JP6110586B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire suitably used for a heavy-duty vehicle.

  In recent years, as can be seen from the fact that wearing of M + S tires (Mud & Snow tires) has become mandatory in some European countries in winter, tires with high winter wet performance are required.

  Incidentally, some pneumatic tires used in heavy-duty vehicles such as trucks, buses, and trailers have the tread described in Patent Document 1. In this pneumatic tire, a plurality of main grooves and land portions are formed in the tread, and narrow grooves and sipes are formed in the land portions to ensure wet performance.

  However, even in the tread described in Patent Document 1, the wet performance is not sufficient and further improvement is required. Moreover, it is calculated | required that wet performance can be exhibited, even after abrasion progresses.

JP 2000-168317 A

  The present invention has been made in consideration of the above facts, and an object thereof is to provide a pneumatic tire having high wet performance.

The pneumatic tire according to claim 1 of the present invention is formed between a pair of shoulder circumferential grooves on the outermost side in the tire width direction, which are formed in a tire tread and extend along the tire circumferential direction, and the shoulder circumferential grooves. A center circumferential groove formed on the tire equatorial plane, a plurality of land portion rows that are partitioned by the center circumferential groove and the shoulder circumferential groove and extend in the tire circumferential direction, and traverse the land portion row in the tire width direction A groove bottom sipe and tire treads of all the groove bottom sipes formed along the groove bottom sipe and shallower than the center circumferential groove and the shoulder circumferential groove, and the land portion row is tired. e Bei the width-direction narrow grooves crossing in the width direction, and the circumferential narrow groove communicating with each other the width-direction narrow grooves adjacent in the tire circumferential direction, wherein the width-direction narrow grooves are tire width of the land row One end of direction The other end is bent so as to form a pair of convex portions protruding in opposite directions in the circumferential direction of the tire, and the circumferential narrow grooves protrude from each other between the adjacent narrow grooves in the width direction. The vertices of the convex portions facing each other are connected to each other .

In the pneumatic tire according to claim 1, circumferential narrow grooves are formed in the land portion row. The circumferential narrow groove is formed so as to allow the widthwise narrow grooves adjacent in the tire circumferential direction to communicate with each other. With this circumferential narrow groove, drainage can be improved, and wet performance can be improved.
Further, by bending the width direction narrow groove, edge components in different directions in the tire width direction and the tire circumferential direction are increased, and the turning performance and the braking performance can be improved. Furthermore, the zigzag shape is formed by the width direction narrow groove by bending the width direction narrow groove so as to form a pair of convex portions that are convex opposite to each other in the tire circumferential direction, and by increasing the edge component, Turning performance and braking performance can be improved.
Furthermore, by connecting the circumferential narrow groove with the apex of the convex portion of the width groove, the angle between the circumferential narrow groove and the width narrow groove can be increased, compared with a case where the angle is small. Uneven wear can be suppressed.

  It should be noted that the shoulder circumferential groove, the center circumferential groove, the width direction narrow groove, and the circumferential direction narrow groove here are such that when the tire tread is grounded, the groove walls are separated from each other so that the groove does not close. It has a groove width. On the other hand, the groove bottom sipe is such that the sipe wall surfaces come into contact with each other and close when the tire tread is grounded. Here, the tire tread comes into contact with a pneumatic tire that is mounted on a standard rim specified in JATMA YEAR BOOK (Japan Automobile Tire Association Standard, 2010 edition), and the maximum size and ply rating applicable to JATMA YEAR BOOK. This is when 100% internal pressure of the air pressure (maximum air pressure) corresponding to the load capacity (internal pressure-load capacity correspondence table) is filled and 70% of the maximum load is applied. When the TRA standard or ETRTO standard is applied at the place of use or manufacturing, the respective standards are followed.

The pneumatic tire according to claim 2 of the present invention is characterized in that the circumferential narrow groove is bent at least once between the adjacent narrow grooves in the width direction.

  As described above, by bending the circumferential narrow groove, edge components in different directions in the tire width direction and the tire circumferential direction are increased, and the turning performance and the braking performance can be improved.

In the pneumatic tire according to claim 3 of the present invention, the shoulder land portion formed on the outer side in the tire width direction than the shoulder circumferential groove extends in the tire width direction and one end opens into the shoulder circumferential groove. A shoulder narrow groove is formed, and the shoulder narrow groove is characterized in that the wide groove portion on the shoulder circumferential groove side is wider than the narrow groove portion on the tire shoulder side.

In the pneumatic tire according to claim 3, shoulder narrow grooves are formed in the shoulder land portion. The shoulder narrow groove opens into the shoulder circumferential groove, and the wide groove portion on the shoulder circumferential groove side is wider than the narrow groove portion on the tire shoulder side.

  Thus, drainage can be secured by widening the groove width on the side of the shoulder narrow groove that opens to the shoulder circumferential groove. Further, by reducing the width of the shoulder narrow groove on the tire shoulder side, it is possible to suppress an increase in the negative rate and improve the wear resistance.

  Here, the shoulder narrow groove has such a groove width that the groove walls are separated from each other even when the tire tread is grounded and the groove is not closed.

In the pneumatic tire according to claim 4 of the present invention, between the shoulder narrow grooves adjacent to each other in the tire circumferential direction, one end extends in the tire width direction and one end opens into the shoulder circumferential groove and is narrower than the wide groove portion. An intermediate narrow groove is formed.

  Thus, the narrow grooves formed in the shoulder land portions are not all shoulder narrow grooves having wide groove portions, but are narrower than the wide groove portions between the shoulder narrow grooves adjacent to each other in the tire circumferential direction. By forming the intermediate narrow groove, it is possible to suppress the increase in the negative rate and improve the wear resistance performance while ensuring the braking performance and turning performance by the edge.

  The intermediate narrow groove here also has such a groove width that the groove walls are not separated from each other even when the tire tread is grounded and the groove is not closed.

The pneumatic tire according to claim 5 of the present invention is characterized in that the shoulder narrow groove is formed at a position where the width-direction narrow groove is extended.

  Thus, drainage can be improved by arrange | positioning a width direction narrow groove and a shoulder narrow groove.

In the pneumatic tire according to claim 6 of the present invention, a circumferential shoulder narrow groove having a width narrower than that of the wide groove portion is formed so as to extend in the tire circumferential direction and intersect the shoulder narrow groove. It is characterized by.

  Thus, drainage can be improved by forming the circumferential shoulder narrow groove.

  As described above, according to the pneumatic tire of the present invention, the wet performance can be improved.

It is a top view of the tread of the pneumatic tire concerning the embodiment of the present invention. (A) of the tread shown in FIG. 1 is an AA sectional view, and (B) is a BB sectional view. (A) of the tread shown in FIG. 1 is a CC cross-sectional view, and (B) is a DD cross-sectional view. (A) of the tread shown in FIG. 1 is an EE sectional view, and (B) is an FF sectional view. It is a top view of the tread of the pneumatic tire concerning a comparative example.

  Hereinafter, a pneumatic tire 10 according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows a tread 12 of a pneumatic tire 10. An arrow S in the figure indicates the tire circumferential direction, and an arrow W indicates the tire width direction.

  In addition, the tread 12 has a ground contact end 12E, which is a pneumatic tire 10 mounted on a standard rim defined in JATMA YEAR BOOK (Japan Automobile Tire Association Standard, 2010 edition) and applicable size / prior rating in JATMA YEAR BOOK. When the maximum load capacity is loaded with 100% internal pressure of the air pressure (maximum air pressure) corresponding to the maximum load capacity (bold load in the internal pressure-load capacity correspondence table). When the TRA standard or ETRTO standard is applied at the place of use or manufacturing, the respective standards are followed.

  In the tread 12 of the pneumatic tire 10 of the present embodiment, three circumferential grooves extending along the tire circumferential direction are formed. Among these, a pair of grooves arranged on the most shoulder side are referred to as shoulder circumferential grooves 22 and 26, and a groove formed on the tire equatorial plane CL is referred to as a center circumferential groove 24. The shoulder circumferential grooves 22 and 26 and the center circumferential groove 24 have a zigzag shape having an amplitude in the tire width direction. The groove widths W0 of the shoulder circumferential grooves 22, 26 and the center circumferential groove 24 are substantially the same, and the groove depth H0 is also substantially the same.

By making the zigzag shape of the shoulder circumferential grooves 22, 26 and the center circumferential groove 24 relatively small in amplitude, it is possible to obtain an edge effect while ensuring sufficient drainage.

  A first shoulder land row 32 is formed on the shoulder side (left side in FIG. 1) from the shoulder circumferential groove 22. A second shoulder land portion row 38 is formed on the shoulder side (the right side in FIG. 1) from the shoulder circumferential groove 26. A first land portion row 34 is formed between the shoulder circumferential groove 22 and the center circumferential groove 24, and a second land portion row 36 is formed between the shoulder circumferential groove 26 and the center circumferential groove 24. Is formed.

  The first land portion row 34 and the second land portion row 36 have substantially the same land portion volume, and the first shoulder land portion row 32 and the second shoulder land portion row 38 have substantially the same land portion volume. ing. The land volume ratio of the first land portion row 34 and the second land portion row 36 and the first shoulder land portion row 32 and the second shoulder land portion row 38 may be 1: 1 to 1: 1.2. Furthermore, it is more preferable that it is 1: 1.1-1: 1.2. By making the land volume of the first shoulder land portion row 32 and the second shoulder land portion row 38 larger than the first land portion row 34 and the second land portion row 36, the first shoulder land portion row 32 and the second land portion row 32 The rigidity of the shoulder land portion row 38 can be increased, and deformation against lateral force can be suppressed. As a result, the wear speed of the shoulder circumferential grooves 22 and 26 can be delayed, and the wear of the tires can be reduced to prolong the tire life.

  In the first land portion row 34, width direction narrow grooves 40 are formed at predetermined intervals in the tire circumferential direction. The width direction narrow groove 40 is formed so as to extend from one end to the other end in the tire width direction of the first land portion row 34 and opens to the shoulder circumferential groove 22 and the center circumferential groove 24. . The width direction narrow groove 40 is inflected so that a pair of convex portions 40A and 40B that are convex in opposite directions in the tire circumferential direction are formed from one end to the other end of the first land portion row 34 in the tire width direction. Has a point and is bent. The width direction narrow groove 40 is narrower than the shoulder circumferential direction groove 22 and the center circumferential direction groove 24 and is formed with a shallow groove depth.

  A groove bottom sipe 42 is formed at the groove bottom of the width direction narrow groove 40. The groove bottom sipe 42 is formed so as to extend from one end to the other end in the tire width direction of the first land portion row 34 along the extending direction of the width direction narrow groove 40.

  Here, as shown in FIG. 2, the groove width W <b> 1 of the width direction narrow groove 40 is narrower than the groove width W <b> 0 of the shoulder circumferential direction groove 22, and the groove depth H <b> 1 of the width direction narrow groove 40 is the shoulder circumferential direction groove 22. It is formed shallower than the groove depth H0. The groove width W2 of the width direction narrow groove 40 is such that the groove walls are not separated even when the tread 12 is grounded, and the groove is not closed, and is about 2 mm to 5 mm. Moreover, the groove depth H1 of the width direction narrow groove 40 is about 1.5 mm to 3.5 mm.

  On the other hand, the groove width W2 of the groove bottom sipe 42 is such that when the tread 12 is grounded, the sipe wall surfaces come into contact with each other and close, and is about 0.7 mm to 1.5 mm. The groove depth H2 (depth from the tread surface to the groove bottom) of the groove bottom sipe 42 is preferably set to 50% to 90% of the groove depth H0 of the shoulder circumferential groove 22 when new. By setting within this range, the rubber flow component in the tire circumferential direction is appropriately blocked by the groove bottom sipe 42, thereby preventing slipping when kicking out and suppressing wear. When the groove depth H2 of the groove bottom sipe 42 is less than 50% of the groove depth H0 of the shoulder circumferential groove 22, the slipping at the time of kicking cannot be effectively suppressed, and the groove depth H2 exceeds 90%. This is because the rigidity of the block is reduced.

  Between the narrow grooves 40 adjacent to each other in the tire circumferential direction, circumferential narrow grooves 43 extending in the tire circumferential direction are formed. The circumferential narrow groove 43 is formed so as to connect the convex portion 40A of one width direction narrow groove 40 and the convex portion 40B of the other width direction narrow groove 40 facing each other. Further, the circumferential narrow groove 43 has two inflection points from the convex portion 40A of one width direction narrow groove 40 to the convex portion 40B of the other width direction narrow groove 40, and is formed to be bent zigzag. ing.

  As shown in FIG. 2, the groove width W3 of the circumferential narrow groove 43 is narrower than the groove width W0 of the shoulder circumferential groove 22, and the groove depth H3 of the circumferential narrow groove 43 is the groove of the shoulder circumferential groove 22. It is formed shallower than the depth H0. The groove width W3 of the circumferential narrow groove 43 is such a groove width that the groove walls are not separated even when the tread 12 is grounded and the groove is not closed, and is about 1 mm to 3 mm.

  In the second land portion row 36, width direction narrow grooves 44 are formed at predetermined intervals in the tire circumferential direction. The width direction narrow grooves 44 are formed so as to extend from one end to the other end in the tire width direction of the second land portion row 36 and open to the shoulder circumferential groove 26 and the center circumferential groove 24. . About the structure of the width direction narrow groove 44, convex part 44A, 44B, and the circumferential direction narrow groove 47 currently formed in the 2nd land part row | line | column 36, the width direction thin groove | channel formed in the 1st land part row | line | column 34, respectively. This is the same as the convex portions 40 </ b> A and 40 </ b> B and the circumferential narrow groove 43 formed in the groove 40, the width narrow groove 40.

  A shoulder narrow groove 50 extending in the tire width direction is formed in the first shoulder land portion row 32. The shoulder narrow groove 50 has one end that opens into the shoulder circumferential groove 22 and the other end that terminates in the first shoulder land portion row 32 from the wide groove portion 50A on the shoulder circumferential groove 22 side and the other end of the wide groove portion 50A. It has a narrow groove portion 50B that continues and reaches the tire shoulder. The end position of the wide groove portion 50A in the first shoulder land portion row 32 is closer to the tire equatorial plane CL in the tire width direction than a circumferential shoulder narrow groove 54 described later. As shown in FIG. 5, the groove width W4 of the wide groove portion 50A is wider than the groove width W5 of the narrow groove portion 50B. The groove width W4 of the wide groove portion 50A can be about 2 mm to 5 mm, and the groove width W5 of the narrow groove portion 50B can be about 1 mm to 3 mm.

  The groove width W4 of the wide groove portion 50A and the groove width W5 of the narrow groove portion 50B of the shoulder narrow groove 50 are narrower than the groove width W0 of the shoulder circumferential groove 22, and the groove depth H4 and narrow groove portion of the wide groove portion 50A. The groove depth H5 of 50B is formed shallower than the groove depth H0 of the shoulder circumferential groove 22. The groove width W4 of the wide groove portion 50A of the shoulder narrow groove 50 and the groove width W5 of the narrow groove portion 50B are such that the groove walls are not separated from each other even when the tread 12 is grounded and the groove is not closed. is there.

  Intermediate narrow grooves 52 are formed between the shoulder narrow grooves 50 adjacent to each other in the tire circumferential direction of the first shoulder land portion row 32. One end of the intermediate narrow groove 52 opens into the shoulder circumferential groove 22 and the other end reaches the tire shoulder. As shown in FIG. 4, the groove width W <b> 6 of the intermediate narrow groove 52 is narrower than the wide groove portion 50 </ b> A of the shoulder narrow groove 50. Further, the groove width W6 of the intermediate narrow groove 52 is such a groove width that the groove walls are not separated from each other even when the tread 12 is grounded and the groove is not closed.

  The shoulder narrow groove 50 and the intermediate narrow groove 52 are formed on an extension line of the width direction narrow groove 40 of the first land portion row 34.

  The first shoulder land portion row 32 is formed with a circumferential shoulder narrow groove 54 extending continuously in the tire circumferential direction so as to intersect with the shoulder narrow groove 50 and the intermediate narrow groove 52. The circumferential shoulder narrow groove 54 has a zigzag shape with the inflection point at a position intersecting with the shoulder narrow groove 50 and the intermediate narrow groove 52. The amplitude in the tire width direction of the circumferential shoulder narrow groove 54 can be set to the same level as that of the shoulder circumferential groove 22. As shown in FIG. 4, the groove width W <b> 7 of the circumferential shoulder narrow groove 54 is narrower than the wide groove portion 50 </ b> A of the shoulder narrow groove 50. Further, the groove width W7 of the circumferential shoulder narrow groove 54 is such that the groove walls are not separated from each other even when the tread 12 is grounded, and the groove is not closed.

  A shoulder narrow groove 60 extending in the tire width direction is formed in the second shoulder land portion row 38. The shoulder narrow groove 60 has one end that opens into the shoulder circumferential groove 26 and the other end that terminates in the second shoulder land portion row 38 from the shoulder circumferential groove 26 side wide groove portion 60A and the other end of the wide groove portion 60A. It has a narrow groove portion 60B that continues and reaches the tire shoulder. The configurations of the shoulder narrow groove 60, the wide groove portion 60A, the narrow groove portion 60B, the intermediate narrow groove 62, and the circumferential shoulder narrow groove 64 formed in the second shoulder land portion row 38 are respectively the first shoulder land portion row 32. The shoulder narrow groove 50, the wide groove portion 50A, the narrow groove portion 50B, the intermediate narrow groove 52, and the circumferential shoulder narrow groove 54 are formed in the same manner as described above. The end position of the wide groove portion 60A in the second shoulder land portion row 38 is closer to the tire equatorial plane CL in the tire width direction than the circumferential shoulder narrow groove 64.

  The shoulder narrow groove 60 and the intermediate narrow groove 62 are formed on an extension line of the width direction narrow groove 44 of the second land portion row 36.

  According to the pneumatic tire 10 of the present embodiment, the first land portion row 34 is formed with the circumferential narrow grooves 43 that allow the adjacent width direction narrow grooves 40 to communicate with each other. Since the circumferential narrow grooves 47 that allow the adjacent widthwise narrow grooves 44 to communicate with each other are formed, drainage can be improved and wet performance can be improved. Further, since the circumferential narrow grooves 43 and 47 are formed so as to be bent zigzag, the turning performance can be improved by increasing the edge component.

  Further, the circumferential narrow groove 43 is formed so as to connect the convex portion 40A of one width direction narrow groove 40 and the convex portion 40B of the other width direction narrow groove 40 facing each other. The angle between the narrow groove 43 and the width direction narrow groove 40 can be increased, and uneven wear of the first land portion row 34 can be suppressed as compared with the case where the angle is small. The same applies to the circumferential narrow groove 47.

  The circumferential narrow grooves 43 and 47 are not necessarily bent in a zigzag shape, and may be linear or bent at only one place.

  Further, in the present embodiment, the width direction narrow groove 40 is formed so as to be bent zigzag between one end and the other end of the first land portion row 34 in the tire width direction. , Turning performance, braking performance can be improved.

  Note that the narrow grooves 40 and 44 in the width direction do not necessarily have to be bent in a zigzag shape, and may be linear, bend only at one place, or be zigzag bent at three or more places.

  In the present embodiment, the shoulder narrow groove 50 formed in the first shoulder land portion row 32 has a wide groove portion 50A that opens to the shoulder circumferential groove 22 and extends from the wide groove portion 50A to the tire shoulder. Since the narrow groove portion 50B is provided, the width of the narrow groove portion 50B is narrowed by suppressing the increase in the negative rate of the first shoulder land portion row 32 while ensuring drainage by the wide groove portion 50A. Abrasion performance can be improved. A similar effect can be obtained with respect to the second shoulder land portion row 38.

  Further, in the present embodiment, since the intermediate narrow groove 52 is formed between the shoulder narrow grooves 50 of the first shoulder land portion row 32, compared to the case where all the shoulder narrow grooves 50 are formed at the same interval, The increase in the negative rate of the 1st shoulder land part row | line | column 32 can be suppressed, and wear resistance performance can be improved. A similar effect can be obtained with respect to the second shoulder land portion row 38.

  In the present embodiment, the shoulder narrow groove 50 and the intermediate narrow groove 52 are formed on the extension line of the width direction narrow groove 40 of the first land portion row 34, and the shoulder narrow groove 60 and the intermediate narrow groove 62 are It is formed on the extension line of the width direction narrow groove 44 of the second land portion row 36. By arranging the width direction narrow grooves 40 and 44 and the shoulder narrow grooves 50 and 60 in this way, drainage can be improved.

  In the present embodiment, only one center circumferential groove 24 is formed between the shoulder circumferential grooves 22 and 26, but two or more circumferential grooves may be formed.

  In order to confirm the effect of the present invention, the tire of the comparative example and the tire of the example to which the present invention was applied were prepared, and the wet turning performance, the wet brake performance, and the wear resistance performance were tested with an actual vehicle.

  As shown in FIG. 5, the tire tread 90 of the comparative example includes a pair of shoulder circumferential grooves 91 on the most shoulder side and a center circumferential groove 92 on the tire equatorial plane CL. A center side land portion row 95 is formed between the shoulder circumferential groove 91 and the center circumferential groove 92, and a shoulder land portion row 94 is formed outside the shoulder circumferential groove 91 in the tire width direction. Yes. The center side land portion row 95 is formed with first narrow grooves 96A and 96B extending in the tire width direction from the center circumferential groove 92 to the shoulder circumferential groove 91 at predetermined intervals in the tire circumferential direction. In the shoulder land portion row 94, second narrow grooves 98 extending in the tire width direction from the shoulder circumferential groove 91 to the tread end 90E are formed at predetermined intervals in the tire circumferential direction.

The test conditions of the examples and comparative examples are as follows.
Vehicle used: Truck (2-D)
Applicable rim: 7.50 × 22.5
Test air pressure: 900KPa
Load: Regular load

(Wet turning performance test)
The road surface of the test course was wet Belgian, and the turning acceleration was evaluated when new and worn (4 mm remaining). The evaluation of turning acceleration shows the index of the comparative example as 100 when it is new and worn (4 mm remaining). The index of the turning acceleration evaluation indicates that the turning performance is higher as the numerical value is higher.

  As shown in the test results in Table 1, the tire of the example to which the present invention is applied obtains a high turning performance on the wet road surface both when new and worn, as compared with the tire of the comparative example. I was able to.

(Wet brake performance)
The road surface of the test course was wet asphalt, and the brake performance was evaluated by the deceleration index when new and worn (4 mm remaining). The index shows 100 as the index of the comparative example when new and worn (4 mm remaining). The index indicates that the higher the value, the higher the braking performance.

  As shown in the test results of Table 2, the tire of the example to which the present invention is applied obtains high braking performance on the wet road surface both when new and worn as compared with the tire of the comparative example. I was able to.

(Abrasion resistance)
The road surface of the test course was dry asphalt, and the wear resistance performance was evaluated by the wear life index. In the evaluation, in the new tire, the distance traveled until the groove disappeared first was indicated by an index. The wear life index is shown as 100 as a comparative example. The wear life index indicates that the higher the numerical value, the higher the wear resistance performance.

  As shown in the test results of Table 3, it is clear that the tire of the example to which the present invention was applied has higher wear resistance than the tire of the comparative example.

10 Pneumatic tire 12 Tread 22 Shoulder circumferential groove 24 Center circumferential groove 26 Shoulder circumferential groove 32 First shoulder land portion row 34 First land portion row 36 Second land portion row 38 Shoulder land portion row 40 Width direction narrow groove 40A, 40B Convex part 42 Groove bottom sipe 43 Circumferential narrow groove 44 Width direction narrow groove 44A, 44B Convex part 47 Circumferential narrow groove 50 Shoulder narrow groove 50B Narrow groove part 50A Wide groove part 52 Intermediate narrow groove 54 Circumferential shoulder narrow groove 60 shoulder narrow groove 60B narrow groove portion 60A wide groove portion 62 intermediate narrow groove 64 circumferential shoulder narrow groove

Claims (6)

A pair of outer circumferential shoulder grooves formed in the tire tread and extending along the tire circumferential direction;
A center circumferential groove formed on the tire equator plane between the shoulder circumferential grooves,
A plurality of land portion rows partitioned by the center circumferential groove and the shoulder circumferential groove and extending in the tire circumferential direction;
A groove bottom sipe traversing the land portion row in the tire width direction;
A width that is formed along the groove bottom sipe on the tire tread tread side of all the groove bottom sipes and is shallower than the center circumferential groove and the shoulder circumferential groove and that crosses the land portion row in the tire width direction. Directional narrow groove,
A circumferential narrow groove communicating the widthwise narrow grooves adjacent to each other in the tire circumferential direction;
Bei to give a,
The width direction narrow groove is bent so that a pair of convex portions protruding in opposite directions in the tire circumferential direction is formed from one end to the other end in the tire width direction of the land portion row,
The said circumferential direction narrow groove is a pneumatic tire which has connected the vertex of the said convex part which a convex mutually faces between the said adjacent width direction narrow grooves . The pneumatic tire according to claim 1, wherein the circumferential narrow groove is bent at least once between the adjacent narrow grooves in the width direction. In the shoulder land portion formed on the outer side in the tire width direction than the shoulder circumferential groove, a shoulder narrow groove extending in the tire width direction and having one end opened to the shoulder circumferential groove is formed.
3. The pneumatic tire according to claim 1 , wherein the shoulder narrow groove has a wider groove portion on the shoulder circumferential groove side than a narrow groove portion on the tire shoulder side. Between the shoulder narrow grooves adjacent in the tire circumferential direction, one end that extends in the tire width direction is opened in the shoulder circumferential groove, and an intermediate narrow groove that is narrower than the wide groove portion is formed. The pneumatic tire according to claim 3 . The pneumatic tire according to claim 3 or 4, wherein the shoulder narrow groove is formed at a position where the width-direction narrow groove is extended. The circumferential shoulder narrow groove having a narrower width than the wide groove portion is formed so as to extend in the tire circumferential direction and intersect the shoulder narrow groove . The pneumatic tire according to item 1 .