JP2012006541A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire, by which snow performance can be improved and furthermore noise performance can be reduced, while dry performance of a tire is secured.SOLUTION: The pneumatic tire 1 includes: a second lug tread 321 going across a second land 32 in a center region of tread while being oblique to a peripheral direction of the tire; a first second small groove 322 connecting the lug treads 321 and 321 while being oblique to the peripheral direction of the tire; a second small groove 323 connecting the first small groove 322 with a circumferential main groove 22 provided outside the width direction of the tire; and a second sipe 324 connecting the first small groove 322 with a circumferential main groove 21 inside the width direction of the tire.

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire that can improve snow performance and noise performance while ensuring dry performance of the tire.

  In recent years, pneumatic tires for passenger cars are contradictory to each other such as tire dry performance (for example, straight traveling performance on a dry road surface, turning performance, steering stability performance) and snow performance (for example, traction performance on a snow road surface). There is a requirement to balance performance. The technique described in Patent Document 1 is known as a conventional pneumatic tire related to this problem.

  In addition, there is a demand for reducing the outside noise performance of a pneumatic tire.

JP 2004-345457 A

  An object of the present invention is to provide a pneumatic tire capable of improving snow performance and noise performance while ensuring tire dry performance.

  In order to achieve the above object, a pneumatic tire according to the present invention includes a plurality of circumferential main grooves extending in the tire circumferential direction and a plurality of land portions defined by the circumferential main grooves. The at least one land portion disposed in the center region of the tread portion is adjacent to a lug groove that crosses the land portion while being inclined with respect to the tire circumferential direction and is inclined with respect to the tire circumferential direction. A first narrow groove connecting the matching lug grooves, a second narrow groove connecting the first narrow groove and the circumferential main groove on the outer side in the tire width direction, and the circumference on the inner side in the tire width direction with the first narrow groove. A sipe that connects the directional main groove is provided.

  In this pneumatic tire, the land portion is divided in the tire circumferential direction by a plurality of lug grooves, and further, the portion divided into these lug grooves is divided by the first narrow groove, the second narrow groove, and the sipes, The block portion is partitioned. At this time, since the lug grooves are inclined with respect to the tire circumferential direction, the plurality of block portions are sequentially grounded at different timings during tire rolling. As a result, there is an advantage that the impact noise generated at the time of grounding the block portion is dispersed and the noise performance of the tire is improved. Moreover, since the 1st fine groove which connects adjacent lug grooves inclines with respect to a tire circumferential direction, arrangement | positioning of each divided | segmented block part becomes non-uniform | heterogenous. Thereby, the impact sound at the time of grounding is further dispersed, and there is an advantage that the noise performance of the tire is further improved. Further, since the second land portion has the lug groove and the first narrow groove, there is an advantage that the edge component of the land portion is increased and the snow performance of the tire is improved. Moreover, since the part located inside the tire width direction among the parts divided into the adjacent lug groove and the first narrow groove is divided by the sipe, compared with the configuration in which this part is divided by the narrow groove, The rigidity of the land portion on the inner side in the tire width direction is ensured. Thereby, there exists an advantage which the steering stability performance of a tire improves. As described above, there is an advantage that the snow performance and the noise performance can be improved while ensuring the dry performance of the tire.

  In the pneumatic tire according to the present invention, the inclination angle α of the lug groove with respect to the tire circumferential direction is in a range of 45 [deg] ≦ α ≦ 75 [deg].

  In this pneumatic tire, since the inclination angle α of the second lug groove is optimized, there is an advantage that the snow performance and noise performance of the tire are compatible.

  In the pneumatic tire according to the present invention, an opening width d1 of the lug groove with respect to the circumferential main groove is in a range of 3 [mm] ≦ d1 ≦ 5 [mm].

  In this pneumatic tire, since the opening width d1 of the second drag groove is optimized, there is an advantage that the dry performance and the snow performance of the tire are compatible.

  In the pneumatic tire according to the present invention, the groove width d2 of the first fine groove and the groove width d3 of the second fine groove are 1 [mm] ≦ d2 ≦ 3 [mm] and 1 [mm] ≦ d3 ≦. It is within the range of 3 [mm].

  In this pneumatic tire, since the groove width d2 of the first second narrow groove and the groove width d3 of the second second narrow groove are optimized, there is an advantage that the dry performance and the snow performance of the tire are compatible.

  In the pneumatic tire according to the present invention, the groove depth h of the lug groove and the groove depth H of the circumferential main groove have a relationship of 0.40 ≦ h / H ≦ 0.80.

  In this pneumatic tire, since the groove depth ratio h / H of the second lug groove is optimized, there is an advantage that the dry performance and the snow performance of the tire are compatible.

  Further, in the pneumatic tire according to the present invention, the block portion divided by the lug groove, the first narrow groove, the second narrow groove, and the sipe alternately has edge portions with respect to the circumferential main groove. It is arranged to project.

  This pneumatic tire has an advantage that the edge component of the second land portion is increased and the traction performance of the tire is improved.

  According to the pneumatic tire concerning this invention, there exists an advantage which can improve snow performance and noise performance, ensuring the dry performance of a tire by said structure.

FIG. 1 is a plan view showing a tread pattern of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a plan view showing a second land portion of the pneumatic tire depicted in FIG. 1. FIG. 3 is a table showing the results of the performance test of the pneumatic tire according to the present invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Further, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

[Pneumatic tire]
FIG. 1 is a plan view showing a tread pattern of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a plan view showing a second land portion of the pneumatic tire depicted in FIG. 1.

  The pneumatic tire 1 is applied to, for example, a passenger car tire. The pneumatic tire 1 includes a plurality of circumferential main grooves 21 and 22 extending in the tire circumferential direction, and a plurality of land portions 31 to 33 defined by the circumferential main grooves 21 and 22 (see FIG. 1). For example, in this embodiment, four circumferential main grooves 21 and 22 are formed, and five rows of land portions 31 to 33 are partitioned by these circumferential main grooves 21 and 22. Further, a tread pattern that is symmetrical with respect to the tire equator line CL is formed. Here, of the land portions 31 and 32 in the tread portion center region, the land portion 31 on the tire equator line CL is referred to as a center land portion, and the land portion 32 on the outer side in the tire width direction from the tire equator line CL, 32 is called the second land. The land portions 33 and 33 in the tread shoulder region are referred to as shoulder land portions.

[Second land]
The second land portion 32 is a block-shaped land portion, and a unit pattern composed of a second lug groove 321, a first second narrow groove 322, a second second narrow groove 323, and a second sipe 324 is continuous in the tire circumferential direction. (See FIGS. 1 and 2). For example, in this embodiment, the second land portion 32 is divided in the tire circumferential direction by a plurality of second lug grooves 321, and further, the portion divided into adjacent second lug grooves 321, 321 is the first second narrow groove 322, A plurality of block portions 325 to 328 are divided into four substantially in a cross shape by the second second narrow groove 323 and the second sipe 324.

  The second lug groove 321 is a lug groove that crosses the second land portion 32 while being inclined with respect to the tire circumferential direction. For example, in this embodiment, the second lug groove 321 has a linear shape, extends in the tire width direction while being inclined at a predetermined inclination angle α with respect to the tire circumferential direction, and the left and right circumferential main grooves 21. , 22.

  The first second narrow groove 322 is a narrow groove that connects the adjacent second lug grooves 321 and 321 while being inclined with respect to the tire circumferential direction. For example, in this embodiment, the first second narrow groove 322 has a linear shape and extends in the tire circumferential direction while inclining in the opposite direction to the second lug groove 321 with respect to the tire circumferential direction. Further, both end portions of the first second narrow groove 322 are opened in the central portion of the adjacent second lug groove 321, respectively. Further, the first second narrow grooves 322 and 322 adjacent to each other in the tire circumferential direction are opened at different positions with respect to the common second lug groove 321. Thereby, the second land portion 32 is divided in a zigzag shape in the tire circumferential direction by the second lug groove 321 and the first second narrow groove 322.

  The second second narrow groove 323 is a narrow groove that connects the first second narrow groove 322 and the circumferential main groove 22 on the outer side in the tire width direction. For example, in this embodiment, the second second narrow groove 323 has a linear shape, extends from the center of the first second narrow groove 322 to the outer side in the tire width direction, and opens to the circumferential main groove 22. . The second second narrow groove 323 is inclined in the same direction (substantially parallel) as the second lug groove 321 with respect to the tire circumferential direction.

  The second sipe 324 is a sipe that connects the first second narrow groove 322 and the circumferential main groove 21 on the inner side in the tire width direction (the tire equator line CL side). For example, in this embodiment, the second sipe 324 has a linear shape, extends from the center of the first second narrow groove 322 in the tire width direction, and reaches the circumferential main groove 21. Further, the second sipe 324 is inclined in the same direction (substantially parallel) as the second lug groove 321 with respect to the tire circumferential direction. Further, the second sipe 324 and the second second narrow groove 323 are opened at different positions with respect to the common first second narrow groove 322.

  In this embodiment, the pneumatic tire 1 has a symmetrical tread pattern, and the left and right second land portions 32, 32 have the above-described configuration (see FIGS. 1 and 2). However, the present invention is not limited to this, and it is sufficient that at least one land portion arranged in the tread portion center region has the configuration of the second land portion 32 described above. For example, the pneumatic tire 1 may have an asymmetric tread pattern, and only the land portion in one region of the tread portion may have the configuration of the second land portion 32 described above, or one region of the tread portion. Two rows of second land portions 32 may be arranged (not shown).

[Center land and shoulder land]
The center land portion 31 has a center groove 311 (see FIG. 1). The center groove 311 is a groove formed by connecting a narrow groove portion and a sipe portion, and extends in the tire width direction while penetrating the center land portion 31 while being inclined with respect to the tire circumferential direction. A plurality of center grooves 311 are arranged at predetermined intervals in the tire circumferential direction while alternately inverting the narrow groove portions and the sipe portions. In such a configuration, the center groove 311 has a narrow groove portion, whereby the edge component of the land portion is increased and the traction performance (snow performance) of the tire is improved. Further, since the center groove 311 has a sipe portion, the rigidity of the center land portion 31 is ensured and the straight running performance (dry performance) of the tire is maintained.

  The shoulder land portion 33 has a first shoulder lug groove 331 and a second shoulder lug groove 332 (see FIG. 1). The first shoulder lug groove 331 is a lug groove having a penetrating structure, and traverses the shoulder land portion 33 in the tire width direction. The second shoulder lug groove 332 is a lug groove having a non-penetrating structure, extends to the outer side in the tire width direction, and has an end portion in the land portion. Further, the first shoulder lug grooves 331 and the second shoulder lug grooves 332 are alternately arranged in the tire circumferential direction. In such a configuration, the first shoulder lug groove 331 has a penetrating structure, whereby the edge component in the land portion is increased and the traction performance (snow performance) of the tire is improved. Further, since the second shoulder lug groove 332 has a non-penetrating structure, the rigidity of the shoulder land portion 33 is ensured and the turning performance (dry performance) of the tire is maintained.

[effect]
As described above, this pneumatic tire 1 has a lug groove in which at least one land portion (second land portion 32) arranged in the tread portion center region crosses the land portion while being inclined with respect to the tire circumferential direction. (Second lug groove 321), a first narrow groove (first second narrow groove 322) connecting the adjacent lug grooves 321 and 321 while being inclined with respect to the tire circumferential direction, and the first narrow groove 322 and the outer side in the tire width direction A second narrow groove (second second narrow groove 323) that connects the circumferential main groove 22 of the tire, and a sipe (second sipe 324) that connects the first narrow groove 322 and the circumferential main groove 21 on the inner side in the tire width direction. Provide (see FIG. 1 and FIG. 2).

  In such a configuration, the land portion 32 is divided in the tire circumferential direction by the plurality of lug grooves 321, and the portions divided into the lug grooves 321, 321 are the first fine groove 322, the second fine groove 323, and the sipe 324. Are divided into a plurality of block portions 325 to 328. At this time, since the lug groove 321 is inclined with respect to the tire circumferential direction, the plurality of block portions 325 to 328 are sequentially grounded at different timings during tire rolling. Thereby, the impact sound generated when the block portions 325 to 328 are grounded is dispersed, and there is an advantage that the noise performance of the tire is improved. Moreover, since the 1st fine groove 322 which connects adjacent lug grooves 321 and 321 inclines with respect to a tire circumferential direction, arrangement | positioning of each divided | segmented block part 325-328 becomes non-uniform | heterogenous. Thereby, the impact sound at the time of grounding is further dispersed, and there is an advantage that the noise performance of the tire is further improved. Further, since the second land portion 32 includes the lug groove 321 and the first narrow groove 322, there is an advantage that the edge component of the land portion is increased and the snow performance of the tire is improved. Moreover, since the part located inside a tire width direction among the parts divided | segmented into the adjacent lug grooves 321 and 321 and the 1st fine groove 322 is divided | segmented by the sipe 324, the structure by which this part is divided | segmented by a fine groove Compared with, the rigidity of the land part in the tire width direction inner side is ensured. Thereby, there exists an advantage which the steering stability performance of a tire improves. As described above, there is an advantage that the snow performance and the noise performance can be improved while ensuring the dry performance of the tire.

  Further, in the pneumatic tire 1, the first narrow grooves 322 and 322 adjacent to each other in the tire circumferential direction open at different positions with respect to the common lug groove 321 (see FIGS. 1 and 2). Thereby, generation | occurrence | production of the air column resonance sound by the 1st fine groove 322 is suppressed, and there exists an advantage which the noise performance of a tire improves. For example, in the configuration in which the adjacent first narrow grooves are opened at the same position with respect to the common lug groove, the first fine grooves communicate with each other in the tire circumferential direction.

  In the pneumatic tire 1, the opposing second narrow groove 323 and sipe 324 open at different positions with respect to the common first narrow groove 322 (see FIGS. 1 and 2). In such a configuration, the arrangement of the divided block portions 325 to 328 becomes uneven, and the impact sound at the time of grounding is further dispersed. Thereby, there exists an advantage which the noise performance of a tire improves further.

  Moreover, in this pneumatic tire 1, the tread areas of the four block portions 325 to 328 formed by the first narrow groove 322, the second narrow groove 323, and the sipe 324 between the adjacent lug grooves 321 and 321 are: It is preferable to set it non-uniformly (see FIGS. 1 and 2). That is, it is preferable that the divided block portions 325 to 328 have different tread areas. At this time, it is not necessary that all of the four block portions 325 to 328 have different tread areas, but it is preferable that at least two types of block portions 325 to 328 having different tread areas are arranged. In such a configuration, the tread area of each of the divided block portions 325 to 328 becomes non-uniform so that the impact sound at the time of ground contact is further dispersed, and the noise performance of the tire is further improved.

  In the above configuration, it is preferable that the maximum value Smax and the minimum value Smin of the tread areas of the four block portions 325 to 328 are in the range of 1.3 ≦ Smax / Smin ≦ 2.0. In such a configuration, since the tread surface area ratio Smax / Smin of the block portions 325 to 328 is optimized, there is an advantage that the noise performance of the tire is improved, and there is an advantage that uneven wear of the land portion is suppressed. For example, if 2.0 <Smax / Smin, the difference in the tread area of each block portion becomes excessive, and uneven wear occurs in the block portion having a large tread area, which is not preferable. Further, if Smax / Smin <1.3, the tread surface area of each block portion is made uniform, and the effect of dispersing impact sound at the time of contact cannot be obtained sufficiently, which is not preferable.

[Modification]
In the pneumatic tire 1, the inclination angle α of the second lug groove 321 with respect to the tire circumferential direction is preferably in the range of 45 [deg] ≦ α ≦ 75 [deg] (see FIG. 2). The inclination angle α of the second lug groove 321 is measured as an angle formed by a straight line connecting the midpoints of the openings of the second lug groove 321 with respect to the circumferential main grooves 21 and 22 and the tire circumferential direction. In such a configuration, since the inclination angle α of the second lug groove 321 is optimized, there is an advantage that the snow performance and noise performance of the tire are compatible. For example, α <45 [deg] is not preferable because the edge component in the tire circumferential direction of the second lug groove decreases and the traction performance decreases. Further, when 75 [deg] <α, the noise outside the vehicle increases, which is not preferable.

  Further, in the pneumatic tire 1, the opening width d1 of the second lug groove 321 with respect to the circumferential main grooves 21 and 22 is preferably in the range of 3 [mm] ≦ d1 ≦ 5 [mm] (see FIG. 2). . In such a configuration, since the opening width d1 of the second lug groove 321 is optimized, there is an advantage that the dry performance and the snow performance of the tire are compatible. For example, d1 <3 [mm] is not preferable because the width of the second drag groove is reduced, the snow column shear force is lowered, and as a result, the traction performance is lowered. On the other hand, when 5 [mm] <d1, the rigidity of the land portion decreases and the steering stability performance decreases, which is not preferable.

  In the above configuration, the left and right opening widths d1 and d1 of the second lug groove 321 may be different from each other, and it is sufficient if it is at least within the above range (3 [mm] ≦ d1 ≦ 5 [mm]).

  In the above configuration, the groove width of the second lug groove 321 may not be uniform. For example, in this embodiment, the second lug groove 321 has a structure in which the groove width is narrowed at the center of the second land portion 32 (see FIG. 2). In such a configuration, since the rigidity of the central portion of the second land portion 32 is ensured, there is an advantage that the steering stability performance of the tire is improved. Specifically, it is preferable that the maximum value (opening width d1) and the minimum value d1 ′ of the second drag groove 321 are in the range of 0.5 ≦ d1 ′ / d1 <1.0. Thereby, there exists an advantage by which the improvement effect of the steering stability performance of a tire is acquired.

  In this embodiment, the groove width (for example, the opening width d1 of the second lug groove 321) is measured in a state where the tire is mounted on the specified rim to apply the specified internal pressure and the load is not loaded.

  Here, the prescribed rim refers to “applied rim” prescribed in JATMA, “Design Rim” prescribed in TRA, or “Measuring Rim” prescribed in ETRTO. The specified internal pressure means “maximum air pressure” specified by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” specified by TRA, or “INFLATION PRESSURES” specified by ETRTO. The specified load means “maximum load capacity” defined in JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined in TRA, or “LOAD CAPACITY” defined in ETRTO. However, in the case of a tire for a passenger car, the specified internal pressure is an air pressure of 180 [kPa], and the specified load is 88 [%] of the maximum load capacity.

  In the pneumatic tire 1, the groove width d2 of the first second narrow groove 322 and the groove width d3 of the second second narrow groove 323 are 1 [mm] ≦ d2 ≦ 3 [mm] and 1 [mm] ≦ d3 ≦. It is preferably within the range of 3 [mm] (see FIG. 2). In such a configuration, the groove width d2 of the first second narrow groove 322 and the groove width d3 of the second second narrow groove 323 are optimized, so that there is an advantage that both the dry performance and the snow performance of the tire are compatible. For example, d2 <1 [mm] or d3 <1 [mm] is not preferable because the edge component of the narrow groove decreases and the traction performance decreases. Further, when 3 [mm] <d2 or 3 [mm] <d3, the rigidity of the land portion is lowered and the steering stability performance is lowered, which is not preferable.

  In the pneumatic tire 1, it is preferable that the first second narrow groove 322 and the second second narrow groove 323 are connected substantially vertically (T-shaped). In such a configuration, since the corners of the land portion are substantially perpendicular, there is an advantage that the rigidity of the land portion is ensured and the steering stability performance of the tire is maintained.

  In the pneumatic tire 1, the groove depth h of the second lug groove 321 and the groove depth H of the circumferential main groove 21 (22) have a relationship of 0.40 ≦ h / H ≦ 0.80. Is preferable (not shown). In such a configuration, since the groove depth ratio h / H of the second drag groove 321 is optimized, there is an advantage that the dry performance and the snow performance of the tire are compatible. For example, h / H <0.40 is not preferable because the groove depth of the lug groove decreases and the traction performance decreases. Further, when 0.80 <h / H, the rigidity of the land portion decreases and the steering stability performance decreases, which is not preferable.

  In the above configuration, the groove depth h of the second lug groove 321 does not have to be uniform, and it is sufficient if it is within the above range. For example, in this embodiment, the groove depth h of the second lug groove 321 is set deep at the opening and shallow at the center of the second land portion 32. In such a configuration, since the rigidity of the central portion of the second land portion 32 is ensured, there is an advantage that the steering stability performance of the tire is improved. Specifically, it is preferable that the groove depth h1 of the opening of the second lug groove 321 and the groove depth h1 'of the central portion are in the range of 0.5 ≦ h1 ′ / h1 <1.0. Thereby, there exists an advantage by which the improvement effect of the steering stability performance of a tire is acquired.

  In the pneumatic tire 1, the block portions 325 to 328 divided by the second lug groove 321, the first second narrow groove 322, the second second narrow groove 323, and the second sipe 324 are provided in the circumferential main grooves 21, 22. It is preferable that the edge portions are alternately projected with respect to (see FIGS. 1 and 2). For example, in this embodiment, a plurality of divided block portions 325 and 326 (327 and 328) are continuously arranged along the circumferential main groove 21 (22). At this time, the adjacent block portions 325, 326 (327, 328) project the edge portions alternately with respect to the circumferential main groove 21 (22), so that the edge portion of the second land portion 32 becomes the circumferential main groove 21. It protrudes stepwise with respect to (22). Thereby, the edge component of the second land part 32 increases, and there exists an advantage which the traction performance of a tire improves.

[performance test]
In this embodiment, performance tests on (1) dry performance, (2) snow performance, and (3) noise performance were performed on a plurality of pneumatic tires with different conditions (see FIG. 3). In this performance test, a pneumatic tire having a tire size P225 / 45R19 92V is assembled to a rim having a rim size of 19 × 8.5 J, and an internal pressure of 240 [kPa] and a load of 4 [kN] are applied to the pneumatic tire. A pneumatic tire is mounted on a FR-drive test vehicle with a displacement of 3700 [cc].

  (1) In the performance test regarding dry performance, a test vehicle equipped with a pneumatic tire travels on a test course having a flat and dry peripheral circuit at a speed of 60 [km / h] to 100 [km / h]. Then, the test driver performs sensory evaluation on the steering performance at the time of lane change and cornering and the stability at the time of straight traveling. This evaluation is performed by index evaluation using the conventional example as a reference (100), and the larger the value, the better. The evaluation of the dry performance can be said to be within the allowable range if it is 103 or more on the assumption that (2) snow performance and (3) noise performance are compatible (evaluation is 100 or more).

  (2) In the performance test related to snow performance, a test vehicle equipped with pneumatic tires travels on a snow road surface of a snow road test site at a speed of 40 [km / h], and a test driver performs sensory evaluation. This evaluation is performed by index evaluation using the conventional example as a reference (100), and the larger the value, the better.

  (3) In a performance test relating to noise performance (road noise), a test vehicle equipped with pneumatic tires coasts on an ISO test road and the sound pressure level is measured. And evaluation is performed on the basis of the conventional pneumatic tire (conventional example) (100). The smaller the numerical value, the lower the sound pressure level, which is preferable.

  Examples 1-10 are the pneumatic tires 1 described in FIG. Specifically, the first land portion 321 connects the second lug groove 321 that crosses the land portion while the second land portion 32 is inclined with respect to the tire circumferential direction, and the adjacent lug grooves 321 and 321 that are inclined with respect to the tire circumferential direction. A second narrow groove 322 connecting the second narrow groove 322, the first narrow groove 322 and the circumferential main groove 22 on the outer side in the tire width direction; the first narrow groove 322 and the circumferential main groove 21 on the inner side in the tire width direction; And a second sipe 324 for connecting the two. Further, the respective block portions 325 to 328 are arranged with the edge portions alternately protruding with respect to the circumferential main grooves 21 and 22.

  The conventional example differs from the pneumatic tire of Example 1 in that, for example, the land portion of the tread portion center region does not have the first second narrow groove, the second second narrow groove, and the second sipe. . Further, the block portion of the land portion is arranged with the edge portion aligned with the circumferential main groove.

  As shown in the test results, when Example 1 is compared with the conventional example, in Example 1, the pneumatic tire 1 has the tread pattern described above, so that the dry performance of the tire is ensured, and the snow performance and It can be seen that the noise performance is improved (see FIG. 3).

  Moreover, when Examples 1-3 are compared, it turns out that the snow performance and noise performance of a tire are compatible, when the inclination-angle (alpha) of the second lug groove 321 is optimized. Further, when Example 1 is compared with Examples 4 and 5, it is understood that the dry performance and the snow performance of the tire are compatible with each other by optimizing the opening width d1 of the second lug groove 321. In addition, when Example 1 is compared with Examples 6 and 7, the groove width d2 of the first second narrow groove 322 and the groove width d3 of the second second narrow groove 323 are optimized, thereby improving the tire dry performance. It turns out that snow performance is compatible. Further, when Example 1 is compared with Examples 8 and 9, it is understood that the dry performance and the snow performance of the tire are compatible by optimizing the groove depth ratio h / H of the second lug groove 321. . Further, comparing Example 1 and Example 10, each block part 325 to 328 causes the edge part to alternately protrude with respect to the circumferential main grooves 21 and 22 (there is an unevenness of the block), so that the tire It can be seen that the traction performance is improved.

  As described above, the pneumatic tire according to the present invention is useful in that it can improve the snow performance and the noise performance while ensuring the dry performance of the tire.

1 Pneumatic tire, 21, 22 circumferential main groove, 31 center land portion, 311 center groove, 32 second land portion, 321 second lug groove, 322 first second narrow groove, 323 second second narrow groove, 324 second sipes, 325-328 Block part, 33 shoulder land part, 331 first shoulder lug groove, 332 second shoulder lug groove

Claims (6)

A pneumatic tire comprising a plurality of circumferential main grooves extending in the tire circumferential direction and a plurality of land portions defined by these circumferential main grooves,
At least one of the land portions disposed in the tread portion center region connects the lug groove that crosses the land portion while being inclined with respect to the tire circumferential direction and the adjacent lug groove that is inclined with respect to the tire circumferential direction. Connecting the first narrow groove, the second narrow groove connecting the first narrow groove and the circumferential main groove on the outer side in the tire width direction, and connecting the first narrow groove and the circumferential main groove on the inner side in the tire width direction. A pneumatic tire comprising a sipe.   The pneumatic tire according to claim 1, wherein an inclination angle α of the lug groove with respect to a tire circumferential direction is in a range of 45 [deg] ≦ α ≦ 75 [deg].   The pneumatic tire according to claim 1 or 2, wherein an opening width d1 of the lug groove with respect to the circumferential main groove is in a range of 3 [mm] ≤ d1 ≤ 5 [mm].   The groove width d2 of the first narrow groove and the groove width d3 of the second narrow groove are in a range of 1 [mm] ≦ d2 ≦ 3 [mm] and 1 [mm] ≦ d3 ≦ 3 [mm]. The pneumatic tire according to any one of 1 to 3.   The air according to any one of claims 1 to 4, wherein a groove depth h of the lug groove and a groove depth H of the circumferential main groove have a relationship of 0.40 ≦ h / H ≦ 0.80. Enter tire.   The block portion formed by dividing the lug groove, the first narrow groove, the second narrow groove, and the sipe is disposed by alternately projecting edge portions with respect to the circumferential main groove. The pneumatic tire according to any one of 5.

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