JP3917406B2 - Pneumatic tire - Google Patents

Description

試験の結果から、本発明の適用された実施例の空気入りタイヤは、従来例の空気入りタイヤに対し、全ての性能が向上していることが分かる。
【０１０８】
【発明の効果】
以上説明したように請求項１に記載の空気入りタイヤは上記の構成としたので、排水性及び雪上性能を向上でき、トレッドのセンター部の摩耗も抑制できる、という優れた効果を有する。また、トレッドのセンター部の摩耗も抑制できるので、排水性及び雪上性能を長期に渡って維持できる、という優れた効果を有する。また、ドライ性能、ウエット性能、及び雪上性能を両立できる、という優れた効果を有する。
【０１０９】
請求項２に記載の空気入りタイヤは上記の構成としたので、ウエット性能を更に向上できる、という優れた効果を有する。
【０１１０】
請求項３に記載の空気入りタイヤは上記の構成としたので、ウエット性能を更に向上できる、という優れた効果を有する。
【０１１１】
請求項４に記載の空気入りタイヤは上記の構成としたので、雪上でのブレーキ性能、トラクション性能、及びフィーリングを向上できる、という優れた効果を有する。
【図面の簡単な説明】
【図１】本発明の一実施形態に係る空気入りタイヤのトレッドの平面図である。
【図２】従来例の空気入りタイヤのトレッドの平面図である。
【符号の説明】
１０ 空気入りタイヤ
ＣＬ タイヤ赤道面
１２ トレッド
１４ 周方向主溝
１６ 横溝
１８ センターブロック
２０ 第１の傾斜溝
２２ 第２の傾斜溝
２２Ａ 幅狭部
２４ 分岐溝
２５ 分岐溝
２６ 第１のセカンドブロック
２８ 第２のセカンドブロック
３０ ショルダーブロック
３２ サイプ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire provided with a plurality of blocks in a tread, and more particularly to a pneumatic tire that improves drainage and performance on snow and suppresses wear of a center portion.
[0002]
[Prior art]
The tread pattern of a pneumatic tire that emphasizes performance on snow is generally a block pattern.
[0003]
FIG. 2 shows a tread pattern of a conventional general studless tire.
[0004]
As shown in FIG. 2, the tread 100 has a first circumferential main groove 102 extending linearly in the tire circumferential direction on the tire equatorial plane CL, and is arranged on both sides of the tire equatorial plane CL and zigzag in the tire circumferential direction. A second circumferential main groove 104 extending in the direction of the tread end of the second circumferential main groove 104, and a third circumferential main groove 106 extending linearly in the tire circumferential direction. A first lateral groove 108 connecting the groove 102 and the second circumferential main groove 104; a second lateral groove 110 connecting the second circumferential main groove 104 and the third circumferential main groove 106; A third lateral groove 112 extending from the circumferential main groove 106 to the tread end side is formed.
[0005]
In the tread 100, a plurality of blocks 114, 116, and 118 are formed by these grooves, and a plurality of sipes 120 that extend along the tire width direction are formed in each block.
[0006]
[Problems to be solved by the invention]
The tire having the tread pattern shown in FIG. 2 also has a certain level of drainage (hydroplaning resistance) and on-snow performance, but from the market further improved drainage, further on-snow performance, and There is a demand for suppression of wear (uneven wear) at the center.
[0007]
In view of the above facts, an object of the present invention is to provide a pneumatic tire that has improved drainage performance and snow performance as compared with the prior art, and that also suppresses wear of the center portion.
[0008]
[Means for Solving the Problems]
  The invention according to claim 1 includes a pair of circumferential main grooves disposed on both sides of the tire equatorial plane and extending in the tire circumferential direction, and a plurality of circumferential main grooves disposed in the tire circumferential direction and sandwiching the tire equatorial plane. A plurality of lateral grooves that connect the groove and the other circumferential main groove, and a plurality of circumferential grooves that extend in the tire circumferential direction from the circumferential main groove toward the tread end, and the circumferential main groove side is closer to the tire rotation direction side than the tread end side The tread includes a plurality of blocks defined by inclined grooves that are inclined so that an angle with respect to the tire circumferential direction increases from the circumferential main groove side toward the tread end side, and the blocks are arranged along the tire circumferential direction. A plurality of block rows arranged in the tire width direction, and a pneumatic tire in which a sipe extending in the tire width direction is formed on the block, and the negative rate of the entire tread is 32-45. Is set within a range of, negative ratio of the tread center region is a central region when the contact region of the tread divided into three equal parts in the tire width direction is set smaller than the negative ratio of the entire tread,The inclined groove includes a first inclined groove whose groove width is substantially constant and an angle with respect to the tire circumferential direction at the end portion on the circumferential main groove side is set to 40 ° or less, and the vicinity of the end portion on the circumferential main groove side. And a second inclined groove having a narrow portion that is narrower than the tread end side and has an angle with respect to the tire width direction set to 30 ° or less, and the circumferential main groove in the first inclined groove; An intermediate portion between the tread end and an intermediate portion between the narrow portion and the tread end in the second inclined groove adjacent to the first inclined groove.And the circumferential main groove has a groove wall on the tire equatorial plane side that extends linearly in the tire circumferential direction, andThe firstConnection part with inclined grooveOf the circumferential main groove atThe groove width is within the circumferential main groove.Other than the connection partIt is characterized by being set wider than other parts.
[0009]
Next, the operation of the pneumatic tire according to claim 1 will be described.
[0010]
First, the tread is provided with a pair of circumferential main grooves extending in the tire circumferential direction on both sides of the tire equatorial plane, and a lateral groove that connects one circumferential main groove and the other circumferential main groove across the tire equatorial plane. By providing, the block edge component of a tread center part is ensured and the performance on snow improves.
[0011]
Furthermore, since the sipe extending in the tire width direction is formed in the tread block, it is possible to achieve both the basic performance of traction, braking and feeling on snow and the drainage performance on a wet road surface.
[0012]
Since a plurality of blocks defined by a pair of circumferential main grooves and lateral grooves are arranged in the tire circumferential direction on the tire equatorial plane, the tire is compared with the case where the circumferential main grooves are arranged on the tire equatorial plane. The contact area near the equator surface can be increased, and a high grip on a dry road surface and a high grip on a low mu (μ) road surface can be obtained.
[0013]
Moreover, since a pair of circumferential direction main groove also plays the role which divides a tread into right and left, on a wet road surface, the water interposed between a road surface and a tread can be divided into right and left.
[0014]
  Here, in the region on the outer side in the tire width direction from the circumferential main groove of the tread, the tire extends in the tire rotation direction side from the tread end side while extending from the circumferential main groove toward the tread end. Inclined and the angle with respect to the tire circumferential direction increases from the circumferential main groove side toward the tread end sideFirstInclined grooveAnd the second inclined grooveHowever, since a plurality of tread patterns are provided in the tire circumferential direction and the tread pattern is a so-called directional pattern, water in the vicinity of the tread center can be smoothly and efficiently discharged from the circumferential main groove to the outside of the tread end.
[0015]
Since the negative rate of the entire tread is set in the range of 32 to 45%, it is possible to achieve a balanced balance of dry performance, wet performance, and performance on snow.
[0016]
In the present invention, since the negative rate of the tread central region is set to be smaller than the negative rate of the entire tread, the tread end region when the block volume of the tread central region divides the ground contact region of the tread into three equal parts in the tire width direction. It is possible to suppress the wear (uneven wear) in the central region of the tread.
[0017]
The central region of the tread is a region that contributes greatly to the performance on the snow, the wet performance, and the like. By suppressing the wear here, the performance on the snow and the wet performance can be maintained for a long time.
[0018]
The detailed definition of the tread central area and the tread side area will be described later.
[0019]
  Normally, simply lowering the negative rate in the tread center area will adversely affect drainage and snow performance, but as mentioned above,FirstInclined grooveAnd the second inclined grooveThe angle with respect to the tire circumferential direction increased from the circumferential main groove side toward the tread end side, and adjacent to each otherFirstInclined grooveAnd the second inclined grooveBy providing the branch groove so as to connect the intermediate portions of each other, it is possible to compensate for the decrease in drainage performance and on-snow performance.
[0020]
For this reason, according to the present invention, it is possible to achieve multi-dimensional trade-off between on-snow performance, drainage performance, and wear in the central region of the tread.
[0021]
In addition, since the circumferential main groove has a groove wall on the tire equatorial plane side that is linear in the tire circumferential direction, water in the groove can flow smoothly in the circumferential direction.
[0022]
  Furthermore, the circumferential main groove isFirstConnection part with inclined grooveOf the circumferential main groove atThe groove width is within the circumferential main groove.Other than the connected partSince it is set wider than other parts, the water in the circumferential main grooveFirstIt can flow smoothly and efficiently to the tread end side through the inclined groove. Since the water that has entered the ground contact surface is allowed to flow in the tire width direction, it can be discharged out of the contact surface at a short distance.
[0023]
  Also, MutualNext toFirstInclined grooveAnd the second inclined grooveSince the middle parts of each other are connected by a branch groove, they are adjacent to each otherFirstInclined grooveAnd the second inclined grooveThe intermediate block is divided into two blocks in the tire width direction by the branch groove.
[0024]
As a result, two block rows are formed on the tread end side of each circumferential main groove.
[0025]
In other words, since at least five block rows are formed on the tread, each of the two row rows provided on the tread end side of each circumferential main groove and the block row arranged on the tire equator plane, Improved cornering performance.
[0026]
  In addition, the inclined groove(First inclined groove, second inclined groove)And the inclined grooves are alternately arranged in the circumferential direction, so that these inclined grooves(First inclined groove, second inclined groove)A zigzag-shaped groove is formed by the branching groove and the block edge component can be increased, and the performance on snow can be improved.
[0027]
In addition, in order to improve drainage more, it is preferable to arrange | position a branch groove in the intermediate part (what is called 1/4 point vicinity of a tread) of a tire equatorial plane and a tread end.
[0028]
Below, the tread center area | region and the definition of a tread side area said by this invention are demonstrated.
[0029]
  In the present invention, a pneumatic tire is mounted on a standard rim described below, filled with standard air pressure, and applied with a normal load, from one tire width direction outermost end (tread end) in the tire width direction to the other. When the region up to the outermost end (tread end) in the tire width direction is equally divided into three, the central region is the tread central region, and the region outside the tread central region is the tread side region.
In the inclined groove, when the angle with respect to the tire circumferential direction at the end on the circumferential main groove side is set to 40 ° or less, the vicinity of the end on the circumferential main groove side of the inclined groove is nearly parallel to the circumferential main groove, The water in the circumferential main groove can flow smoothly into the inclined groove, and high wet performance can be obtained.
However, with only the first inclined groove whose angle with respect to the tire circumferential direction at the end on the circumferential main groove side is set to 40 ° or less, only the block in which the corner on the circumferential main groove side has an acute angle is the tire circumference. It will continue in the direction. If the corner of the block is an acute angle, the block rigidity is lowered and the block is likely to be deformed, and the dry performance and on-snow performance are degraded.
On the other hand, in the second inclined groove, if the angle with respect to the tire width direction at the end on the circumferential main groove side is set to 30 ° or less, the rigidity of the corner of the block is secured, and the block is difficult to deform. Dry performance and performance on snow can be secured.
Accordingly, the first inclined groove in which the groove width is substantially constant and the angle with respect to the tire circumferential direction at the end on the circumferential main groove side is set to 40 ° or less, and the vicinity of the end on the circumferential main groove side is the tread end. By alternately arranging the second inclined grooves having narrow portions narrower than the side and having an angle with respect to the tire width direction set to 30 ° or less in the tire circumferential direction, dry performance, wet performance, and Both snow performance can be achieved.
[0030]
A standard rim is a rim specified by the Yearbook 2001 version of JATMA (Japan Automobile Tire Association). The load is a load corresponding to the maximum load capacity when the single wheel of Year Book 2001 version of JATMA (Japan Automobile Tire Association) is applied.
[0031]
Outside Japan, the load is the maximum load (maximum load capacity) of a single wheel at the applicable size described in the following standards, and the air pressure is the maximum load of a single wheel (specified in the following standards). The rim is a standard rim (or “ApprovedRim” or “Recommended Rim”) in the applicable size described in the following standards.
[0032]
The standards are determined by industry standards that are valid in the region where the tire is produced or used. For example, it is “The Tire and Rim Association Inc. Year Book” in the United States, and “The European Tire and Rim Technical Organization Standards Manual” in Europe.
[0033]
  The invention according to claim 2 is the pneumatic tire according to claim 1, wherein the branch groove has an extension line on the outer side in the tire width direction.SecondThe outer end of the inclined groove in the tire width direction is arranged.
[0034]
Next, the operation of the pneumatic tire according to claim 2 will be described.
[0035]
  On the extension line on the outer side of the branch groove in the tire width directionSecondWhen the outer edge of the inclined groove in the tire width direction is placed, the water that flows through the branch grooveSecondThe tire can be smoothly discharged to the tread end side through the outer end of the inclined groove in the tire width direction.
[0036]
  The invention according to claim 3 is the pneumatic tire according to claim 2, wherein the outer end of the branch groove in the tire width direction is the tire.SecondIt is characterized by being disposed closer to the tread end than the central portion of the inclined groove in the tire width direction.
[0037]
Next, the operation of the pneumatic tire according to claim 3 will be described.
[0038]
  The pneumatic tire having the configuration according to claim 2, wherein the outer end of the branch groove in the tire width direction isSecondIf it is arranged closer to the tread end than the center part in the tire width direction of the inclined groove,SecondIt can flow more smoothly to the outer end of the inclined groove in the tire width direction.
[0039]
The invention according to claim 4 is the pneumatic tire according to any one of claims 1 to 3, wherein the branch groove has an angle with respect to a tire width direction set to 20 ° or less. It is characterized by.
[0040]
Next, the operation of the pneumatic tire according to claim 4 will be described.
[0041]
If the angle of the branch groove with respect to the tire width direction is set to 20 ° or less, the direction of the branch groove approaches the tire width direction, and the braking performance, traction performance, and feeling on snow can be improved.
[0048]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a plan view showing a tread 12 of a pneumatic tire 10 according to an embodiment of the present invention.
[0049]
As shown in FIG. 1, the tread 12 has a circumferential direction extending along the circumferential direction (arrow A direction and arrow B direction, where the arrow A direction is the tire rotation direction) on both sides of the tire equatorial plane CL. A main groove 14 is provided.
[0050]
Between one circumferential main groove 14 and the other circumferential main groove 14, a plurality of lateral grooves 16 that connect both the circumferential main grooves 14 are arranged at intervals in the tire circumferential direction.
[0051]
Hereinafter, the land portion on the tire equatorial plane CL defined by the pair of circumferential main grooves 14 and the plurality of lateral grooves 16 is referred to as a center block 18.
[0052]
On the outer side in the tire width direction of the circumferential main groove 14, first inclined grooves 20 and second inclined grooves 22 extending from the circumferential main groove 14 to the tread end 12 </ b> E are alternately provided in the tire circumferential direction.
[0053]
In addition, the code | symbol W of FIG. 1 represents the contact width and C represents the tire width direction.
[0054]
The first inclined groove 20 and the second inclined groove 22 are inclined such that the end portion on the circumferential main groove 14 side is closer to the tire rotation direction side than the tread end 12E side. The angle (θ1) increases from the circumferential main groove 14 side toward the tread end 12E side.
[0055]
When the tread 12 is viewed in plan, the overall shape of the first inclined groove 20 and the overall shape of the second inclined groove 22 are substantially arc shapes each having a center of curvature near the tread end 12E.
[0056]
The first inclined groove 20 is smoothly connected to the circumferential main groove 14, and the angle of the end portion of the first inclined groove 20 on the circumferential main groove 14 side with respect to the tire circumferential direction is approximately 15 °. is there. The angle of the end portion of the first inclined groove 20 on the circumferential main groove 14 side with respect to the tire circumferential direction is preferably 40 ° or less.
[0057]
On the other hand, the angle with respect to the tire circumferential direction at the tread end 12E of the first inclined groove 20 is approximately 80 °.
[0058]
The groove width of the first inclined groove 20 tends to become slightly wider toward the tread end 12E side, but is generally constant as a whole.
[0059]
Next, the second inclined groove 22 has a generally arc shape as a whole, but is formed with a narrow portion 22A that is bent near the end on the circumferential main groove 14 side.
[0060]
The groove width of the narrow portion 22A is set to be narrower than the groove width of the first inclined groove 20.
[0061]
The groove width of the second inclined groove 22 is narrowest at the narrow portion 22A, and the other portions are gradually widened toward the tread end 12E side.
[0062]
The angle of the narrow portion 22A with respect to the tire width direction is preferably 30 ° or less.
[0063]
The intermediate portion of the first inclined groove 20 and the intermediate portion of the second inclined groove 22 are connected by a branch groove 24 or a branch groove 25.
[0064]
The angle (θ2) of the branch groove 24 and the branch groove 25 with respect to the tire width direction is preferably within 20 °.
[0065]
The branch groove 24 and the branch groove 25 of this embodiment are inclined in the same direction as the first inclined groove 20 and the second inclined groove 22 connected thereto, but the angle with respect to the tire width direction is 20 °. If it is within, it may be inclined in the opposite direction.
[0066]
The branch groove 24 and the branch groove 25 of the present embodiment have an angle of about 10 ° with respect to the tire width direction.
[0067]
Here, the outer end in the tire width direction of the branch groove 24 opens near the end of the first inclined groove 20 on the tread end 12E side, and the tread end 12E of the first inclined groove 20 extends on the extension line of the branch groove 24. The outer end of the branch groove 25 in the tire width direction is open near the end of the second inclined groove 22 on the tread end 12E side, and the second end is on the extension line of the branch groove 25. The end of the inclined groove 22 on the tread end 12E side is located.
[0068]
On the outer side in the tire width direction of the circumferential main groove 14, a first second block 26 and a second block partitioned by the circumferential main groove 14, the first inclined groove 20, the second inclined groove 22, and the branch groove 24. The second block 28 and the shoulder block 30 are partitioned.
[0069]
A chamfer 26 </ b> A is formed at the corner of the first second block 26 on the tire rotation direction side (stepping side).
[0070]
The first second block 26 and the second second block 28 form a row in the tire circumferential direction, and the shoulder block 30 also forms a row in the tire circumferential direction.
[0071]
That is, the tread 12 has one row of blocks composed of the center blocks 18, two rows of blocks composed of the first second block 26 and the second second block 28, two rows of blocks composed of the shoulder blocks 30, A total of five block rows are formed.
[0072]
Here, the groove wall (wall surface of the center block 18) on the tire equatorial plane CL side of the circumferential main groove 14 extends linearly in the tire circumferential direction.
[0073]
On the other hand, the groove wall on the tread end 12E side of the circumferential main groove 14 has a wave shape in which a plurality of arc-shaped portions that coincide with the extension line of the groove wall on the tire rotation direction side of the first inclined groove 20 are continued.
[0074]
For this reason, in the circumferential main groove 14, wide portions (connection portions between the circumferential main groove 14 and the first inclined groove 20) and narrow portions are alternately arranged.
[0075]
The center block 18, the first second block 26, the second second block 28, and the shoulder block 30 are formed with a plurality of sipes 32 having a width of 0.5 mm extending zigzag along the tire width direction. .
[0076]
Further, the negative rate of the entire tread 12 needs to be set within a range of 32 to 45%, and the negative rate of the tread central region 12C which is a central region when the tread 12 is divided into three equal parts in the tire width direction. It is necessary to set it smaller than the negative rate of the entire tread 12.
[0077]
The definition of the tread central region 12C is as described in the operation of claim 1.
[0078]
In the present embodiment, the negative rate of the entire tread 12 is set to 38%, and the negative rate of the tread central region 12C is set to 36.6%.
(Function)
Next, the operation and effect of the pneumatic tire 10 of the present embodiment will be described.
[0079]
First, the effect | action regarding abrasion is demonstrated.
[0080]
In the pneumatic tire 10 of the present embodiment, since the negative rate of the tread central region 12C is made smaller than the negative rate of the entire tread 12, the block volume of the tread central region 12C increases as compared with the tread side region 12S. Wear (including uneven wear) in the central region 12C can be suppressed.
[0081]
The tread central region 12C is a region having a high contribution to on-snow performance, wet performance, and the like. By suppressing the wear here, the on-snow performance and the wet performance can be maintained for a long time.
[0082]
Next, the effect | action regarding on-snow performance is demonstrated.
[0083]
In the pneumatic tire 10 of the present embodiment, since the center blocks 18 are arranged in a line on the tire equatorial plane CL of the tread 12, the block edge component of the tread center portion is ensured and the performance on snow is improved.
[0084]
Since the tread 12 is provided with five block rows, cornering performance on snow can be improved.
[0085]
The center block 18, the first second block 26, the second second block 28, and the shoulder block 30 are formed with a plurality of sipes 32 extending zigzag along the tire width direction, and the tread pattern is directional. Since it is a pattern, it is possible to achieve both the basic performance of traction, braking, and feeling on snow and drainage performance on a wet road surface (details will be described later).
[0086]
Since the first inclined groove 20, the second inclined groove 22, and the branch grooves 24 and 25 form a zigzag groove and the block edge component increases, the performance on snow can be improved.
[0087]
Further, by setting the angle of the branch grooves 24 and 25 with respect to the tire width direction to 20 ° or less, it is possible to improve braking performance, traction performance, and feeling on snow.
[0088]
Next, the effect | action regarding wet performance is demonstrated.
[0089]
The water in the ground contact surface when traveling on a wet road surface is out of the ground contact surface via the circumferential main groove 14, the lateral groove 16, the first inclined groove 20, the second inclined groove 22, and the branch grooves 24 and 25. Discharged.
[0090]
In the circumferential main groove 14, since the groove wall on the tire equatorial plane CL side is linear in the tire circumferential direction, the water in the groove can flow smoothly in the circumferential direction.
[0091]
Moreover, since the groove width of the connection part with the 1st inclination groove | channel 20 set the circumferential direction main groove 14 wider than the other part in the circumferential direction main groove 14, the water in the circumferential direction main groove 14 is made into the 1st. It is possible to flow smoothly and efficiently through the one inclined groove 20 toward the tread end 12E.
[0092]
In addition, the pair of circumferential main grooves 14 diverts the water interposed between the road surface on the wet road surface and the tread 12 to the left and right.
[0093]
The first inclined groove 20 and the second inclined groove 22 provided on the tread end 12E side with respect to the circumferential main groove 14 extend from the circumferential main groove 14 toward the tread end 12E, and the circumferential main groove 14 side is on the side. The tire is inclined so as to be on the tire rotation direction side with respect to the tread end 12E side, and the angle with respect to the tire circumferential direction increases from the circumferential main groove 14 side toward the tread end 12E side. Therefore, the water in the vicinity of the tread center can be smoothly and efficiently discharged from the circumferential main groove 14 to the outside of the tread end 12E.
[0094]
Further, since the first inclined groove 20 and the second inclined groove 22 are connected by the branch grooves 24 and 25 as described above, the water flowing through the branch groove 24 is discharged from the outer edge of the first inclined groove 20 in the tire width direction. Thus, the water that has flowed through the branch groove 25 can be smoothly discharged to the outside of the tread end via the outer end of the second inclined groove 22 in the tire width direction.
[0095]
Next, the effect | action regarding dry performance is demonstrated.
[0096]
Since the center blocks 18 form a line on the tire equatorial plane CL, the ground contact area near the tire equatorial plane CL may be increased as compared with the conventional tire in which the circumferential main groove is arranged on the tire equatorial plane CL. High grip on dry road surfaces, and high grip on low mu (μ) road surfaces.
[0097]
Furthermore, in the pneumatic tire 10 of the present embodiment, the negative rate of the entire tread 12 is set within a range of 32 to 45%, so that a balanced balance of dry performance, wet performance, and on-snow performance is achieved in a balanced manner. Can do.
[0098]
Further, since the pattern of the tread 12 is a directional pattern and is connected by the first inclined groove 20, the second inclined groove 22, and the branch groove 24 or the branch groove 25, the negative rate of the tread central region 12C is set to tread 12. It can compensate for the decrease in drainage and performance on the snow due to setting it lower than the overall negative rate.
[0099]
Further, the corner portion on the rotation direction side (stepping side) of the first second block 26 sandwiched between the circumferential main groove 14 and the first inclined groove 20 is formed at an acute angle (when the tread 12 is viewed in plan). However, since the chamfer 26A is formed in the vicinity of the corner, a decrease in block rigidity is suppressed.
[0100]
Further, the corner portion on the rotation direction side (stepping side) of the second second block 28 sandwiched between the circumferential main groove 14 and the second inclined groove 22 faces the narrow portion 22A having a small angle with respect to the tire width direction. In addition, since it is formed at an obtuse angle (when the tread 12 is viewed in plan), a decrease in block rigidity is suppressed.
[0101]
Therefore, in the pneumatic tire 10 of the present embodiment, it is possible to achieve a multi-dimensional trade-off between on-snow performance, drainage performance, and wear in the tread central region.
[0102]
In addition, wet performance and on-ice performance are also improved by the edge component of the sipe 32 formed in each block.
(Test example)
In order to confirm the effect of the present invention, a pneumatic tire of a conventional example and a pneumatic tire of an example to which the present invention is applied are prepared, and snow feeling, snow braking performance, snow traction performance, wet hydroplaning performance, and The center wear performance was compared.
[0103]
The pneumatic tire of the example is the pneumatic tire described in the above embodiment, and the pneumatic tire of the conventional example is a pneumatic tire having the pattern shown in FIG.
[0104]
Here, in the conventional pneumatic tire shown in FIG. 2, reference numeral 100 denotes a tread end, 100C denotes a tread central region, 100S denotes a tread side region, and W denotes a contact width.
[0105]
The tire size is PSR195 / 65R15 for all tires.
[0106]
The test method and evaluation will be briefly described below.
-Feeling performance on snow: Comprehensive evaluation of braking performance, startability and cornering performance (by test driver) on a test course on a snowy road surface. The evaluation is represented by an index with the conventional feeling as 100, and the larger the value, the better the feeling on snow.
・ Brake performance on snow: Measures braking distance when full braking is performed from 40km / h on snow. The evaluation is represented by an index in which the reciprocal of the braking distance of the conventional example is 100, and the larger the value, the better the snow braking performance.
-Snow traction performance: Measures acceleration time from start at a distance of 50m above snow. The evaluation is represented by an index with the reciprocal of the acceleration time of the conventional example as 100, and the larger the value, the better the traction performance on snow.
-Wet hydroplaning performance: Feeling evaluation of the critical speed of hydroplaning when passing through a wet road surface with a water depth of 5 mm.
Center wear performance: The difference in wear amount between the tread center region and the tread side region after traveling 10,000 km on a general road was measured.
[0107]
[Table 1]

From the test results, it can be seen that the pneumatic tires of the examples to which the present invention is applied are all improved in performance compared to the conventional pneumatic tires.
[0108]
【The invention's effect】
  As described above, since the pneumatic tire according to claim 1 has the above-described configuration, it has an excellent effect that drainage performance and performance on snow can be improved and wear of the center portion of the tread can be suppressed. Moreover, since the wear of the center portion of the tread can be suppressed, the drainage and the performance on snow can be maintained for a long time.Moreover, it has the outstanding effect that dry performance, wet performance, and on-snow performance are compatible.
[0109]
Since the pneumatic tire according to claim 2 has the above configuration, it has an excellent effect that the wet performance can be further improved.
[0110]
Since the pneumatic tire according to claim 3 has the above configuration, it has an excellent effect that the wet performance can be further improved.
[0111]
Since the pneumatic tire according to claim 4 has the above-described configuration, it has an excellent effect that the braking performance on snow, the traction performance, and the feeling can be improved.
[Brief description of the drawings]
FIG. 1 is a plan view of a tread of a pneumatic tire according to an embodiment of the present invention.
FIG. 2 is a plan view of a tread of a conventional pneumatic tire.
[Explanation of symbols]
10 Pneumatic tire
CL tire equator
12 tread
14 Circumferential main groove
16 Horizontal groove
18 Center block
20 First inclined groove
22 Second inclined groove
22A narrow part
24 branch groove
25 branch groove
26 First second block
28 Second second block
30 shoulder block
32 Sipe

Claims (4)

A pair of circumferential main grooves disposed on both sides of the tire equatorial plane and extending in the tire circumferential direction; a plurality of circumferential main grooves disposed in the tire circumferential direction with one circumferential main groove and the other circumferential main groove sandwiching the tire equatorial plane; A plurality of transverse grooves that are connected in the tire circumferential direction, extending from the circumferential main groove toward the tread end, and inclined so that the circumferential main groove side is closer to the tire rotation direction side than the tread end side, The tread includes a plurality of blocks defined by inclined grooves whose angle with respect to the direction increases from the circumferential main groove side toward the tread end side, and a block row in which the blocks are arranged along the tire circumferential direction A pneumatic tire having a plurality of rows and a sipe extending in the tire width direction on the block,
The negative rate of the entire tread is set within the range of 32-45%,
The negative rate of the tread central region which is the central region when the ground contact region of the tread is equally divided into three in the tire width direction is set to be smaller than the negative rate of the entire tread,
The inclined groove includes a first inclined groove whose groove width is substantially constant and an angle with respect to the tire circumferential direction at the end on the circumferential main groove side is set to 40 ° or less, and an end portion on the circumferential main groove side And a second inclined groove having a narrow portion that is narrower than the tread end side and has an angle with respect to the tire width direction set to 30 ° or less,
An intermediate portion between the circumferential main groove and the tread end in the first inclined groove, a narrow portion in the second inclined groove adjacent to the first inclined groove, and the tread end. The middle part between them is connected by a branch groove,
In the circumferential main groove, the groove wall on the tire equatorial plane side extends linearly in the tire circumferential direction, and the groove width of the circumferential main groove at the connection portion with the first inclined groove is the circumferential direction. A pneumatic tire characterized by being set wider than other portions other than the connection portion in the main groove. 2. The pneumatic tire according to claim 1, wherein an outer end in the tire width direction of the second inclined groove is disposed on an extension line on the outer side in the tire width direction of the branch groove. 3. The pneumatic tire according to claim 2 , wherein an outer end in the tire width direction of the branch groove is disposed closer to a tread end side than a central portion in the tire width direction of the second inclined groove.   The pneumatic tire according to any one of claims 1 to 3, wherein the branch groove has an angle with respect to a tire width direction set to 20 ° or less.

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