JP2005161878A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of securing a pattern noise and steering stability without sacrificing wet performance. <P>SOLUTION: The pneumatic tire is configured by arranging a steep slope groove 16 on the tread center side and arranging a gentle slope groove 14 outside it. Thus, the water in the grounding surface can be drained smoothly and high wet performance can be obtained. The gentle slope groove 14 on one side and the gentle slope groove 14 on the other side of a tire equatorial plane CL are arranged with a phase difference in circumferential direction, and the steep slope groove 16 on one side and the steep slope groove 16 on the other side of the tire equatorial plane CL are arranged with a phase difference in circumferential direction, so that the pattern noise is improved. The side ends of the tire equatorial plane CL of the steep slope groove 16 terminate in a land section 22 and are arranged with phase difference of 1/2P2 on the right and left sides of the tire equatorial plane CL, so that the rigidity of the center section of the tread 12 is high and uniform, thereby high steering stability is obtained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire that can ensure pattern noise and steering stability without sacrificing wet performance.

  In summer tires, a block pattern is generally formed by a combination of a straight main groove extending in the tire circumferential direction and an inclined groove inclined with respect to the tire circumferential direction (see, for example, Patent Document 1).

  In such a pattern, in order to improve wet hydroplaning performance, a method of increasing the groove area (negative) such as increasing the groove width is generally used.

  It is also known to improve drainage by making the inclined groove at the center of the tread a high angle (small angle with respect to the tire circumferential direction) (for example, Patent Documents 2 to 4).

  Further, noise can be reduced by stopping the inclined groove without opening it in the circumferential groove.

  In general, it is possible to reduce noise by providing a half-pitch phase difference between the inclined grooves on the left and right of the tread.

  It is also known that steering stability is improved by increasing the rigidity of the central portion of the tread.

Furthermore, in the block pattern, heel and toe wear may occur, and in order to suppress this heel and toe wear, it is common to close the lug groove and arrange the rib (for example, (See Patent Document 5).
JP-A-5-246214 JP-A-7-96717 JP-A-5-286212 JP-A-4-218410 Japanese Patent Laid-Open No. 62-15807

  However, if the groove area is widened, drainage generally improves, but simply widening the groove width causes problems such as insufficient rigidity of the block or deterioration of pattern noise due to an increase in the air volume in the groove.

  Generally, the land portion row is provided with a lug groove for drainage, but the continuous smooth grounding is impaired by the lug groove, and it is often a source of pattern noise.

  On the other hand, plain land rows (ribs) with no cuts not only reduce wet drainage, but also deteriorate the ride comfort due to grip on low μ (low friction coefficient) roads and too high land stiffness. May cause.

  In addition, in order to ensure the rigidity of the high angle part at the center of the tread, it is preferable to set the center of the tread to a smaller pitch than both sides and shift the half pitch phase on the left and right of the tread to reduce noise. As shown in FIG. 6, when the number of grooves is center: shoulder = 1: 2, shifting the center half-pitch (1 / 2P2) of the groove results in the shoulder having the same phase, and the shoulder half-pitch of the groove as shown in FIG. The (1 / 2P1) shift becomes a center 1/4 pitch (1 / 4P2) shift.

  These are insufficient in terms of noise, and in the case of FIG. 7, the rigidity of the center portion tends to be non-uniform.

  In order not to make it non-uniform, it is only necessary to divide the left and right of the tread with circumferential grooves.

  Further, when center: shoulder = 1: 3, both can be shifted by a half pitch, but there is a problem that the number of mold pitches increases.

  The present invention has been made to solve the above-described problem, and an object thereof is to provide a pneumatic tire that can ensure pattern noise and steering stability without sacrificing wet performance.

  The invention according to claim 1 is the tire of the tread when the tread width when the tread width is divided into three equal parts in the tire width direction is a tread center area, and both sides of the tread center area are tread side areas. A steeply inclined groove disposed on both sides of the equator plane and extending at an inclination with respect to the tire circumferential direction at least in the tread central region and terminating at the tire equator side end portion in the land portion, and at least disposed in the both side areas. A gently inclined groove that is inclined in the same direction as the steeply inclined groove toward the grounding end and whose angle with respect to the tire circumferential direction is set larger than that of the steeply inclined groove. On the other hand, the number of the gently inclined grooves arranged in the circumferential direction is set to be twice, and the steeply inclined grooves and the gently inclined grooves are arranged at substantially equal intervals in the circumferential direction, and one side of the tire equatorial plane The gently inclined groove and the gently inclined groove on the other side are arranged to be shifted in the circumferential direction by a half pitch of the circumferential pitch of the gently inclined groove, and the steeply inclined groove on one side of the tire equatorial plane is arranged. And the steeply inclined groove on the other side are arranged so as to be shifted in the circumferential direction, and the end portion on the tire equatorial plane side is shifted in the circumferential direction by a half pitch of the circumferentially arranged pitch of the steeply inclined groove. It is characterized by that.

  Next, the operation of the pneumatic tire according to claim 1 will be described.

  In the pneumatic tire according to claim 1, since it has a directional pattern in which a steeply inclined groove is disposed on the tread central side and a gently inclined groove is disposed on the outer side thereof, water in the ground plane can be smoothly drained, and high wet performance is achieved. can get.

  In addition, the gently inclined groove on one side of the tire equator surface and the gently inclined groove on the other side are arranged so as to be shifted from each other in the circumferential direction by a half pitch of the circumferential pitch of the gently inclined groove, and on one side of the tire equator surface Since the steeply inclined groove and the steeply inclined groove on the other side are shifted from each other in the circumferential direction, pattern noise can be improved.

  In addition, the gently inclined groove on one side of the tire equatorial plane and the gently inclined groove on the other side are shifted from each other in the circumferential direction by a half pitch of the circumferential pitch of the gently inclined groove. When the positional relationship in the tire circumferential direction with adjacent steeply inclined grooves is set to be the same on both the left and right sides of the tire equator plane, the steeply inclined grooves on one side of the tire equator plane and the steeply inclined grooves on the other side are 1/4 pitch Although it is in a state of deviation, the rigidity of the tread center part is made uniform because the tire equatorial plane side end is set to be shifted in the circumferential direction by a half pitch of the circumferentially arranged pitch of the steeply inclined grooves. High steering stability can be obtained.

  According to a second aspect of the present invention, in the pneumatic tire according to the first aspect, the steeply inclined groove on one side and the steeply inclined groove on the other side have different lengths across the tire equatorial plane. It is a feature.

  Next, the operation of the pneumatic tire according to claim 2 will be described.

  In the pneumatic tire according to claim 2, the left and right tire equatorial plane side end portions are made different by making the length of the steeply inclined groove on one side different from the length of the steeply inclined groove on the other side across the tire equatorial plane. It is possible to shift in the circumferential direction by ½ pitch.

  According to a third aspect of the present invention, in the pneumatic tire according to the first or second aspect, a land portion continuous in a tire circumferential direction is provided in the tread central region, and the steeply inclined groove is formed on the tire. The angle with respect to the circumferential direction is set to 45 ° or less.

  Next, the operation of the pneumatic tire according to claim 3 will be described.

  Since a land portion continuous in the tire circumferential direction is provided in the tread central region, high rigidity is secured in the tread central region, and steering stability is improved.

  In addition, by setting the angle of the steeply inclined groove with respect to the tire circumferential direction to be 45 ° or less, the steeply inclined groove substantially coincides with the water stream direction in the central region of the tread, thereby improving wet drainage.

  According to a fourth aspect of the present invention, in the pneumatic tire according to any one of the first to third aspects, a tread is provided on both sides of the tire equatorial plane of the tread from the tire equatorial plane toward the tread ground contact edge. A circumferential groove extending in the tire circumferential direction is formed in a region of 40 to 60% of the half width.

  Next, the operation of the pneumatic tire according to claim 4 will be described.

  By providing circumferential grooves extending in the tire circumferential direction in the region of 40-60% of the tread half-width from the tire equatorial plane to the tread ground contact edge on both sides of the tread tire equatorial plane, the drainage performance is improved and wet hydro is improved. Planing performance is further improved.

  In addition, when the arrangement | positioning position of a circumferential groove | channel is arrange | positioned on the tire equatorial plane side rather than the said area | region, sufficient drainage of a tread central area will no longer be obtained.

  On the other hand, if the arrangement position of the circumferential groove is arranged on the tread grounding end side with respect to the region, the rigidity of the block outside the circumferential groove is lowered, and the steering stability and the falling wear are deteriorated.

  According to a fifth aspect of the present invention, in the pneumatic tire according to any one of the first to fourth aspects, the steeply inclined groove is closer to the tire equatorial plane side end portion than the groove longitudinal direction intermediate portion. It is characterized by being set wide.

  Next, the operation of the pneumatic tire according to claim 5 will be described.

  If the vicinity of the tire equatorial plane side end portion of the steeply inclined groove is set wider than the middle portion in the longitudinal direction of the groove, the surface pressure at the center portion of the tread increases and drainage performance can be enhanced. In addition, since the center part of a tread receives a hydraulic resistance first at the time of rotary contact, the center surface pressure is important.

  As described above, since the pneumatic tire according to claim 1 has the above-described configuration, it has an excellent effect of ensuring pattern noise and steering stability without sacrificing wet performance.

  Since the pneumatic tire according to claim 2 has the above-described configuration, it is possible to easily set the pitch shift.

  Since the pneumatic tire according to claim 3 has the above-described configuration, it has an excellent effect that the steering stability is improved and the wet drainage is improved.

  Since the pneumatic tire according to claim 4 has the above-described configuration, it has an excellent effect of further improving the wet hydroplaning performance.

  Since the pneumatic tire according to claim 5 has the above-described configuration, it has an excellent effect of improving wet drainage.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the tread 12 of the pneumatic tire 10 has, on each tread grounding end 12E side, a gently inclined groove 14 that is inclined with respect to the tire axial direction (arrow W direction) in the tire circumferential direction (arrow A direction). Are formed at regular intervals (pitch) in the tire rotation direction).

  The slowly inclined groove 14 on the left side of the tire equator plane CL is inclined upward to the left, and the gently inclined groove 14 on the right side of the tire equator plane CL is inclined upward.

  The gently inclined groove 14 is open to the tread grounding end 12 on the outer side in the tire axial direction.

  Here, the arrangement number of the left gently inclined grooves 14 and the arrangement number of the right gently inclined grooves 14 are the same with respect to the tire equatorial plane CL.

  Further, in order to improve pattern noise, the gentle slope groove 14 on the left side of the tire equator plane CL and the gentle slope groove 14 on the right side of the tire equator plane CL are shown in FIG. 1 and FIG. As shown in FIG. 3, the left side gently inclined groove 14 and the right side gently inclined groove 14 are arranged with a phase difference in the tire circumferential direction across the tire equatorial plane CL so as not to line up in the tire width direction.

  In FIG. 2A, P1 indicates the circumferential pitch of the gently inclined groove 14, and P2 indicates the circumferential pitch of the steeply inclined groove 16 described later. In this embodiment, P2 = 2 · P1.

  In the present embodiment, for example, a phase difference is provided so that the tire circumferential position of the left gently inclined groove 14 on the left side of the tire equatorial plane CL is the tire circumferential position of the center portion of the two right slowly inclined grooves 14. (That is, the right side and the left side are shifted by 1 / 2P1).

  On the tire equatorial plane CL side of these gently inclined grooves 14, there is a steep slope that is inclined in the same direction as the gently inclined grooves 14 adjacent to the outer side in the tire width direction and has a smaller angle with respect to the tire circumferential direction than the gently inclined grooves 14. A plurality of inclined grooves 16 are formed at intervals in the tire circumferential direction.

  The number of the steeply inclined grooves 16 on the left and the number of the steeply inclined grooves 16 on the right side of the tire equatorial plane CL is the same, but the number of disposed is ½ of the number of the gently inclined grooves 14.

  In the present embodiment, as shown in FIG. 1, two gently inclined grooves 14 are connected to one steeply inclined groove 16, and one of the two gently inclined grooves 14 is a circumferential groove. 18 is connected.

  The outer end in the tire axial direction of the steeply inclined groove 16 is connected to the longitudinally intermediate portion (near the circumferential groove 18) of one (in the direction opposite to the tire rotating direction) of the slowly inclined groove 14, and the other (tire rotating direction). The end portion in the tire axial direction of the gently inclined groove 14 is connected to the intermediate portion in the longitudinal direction of the steeply inclined groove 16 via the circumferential groove 18.

  The circumferential groove 18 is preferably provided in a region of 40 to 60% of the tread half width (TW / 2) from the tire equatorial plane CL toward the tread ground contact end 12E.

  Note that one gently inclined groove 14 connected to the steeply inclined groove 16 and the other gently inclined groove 14 are connected via a steeply inclined sub-groove 20 that is substantially parallel to the steeply inclined groove 16.

  The steeply inclined groove 16 on the left side of the tire equator plane CL and the steeply inclined groove 16 on the right side of the tire equator plane CL are only 1/4 P2 as shown in FIG. There is a phase difference in the tire circumferential direction.

  However, in the embodiment, as shown in FIGS. 1 and 2, the steeply inclined groove 16 on the left side of the tire equator plane CL is set to be relatively longer than the steeply inclined groove 16 on the right side of the tire equator plane CL. Therefore, the end portion of the steeply inclined groove 16 on the left side of the tire equator plane CL and the end portion of the steeply inclined groove 16 on the right side of the tire equator plane CL are phase-differed in the tire circumferential direction by 1 / 2P2. Yes.

  Note that the steeply inclined grooves 16 on both sides of the tire equator plane CL end in the land portion without being connected to other grooves at the end portion on the tire equator plane CL side. 22 is continuous in the tire circumferential direction.

  Since the steeply inclined groove 16 on the left side of the tire equator plane CL is extended to the tire equator plane CL, the end of the steeply inclined groove 16 on the left side of the tire equator plane CL is steep on the right side of the tire equator plane CL. It is closer to the tire equatorial plane CL than the end of the inclined groove 16.

  Therefore, the center line RCL (the land portion continuous in the tire circumferential direction at the tire center) between the end of the steeply inclined groove 16 on the left side of the tire equator plane CL and the end of the steeply inclined groove 16 on the right side of the tire equator plane CL. The apparent center line) is slightly displaced to the right side of the drawing with respect to the tire equatorial plane CL.

  When the central portion of the tread 12 when the tread width TW is divided into three equal parts in the tire axial direction is the tread central region 12C and both sides of the tread central region 12C are the tread side regions 12S, the tread central region 12C has a steeply inclined groove. 16, a part of the steeply inclined groove 16, a gently inclined groove 14, a circumferential groove 18, and a steeply inclined subgroove 20 are disposed in the tread both side regions 12S.

  In the steeply inclined groove 16, a part on the tire equatorial plane CL side is wide, and the remaining part on the outer side in the tire axial direction is narrow.

  The groove width of the wide portion of the steeply inclined groove 16 on the tire equatorial plane CL side is preferably 5 mm or more in the case of a tire for a passenger car.

  A kick-out edge chamfer 24 is formed at the kick-out edge of the land portion 22 facing the narrow portion of the steeply inclined groove 16.

  The gently inclined groove 14 has a portion in the vicinity of the tread ground contact end 12E that is wide, and the remaining portion on the inner side in the tire axial direction is narrow.

  A stepping edge chamfered portion 26 is formed at the stepping edge of the land portion 22 facing the narrow portion of the gently inclined groove 14.

  The steeply inclined sub-groove 20 is set to have a width substantially the same as the narrow portion of the steeply inclined groove 16, and the kicking edge of the land portion 22 facing the steeply inclined subgroove 20 has a kicking edge. A chamfer 29 is formed.

  The kicking edge chamfered portion 24 is inclined at a certain angle as shown in the cross-sectional view of FIG. 3, but may be rounded and be at least lower than the tread surface 22A. May be.

  The stepping edge chamfered portion 26 and the kicked edge chamfered portion 29 are also set to have the same shape as the kicked edge chamfered portion 24.

The steeply inclined groove 16 has a widened portion 28 whose groove width is set wider than the intermediate portion of the groove depth on the groove bottom side of the portion where the kicking edge chamfered portion 24 is formed.
Here, the widened portion 28 provided in the steeply inclined groove 16 is provided by being displaced toward the kicking edge chamfered portion 24 as shown in FIG.

  A similar widened portion 28 (not shown) is also provided in the gently inclined groove 14 so as to be displaced toward the stepping edge chamfered portion 26, and a similar widened portion 28 (not shown) is also provided in the steeply inclined sub-groove 20. ) Is provided to be displaced toward the edge chamfered portion 29 side.

  The tread grounding end 12E means that a pneumatic tire is mounted on a standard rim specified in JATMA YEAR BOOK (2003 edition, Japan Automobile Tire Association Standard), and is the maximum size and ply rating applicable to JATMA YEAR BOOK. This is the outermost end in the tire width direction when 100% of the air pressure (maximum air pressure) corresponding to the load capacity (internal pressure-load capacity correspondence table) is filled and the maximum load capacity is loaded.

  When the TRA standard or ETRTO standard is applied at the place of use or manufacturing, the rim, air pressure, and load comply with the respective standards.

Further, the tread width TW is a dimension measured along the tire width direction from the tread ground contact end 12E on one side in the tire width direction to the tread ground contact end 12E on the other side.
(Function)
Next, the effect | action of the pneumatic tire 10 of this embodiment is demonstrated.

  In the pneumatic tire 10 of the present embodiment, a directional pattern in which the steeply inclined groove 16 is disposed on the center side of the tread and the gently inclined groove 14 is disposed on the outer side thereof, and the circumferential groove 18 and the steeply inclined subgroove 20 are disposed. As a result, the water in the ground plane can be drained smoothly, and high wet performance can be obtained.

  Further, the gently inclined groove 14 on one side of the tire equatorial plane CL and the gently inclined groove 14 on the other side are arranged with a phase difference in the circumferential direction, and the steeply inclined groove 16 on one side of the tire equatorial plane CL Since the steeply inclined groove 16 on the other side is arranged with a phase difference in the circumferential direction, pattern noise can be improved.

  Further, the land portion 22 is continuous in the circumferential direction on the tire equatorial plane CL, and the end portion on the tire equatorial plane CL side of the steeply inclined groove 16 has a phase difference of 1 / 2P2 on the left and right of the tire equatorial plane CL. Since it is provided and arranged, the rigidity of the center portion of the tread 12 is high and uniform, and high steering stability is obtained.

  Strictly speaking, although the left and right sides of the steeply inclined groove 16 are asymmetric in the tire equator plane CL side, the angle on the tire equator plane CL side is a high angle. For example, as shown in FIG. If the angle θ with respect to the direction is 20 °, for example, the pitch P2 is 60 mm, the left end of the tire equatorial plane CL is 7.5 mm toward the tire equatorial plane CL, and the right end of the tire equatorial plane CL is the tire equatorial plane CL. The center line RCL of the land portion continuous in the circumferential direction is only an offset of 2.25 mm with respect to the tire equatorial plane CL (for example, to a tread width TW of 170 mm). In fact, the amount is 1.2%.) In fact, there is no asymmetric influence on the tire performance.

  Further, by setting the angle of the steeply inclined groove 16 with respect to the tire circumferential direction to be 45 ° or less, the steeply inclined groove 16 substantially coincides with the water stream direction of the tread central region 12C, and wet drainage is improved.

  Further, since the steeply inclined groove 16 is set wide near the end portion on the tire equatorial plane CL side, the surface pressure at the center of the tread is increased, and drainage can be improved.

  Here, when the arrangement position of the circumferential groove 18 is arranged closer to the tire equatorial plane CL than the above region, sufficient drainage of the tread central region 12C cannot be obtained.

  On the other hand, when the arrangement position of the circumferential groove 18 is arranged on the tread grounding end 12E side with respect to the above region, the rigidity of the land portion 22 outside the circumferential groove 18 becomes low, and steering stability and falling wear are deteriorated. To do.

  In this embodiment, the pitch of the gently inclined groove 14 is constant and the pitch of the steeply inclined groove 16 is also constant. However, in order to improve pattern noise, the pitch is intentionally different for each circumferential portion. (So-called pitch variation).

  However, the ratio Pmin / Pmax between the maximum pitch Pmax and the minimum pitch Pmin is 0.6 or more.

  In the present embodiment, the left side gently inclined groove 14 and the right side gently inclined groove 14 of the tire equatorial plane CL have a phase difference of 1/2 P1 in the circumferential direction, but in the present invention, within ± 10% Variation of is allowed.

Similarly, in the present embodiment, the tire equatorial plane CL side end portion of the left steeply inclined groove 16 on the left side of the tire equator plane CL and the tire equatorial plane CL side end portion of the right steeply inclined groove 16 are 1 / 2P2 in the circumferential direction. However, in the present invention, a variation within ± 10% is allowed.
(Test example)
In order to confirm the effect of the present invention, two types of conventional pneumatic tires and one type of tires according to the present invention were prepared, and the wet hydroplaning performance, pattern noise, and dry steering stability performance were prepared. Examined.

  -Wet hydroplaning performance test method and evaluation method: Feeling evaluation by a test driver at the hydroplaning limit speed when passing through a wet road with a depth of 5 mm. The evaluation is expressed as an index with the conventional example being 100, and the larger the value, the better the performance.

  Pattern noise test method and evaluation method: Feeling evaluation by a test driver of in-vehicle sound when a straight smooth road is practiced from 100 km / h. The evaluation is expressed as an index with the conventional example being 100, and the larger the value, the better the performance.

  ・ Test method and evaluation method of dry maneuvering stability performance: Feeling evaluation of test driver when driving on dry circuit course in various driving modes. The evaluation is expressed as an index with the conventional example being 100, and the larger the value, the better the performance.

  -Example tire: The pneumatic tire of the above-described embodiment. The dimensions and angles of each part are as shown in Table 1 below.

  Tire of conventional example 1: tire having the pattern shown in FIG. In addition, the same code | symbol is attached | subjected to the same structure as embodiment. The phase of the groove is different from that of the tire of the example. See FIG. 6 for the phase of the groove.

  Tire of conventional example 2: tire having the pattern shown in FIG. In addition, the same code | symbol is attached | subjected to the same structure as embodiment. The phase of the groove is different from that of the tire of the example. See FIG. 7 for the phase of the grooves.

  The dimensions, angles, and the like of each part of the tire are as shown in Table 1, and the results are as shown in Table 2.

  The tire size, internal pressure, and load are as follows.

Tire size: 205 / 55R16
Internal pressure: 230 kPa
Load: Equivalent to two real cars

  The offset dimension of the center line RCL with respect to the tire equator plane CL is 2 mm.

  θa: Angle with respect to the circumferential direction

  From the results of the test, it can be seen that the tire of the example to which the present invention is applied can ensure the pattern noise and the steering stability without sacrificing the wet performance.

It is a top view of the tread of the pneumatic tire concerning a 1st embodiment of the present invention. (A) is a simplified groove layout of the tread of the first embodiment, and (B) is a simplified groove layout of a steeply inclined groove near the tire equator plane. It is sectional drawing of an inclination groove | channel. It is a top view of the tread of the pneumatic tire which concerns on the prior art example 1. It is a top view of the tread of the pneumatic tire which concerns on the prior art example 2. FIG. 6 is a simplified groove arrangement diagram of the tread of Conventional Example 1. FIG. 6 is a simplified groove arrangement diagram of the tread of Conventional Example 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Pneumatic tire 12E Tread grounding end 12 Tread 12C Tread center area 12S Tread both sides area 14 Steeply inclined part 16 Slowly inclined part 18 Circumferential groove 22 Land part

Claims (5)

When the tread width is divided into three equal parts in the tire width direction, the tread center area is the tread center area, and both sides of the tread center area are the tread side areas. A steeply inclined groove that is disposed in the region and extends while inclining with respect to the tire circumferential direction, the tire equatorial plane side end portion terminating in the land portion, and the steeply inclined groove that is disposed in at least the both side areas toward the tread grounding end And a gently inclined groove that is inclined in the same direction and has an angle with respect to the tire circumferential direction set larger than that of the steeply inclined groove,
The number of the gently inclined grooves arranged in the circumferential direction is set to be twice the number of the circumferentially arranged steeply inclined grooves, and the steeply inclined grooves and the gently inclined grooves are arranged at substantially equal intervals in the circumferential direction. And
The gently inclined groove on one side of the tire equatorial plane and the gently inclined groove on the other side are arranged so as to be shifted from each other in the circumferential direction by a half pitch of the circumferential pitch of the gently inclined groove,
The steeply inclined groove on one side of the tire equator plane and the steeply inclined groove on the other side are arranged so as to be shifted from each other in the circumferential direction, and the tire equatorial plane side end is 1 of the circumferentially arranged pitch of the steeply inclined groove. / Pneumatic tire characterized by being shifted in the circumferential direction by 2 pitches.   2. The pneumatic tire according to claim 1, wherein the steeply inclined groove on one side and the steeply inclined groove on the other side have different lengths across the tire equatorial plane. In the central region of the tread, a land portion continuous in the tire circumferential direction is provided,
The steeply inclined groove has an angle with respect to the tire circumferential direction set to 45 ° or less,
The pneumatic tire according to claim 1 or 2, characterized in that.   On both sides of the tire equatorial plane of the tread, circumferential grooves extending in the tire circumferential direction are formed in a region of 40 to 60% of the tread half width from the tire equatorial plane to the tread ground contact edge. The pneumatic tire according to any one of claims 1 to 3.   The pneumatic tire according to any one of claims 1 to 4, wherein the steeply inclined groove is set to be wider in the vicinity of the end portion on the tire equatorial plane side than the intermediate portion in the groove longitudinal direction. tire.

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