JP4583846B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a high-performance radial tire having an asymmetric tread pattern that is preferably used in a passenger car.

In recent years, high-performance radial tires having asymmetric tread patterns in which patterns formed on the tire tread surface are associated with a vehicle and different patterns are formed on the vehicle outer side and the vehicle inner side of the tire when the vehicle is mounted have been proposed.
FIG. 3 is a diagram showing an example of the pneumatic tire 50. The pneumatic tire 50 is provided with a central land portion 53 partitioned by circumferential grooves 51 and 52, and is provided so as to be substantially orthogonal to the circumferential groove 52 inside the vehicle. Further, at most every other lug groove 55A defining the block 54A of the shoulder portion on the vehicle inner side is extended in a substantially arc shape toward the central land portion 53 side, and the central land portion 53 is extended. The drainage performance is improved by making the groove almost crossing. In addition, the code | symbol 55B of the figure is a lug groove which divides the block 54B of the shoulder part outside a vehicle. Further, in the conventional art, the tread strips 56 and 56 and the block row 57 are arranged between the circumferential grooves 51 and 52 and the blocks 54A and 54B of the shoulder portions, respectively, so that the response to the steering force is obtained. It is made to raise (for example, refer patent document 1).
As shown in FIG. 4, the high-performance radial tire having an asymmetric tread pattern is defined by dividing the vehicle inner side of the tread 60 with circumferential grooves 61A and 61B and lug grooves 62 substantially orthogonal to the circumferential grooves 61A and 61B. Block patterns 63A and 63B, and the outer side of the vehicle is constituted by rib patterns 64A and 64B partitioned by circumferential grooves 61B and 61C, thereby increasing the rigidity of the outer side of the vehicle and increasing the lateral rigidity during restricted turning. As shown in FIG. 5, the center line C of the central circumferential rib 75 which is partitioned by the circumferential grooves 71 and 72 and the block rows 73 and 74 are arranged on both sides thereof, as shown in FIG. Accordingly, the steering wheel responsiveness is improved by shifting the tire circumferential direction rib 75 from the tire equatorial plane E to the vehicle inner side. Etc. have been proposed those manner (e.g., see Patent Documents 2 and 3).
In these asymmetric tread patterns, the lug grooves are often at a relatively large angle from the circumferential direction, such as the lug grooves 55A and 55B and the lug grooves 62, and even when sipes are provided, The extending direction is not so much related to the shape of the lug groove or the block, and an appropriate one is put in parallel or opposite direction to the groove.
In order to improve the running performance on the WET road surface, it is common to increase the groove area (negative rate) by increasing the groove width.
JP 2000-238510 A JP-A-11-208217 Japanese Patent Laid-Open No. 11-245626

However, when the angle from the circumferential direction of the lug groove is large, although the grip force is large and the handling stability is ensured, the pattern noise is large and not only uneven wear such as step wear is likely to occur, Drainage performance was not enough.
Further, as in the example of FIG. 3 described above, when a part of the lug groove 55A is extended to the central land portion 53 and the angle from the circumferential direction of a part of the lug groove is reduced, the drainage performance is improved. Since the steering stability is lowered, it is necessary to increase the tire rigidity by arranging the tread strips 56, 56, the block row 57, and the like. As a result, the area of the circumferential grooves 51 and 52 is reduced, so that even if the angle from the circumferential direction of a part of the lug groove extending to the central land portion 53 is reduced, the drainage performance is sufficiently improved. It was difficult to improve. Further, during running on a relatively deep WET road surface, a large amount of water is mainly discharged from the inside of the vehicle to the outside, so the lug groove that terminates in the central land portion 53 is opened to the circumferential groove 52 side on the inside of the vehicle. The construction to be made is disadvantageous in terms of drainage.

  The present invention has been made in view of the conventional problems, and in a pneumatic tire having an asymmetric tread pattern, while ensuring high steering stability and drainage performance, the tire noise is suppressed, and uneven wear resistance is achieved. It aims to improve the ride comfort.

The invention according to a first aspect of the present invention, at least three circumferential grooves extending along a tire circumferential direction are provided on the tread surface, a plurality of center land portions partitioned by these circumferential grooves, said A pneumatic tire provided with a plurality of inclined lug grooves provided on each of the central land portions and extending in an inclined manner with respect to the tire circumferential direction, wherein the inclined lug groove has one end provided with the lug groove. Of the circumferential grooves that define the central land portion, the tire is opened only on the circumferential groove side located on the vehicle outer side of the tire when the vehicle is mounted , and the other end terminates in the central land portion. the land portion, inclined opposite to the inclined lug grooves and the tire circumferential direction, and inclined sipes which are arranged in the tire circumferential direction of the arrangement pitch substantially the same pitch of the inclined lug grooves provided der those characterized by that you are .
The invention according to claim 2 is the pneumatic tire according to claim 1, wherein the inclined lug groove is located on the opening side and is inclined at a large angle with respect to the tire circumferential direction; and The lug groove is located on the end side and has a steeply inclined portion inclined at a small angle with respect to the tire circumferential direction.

According to a third aspect of the present invention, in the pneumatic tire according to the first or second aspect, the end of the inclined lug groove is formed on the central land portion from the opening side of the inclined lug groove of the central land portion. The positions are separated by 40% to 90% of the width.
According to a fourth aspect of the present invention, in the pneumatic tire according to the second aspect, the angle of the gently inclined portion with respect to the tire circumferential direction is 30 ° to 90 °, and the angle of the steeply inclined portion with respect to the tire circumferential direction is 0. (In general, when the extending direction of the lug groove is inclined from the direction orthogonal to the circumferential groove, the lug groove is defined as an “inclined lug groove”. The smaller the angle to the, the steeper the lug groove).
According to a fifth aspect of the present invention, in the pneumatic tire of the fourth aspect, the groove width of the gently inclined portion is narrower than the groove width of the steeply inclined portion.

A sixth aspect of the present invention is the pneumatic tire according to the second aspect, wherein chamfering is performed on an acute angle side corner portion of a land portion defined by the gently inclined portion and the circumferential groove.
According to a seventh aspect of the present invention, in the pneumatic tire according to the second aspect, the steeply inclined portion of the inclined lug groove is terminated in the vicinity of the connecting portion between the gently inclined portion and the steeply inclined portion of the adjacent inclined lug groove. In addition, a virtual pseudo block having an acute angle side corner is formed on the steeply inclined portion side between adjacent inclined lug grooves, and the acute angle side corner of the virtual pseudo block is chamfered.

According to an eighth aspect of the present invention, in the pneumatic tire according to the first aspect, the inclined sipe crosses the central land portion from the vehicle outer tread end of the tire when the vehicle is mounted, and is positioned inside the vehicle. It is formed so as to open in a circumferential groove.
According to a ninth aspect of the present invention, in the pneumatic tire according to the eighth aspect, the angles of the gently inclined portion and the steeply inclined portion of the inclined lug groove positioned on the vehicle outer side are respectively positioned on the vehicle inner side. The angle of the sloping lug groove to the tire circumferential direction is larger than the angle of the sloping lug groove to the tire circumferential direction, and the inclination angle of the inclined sipe to the tire circumferential direction is gradually decreased from the vehicle outer side to the vehicle inner side. Is.

According to a tenth aspect of the present invention, in the pneumatic tire according to the first aspect, a circumferential sipe extending substantially parallel to the circumferential groove is provided at land portions of both ends of the tire defined by the circumferential groove. In addition, a sub-inclined sipe that is inclined and extended in a direction opposite to the inclined sipe is provided at a portion surrounded by the circumferential sipe and the circumferential groove of the land portion inside the vehicle when the vehicle is mounted. It is.
According to an eleventh aspect of the present invention, in the pneumatic tire according to the tenth aspect, a plurality of small holes are provided on the side of the land portion inside the vehicle where the sub-inclined sipes are not provided.
According to a twelfth aspect of the present invention, in the pneumatic tire according to the eleventh aspect, the diameter of the small hole is 0.5 mm to 7 mm.
According to a thirteenth aspect of the present invention, in the pneumatic tire according to the tenth aspect, in a direction opposite to the inclined sipe from the circumferential sipe to the outer portion of the land portion outside the vehicle when the vehicle is mounted. A sub-inclined sipe that is inclined and extended is provided.
The invention according to claim 14 is the pneumatic tire according to claim 1, wherein the groove width of the circumferential groove located on the vehicle inner side of the tire when the vehicle is mounted is the circumferential groove located in the tire central portion. 20% to 90% of the groove width.

According to the present invention, at least three circumferential grooves provided on the tread surface and extending along the tire circumferential direction, a plurality of central land portions defined by these circumferential grooves, and each of the central land portions. a pneumatic tire having a plurality of inclined lug grooves extend inclined with respect to the tire circumferential direction provided, the inclined lug grooves, the center land portion having one end provided with the lug grooves open only in the circumferential groove side located on the vehicle outer side of the tire in the vehicle when mounted within the circumferential grooves defining lug grooves and be Rutotomoni the other end terminates in the central land portion, the land portion of the tread Since the inclined sipe is inclined to the opposite side to the tire circumferential direction with respect to the inclined lug groove and arranged at substantially the same pitch as the arrangement pitch in the circumferential direction of the inclined lug groove. Steering stability and drainage It is possible to ensure the ability to suppress the tire noise, it is possible to improve the uneven wear resistance and ride comfort, it is possible to greatly improve the performance of the tire.
In addition, the inclined lug groove is located on the opening side and is inclined gently at a large angle with respect to the tire circumferential direction, and is steeply inclined on the terminal side and inclined at a small angle with respect to the tire circumferential direction. If the lug groove has a portion, the drainage performance can be further improved, the block rigidity can be secured, and the maneuverability on the DRY and WET road surfaces can be further improved. In addition, since the gently inclined portion on the opening side has a large angle with the circumferential groove, the wear resistance is also improved.
At this time, if the groove width of the steeply inclined portion is widened and the groove width of the gently inclined portion is narrowed, the drainage performance and uneven wear properties are further improved, and the block rigidity can be secured, so that the maneuverability is also improved.

  Further, the angle of the gently inclined portion and the steeply inclined portion located on the vehicle outer side with respect to the tire circumferential direction is larger than the angle of the gently inclined portion and the steeply inclined portion located on the vehicle inner side with respect to the tire circumferential direction, If the inclination angle of the inclined sipe with respect to the tire circumferential direction is gradually decreased from the outside of the vehicle to the inside of the vehicle, the inclined lug groove and the inclined sipe intersect at an appropriate angle in the tire axial direction. Therefore, appropriate block rigidity can be ensured and maneuverability can be improved. Further, the sharp-angled corners of the land part partitioned by the gentle slope part and the circumferential groove and the steep slope part of the sloped lug groove are connected to the slow slope part and the steep slope part of the adjacent slope lug groove. If chamfering is performed on the acute-angled corners sandwiched between the two gently inclined portions that are terminated in the vicinity of the portion, the drainage performance can be further improved while ensuring the block rigidity.

Hereinafter, the best mode of the present invention will be described with reference to the drawings.
FIG. 1 is a plan view showing an example of a tread pattern of a pneumatic tire 10 according to the best mode of the present invention, and on the surface of the tread 11 of the pneumatic tire 10 of the present example, three pieces extending along the tire circumferential direction. Circumferential grooves 12a to 12c are formed, and these circumferential grooves 12a to 12c allow the first and second central land portions 13a and 13b located at the center in the tire width direction to be located outside the vehicle when the vehicle is mounted. The outer land portion 14a positioned and the inner land portion 14b positioned inside the vehicle are partitioned. The first and second central land portions 13a and 13b are respectively open to the circumferential grooves 12a and 12b located on the vehicle outer side when the first and second central land portions 13a and 13b are mounted on the vehicle. In addition, a plurality of inclined lug grooves 15 whose other ends terminate in the central land portion are provided.
The inclined lug groove 15 is located on the circumferential groove 12a, 12b side which is the opening side, and is inclined at an angle of 30 ° to 90 ° with respect to the tire circumferential direction and extended to the end side. And a steeply inclined portion 15b extending at an angle of 0 ° to 30 ° with respect to the tire circumferential direction, and in this example, the groove width of the gently inclined portion 15a is narrowed, The groove width of the steeply inclined portion 15b is increased.
In this example, among the circumferential grooves 12a to 12c, the groove width of the circumferential groove 12b located in the center is made wider than the groove width of the circumferential groove 12c that defines the inner land portion 14b. The width of the first central land portion 13a located outside the vehicle is made wider than the width of the second central land portion 13b located inside the vehicle. Accordingly, the angle of the gently inclined portion 15a and the steeply inclined portion 15b of the inclined lug groove 15 formed in the first central land portion 13a with respect to the tire circumferential direction is formed in the second central land portion 13b. The angle of the gently sloping portion 15a and steeply sloping portion 15b of the inclined lug groove 15 is set to be larger than the angle with respect to the tire circumferential direction.

Further, the land portion of the tread 11, more specifically, the first and second central land portions 13a, 13b and the outer land portion 14a, the first and second central land portions 13a, 13b from the vehicle outer tread end 11b. The inclined lug groove 15 that opens to the circumferential groove 12a located on the inner side of the vehicle is inclined to the opposite side to the tire circumferential direction, and the circumferential arrangement pitch of the inclined lug groove 15 is substantially the same. A plurality of inclined sipes 16 arranged at the same pitch are provided. The inclination angle of the inclined sipe 16 with respect to the tire circumferential direction gradually decreases from the outside of the vehicle to the inside of the vehicle, thereby forming the first and second central land portions 13a and 13b having different inclination angles. The crossing angle with the inclined lug groove 15 is substantially the same.
Furthermore, in this example, the outer land portion 14a and the inner land portion 14b, which are land portions at both ends of the tire defined by the circumferential grooves 12a and 12c, extend substantially parallel to the circumferential grooves 12a and 12c. Each of the peripheral sipes 17a and 17b is provided, and a sub-inclined sipe 18b extending in a direction opposite to the inclined sipe 16 is extended in a portion surrounded by the circumferential groove 12c and the peripheral sipe 17b of the inner land portion 14b. A plurality of small holes 20 having a diameter of 0.5 mm to 7 mm are provided on the inner side of the vehicle from the peripheral sipe 17b of the inner land portion 14b.
Further, in the outer land portion 14a, a sub-inclined sipe 18a that is inclined and extended in a direction opposite to the inclined sipe 16 is provided on a portion outside the circumferential sipe 17a outside the vehicle, and is substantially smaller than the sub-block 19b. A trapezoidal or substantially triangular sub-block 19a was formed.

Next, the operation of the pneumatic tire 10 having the above configuration will be described.
In the pneumatic tire 10 of this example, first, the basic drainage performance is ensured by the three circumferential grooves 12a to 12c, and the DRY road surface and the WET road surface are formed by the first and second central land portions 13a and 13b. To ensure basic maneuverability and stability. At this time, it is important to make the groove width of the circumferential groove 12b located in the center portion wider than the groove width of the circumferential groove 12c located inside the vehicle. Drainage efficiency can be obtained. Specifically, the groove width of the circumferential groove 12c on the vehicle inner side is preferably 20% to 90% of the groove width of the circumferential groove 12b at the center. That is, when the groove width of the circumferential groove 12c is less than 20% of the groove width of the circumferential groove 12b, the drainage efficiency inside the tire is extremely reduced, and conversely, when it exceeds 90%, Since the rigidity in the vicinity of the circumferential groove 12c is reduced and there is a risk of early wear, partial wear, etc., the groove width of the circumferential groove 12c on the vehicle inner side is 20% to the groove width of the circumferential groove 12b in the center portion. Set to the range of 90%.

Next, the operation of the inclined lug groove 15 will be described.
The reason why the inclined lug grooves 15 are arranged in the first and second central land portions 13a and 13b from the vehicle inner side toward the vehicle outer side is to improve drainage performance when traveling on a wet road surface having a deep water depth. That is, when running on a wet road surface with a deep water depth, a lot of water tends to be drained from the inside of the vehicle toward the outside of the vehicle. Therefore, in order to guide the water to the outside of the vehicle, an inclined lug groove is used as in this example. It is preferable to have a shape in which 15 is opened to the outside of the vehicle and ends on the inside of the vehicle.
That is, in order to smoothly flow water from the inclined lug groove 15 to the circumferential groove 12a or the circumferential groove 12b, the inclined lug groove 15 is provided on the land portion (first or second central land portion 13a, 13b). It is important to open only to the circumferential groove (circumferential groove 12a or circumferential groove 12b) located on the outer side of the vehicle, rather than opening to both sides or the circumferential groove located on the inner side of the vehicle. The drainage performance is also improved.
Further, the circumferential grooves 12a to 12c emit a high-frequency resonance sound when the vehicle is running, which becomes tire noise. By passing the inclined lug groove 15 through one wall of the circumferential grooves 12a to 12c, this resonance sound is generated. Is dispersed, so that high-frequency tire noise is reduced.
Further, in this example, the circumferential groove side where the inclined lug groove 15 opens is a gentle inclined portion 15a so that the angle between the inclined lug groove 15 and the circumferential groove does not become an extremely acute angle, and the groove width thereof Therefore, tire noise can be suppressed and wear resistance can be improved. At this time, in consideration of uneven wear, the angle between the gently inclined portion 15a and the circumferential groove 12a (or circumferential groove 12b) is preferably 30 ° to 90 ° with respect to the tire circumferential direction. .
On the other hand, since the end of the inclined lug groove 15 is a steeply inclined portion 15b and the groove width is widened, the water in the first and second central land portions 13a and 13b is quickly drained. In addition, since the central land portions 13a and 13b are substantially continuous ribs, block rigidity can be ensured, and steering stability in DRY and WET can be ensured. At this time, the angle between the steeply inclined portion 15b and the circumferential groove 12a (or circumferential groove 12b) is preferably 0 ° to 30 ° with respect to the tire circumferential direction in consideration of drainage performance.
The end position of the inclined lug groove 15 is preferably set so as to be separated from the opening side of the inclined lug groove 15 by 40% to 90% of the width of the central land portion. When the end position is less than 40% of the width of the central land portion, not only the rigidity of the block becomes too high and the ride comfort deteriorates, but also the volume of the inclined lug groove 15 decreases. There is a concern that the drainage performance will deteriorate. On the other hand, if it exceeds 90%, the distance to the adjacent circumferential groove becomes too small, the rigidity of the continuous rib cannot be secured, and there is a concern that the steering performance deteriorates and the uneven wear property deteriorates.

Further, in this example, the first central land portion 13a (or the second land portion) defined by the gently inclined portion 15a that is the opening end of the inclined lug groove 15 and the circumferential groove 12a (or the circumferential groove 12b). The central land portion 13b) is chamfered at the acute angle side corner portion 13m. Thereby, since the flow of the water to the circumferential groove | channel 12a (or circumferential groove | channel 12b) can be made smooth, drainage performance can be improved further and hydroplaning performance can be improved. Moreover, since block rigidity can be ensured, DRY and WET steering stability is also improved.
In addition, the steeply inclined portion 15b of the inclined lug groove 15 is terminated in the vicinity of the connecting portion between the gently inclined portion 15a and the steeply inclined portion 15b of the adjacent inclined lug groove 15, and the above described between the adjacent inclined lug grooves 15 and 15 is performed. A virtual pseudo block 13z having an acute angle corner 13n is formed on the steeply inclined portion 15b side, and the acute angle corner 13n of the virtual pseudo block 13z is chamfered. Thereby, although the 1st and 2nd center land parts 13a and 13b are connected as a rib, since it becomes the independent composition as a block on the tire surface, it can improve riding comfort, ensuring rigidity. it can. Further, by chamfering the sharp corner 13n, the flow of water can be made smooth, and the drainage performance can be further improved.

In this example, when the inclined lug groove 15 is inclined in the opposite direction, the block shape and wear resistance are ensured by the inclined sipe 16.
That is, in the case of only the inclined lug groove 15, the inclined lug groove 15 is inclined only in one direction, and therefore there is a possibility that a single flow of the vehicle may occur when traveling on the DRY and WET road surfaces. Therefore, if the inclined sipe 16 is provided when inclined in the direction opposite to the inclined lug groove 15, the running stability on the DRY and WET road surfaces can be improved by canceling out the single flow component.
In this example, the inclined sipe 16 is formed so that the crossing angles with the inclined lug grooves 15 formed in the first and second central land portions 13a and 13b having different inclination angles are substantially the same, and Since it is formed so as to pass through the acute-angle side corners 13m and 13n, the tire surface can be made similar to the block pattern, and riding comfort can be improved while ensuring rigidity.
Further, since the inclination angle of the inclined sipe 16 with respect to the tire circumferential direction is small on the vehicle outer side and large on the vehicle inner side, the block rigidity at the intersection with the inclined lug groove 15 is made appropriate, and both ride comfort and maneuverability are achieved. Can be improved.

Next, the outer land portion 14a and the inner land portion 14b will be described.
In this example, the outer land portion 14a and the inner land portion 14b are divided by the circumferential sipes 17a and 17b, respectively, thereby optimizing the block rigidity and improving the riding comfort, and the outer land portion 14a and the inner land portion 14b. Each of 14b is divided into two parts having different functions. Specifically, in the inner land portion 14b, the inclined sipe 16 and the inclined sipe 16 are provided to extend in a direction opposite to the inclined sipe 16 in a portion surrounded by the circumferential groove 12c and the circumferential sipe 17b. The sub-block 19b divided by the inclined sipe 18b optimizes the block rigidity in this region, suppresses uneven wear, and has a diameter of 0 provided on the vehicle inner side from the circumferential groove 12c of the inner land portion 14b. The rigidity of this region is lowered by a large number of small holes 20 of 5 mm to 7 mm, and the familiarity at the time of ground contact during rolling of the tire is improved to suppress the uneven wear characteristics inside the vehicle. In addition, when the size of the small hole 20 is less than 0.5 mm, the rigidity is not significantly reduced, and when it exceeds 7 mm, the rigidity is excessively lowered, and the uneven wear characteristic is deteriorated. Therefore, the diameter of the small hole 20 is 0.5 mm or more, It is preferable to be 7 mm or less.
On the other hand, in the outer land portion 14a, the portion surrounded by the circumferential groove 12c and the circumferential sipe 17b is only the inclined sipe 16, and the outer portion from the circumferential sipe 17a outside the vehicle is opposite to the inclined sipe 16. By providing a sub-inclined sipe 18a that is inclined and extended to form a substantially trapezoidal or substantially triangular sub-block 19a smaller than the sub-block 19b, the block rigidity in this region is optimized and uneven wear is reduced. Suppress.

In the above-described best mode, three circumferential grooves are provided and the central land portions 13a and 13b are arranged in two rows. However, the present invention is not limited to this, and the number of circumferential grooves is three or more. If so, drainage performance and handling stability can be ensured.
Moreover, in the said example, although the groove width of the circumferential groove | channel 12c which divides the inner land part 14b was made narrower than the groove width of the circumferential groove | channel 12b located in a center part, the circumferential groove | channel which divides the outer land part 14a The groove width of 12a may also be narrower than the groove width of the circumferential groove 12b. Thereby, block rigidity can be ensured, ensuring drainage performance.
Further, the intersecting angle between the inclined lug groove 15 and the inclined sipe 16 is not particularly limited as long as an extremely acute angle portion is not formed.
Further, the ratio between the width of the first central land portion 13a and the width of the second central land portion 13b located inside the vehicle or the angle of the inclined sipe 16 also depends on the required characteristics of the pneumatic tire 10. Are set as appropriate.

表１から明らかなように、本発明の非対称トレッドパターンを有するタイヤは、ＷＥＴハイドロプレーニング性能、ＤＲＹ路面及びＷＥＴ路面での操縦安定性、タイヤパターンノイズ、乗り心地性、耐偏摩耗性能のいずれにおいても、従来の非対称トレッドパターンを有するタイヤよりも優れた性能を備えていることが確認された。 The tire having the asymmetric tread pattern of the present invention shown in FIG. 1 and the circumferential grooves 41 and 42 and the inclined lug grooves 43 in the center of the tread 40 shown in FIG. , 42, a tire having a conventional asymmetric tread pattern, including a block row 44 in which blocks 44B having sipes 44a extending in a direction perpendicular to the circumferential direction are arranged, and ribs 45, 46 arranged on both sides thereof. Table 1 below shows the results of running tests on various road surfaces.
The tire size was 205 / 55R16, and the groove depth was all 8.3 mm.
In the tire of the example, the number of circumferential grooves is three (4 blocks), and the groove width is 10 mm on the OUT side, 11.5 mm on the center, and 7 mm on the IN side. The groove width of the inclined lug groove outside the vehicle is 3 mm at the gently inclined portion, 6 mm at the steeply inclined portion, and the groove width of the inclined lug groove inside the vehicle is 2.5 mm at the gently inclined portion, and 5. The angle of the inclined lug groove on the outside of the vehicle with respect to the circumferential groove is 55 ° at the gently inclined portion, 10 ° with the steeply inclined portion, and the angle of the inclined lug groove on the inside of the vehicle with respect to the circumferential groove is at the gently inclined portion. 45 ° and 10 ° at the steep slope.
Moreover, the slope lug terminal part on the vehicle outer side is 77% from the circumferential opening, 73% on the vehicle inner side, and the diameter of the small hole formed in the inner land part is 2 mm and 2 mm.
In the running test, the tire internal pressure was 230 kPa, the load was equivalent to two real vehicles, and each performance was evaluated on the following road surfaces.
(1) WET hydroplaning performance (straight line)
Feeling evaluation at the hydroplaning limit speed when passing through a wet road surface with a water depth of 5 mm.
(2) Dry handling stability test Feeling evaluation of test driver when driving on circuit course in DRY state in various driving modes.
(3) WET handling stability test Feeling evaluation of the test driver when driving on the circuit in the WET state in various driving modes.
(4) Tire pattern noise test Feeling evaluation of a test driver when a general road in the DRY state is driven by sports in various driving modes.
(5) Ride comfort test Test driver's feeling evaluation when driving on a general road in DRY state in various driving modes.
(6) Uneven wear resistance performance Sport running in various driving modes on a general road in the DRY state, and evaluating the amount of wear on the step between adjacent blocks after running 5000 km.

As is apparent from Table 1, the tire having the asymmetric tread pattern of the present invention is in any of WET hydroplaning performance, driving stability on DRY road surface and WET road surface, tire pattern noise, riding comfort, and uneven wear resistance performance. In addition, it was confirmed that the tire had performance superior to that of a tire having a conventional asymmetric tread pattern.

  As described above, according to the present invention, in a pneumatic tire having an asymmetric tread pattern, high steering stability and drainage performance are ensured, tire noise is suppressed, and uneven wear resistance and riding comfort are improved. Therefore, the running stability of the vehicle can be greatly improved.

It is a figure which shows the tread pattern of the pneumatic tire which concerns on the best form of this invention. It is a figure which shows the conventional tread pattern used for the running test. It is a figure which shows the tread pattern of the conventional pneumatic tire. It is a figure which shows the other example of the tread pattern of the conventional pneumatic tire. It is a figure which shows the other example of the tread pattern of the conventional pneumatic tire.

Explanation of symbols

10 Pneumatic tire, 11 tread, 11b Vehicle outer tread end,
12a, 12b, 12c circumferential groove, 13a first central land portion, 13b second central land portion, 13m, 13n acute angle corner, 13z virtual pseudo block, 14a outer land portion,
14b Inner land part, 15 slope lug groove, 15a gentle slope part, 15b steep slope part,
16 Inclined sipes, 17a, 17b Circumferential sipes, 18a, 18b Sub-inclined sipes,
19a, 19b Sub-block, 20 small holes.

Claims (14)

At least three circumferential grooves provided on the tread surface and extending along the tire circumferential direction, a plurality of central land portions defined by the circumferential grooves, and the central land portions, respectively. A pneumatic tire provided with a plurality of inclined lug grooves extending obliquely with respect to a direction,
The inclined lug groove is
One end of the circumferential groove defining the central land portion where the lug groove is provided opens only to the circumferential groove side located on the vehicle outer side of the tire when the vehicle is mounted , and the other end is within the central land portion. Terminated with
In the land portion of the tread, there is an inclined sipe that is inclined to the opposite side of the inclined lug groove with respect to the tire circumferential direction and arranged at substantially the same pitch as the arrangement pitch of the inclined lug groove in the tire circumferential direction. A pneumatic tire characterized by being provided.   The inclined lug groove is located on the opening side, and is a gently inclined portion that is inclined at a large angle with respect to the tire circumferential direction, and a steeply inclined portion that is located on the terminal end side and is inclined at a small angle with respect to the tire circumferential direction. The pneumatic tire according to claim 1, wherein   The inclined lug groove is formed so that the end of the inclined lug groove is at a position separated from the opening side of the inclined lug groove of the central land portion by 40% to 90% of the width of the central land portion. The pneumatic tire according to claim 1 or 2, characterized in that.   The pneumatic tire according to claim 2, wherein an angle of the gently inclined portion with respect to the tire circumferential direction is set to 30 ° to 90 °, and an angle of the steeply inclined portion with respect to the tire circumferential direction is set to 0 ° to 30 °. .   The pneumatic tire according to claim 4, wherein a groove width of the gently inclined portion is narrower than a groove width of the steeply inclined portion.   The pneumatic tire according to claim 2, wherein chamfering is applied to an acute angle side corner of a land portion defined by the gently inclined portion and the circumferential groove.   The steeply inclined portion of the inclined lug groove is terminated in the vicinity of the connecting portion between the gently inclined portion and the steeply inclined portion of the adjacent inclined lug groove, and between the adjacent inclined lug grooves, the acute angle side corner 3. The pneumatic tire according to claim 2, wherein a virtual pseudo block having the shape is formed, and the acute angle side corner portion of the virtual pseudo block is chamfered.   2. The pneumatic tire according to claim 1, wherein the inclined sipe traverses the central land portion from a vehicle outer tread end of the tire when the vehicle is mounted, and opens in a circumferential groove located on the vehicle inner side. tire.   The angle with respect to the tire circumferential direction of the gently sloping portion and steeply inclined portion of the inclined lug groove located on the vehicle outer side is larger than the angle with respect to the tire circumferential direction of the gently sloping portion and steeply inclined portion of the inclined lug groove located on the vehicle inside, respectively. The pneumatic tire according to claim 8, wherein the pneumatic tire is gradually increased and an inclination angle of the inclined sipe with respect to a tire circumferential direction is gradually decreased from the outside of the vehicle toward the inside of the vehicle.   A circumferential sipe extending substantially parallel to the circumferential groove is provided at the land portions at both ends of the tire defined by the circumferential groove, and the circumferential sipe and the circumferential portion of the land portion inside the vehicle when the vehicle is mounted. 2. The pneumatic tire according to claim 1, wherein a sub-inclined sipe that is inclined and extended in a direction opposite to the inclined sipe is provided in a portion surrounded by the directional groove. 3.   The pneumatic tire according to claim 10, wherein a plurality of small holes are provided inside the vehicle of the circumferential sipe.   The pneumatic tire according to claim 11, wherein a diameter of the small hole is 0.5 mm to 7 mm.   11. A sub-inclined sipe that is inclined and extended in a direction opposite to the inclined sipe is provided in a portion outside the circumferential sipe of the land portion outside the vehicle when the vehicle is mounted. The described pneumatic tire.   2. The pneumatic tire according to claim 1, wherein the groove width of the circumferential groove located on the inner side of the vehicle when mounted on the vehicle is 20% to 90% of the groove width of the circumferential groove located in the tire central portion. .

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