JP2011168222A - Tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire allowing improvement of drainage property, while suppressing lowering of braking performance, when a main groove is formed. <P>SOLUTION: This pneumatic tire 1 includes a land part 10 extending along a tire peripheral direction TR, and a land part 20 extending along the tire peripheral direction TR. The main groove 50 extending along the tire peripheral direction TR is formed between the land part 10 and the land part 20. A groove wall 10a of the land part 10 and a groove wall 20a of the land part 20 meander along the tire peripheral direction TR in a tread surface view. A groove width of the main groove 50 along a tread width direction TW is changed at a prescribed repeated period along the tire peripheral direction TR. When a maximum width part of the groove width is W<SB>MAX</SB>, a minimum width part of the groove width is W<SB>MIN</SB>and an average length along the tread width direction TW of the main groove 50 is A, relation of (W<SB>MAX</SB>-W<SB>MIN</SB>)/A≤0.25 is satisfied. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a tire in which a main groove extending along the tire circumferential direction is formed, and more particularly to a tire that suppresses a decrease in drainage.

  Conventionally, in a pneumatic tire (hereinafter referred to as a tire), various methods for improving the drainage of water that has entered between the road surface and the tread have been used in order to suppress hydroplaning. For example, a method for forming a depression in a groove wall of a land portion that forms a main groove provided along the tire circumferential direction is known (for example, Patent Document 1). According to such a tire, the turbulent flow of water flowing in the main groove can be suppressed, and drainage performance is improved.

Japanese Patent Laying-Open No. 2006-205824 (page 5, FIG. 1)

  However, the conventional tire described above has the following problems. That is, there is a problem that the rigidity of the land portion is lowered by the depression and the braking performance is lowered. On the other hand, when the depression is made small in order to suppress a decrease in the rigidity of the land portion, the drainage is hardly improved and hydroplaning is likely to occur.

  Therefore, an object of the present invention is to provide a tire that can improve drainage while suppressing a decrease in braking performance when a main groove is formed.

In order to solve the above-described problems, the present invention has the following features. First, the first feature of the present invention extends along the tire circumferential direction (tire circumferential direction TR), and extends along the tire circumferential direction, a first land portion (for example, the land portion 10) in contact with the road surface, A main groove (e.g., main groove) that extends along the tire circumferential direction between the first land portion and the second land portion, and a second land portion (e.g., land portion 20) that contacts the road surface. 50) formed in the tire (for example, pneumatic tire 1), the first land portion includes a first groove wall (for example, a groove wall 10a) that forms the main groove, and the second land portion. The land portion has a second groove wall (for example, a groove wall 20a) that forms the main groove, and the first groove wall and the second groove wall are along the tire circumferential direction in a tread surface view. The groove width of the main groove meandering along the tread width direction (tread width direction TW) is set along the tire circumferential direction. Repetition period in change, the widest part of the groove width is W _MAX, the minimum width portion of the groove width is W _MIN, if the average length along the tread width direction of the main groove is A, and The gist is to satisfy the relationship of (W _MAX −W _MIN ) /A≦0.25.

  According to such a feature, the first groove wall and the second groove wall meander along the tire circumferential direction in a tread surface view, and the groove width of the main groove changes at a predetermined repetition period along the tire circumferential direction. To do. According to this, the flow of water along the meandering of the first groove wall and the second groove wall is generated in the main groove.

Specifically, water flowing through the main groove after passing through the widest part W _MAX, with decreasing the groove width of the main groove, the first groove wall towards the widest part W _MAX to the minimum width portion W _MIN And drained in the direction of the extension of the streamline along the second groove wall. That is, the water flowing in the main groove 50 pulsates at a predetermined repetition period, and is an extension of streamlines along the first groove wall and the second groove wall from the maximum width portion W _MAX to the minimum width portion W _MIN. Drained in the direction. Accordingly, it is possible to suppress a decrease in drainage that drains water that has entered between the road surface and the tread.

Further, the relationship (W _MAX −W _MIN ) /a≦0.25 is satisfied. According to _{this, (W MAX -W MIN) /} a> 0.25 as compared with the case of a reduction in the rigidity of the land portion can be reliably inhibited, it is possible to suppress the deterioration of the braking performance.

  Thus, in the case where the main groove is formed, it is possible to provide a tire that can improve drainage while suppressing a decrease in braking performance.

A second feature of the present invention relates to the first feature of the present invention, wherein the ratio W _MIN / W _MAX between the minimum width portion W _MIN of the groove width and the maximum width portion W _MAX of the groove width is 35 The gist is that it is in the range of% to 85%.

  A third feature of the present invention relates to the first or second feature of the present invention, wherein the first groove wall and the second groove wall have a predetermined amplitude (amplitude a) along the tread width direction. The predetermined repetition period (period λ) is 15 to 100 times the predetermined amplitude.

A fourth feature of the present invention relates to the first to third features of the present invention, wherein the main groove is provided with a wide groove portion (wide portion 50A) including the maximum width portion W _MAX of the groove width, At the bottom of the main groove (for example, the bottom 50 btm), a bulge portion (bulge portion 70) that bulges outward in the tire radial direction (tire radial direction TR) is formed, and the bulge portion is formed in the wide groove portion. This is the gist.

  A fifth feature of the present invention relates to the fourth feature of the present invention, wherein a first side portion (side portion 70a) of the raised portion facing the first groove wall is along the first groove wall. The gist is that the second side portion (side portion 70b) of the raised portion that extends and faces the second groove wall extends along the second groove wall.

  A sixth feature of the present invention relates to the fourth or fifth feature of the present invention, wherein the raised portion has a front end portion (front end 70f) and a rear end portion (rear end 70r) of the raised portion in the tread surface view. ) The gist is that it gets thinner as you go.

  A seventh feature of the present invention relates to the fourth to sixth features of the present invention, wherein the height of the raised portion (the raised height H70) is less than the depth of the main groove (main groove depth H10). It is a summary.

  According to the characteristics of the present invention, it is possible to provide a tire that can improve drainage while suppressing a decrease in braking performance when the main groove is formed.

FIG. 1 is a development view showing a tread pattern of the pneumatic tire 1 according to the first embodiment. FIG. 2 is a perspective view showing a part of the pneumatic tire 1 according to the first embodiment. FIG. 3 is an enlarged development view showing the main groove 50 formed in the pneumatic tire 1 according to the first embodiment. FIG. 4 is a development view showing a tread pattern of the pneumatic tire 2 according to the second embodiment. FIG. 5 is a perspective view showing a part of the pneumatic tire 2 according to the second embodiment. FIG. 6 is a cross-sectional view (a cross-sectional view taken along line A-A ′ in FIGS. 4 and 5) showing a part of the pneumatic tire 2 according to the second embodiment. FIG. 7 is a development view showing a tread pattern of the pneumatic tire 3 according to Comparative Example 1.

  Next, an embodiment of a pneumatic tire according to the present invention will be described with reference to the drawings. Specifically, (1) the first embodiment, (2) the second embodiment, (3) comparative evaluation, and (4) other embodiments will be described.

  In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones.

  Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(1) First Embodiment Hereinafter, (1.1) a configuration of a pneumatic tire, (1.2) a detailed configuration of a main groove, and (1.3) actions and effects will be described in order.

(1.1) Configuration of Pneumatic Tire First, the pneumatic tire 1 according to the first embodiment will be described with reference to the drawings. FIG. 1 is a development view showing a tread pattern of the pneumatic tire 1 according to the first embodiment. FIG. 2 is a perspective view showing a part of the pneumatic tire 1 according to the first embodiment.

  As shown in FIGS. 1 and 2, the pneumatic tire 1 includes a rib-shaped land portion 10 that extends along the tire circumferential direction TR and is in contact with a road surface, a land portion 20, and a land portion 30. Further, the pneumatic tire 1 includes a main groove 50 extending along the tire circumferential direction TR between the land portion 10 and the land portion 20, and a tire circumferential direction TR between the land portion 10 and the land portion 30. And a main groove 60 extending.

  The land portion 10 includes a groove wall 10 a that forms the main groove 50 and a groove wall 10 b that forms the main groove 60. The land portion 20 includes a groove wall 20 a that forms the main groove 50 and a groove wall 20 b that forms the main groove 60. The land portion 30 has a groove wall 30 a that forms the main groove 60. Further, the land portion 30 is formed with a lateral groove 110 that opens to the outside in the tread width direction TW.

  On the other hand, the main groove 50 is provided on the tire equator line CL. The main groove 60 is provided outside the tire equator line CL in the tread width direction TW. The detailed configuration of the main groove 50 and the main groove 60 will be described later.

  Here, in the first embodiment, the configuration of one (left side in FIG. 1) in the tread width direction TW has been described with respect to the tire equator line CL, but the configuration of the other (right side in FIG. 1) Since it is substantially the same as the above-described one configuration, a detailed description thereof is omitted here.

(1.2) Detailed structure of main groove Next, the detailed structure of the main groove 50 mentioned above is demonstrated, referring FIGS. 1-3. FIG. 3 is an enlarged development view showing the main groove 50 formed in the pneumatic tire 1 according to the first embodiment. Since the configuration of the main groove 60 is substantially the same as the configuration of the main groove 50, the main groove 50 will be described as an example.

  As shown in FIGS. 1 to 3, the main groove 50 is formed by the groove wall 10 a of the land portion 10 and the groove wall 20 a of the land portion 20. The groove wall 10a and the groove wall 20a meander along the tire circumferential direction TR in the tread surface view. The groove wall 10a and the groove wall 20a are provided symmetrically about the center line (tire equator line CL) of the main groove 50.

  The bottom 50btm of the main groove 50 is formed in a smooth shape. The main groove 50 has a groove width that changes at a predetermined repetition period along the tire circumferential direction TR. The groove width of the main groove 50 indicates the width along the tread width direction TW, and indicates the distance in the tread width direction TW from an arbitrary point on the groove wall 10a to the groove wall 20a.

As shown in FIG. 3, the groove width of the main groove 50 changes with a period λ along the tire circumferential direction TR. That is, the groove wall 10a and the groove wall 20a have an amplitude a along the tread width direction TW. The groove wall 10a and the groove wall 20a change with a period λ along the tire circumferential direction TR in the tread surface view. The groove wall 10a and the groove wall 20a are provided in a symmetrical shape on the front side and the rear side in the tire rotation direction R, with the maximum width part W _MAX as a boundary, when the minimum width part W _MIN is the starting point of the period λ. .

  The period λ of the groove wall 10a and the groove wall 20a in the tire circumferential direction TR is 15 to 100 times the amplitude a. In addition, the tread length in the tire circumferential direction TR of the tread that contacts the road surface during rolling of the tire is 0.5 to 20 times the period λ of the main groove 50.

In such a main groove 50, a wide portion 50A and a narrow portion 50B are provided. The wide portion 50A includes a maximum width portion W _MAX of the groove width of the main groove 50 along the tread width direction TW. On the other hand, the narrow portion 50B includes a minimum width portion W _MIN of the groove width of the main groove 50 along the tread width direction TW. The wide portions 50A and the narrow portions 50B are provided alternately with respect to the tire circumferential direction TR.

Here, the maximum width portion of the main groove 50 is W _MAX , the minimum width portion of the main groove 50 is W _MIN, and the average length of the main groove 50 along the tread width direction is A. In this case, the relationship of (W _MAX −W _MIN ) /A≦0.25 is satisfied. The ratio W _MIN / W _MAX between the minimum width portion W _MIN of the main groove 50 and the maximum width portion W _MAX of the main groove 50 is in the range of 35% to 85%.

  The configuration of the main groove 50 is the same as the configuration of the main groove 60, but the cycle λ of the main groove 50 and the cycle λ of the main groove 60 are shifted by a half cycle.

(1.3) Actions / Effects Hereinafter, actions / effects of the pneumatic tire 1 according to the first embodiment will be described. Since the configuration of the main groove 60 is the same as that of the main groove 50, the main groove 50 will be described as an example.

In the first embodiment, the groove wall 10a and the groove wall 20a meander along the tire circumferential direction TR in the tread surface view, and the groove width of the main groove 50 is a predetermined period λ along the tire circumferential direction TR. Change. According to this, in the main groove 50, the flow of water along the meandering of the groove wall 10a and the groove wall 20a is generated. That is, the main in the groove 50 within, streamline S _10a and streamline S _20a is a flow of water along the groove wall 10a and the groove wall 20a is generated (see FIG. 3).

Specifically, water flowing through the main groove 50 after passing through the widest part W _MAX, with decreasing the groove width of the main groove 50, toward the widest part W _MAX to the minimum width portion W _MIN groove wall The water is drained in the direction of the extension of the streamlines (streamline _S10a and streamline _S20a ) along 10a and the groove wall 20a. That is, the water flowing in the main groove 50 pulsates with a predetermined period λ, and extends from the maximum width portion W _MAX to the minimum width portion W _MIN in the direction of the streamline extending along the groove wall 10a and the groove wall 20a. Drained. Accordingly, it is possible to suppress a decrease in drainage that drains water that has entered between the road surface and the tread.

Further, the relationship (W _MAX −W _MIN ) /a≦0.25 is satisfied. According to this, as compared with the case of (W _MAX −W _MIN ) / a> 0.25, it is possible to reliably suppress the decrease in rigidity of the land portion 10, the land portion 20, and the land portion 30, and to reduce the braking performance. Can be suppressed.

  Thus, in 1st Embodiment, when the main groove 50 and the main groove 60 are formed, the tire which can improve drainage can be provided, suppressing the fall of braking performance.

In the first embodiment, the ratio W _MIN / W _MAX between the minimum width portion W _MIN of the groove width of the main groove 50 and the maximum width portion W _MAX of the groove width of the main groove 50 is in the range of 35% to 85%. is there. According to this, the water flowing along the groove wall 10a and the groove wall 20a passes through the maximum width portion W _MAX and then decreases in the groove width of the main groove 50, so that the groove wall 10a and the groove at the minimum width portion W _MIN. It becomes easier to drain in the direction of the extension of the streamline along the wall 20a. That is, the water flowing in the main groove 50 is likely to go outward in the tread width direction TW. Therefore, drainage can be improved more reliably.

If the ratio W _MIN / W _MAX is smaller than 35%, the water flow along the groove wall 10a and the groove wall 20a at the minimum width portion W _MIN and the water flow along the tire circumferential direction TR are excessive. In some cases, the concentration of water may be reduced, and deterioration of drainage performance may not be suppressed. On the other hand, if the ratio W _MIN / W _MAX is greater than 85%, the water in the main groove 50 is unlikely to pulsate and it may be difficult to improve drainage.

  In the first embodiment, the groove wall 10a and the groove wall 20a have an amplitude a along the tread width direction TW, and the period λ is 15 to 100 times the amplitude a. According to this, since the water flowing in the main groove 50 can be effectively drained to the outside of the main groove 50, the drainage performance is further improved.

Incidentally, the period lambda, it allows the minimum width portion W _MIN, the flow along the groove wall 10a and the groove wall 20a, flows along the tire circumferential direction TR excessively concentrated is at least 15 times the amplitude a This can be sufficiently suppressed. Further, since the period λ is 100 times or less of the amplitude a, the water in the main groove 50 can sufficiently pulsate, and the water flowing in the main groove 50 can be effectively moved outside the main groove 50. Can drain.

  In particular, the period λ of the main groove 50 and the period λ of the main groove 60 are shifted by a half period. According to this, the water flowing through the main groove 50 and the main groove 60 alternately pulsates during tire rolling while reliably suppressing the decrease in rigidity of the land portion 10, the land portion 20, and the land portion 30. Drained alternately. For this reason, braking performance and drainage can be compatible at a high level.

  In the first embodiment, the tread length in the tire circumferential direction TR of the tread that comes in contact with the road surface during rolling of the tire is 0.5 to 20 times the period λ of the main groove 50. When the tread length is 0.5 times or more the period λ of the main groove 50, the main groove 50 is grounded by a sufficient number to pulsate along the tire circumferential direction TR when the tire rolls. For this reason, the water flowing in the main groove 50 can be effectively drained to the outside of the main groove 50. On the other hand, when the tread length is 20 times or less of the period λ of the main groove 50, a flow of water along the groove wall 10a and the groove wall 20a is generated in the main groove 50. For this reason, the water flowing in the main groove 50 can be effectively drained to the outside of the main groove 50.

(2) Second Embodiment Hereinafter, a pneumatic tire 2 according to a second embodiment of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same part as the pneumatic tire 1 which concerns on 1st Embodiment mentioned above, and a different part is mainly demonstrated.

  Here, in the first embodiment described above, the main groove 50 of the pneumatic tire 1 is not provided with a raised portion described later, and the bottom 50btm of the main groove 50 is formed in a smooth shape.

  On the other hand, in the second embodiment, the main groove 50 of the pneumatic tire 2 is provided with a raised portion described later. Specifically, in the second embodiment, (2.1) a detailed configuration of the main groove and (2.2) functions and effects will be described with reference to FIGS.

  FIG. 4 is a development view showing a tread pattern of the pneumatic tire 2 according to the second embodiment. FIG. 5 is a perspective view showing a part of the pneumatic tire 2 according to the second embodiment. FIG. 6 is a cross-sectional view (a cross-sectional view taken along line A-A ′ in FIGS. 4 and 5) showing a part of the pneumatic tire 2 according to the second embodiment.

(2.1) Detailed Configuration of Main Groove As shown in FIGS. 4 and 5, the bottom portion 50 btm of the main groove 50 is formed with a raised portion 70 that protrudes outward in the tire radial direction TR. The raised portion 70 is formed in a vertically long shape along the tire circumferential direction TR in the tread surface view. The raised portion 70 is formed in the wide portion 50A, and is provided symmetrically about the center line (tire equator line CL) of the main groove 50 in a tread surface view.

  In the tread surface view, the raised portion 70 becomes narrower as it goes to the front end 70f (front end portion) in the front of the tire rotation direction R and the rear end 70r (rear end portion) in the rear of the tire rotation direction R. Further, the side portion 70a of the raised portion 70 that faces the groove wall 10a that forms the main groove 50 extends along the groove wall 10a. Similarly, the side portion 70b of the raised portion 70 that faces the groove wall 20a that forms the main groove 50 extends along the groove wall 20a.

  As shown in FIG. 6, a raised height H70, which is the height of the raised portion 70, is a height along the tire radial direction TR from the bottom 50btm. The raised height H70 is less than the main groove depth H10, which is the depth of the main groove 50.

(2.2) Action / Effect In the second embodiment described above, the raised portion 70 is formed at the bottom portion 50btm of the wide portion 50A of the main groove 50 so as to protrude outward in the tire radial direction TR. According to this, the water flowing in the wide portion 50 </ b> A is likely to flow along the groove wall 10 a and the groove wall 20 a by the raised portion 70. That is, the water flowing in the wide portion 50 </ b> A is easily drained to the outside of the main groove 50 by the raised portion 70. For this reason, the water which flows in the wide part 50A can be drained efficiently, and the drainage is further improved.

  In the second embodiment, the side portion 70a of the raised portion 70 that faces the groove wall 10a extends along the groove wall 10a, and the side portion 70b of the raised portion 70 that faces the groove wall 20a extends along the groove wall 20a. Extend. According to this, the water flowing in the wide portion 50A becomes easier to flow along the groove wall 10a and the groove wall 20a, and the drainage performance is further improved.

  In the second embodiment, the raised portion 70 becomes narrower as it goes to the front end 70f in the front of the tire rotation direction R and the rear end 70r in the rear of the tire rotation direction R in the tread surface view. According to this, the water flowing in the wide portion 50A is effectively flowed along the groove wall 10a and the groove wall 20a without the flow suddenly changing by the raised portion 70.

  In the second embodiment, the raised portions 70 are provided symmetrically about the center line (tire equator line CL) of the main groove 50 in the tread surface view. For this reason, the water flowing in the wide portion 50A is likely to flow evenly along the groove wall 10a and the groove wall 20a by the raised portion 70.

  In the second embodiment, the raised height H70 is less than the main groove depth H10. According to this, compared with the case where the protruding height H70 is not less than the main groove depth H10, the flow of water along the tire circumferential direction TR can be sufficiently ensured in the wide portion 50A.

(3) Comparative Evaluation Next, in order to further clarify the effects of the present invention, comparative evaluation performed using pneumatic tires according to the following comparative examples and examples will be described. Specifically, (3.1) Configuration of each pneumatic tire and (3.2) Evaluation result will be described with reference to Table 1. In addition, this invention is not limited at all by these examples.

(3.1) Configuration of each pneumatic tire Data on each pneumatic tire was measured under the following conditions.

・ Tire size: 225 / 45R17
・ Rim wheel size: 17 × 7J
-Tire type: Normal tire (tires other than studless tires)
-Vehicle type: Domestic car sedan-Load condition: 600N + driver's weight The pneumatic tire 1 according to Example 1 is the same as that described in the first embodiment (see FIGS. 1 to 3). The pneumatic tire 2 according to Example 2 has been described in the second embodiment (see FIGS. 4 to 6).

  As shown in FIG. 7, the pneumatic tire 3 according to the comparative example 1 is different in the configuration of the main groove 100 and the main groove 101 from the pneumatic tire of the example. Specifically, the groove walls forming the main groove 100 and the main groove 101 are not meandering, and are formed in a substantially linear shape along the tire circumferential direction TR. Different from tire 1.

The pneumatic tire according to Comparative Example 2 has the same configuration as that of the pneumatic tire 1 according to the first embodiment, but the value of (W _MAX −W _MIN ) / a is (a value of 0.25 or more). . The pneumatic tire according to Comparative Example 3 has the same configuration as that of the pneumatic tire 2 according to the second embodiment, but the value of (W _MAX −W _MIN ) / a is (a value of 0.25 or more). .

(3.2) Evaluation results (3.2.1) Hydroplaning test A vehicle equipped with pneumatic tires is accelerated by entering a rainy road with a depth of 10 mm at a speed of 80 km / h. The speed at which hydroplaning occurred in the vehicle equipped with tire 3 was taken as “100”, and the speed at which hydroplaning occurred in other vehicles equipped with pneumatic tires was indexed. In addition, hydroplaning is hard to generate | occur | produce, so that an index | exponent is large.

  As a result, as shown in Table 1, the vehicle equipped with the pneumatic tires according to Examples 1 and 2 is less likely to cause hydroplaning than the vehicle equipped with the pneumatic tire 3 according to Comparative Example 1. I found out.

(3.2.2) Brake Performance Test A vehicle equipped with each pneumatic tire is run on a test course with a water depth of 2 mm, and a vehicle equipped with the pneumatic tire 3 according to Comparative Example 1 is fully loaded from a speed of 60 km / h. The distance (deceleration) from when the brakes were lost to the stop was set to '100', and the deceleration of a vehicle equipped with other pneumatic tires was evaluated by a professional driver. The larger the index, the better the braking performance.

  As a result, as shown in Table 1, the vehicle equipped with the pneumatic tires according to Examples 1 and 2 is superior in braking performance compared to the vehicle equipped with the pneumatic tire according to Comparative Examples 1 to 3. I found out.

(4) Other Embodiments As described above, the contents of the present invention have been disclosed through the embodiments of the present invention. However, it is understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. Should not. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, the embodiment of the present invention can be modified as follows. Specifically, the tire may be a pneumatic tire 1 filled with air, nitrogen gas, or the like, or may be a solid tire that is not filled with air, nitrogen gas, or the like.

  The number of land portions and main grooves provided in the pneumatic tire described above and the arrangement positions are not limited to those described in the embodiment, and can be appropriately selected according to the purpose.

In the embodiment described above, it is sufficient that at least the land portion and the main groove are provided in the pneumatic tire. For example, a lug groove or the like may be further provided. In this case, it is preferable that the lug groove is provided along the direction of the stream line S _10a and the extension line of the stream line S _20a (see FIG. 3). Thereby, it becomes easy to discharge | emit the water which flows in the main groove 50 to the extension line direction of a streamline.

  In the above-described embodiment, the groove wall 10a and the groove wall 20a have been described as meandering repeatedly along the tire circumferential direction TR in the tread surface view. However, the present invention is not limited to this, and the groove wall is not necessarily limited to this. 10a and the groove wall 20a do not need to meander repeatedly, for example, a part may be provided linearly along the tire circumferential direction TR.

In the above-described embodiment, the groove wall 10a and the groove wall 20a change in a predetermined repetition cycle along the tire circumferential direction TR in the tread surface view, and the maximum width portion _WMAX is a boundary within one cycle. The front side and the rear side are provided in a symmetrical shape. However, the groove wall 10a and the groove wall 20a do not need to be provided in a symmetrical shape between the front side and the rear side when the maximum width portion W _MAX is a boundary in one cycle. In this case, the groove width may be provided so as to be abruptly narrowed.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

DESCRIPTION OF SYMBOLS 1, 2 ... Pneumatic tire 10, 20, 30 ... Land part, 10a, 10b, 20a, 30a ... Groove wall, 50, 60 ... Main groove, 50btm ... Bottom part, 50A ... Wide groove part, 50B ... Narrow part, 70 ... raised portion, 70a, 70b ... side, 70f ... front end (front end portion), 70r ... rear end (rear end portion)

Claims (7)

A first land portion extending along the tire circumferential direction and in contact with the road surface;
A second land portion extending along the tire circumferential direction and in contact with the road surface;
A tire in which a main groove extending along the tire circumferential direction is formed between the first land portion and the second land portion,
The first land portion has a first groove wall that forms the main groove,
The second land portion has a second groove wall that forms the main groove,
The first groove wall and the second groove wall meander along the tire circumferential direction in a tread surface view,
The groove width of the main groove along the tread width direction changes at a predetermined repetition period along the tire circumferential direction,
When the maximum width portion of the groove width is W _MAX , the minimum width portion of the groove width is W _MIN, and the average length along the tread width direction of the main groove is A, (W _MAX −W _MIN ) A tire satisfying the relationship of /A≦0.25. The tire according to claim 1, wherein a ratio W _MIN / W _MAX between a minimum width portion W _MIN of the groove width and a maximum width portion W _MAX of the groove width is in a range of 35% to 85%.   The first groove wall and the second groove wall have a predetermined amplitude along the tread width direction, and the predetermined repetition period is 15 to 100 times the predetermined amplitude. 2. The tire according to 2. The main groove is provided with a wide groove portion including a maximum width portion W _MAX of the groove width,
At the bottom of the main groove is formed a raised portion that protrudes outward in the tire radial direction,
The tire according to any one of claims 1 to 3, wherein the raised portion is formed in the wide groove portion. A first side portion of the raised portion facing the first groove wall extends along the first groove wall;
The tire according to claim 4, wherein a second side portion of the raised portion facing the second groove wall extends along the second groove wall.   6. The tire according to claim 4, wherein the raised portion becomes thinner as it goes to a front end portion and a rear end portion of the raised portion in the tread surface view.   The tire according to any one of claims 4 to 6, wherein a height of the raised portion is less than a depth of the main groove.

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