges, respectively. In this embodiment, when the tire is mounted on a vehicle, the tread end indicated by the To among the tread ends of the tire is placed on the outside of the vehicle.

Each of 1a, 1b and 1c shown in FIG.
It is a substantially straight main groove extending in the tread circumferential direction substantially in parallel with the line XX. Reference numeral 2 shown in the drawing is opened to the innermost main groove 1a in the mounting posture among the main grooves, and extends from the main groove 1a in the same direction with respect to the circumferential direction and extends in the width direction of the tread. A first widthwise groove that crosses the groove 1b and further extends further across the main groove 1c that is the outermost side in the mounting posture among the main grooves and ends at 2e inside the tread end To is shown. A plurality of these grooves are arranged.

Further, in FIG. 1, 3 shown in the drawing is opened to the tread end To, and from this tread end To,
A second widthwise groove extending obliquely in the direction opposite to the first widthwise groove 2 with respect to the circumferential direction and ending at 3e in the drawing is shown, and a plurality of these grooves are arranged.

Here, among the groove edges of the outermost main groove 1c, a groove edge close to the tread edge To is indicated by 1co, and a region defined by the groove edge 1co and the tread edge To is defined as a tread edge. The outer region is shown by R. According to the present invention, the end portions 2e of the plurality of grooves of the first widthwise groove 2 and the end portions 3e of the plurality of grooves of the second widthwise groove 3 are both outside regions of the tread. It is located at R. In FIG. 1, the contact width of the outer region R from the groove edge 1co to the tread end To is Tr.
And the Tr width of the tread indicated by TW is 30
% To 50% is preferable.

The respective main grooves 1a, 1b and 1c and a plurality of grooves of the first widthwise groove 2 form a block shown in FIG. Further, each one groove of the first widthwise groove 2 is provided with at least two (two in the illustrated example) grooves of the second widthwise groove 3 which are adjacent to each other, and an outer region of the tread. At R, in the example shown in the drawing, the C ₁ and C ₂ sections are cross-opened.

Further, each one groove of the second widthwise grooves 3 is provided with at least two adjacent ones of the first widthwise grooves 2.
The grooves of the book (two in the illustrated example) and the outer region R of the tread are cross-opened at the portions C ₃ and C _{1 in the} illustrated example.

In the present invention, the first and second widthwise grooves are cross-opened to each other in the outer region R of the tread as described above, so that in the illustrated example, the C ₁ portion, C ₂ portion and With each part of the C ₃ part as the top part, one zigzag circumferential groove 4 is formed by mixing the first widthwise groove 2 and the second widthwise groove 3.

In the above-described embodiment, each one of the first and second widthwise grooves is cross-opened with two adjacent grooves of the other groove, and one groove is formed in the outer region of the tread. Although a zigzag circumferential groove is formed, in the present invention, one widthwise groove is cross-opened with three or more widthwise grooves adjacent to each other to form two or more zigzag circumferential grooves. It is also possible to form directional grooves.

In the present invention, the P of at least one zigzag circumferential groove formed in the outer region of the tread.
10% of the tread contact width TW
The value is in the range of 30% or less. Furthermore, U
The amplitude in the width direction of the zigzag circumferential groove, that is, the swing width is set to a value in the range of 5% to 20% of the tread ground contact width TW.

The asymmetric pattern in the present invention is based on the above-mentioned structure. An embodiment suitable for further adding to the pattern having the basic structure of the present invention will be described below in more detail with reference to FIG.

In FIG. 1, the inner tread end Ti
The region of the side wall surface of the tread extending inward in the radial direction of the tire from is indicated by Tib. Reference numeral 6 in the drawing denotes a substantially linear circumferential groove provided in the Tib region. Reference numeral 5 indicates a width direction which opens to the main groove 1a and extends from the main groove 1a toward the circumferential groove 6 while being inclined in a direction opposite to the first width direction groove 2 in the circumferential direction. A plurality of grooves are provided. In the present invention, the widthwise groove 5 is opened to the circumferential groove 6, and the main groove 1a and the circumferential groove 6 are formed.
It is desirable to form the block indicated by Bi by the widthwise groove 5.

Further, in FIG. 1, the second widthwise groove 3 is opened to the end portion 3e thereof, and extends from the end portion 3e of the groove in a direction substantially the same as that of the second widthwise groove. Then, a third widthwise groove shown in FIG. 7 is provided, which traverses the main grooves 1c, 1b and 1a in order and opens to at least the main groove 1a. The third widthwise groove 7 has a groove width narrower than the second groove width, and the block B is divided so as to be substantially along the diamond-shaped diagonal line of the substantially diamond-shaped block B, and is illustrated. Sub-block Bt having a substantially triangular shape is formed. At this time, the third widthwise groove 7 is formed in the tread end T further inside the tread.
It is desirable to extend it to i and open it.

Further, the average inclination angle of the first widthwise groove with respect to the circumferential direction of the tread is similarly set to be equal to or smaller than the average inclination angle of the second widthwise groove with respect to the circumferential direction of the tread. In FIG. 1, at the widthwise position indicating the average inclination angle, the average inclination angle of the first widthwise groove with respect to the circumferential direction of the tread is indicated by α, and similarly, the average inclination angle of the second widthwise groove is indicated by β. It was Here, the average inclination angle is defined as an average value of the inclination angles of the start point and the end point of the groove with respect to the circumferential direction of the tread. Further, in the present invention, the inclination angle of each of the first and second widthwise grooves with respect to the tread circumferential direction can be made constant regardless of the widthwise position. The relationship between α and β is 0.7β ≦ α ≦ β and 60 ° ≦ β ≦ 80.
It is preferable that the angle is °.

Furthermore, the groove widths of the main grooves 1a, 1b and 1c are substantially the same, and the groove widths of these main grooves are the maximum of the first width direction groove 2 and the second width direction groove 3 respectively. The groove width should be greater than the width. Here, the mutual relation of the groove widths is preferably set as follows. That is, the width of the main groove is Wm,
The average groove width in the normal direction of the first widthwise groove is W ₁ , the average groove width in the normal direction of the second widthwise groove is W _2, and the groove width in the normal direction of the third widthwise groove. Is W ₃ , and 0.3 Wm ≦ W ₁
≦ 1.0 × Wm, 0.5 Wm ≦ W ₂ ≦ 1.0 × Wm, W
_It is preferable to set each groove width so as to satisfy the relationship of ₁ <W ₂ , 0.1 × W ₂ ≦ W ₃ <W ₂ .

In FIG. 1, a notch indicated by K in the drawing, which extends from each obtuse angle forming portion forming the substantially rhombic shape of the substantially rhombic block B toward the other obtuse angle forming portion and ends inside the block B. Set up a section. At this time, the notch K is provided in the vicinity of both obtuse angle forming parts of each substantially diamond-shaped block.
The block B is not divided. Further, the width of the notch K in the normal direction is set to a value exceeding the groove width W ₃ of the third widthwise groove. Although S in the drawing is a sipe, it is not always necessary in the present invention.

[0029]

First, the force applied to the tire during cornering, which is most important in the running state of the vehicle regardless of whether it is a snowy road or a snowy road, will be taken up. When cornering,
It is well known that, of the tires mounted on a vehicle, the tire located outside the turning bears a larger force than the tire located inside the turning. Regarding the tread of the tire located on the outer side, the tread portion on the outer side bears a larger force than the tread portion on the inner side when viewed in the mounted posture. Therefore, during cornering, the outer portion of the tread becomes an extremely important area, and the pattern of the outer area of the tread plays an important role in determining the quality of cornering.

In the present invention, as described above, by providing the zigzag circumferential groove 4 in the outer region R of the tread which plays an important role during cornering, in cornering on a snowy road, the groove per pitch of this groove is provided. By increasing the total value of the edge lengths, the so-called edge effect can be remarkably enhanced, and the snow performance represented by slip resistance can be made excellent.

Further, when cornering a vehicle including lane transfer on a dry non-snow road, the comparatively narrow groove width of the present invention is provided in comparison with a tread having a linear groove having a wide groove width. The tread surface of the tread in which the zigzag circumferential groove is provided in the outer region of the tread has an advantage that it is difficult to buckle against a large input to the tread surface due to a large lateral acceleration received by the vehicle. The advantage of this buckling is that, particularly, the grounding property of the outer portion of the tread is improved and the rigidity of the portion is maintained high, thereby exhibiting excellent steering stability. At the same time, the high rigidity suppresses wear of the tread surface of the outer portion of the tread that occurs during severe cornering.

Further, it goes without saying that the same excellent steering stability as described above is exhibited even in cornering on a wet road surface, but in addition to this, a zigzag circumferential groove is formed between the first and second widthwise grooves. Since it is composed of a part of each, extremely efficient drainage is possible. As a result, excellent wet performance, which is often a problem during cornering, is further improved.

The pitch of the zigzag circumferential grooves is 10% or more of the tread contact width, and the widthwise amplitude of the grooves is 20% or less of the tread contact width.
If the value is less than 20% and more than 20%, the zigzag circumferential groove portion of the tread land portion formed at the position (C ₁ , C ₂ and C _{3 in} FIG. 1) that changes the extending direction thereof. Is too sharp and may cause uneven wear or chipping in this portion.

The pitch of the zigzag circumferential grooves is set to 30% or less of the tread contact width, and the widthwise amplitude of the grooves is set to 5% or more of the tread contact width. In addition, if the value is less than 5%, it is difficult for the zigzag circumferential groove to exhibit the above-mentioned excellent performance.

Next, the function and effect of the present invention mainly for straight running of the vehicle will be described. First, by disposing a plurality of linear main grooves in the tread by biasing it toward the inside of the tread when the vehicle is mounted, excellent drainage is imparted when driving on a relatively deep road surface, and hydroplaning resistance is provided. Improve sex. Needless to say, this hydroplaning resistance is also excellent during cornering as described above. This enhances the stability of the vehicle running on the wet road surface.

The edge portion of the substantially rhombic block formed by the plurality of linear main grooves and the first widthwise groove that opens and crosses all of these main grooves has an edge especially on a snowy road. Exert an effect. Similarly, the innermost main groove (1 in FIG. 1)
a), the circumferential groove provided on the tread side wall surface radially inward of the inner tread end, and the widthwise groove extending over these grooves, the edge effect of the edge portion of the block (Bi in FIG. 1) is In addition to the above, improve snow performance.

With the third widthwise groove, the edge portion formed by the substantially triangular sub-block obtained by dividing the substantially diamond-shaped block on the substantially diagonal line further amplifies the edge effect,
Greatly improves snow performance such as traction, braking, and slip resistance on snow. Moreover, the substantially rhombic blocks have directionality, and although the blocks Bi are arranged in a direction that cancels this directionality, they are not sufficient. It becomes possible to remove the sex. As a result, the straight running stability of the vehicle can be significantly improved not only when traveling on a non-snowy road but also when traveling on a snowy road.

By providing the notch (K in FIG. 1) in the obtuse angle forming portion of the substantially rhombic block, the edge effect of the obtuse angle forming portion can be further enhanced.

On the other hand, the average inclination angle of the first widthwise groove (α in FIG. 1) is set to be equal to or smaller than the average inclination angle of the second widthwise groove (β in FIG. 1). This is to increase drainage efficiency when traveling, and on the other hand, to increase block rigidity in the outer region of the tread to improve steering stability.

On the other hand, the groove width of the main groove is set to be equal to or larger than the groove width of each of the first and second widthwise grooves. On the other hand, when traveling on a wet road surface with a certain water depth, the tread This is because the main groove mainly takes charge of drainage of water on the ground contact surface, and the maximum groove width of this main groove can maximize drainage efficiency. On the other hand, even if the groove width of each of the first and second widthwise grooves is larger than the main groove, it does not contribute to the improvement of steering stability or the performance on snow, but also the level of pattern noise is increased. To lower the comfortability of the tread, and also to cause problems such as the wear resistance of the tread.

[0041]

EXAMPLE An all-season radial tire for passenger cars, the size of which is 225 / 60R16. This tire is a pneumatic tire having a tread provided with the asymmetric pattern shown in FIG. The tread contact width TW was 180 mm, and the groove widths of the main grooves 1a, 1b and 1c were 10 mm. Further, the width Tr of the outer region of the tread is set to 42 of the tread ground contact width TW.
It was set to 75 mm corresponding to%.

Regarding the first widthwise groove 2, the groove width in the normal direction is set to 5.5 mm at the position where it opens into the main groove 1a, and the groove width is gradually narrowed from this position at the groove end portion 2e. The groove width is 4.5 mm. Further, the inclination angle of the groove 2 with respect to the circumferential direction is 55 ° at the position of the main groove 1a, and the inclination angle is gradually decreased from this position to 45 ° at the groove end portion 2e. The average inclination angle of the groove 2 with respect to the circumferential direction is 50 °.

For the second widthwise groove 3, the groove width in the direction of the normal is defined from the outer tread end To to the end portion 3e of the groove 3.
It was 5.5 mm, which was substantially uniform over the entire length. Further, the inclination angle of the groove 3 with respect to the circumferential direction is set to 75 ° at the tread end To, and the inclination angle is sequentially decreased from this position to 65 ° at the groove end portion 3e. The average inclination angle of the groove 3 with respect to the circumferential direction is 70 °.

From the main groove 1a to the circumferential groove 6 on the sidewall surface of the tread.
The groove width of the groove 5 extending in the normal direction is set to be substantially uniform at 7 mm, and the inclination angle with respect to the circumferential direction is set to be substantially uniform at 75 °.
The groove width in the normal direction of the third widthwise groove 7 is 1.2 mm.
And Furthermore, the pitch P of the zigzag circumferential groove 4 is set to 35 mm, which corresponds to about 19.4% of the tread contact width TW, and the width direction amplitude U of the groove 4 is set to the tread contact width TW.
To 23 mm, which corresponds to about 12.8%.

In order to confirm the all-season performance of the tire of the example, an all-season tire of the comparative example having the tread pattern shown in FIG. 2 was prepared. The tire of the comparative example is a tire having an all-season pattern which is an extension of the conventional technique. Except for this pattern, the other configurations including size are all the same as those of the example tire.
The pattern of the comparative example will be described below.

The pattern is a point-symmetrical pattern in which the tire equatorial plane is point-symmetric with respect to an arbitrary point on the line XX passing through the tread surface. The main groove is composed of four substantially linear grooves extending in the circumferential direction of the tread. Mutual main grooves of adjacent main grooves are inclined with respect to the circumferential direction, extend in the width direction, and are connected to each other by a plurality of width-direction grooves open to the respective main grooves. As a result, a large number of blocks are formed. Further, another width direction groove is provided which is inclined in a direction opposite to the inclination direction of the adjacent width direction groove and is opened to each width direction groove to divide the block into substantially equal parts.

Further, each of the main grooves closest to both side ends of the tread is opened, and the main grooves are extended in the width direction while being inclined with respect to the circumferential direction so as to extend radially inward of each tread end. Still another widthwise groove is provided which opens into each circumferential groove extending on the tread side wall surface. The ground contact width TW of the tread was 180 mm, the groove width of the main groove was 9 mm, and the groove widths of the width direction groove and the other width direction grooves in the normal direction were 4.5 mm and 1.2 mm, respectively. .. still,
The pitch P was 30 mm.

Comparative tests were conducted on the all-season radial tires of the above-mentioned Examples and Comparative Examples by the following evaluation methods. That is, the tire internal pressure was set to 2.2 kgf / cm ^{2 which} is the designated internal pressure of the vehicle, and ^two passengers ran on the circuit course and compared with the passenger's feeling rating. First, the steering stability performance was comprehensively evaluated by straight running, curved running and slalom running on a dry road surface. Then, the vehicle was run on a wet road surface with a water depth of about 5 mm, and the limit vehicle speed at which the hydroplaning phenomenon occurred was sensed to give a rating. Regarding snow performance, starting, turning, climbing, and braking were repeated on a snow-covered road surface, and the performance was comprehensively evaluated and scored.

The following results were obtained by summarizing the above evaluations by an index with the tire of Comparative Example being 100. In both cases, the larger the index value, the better. That is, the tires of the examples had a steering stability performance of 105 on a dry road surface, a hydroplaning resistance of 100 on a wet road surface, and a snow performance of 105.

As is apparent from the results of the above comparative evaluation test, the all-season radial tire of the present invention has the same wet performance as that of hydroplaning resistance, which is equivalent to that of a tire which emphasizes this performance. In addition, it is understood that it has more improved on-snow performance than conventional all-season tires, and exhibits even better steering stability performance.

[0051]

According to the present invention, the tread pattern enables the compatibility of both the steering stability performance and the snow performance, which cannot be solved by the conventional all-season tires, to be desirable performance. It is possible to provide a filled tire. That is, according to the present invention, the steering stability performance including the hydroplaning resistance is further improved not only on a dry road surface but also on a wet road surface, and at the same time, the snow performance of a conventional snow road tire is improved on a snow road surface. It is possible to provide a high-performance all-season pneumatic tire for automobiles, which exhibits a performance extremely close to that of the vehicle and which has an appearance desired by the user.

[Brief description of drawings]

FIG. 1 is a development view showing an asymmetric pattern of a pneumatic tire according to an embodiment of the present invention.

FIG. 2 is a development view showing a pattern of a pneumatic tire of a comparative example.

[Explanation of symbols]

 1a Main groove 1b Main groove 1c Main groove 2 First widthwise groove 3 Second widthwise groove 4 Zigzag circumferential groove 5 Widthwise groove 6 Circumferential groove 7 Third widthwise groove 8 Notch B B Shaped block Bt Substantially triangular block Bi Tread inner block K Notch P Pitch U Width direction amplitude R Tread outer area TW Tread ground width Tr Tread outer area width To Outer tread edge Ti Inner tread edge α First width direction Average tilt angle of groove β Average tilt angle of second widthwise groove

Claims (6)

[Claims] 1. A plurality of main grooves extending substantially in the circumferential direction of the tread, and a main groove located on the innermost side of the vehicle of the tire in a mounting attitude to the vehicle among the main grooves in the tread circumferential direction. Against the same direction, a plurality of first width direction grooves extending in the tread width direction across the outermost main groove of the vehicle and extending in the width direction from the outer tread end of the vehicle, An asymmetric pattern pneumatic radial tire comprising a plurality of second widthwise grooves inclined in a direction opposite to the first widthwise groove with respect to the tread circumferential direction, wherein the plurality of main grooves and the plurality of main grooves are provided. Each of the first widthwise grooves is formed in the outer region which forms a substantially rhombic block with the plurality of first widthwise grooves and is defined by the outermost main groove and the outer tread end. Book into at least two of the second widthwise grooves adjacent to each other Each of the second widthwise grooves is made to intersect with at least two of the first widthwise grooves which are adjacent to each other, and the first and second widthwise grooves allow the outside At least one zigzag circumferential groove is formed in the region, the pitch of the zigzag circumferential groove is set to 10% or more and 30% or less of the tread contact width, and the widthwise amplitude of this groove is 5% of the tread contact width. A pneumatic radial tire characterized by being 20% or less. 2. A main groove located on the innermost side, and a circumferential groove extending on a tread side wall surface radially inward of an inner tread end, wherein the first widthwise groove is formed in the tread circumferential direction. The pneumatic radial tire according to claim 1, wherein the two are communicated with each other by a plurality of widthwise grooves that are inclined in opposite directions. 3. The second widthwise groove has an end portion in the outer region, and the second widthwise groove is inclined from the end portion in substantially the same direction as the second widthwise groove. Form a third widthwise groove having a narrow groove width and extend the third widthwise groove across all of the main grooves so that the approximately rhombic block is approximately on its diagonal. The pneumatic radial tire according to claim 1, wherein the pneumatic radial tire is divided to form sub-blocks having a substantially triangular shape. 4. The average inclination angle of the first widthwise groove with respect to the tread circumferential direction is defined by the second inclination angle with respect to the tread circumferential direction.
The pneumatic radial tire according to any one of claims 1 to 3, wherein the angle is equal to or less than the average inclination angle of the widthwise groove. 5. The groove width of each main groove is set to be equal to or larger than the groove width of each of the first widthwise groove and the second widthwise groove. The pneumatic radial tire according to 1 above. 6. The substantially rhombic block is provided with a notch portion extending from each obtuse angle forming part of the approximately rhombic shape toward the other obtuse angle forming part and ending inside each block. The pneumatic radial tire according to any one of claims 1 to 5.