JP2013166455A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire in which occurrence of uneven wear can be fully suppressed.SOLUTION: There is provided a pneumatic tire in which at least one main groove extending in a tire circumferential direction and a plurality of lateral grooves extending in a tire width direction between the main groove and a tread end are arranged on a tread surface of a tread section positioned between both tread ends, and a shoulder block land arrays comprising a plurality of shoulder block land sections are defined and formed between the main groove and the tread end. The pneumatic tire is characterized in that: in at least a part of the shoulder block land section, such a reduced width part is formed that a tire circumferential average dimension of a tire diameter-direction outer part positioned in a range from a shoulder block land section tread surface to 1/3 of a height of the shoulder block land section in a tire circumferential direction cross sectional view, is larger than a tire circumferential direction average dimension of a tire radial direction inner part positioned in a tire diameter-inner side than the tire diameter-direction outer part.

Description

  The present invention relates to a pneumatic tire, and particularly to a pneumatic tire excellent in uneven wear resistance.

  Generally, in a pneumatic tire such as a tire for a passenger car, a tread portion is formed with a smooth curved surface that protrudes outward in the tire radial direction. That is, in the pneumatic tire, the outer diameter of the tire at the center of the tread portion is larger than the outer diameter of the tire in the tread portion side region (shoulder portion), and a diameter difference occurs in the tire width direction.

  Therefore, in a pneumatic tire having a diameter difference in the tire width direction, the rubber of the shoulder portion is dragged against the road surface when the tire rolls, so that the rubber of the shoulder portion receives a large shearing force and compared with the center of the tread portion. Parts wear out early (uneven wear). As a result of the occurrence of uneven wear, the tire life is reduced. Such uneven wear of the shoulder portion (sometimes referred to as “shoulder fall wear” or “half-removed wear”) has a high rigidity in the sidewall portion and generates a large braking force near the ground contact end. This is particularly likely to occur in low-flat tires and run-flat tires that are easily damaged. In addition, uneven wear of the shoulder portion can occur when a negative camber is applied and the tire is mounted on a vehicle and the ground contact edge is positioned outside the belt crossing layer of the tire in the width direction of the tire, or a wide lateral groove (tire It is also likely to occur when a large number of (widthwise grooves) are provided to improve drainage performance, ice / snow performance, and the like.

  Here, with respect to the problem of uneven wear of the shoulder portion as described above, as a pneumatic tire that can suppress the occurrence of uneven wear, a rib-like land portion (hereinafter referred to as “shoulder rib”) located in the shoulder portion. In addition, a tire has been proposed in which a plurality of sipes extending in the tire width direction and convex portions that are formed at predetermined intervals in the tire circumferential direction and project outward in the tire radial direction are disposed (for example, Patent Document 1). Further, according to this pneumatic tire, the rigidity of the shoulder rib in the tire circumferential direction can be reduced by arranging a plurality of sipes, so that the followability of the rubber of the shoulder rib is improved, and uneven wear is generated. Can be suppressed.

  In addition, as another pneumatic tire capable of suppressing the occurrence of uneven wear, a pneumatic tire in which a tread portion tread has a block land portion having recesses with substantially circular cross sections in the tire circumferential direction on the groove wall surfaces on both sides of the tire circumferential direction. Tires have also been proposed (see, for example, Patent Documents 2 and 3). According to this pneumatic tire, the block land portion is easily compressed and deformed at the time of tire contact, so that the shear force generated on the contact surface of the block land portion located at the shoulder portion is reduced to suppress the occurrence of uneven wear. Can do.

Japanese Unexamined Patent Publication No. 5-201205 JP 2001-10309 A JP 2006-51927 A

  However, the conventional pneumatic tire described above in which a plurality of sipes and convex portions are disposed on the shoulder rib, and the conventional air in which block land portions having recesses on the groove wall surfaces on both sides in the tire circumferential direction are formed on the tread portion tread surface. In the entering tire, the occurrence of uneven wear could not be sufficiently suppressed.

  Then, an object of this invention is to provide the pneumatic tire which can fully suppress generation | occurrence | production of uneven wear.

An object of the present invention is to advantageously solve the above-described problems, and the pneumatic tire according to the present invention has at least one main tire extending in the tire circumferential direction on a tread portion tread located between both tread ends. A plurality of lateral grooves extending in the tire width direction between the groove and the main groove and the tread end, and a shoulder block land portion row formed of a plurality of shoulder block land portions is connected to the main groove and the tread end. A pneumatic tire that is partitioned between the shoulder block land portion and at least a portion of the shoulder block land portion from the tread of the shoulder block land portion to 1/3 of the shoulder block land portion height. The tire radial direction average dimension of the tire radial outer portion located in the range is flat in the tire circumferential direction of the tire radial inner portion located inward of the tire radial direction from the tire radial outer portion. Characterized in that the formation of the reduced width portion is larger than the dimension. Thus, if the reduced width portion is formed in the shoulder block land portion where the average size in the tire circumferential direction of the tire radial direction outer portion in the tire circumferential direction sectional view is larger than the average size in the tire circumferential direction of the tire radial direction inner portion. The shear rigidity in the reduced width portion of the shoulder block land portion decreases at the inner portion in the tire radial direction and increases at the outer portion in the tire radial direction. Therefore, even if the shoulder block land portion is dragged with respect to the road surface when the tire rolls, shear deformation on the tread surface (grounding surface) side of the reduced width portion formed on the shoulder block land portion is reduced, and the reduced width portion is Early wear can be suppressed. That is, it is possible to prevent the shoulder block land portion row located in the side region (shoulder portion) of the tread portion from being worn at an early stage and causing uneven wear (one-sided wear) on the tire.
In the present invention, “extending in the tire circumferential direction” means extending in the tire circumferential direction, and “extending in the tire circumferential direction” is inclined with respect to a direction parallel to the tire circumferential direction. The case of extending is also included. Further, “extending in the tire width direction” means extending in the tire width direction, and “extending in the tire width direction” includes a case of extending in a direction parallel to the tire width direction. It is. Further, the “average size in the tire circumferential direction” refers to a value obtained by dividing the cross-sectional area in the tire circumferential cross section by the height of each portion for each of the tire radial direction outer portion and the tire radial direction inner portion. That is, the “average dimension in the tire circumferential direction of the tire radial direction outer portion” means the cross-sectional area of the tire radial direction outer portion in the tire circumferential cross section, the height of the tire radial direction outer portion (the height of the shoulder block land portion). The value divided by 1/3). Further, the “average tire circumferential direction dimension of the tire radial inner portion” means the cross-sectional area of the tire radial inner portion in the tire circumferential cross section, the height of the tire radial inner portion (the height of the shoulder block land portion). The value divided by 2/3).

  Here, in the pneumatic tire according to the present invention, the size of the reduced width portion in the tire circumferential direction is the same or less in the tire circumferential direction cross-sectional view from the reduced width portion tread side toward the inner side in the tire radial direction. Preferably it is. If the size in the tire circumferential direction at an arbitrary position in the tire radial direction of the reduced width portion is set to be equal to or less than the size in the tire circumferential direction of the portion located on the outer side in the tire radial direction from the position, the reduced width portion of the shoulder block land portion is This is because the shear deformation on the reduced width portion tread surface (grounding surface) side in the formed portion can be reliably reduced to sufficiently suppress the occurrence of uneven wear on the tire.

In the pneumatic tire of the present invention, the grounding end of the tire is attached to the outer rim of the reduced width portion and the tire under a grounding condition in which the tire is mounted on an applied rim and a predetermined internal pressure and a predetermined load are applied. It is preferably located between the inner end in the width direction. The ground contact end of the tire is located between the outer end in the tire width direction and the inner end in the tire width direction of the reduced width portion, that is, the reduced width portion exceeds the contact end from the inner side in the tire width direction toward the outer side in the tire width direction. If it extends, the tread part will wear due to the use of the tire, and the occurrence of uneven wear will be effectively suppressed even when the position of the ground contact edge moves to the outside in the tire width direction from the beginning of use of the tire. Because you can.
In the present invention, the “applicable rim” is an industrial standard effective in the area where tires are produced and used. In Japan, JATMA (Japan Automobile Tire Association) YEAR BOOK is used. In Europe, ETRTO (European Tire and Rim Technical Organization (STANDARD MANUAL) In the United States, it refers to the rim defined by TRA (THE TIRE and RIM ASSOCIATION INC.) YEAR BOOK, etc. “Grounding conditions with tires attached to the applicable rim and applying the specified internal pressure and load” means that the tire is attached to the applicable rim and conforms to the maximum tire load capacity of standards such as JATMA for applicable size tires. The air pressure (maximum air pressure) to be applied, and 75% of the maximum tire load capacity of the standard such as JATMA is applied to indicate a grounded state. Further, the “grounding end” refers to a grounding end when an unused tire is grounded.

  In the pneumatic tire of the present invention, the mounting direction with respect to the vehicle is specified, and the reduced width portion is a shoulder block land portion that constitutes a shoulder block land portion row located inside the vehicle when the tire is mounted on the vehicle. Preferably it is formed. If the shoulder block land portion constituting the shoulder block land portion row located inside the vehicle is formed with a reduced width portion, the shoulder located inside the vehicle is particularly easily worn when a tire is attached to the vehicle with a negative camber. This is because early wear of the block land portion rows can be suppressed and occurrence of uneven wear can be suppressed.

  According to the pneumatic tire of the present invention, occurrence of uneven wear can be sufficiently suppressed.

FIG. 3 is a development view of a part of a tread portion of a typical pneumatic tire according to the present invention. It is sectional drawing which follows the II line | wire of FIG. (A)-(c) is a figure which shows the cross section in the same position as the II line | wire of FIG. 1 about the shoulder block land part of the other pneumatic tire according to this invention. It is a top view which shows the shape of the shoulder block land part of another pneumatic tire according to this invention.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a development view of a part of the tread portion of an example of the pneumatic tire of the present invention. The pneumatic tire is a tire that is designated using a means whose mounting direction with respect to the vehicle is known, and is mounted on the vehicle such that the right side is located inside the vehicle in FIG.

Here, the pneumatic tire shown in FIG. 1 has a plurality of (four in FIG. 1) main grooves 2 extending linearly along the tire circumferential direction on the tread portion tread surface 1 located between the tread ends TE. And a plurality of lateral grooves 3 extending along the tire width direction are disposed between the main groove 2 and the tread end TE. In this pneumatic tire, a shoulder block land portion row composed of a plurality of shoulder block land portions 4 defined by the main groove 2, the tread end TE, and the lateral groove 3 in the side regions (shoulder portions) of both tread portions. 5 is disposed.
In addition, a total of three block land portion rows 7 and 9 are also arranged in the central region of the tread portion of the pneumatic tire. Specifically, the two main grooves 2 and 2 and the main grooves 2 and 2 are inclined toward the upper left direction in FIG. A block land portion row 7 composed of a plurality of block land portions defined by a plurality of extending inclined grooves 6 is disposed. Further, in the central portion of the tread central region, there are two main grooves 2 and 2 and a plurality of main grooves 2 and 2 extending obliquely toward the upper right direction in FIG. 1 with respect to the tire width direction. A block land portion row 9 made up of a plurality of block land portions partitioned by the inclined grooves 8 is disposed.

  In this pneumatic tire, a part of the quadrangular shoulder block land portion 4 formed between the main groove 2 located on the outermost side in the tire width direction and the tread end TE (enclosed by a broken line in FIG. 1). A reduced width portion 41 is formed in the portion. That is, a part of the shoulder block land portion 4 on the tread end TE side is 1 in height of the shoulder block land portion 4 from the tread surface (surface on the outer side in the tire radial direction) of the shoulder block land portion 4 in the tire circumferential cross-sectional view. Tire in the tire radial inner portion where the tire circumferential direction average dimension of the tire radial outer portion located in the range of up to / 3 is located inward of the tire radial direction of the shoulder block land portion 4 in the tire radial direction. The reduced diameter portion 41 is larger than the average dimension in the circumferential direction.

  Specifically, in the pneumatic tire shown in FIG. 1, as shown in FIG. 2, the tire in the portion where the reduced width portion 41 of the shoulder block land portion 4 is formed as shown in FIG. 2. The circumferential cross section has an isosceles trapezoidal shape in which the lower base is shorter than the upper base. That is, the dimension W in the tire circumferential direction of the reduced width portion 41 gradually decreases from the tread surface side of the shoulder block land portion 4 toward the inner side in the tire radial direction. The reduced width portion 41 has a plane-symmetric shape with a plane passing through the center in the tire circumferential direction of the shoulder block land portion 4 as a plane of symmetry.

  In other words, in the pneumatic tire shown in FIG. 1, the tire circumferential direction cross section of the lateral groove 3 in the portion where the reduced width portion 41 is formed has an isosceles trapezoidal shape whose lower bottom is longer than the upper bottom, The width in the tire circumferential direction of the lateral groove 3 gradually increases from the opening side of the lateral groove 3 toward the groove bottom side.

In this pneumatic tire, in the portion where the reduced width portion 41 is formed, the outer portion in the tire radial direction of the shoulder block land portion 4 (the portion from the tread to 1/3 of the height H of the shoulder block land portion 4). ) Is the tire circumferential direction of the tire radial direction inner portion of the shoulder block land portion 4 (the portion from the groove bottom position of the lateral groove 3 to 2/3 of the height H of the shoulder block land portion 4). Therefore, the shear rigidity in the tire circumferential direction of the reduced width portion 41 is reduced at the inner portion in the narrow tire radial direction, and is increased at the outer portion in the wide tire width direction. Therefore, even if the shoulder block land portion 4 is dragged with respect to the road surface due to the difference in diameter between the center C of the tread portion and the shoulder portion when the tire rolls, the tread (landing surface) in the reduced width portion 41 The shear deformation in the tire circumferential direction on the side can be reduced. Therefore, it is possible to prevent the portion where the reduced width portion 41 of the shoulder block land portion 4 is formed from being worn at an early stage, so that the shoulder block land portion row 5 located in the shoulder portion is worn early and becomes a tire. It is possible to suppress the occurrence of uneven wear (half wear). And since generation | occurrence | production of uneven wear can be suppressed, it can suppress that a tire life falls.
Here, in the pneumatic tire of the present invention, the tire radial direction outer portion which is a portion from the tread surface to 1/3 of the height H of the shoulder block land portion 4, and the tire radial inner side than the tire radial outer portion. The average value of the tire circumferential dimension was compared with the tire radial inner portion located in the area of the tire radial direction as the difference in shear rigidity between the tire radial outer portion and the tire radial inner portion located in the above range was larger. This is because the shear deformation in the tire circumferential direction on the tread surface side (contact surface) can be reduced. Further, when the outer portion in the tire radial direction is a portion less than 1/3 of the height H from the tread surface, the thickness of the outer portion in the tire radial direction is reduced, and the effect of suppressing the occurrence of uneven wear is obtained at the initial stage of wear. Because it will disappear.

  In this pneumatic tire, the tire circumferential direction dimension W of the reduced width portion 41 formed in the shoulder block land portion 4 is within the tire radial direction from the tread side of the reduced width portion 41 in the tire circumferential cross-sectional view. The size in the tire circumferential direction at an arbitrary position in the tire radial direction of the reduced width portion is set to be equal to or less than the size in the tire circumferential direction of the portion located on the outer side in the tire radial direction than the position. . Therefore, it is possible to reliably reduce shear deformation on the tread surface (grounding surface) side in the reduced width portion 41 and sufficiently suppress occurrence of uneven wear on the tire.

  In addition, in this pneumatic tire, the occurrence of uneven wear is suppressed by changing the size of the shoulder block land portion 4 in the tire circumferential direction, and compared with a conventional pneumatic tire or the like in which a sipe is provided on the shoulder rib. And since the groove | channel volume of the horizontal groove 3 can fully be ensured, sufficient drainage can be ensured. Accordingly, it is possible to prevent a decrease in steering stability on a wet road surface or the like.

  Here, in the pneumatic tire according to the present invention as shown in FIG. 1, the ground contact end E of the tire is connected to the reduced width portion 41 under a ground contact condition in which the tire is mounted on an applied rim and a predetermined internal pressure and a predetermined load are applied. It is preferable to be located between the outer end in the tire width direction and the inner end in the tire width direction. If the reduced width portion 41 extends beyond the ground contact end E from the inner side in the tire width direction toward the outer side in the tire width direction, the reduced width portion also extends outward in the tire width direction from the position where the ground contact pressure of the tire becomes maximum. 41 is formed, and it is possible to suppress early wear of a slippery portion (that is, a portion where wear is large) with a low ground pressure and effectively suppress the occurrence of uneven wear. From the viewpoint that the compression rigidity of the portion where the reduced width portion 41 is formed is reduced, it is preferable that the reduced width portion 41 is provided only on the outer side in the tire width direction than the position where the ground contact pressure of the tire is maximized.

  In the pneumatic tire shown in FIG. 1, the tire circumferential dimension on the tread surface of the reduced width portion 41 is the bottom of the reduced width portion 41 (the same tire radial direction as the groove bottom position of the lateral groove 3). It is preferable that it is 1.1 times or more and 2.0 times or less of the tire circumferential direction dimension at the position). If the tire circumferential dimension on the tread is 1.1 times or more of the tire circumferential dimension on the bottom, uneven wear can be effectively suppressed, and if it is 2.0 or less, the durability of the reduced width portion 41 is achieved. It is because it can suppress that falls.

  Here, in the pneumatic tire of the above example, the reduced width portion 41 is formed on all the shoulder block land portions 4 located on both outer sides in the tire width direction. However, in the pneumatic tire of the present invention, some shoulder block land portions are formed. You may form a reduced width part only in a part. Further, the reduced width portion may be formed over the entire tire width direction of the shoulder block land portion. Further, the reduced width portion may be formed only in the shoulder block land portion constituting the shoulder block land portion row located on the vehicle inner side (right side in FIG. 1) when the tire is mounted on the vehicle. Note that when the tire is mounted with a negative camber angle of 3 °, for example, the shoulder block moves to the inside of the vehicle and the shoulder block moves to the inside of the vehicle compared to the case where the negative camber angle is not applied. The ground pressure of the land part 4 increases. Therefore, when the tire is fitted with a negative camber, it is preferable that the reduced width portion is formed at least in the shoulder block land portion located inside the vehicle.

  Further, in the pneumatic tire of the present invention, the shape of the reduced width portion is such that the average dimension in the tire circumferential direction of the outer portion in the tire radial direction is the average dimension in the tire circumferential direction of the inner portion in the tire radial direction in the tire circumferential cross-sectional view. It can be appropriately changed within a range that becomes larger than the above. Specifically, the tire circumferential direction cross-sectional shape of the portion where the reduced width portion of the shoulder block land portion is formed can be a shape as shown in FIGS.

A reduced width portion 41A showing a tire circumferential cross section in FIG. 3 (a) is a gently inclined portion in which the tire circumferential dimension gradually decreases at a first rate from the tread surface (contact surface) side toward the tire radial direction inner side, The tire circumferential direction dimension is composed of a steeply inclined portion that gradually decreases at a second rate larger than the first rate, and a straight body portion where the tire circumferential direction size is constant. That is, the reduced width portion 41A includes a gently inclined portion in which an angle formed between a plane parallel to the tread and the groove wall is a first angle from the tread side toward the inner side in the tire radial direction, and a plane and groove parallel to the tread. A steeply inclined portion having a second angle smaller than the first angle formed by the wall and a straight body portion having an angle formed by a plane parallel to the tread surface and the groove wall of 90 ° are sequentially arranged. It becomes. And in the pneumatic tire which formed this reduced width part 41A in the shoulder block land part 4, the load distribution of the shear strain in the reduced width part 41A is changed smoothly in the tire radial direction, and the durability of the reduced width part 41A decreases. Can be suppressed. Further, the concentration of shear strain on the tread surface side can be suppressed.
In addition, from the viewpoint of further suppressing a decrease in durability of the reduced width portion, the groove walls on both sides in the tire circumferential direction of the reduced width portion may draw a smooth curve in the cross section in the tire circumferential direction. That is, for example, the groove wall of the gently inclined portion or the steeply inclined portion may draw a smooth curve in the tire circumferential cross section.
Incidentally, when the ratio of the reduction in the tire circumferential dimension of the reduced width portion is changed in the tire radial direction as in the reduced width portion 41A shown in FIG. 3A, the ratio of the reduction in the tire circumferential dimension is different. It is preferable that the groove walls are connected by drawing a smooth curved surface. This is because cracks and the like are unlikely to occur in the portion where the ratio of the decrease in the tire circumferential dimension changes when the groove walls of the portions where the ratio of the decrease in the tire circumferential dimension decreases form a smooth curve.

  Further, the reduced width portion 41B, which shows a tire circumferential cross section in FIG. 3B, is located on the tread surface side and has a first tire circumferential dimension, and is located on the inner side in the tire radial direction than the wide width portion. And a narrow width portion having a second tire circumferential dimension smaller than the first tire circumferential dimension. And in the pneumatic tire which formed this reduced width part 41B in the shoulder block land part 4, transmission of the shear strain to the tread side can be decreased.

  Further, the reduced width portion 41C showing the tire circumferential cross section in FIG. 3C is located on the tread surface side, and has a wide width portion having a first tire circumferential dimension and a smaller width than the first tire circumferential dimension. An uneven portion formed by alternately arranging narrow portions having a tire circumferential dimension in the tire radial direction, and a second tire circumferential dimension located on the inner side in the tire radial direction from the uneven portion. And a straight body portion having

  Further, in the pneumatic tire shown in FIG. 1, the shape of the shoulder block land portion 4 in plan view is rectangular, but in the pneumatic tire of the present invention, the shape of the shoulder block land portion in plan view is as shown in FIG. It can also be a shape. Specifically, with respect to the portion where the reduced width portion 41 ′ of the shoulder block land portion 4 ′ is formed, the tire circumferential direction dimension on the tread surface side is the portion of the portion where the reduced width portion 41 ′ of the shoulder block land portion 4 ′ is not formed. It can also be larger than the tire circumferential dimension. Thus, the enlarged portion 42 having a large tire circumferential dimension of the tread surface is formed on the tread end TE side of the shoulder block land portion 4 ′, and the tire circumferential dimension of the tread surface of the portion where the reduced width portion 41 ′ is formed is increased. For example, the groove volume is made large enough to ensure drainage, while compressive rigidity is secured on the inner side in the tire width direction with high contact pressure to support the load, while circumferential shear deformation is applied on the outer side in the tire width direction with low contact pressure. This is because it can be reduced.

  As mentioned above, although embodiment of this invention was described with reference to drawings, the pneumatic tire of this invention is not limited to the example mentioned above, A change can be suitably added to the pneumatic tire of this invention. .

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to the following Example at all.

Example 1
4 except that the shape of the shoulder block land portion is the shape shown in FIG. 4, and the tread portion tread has the same shape as the tread portion tread shown in FIG. 1, and the tire circumferential cross-sectional shape as shown in FIG. A pneumatic tire (size: 195 / 65R15) in which the width portion is formed in the shoulder block land portion was prototyped according to the specifications shown in Table 1. And performance evaluation was performed by the following method. The results are shown in Table 1.

(Examples 2-3)
A pneumatic tire was prepared in the same manner as in Example 1 except that the cross-sectional shape in the tire circumferential direction of the reduced width portion was changed as shown in FIGS. 3A to 3B and the specifications were shown in Table 1. Prototype. And performance evaluation was performed like Example 1. FIG. The results are shown in Table 1.

(Comparative Example 1)
A pneumatic tire was prototyped in the same manner as in Example 1 except that the reduced width portion was not formed and the tire circumferential direction dimension of the shoulder block land portion was not changed with respect to the tire radial direction. And performance evaluation was performed like Example 1. FIG. The results are shown in Table 1.

<Evaluation of wear ratio>
The prepared tire was mounted on a rim having a rim size of 15 × 6 J, the internal pressure was set to 230 kPa, and the test tire was mounted at a negative camber angle of 1 °. Thereafter, the test course was run for 10,000 km, and the amount of wear at the center of the tread portion and the amount of wear in the side region of the tread portion (shoulder portion) located inside the vehicle were measured. Then, the ratio of the wear amount of the shoulder portion to the wear amount at the center of the tread portion was calculated. In the table, the smaller the ratio of the wear amount of the shoulder portion to the wear amount at the center of the tread portion, the better the uneven wear resistance.
<Drainage>
The prepared tire was mounted on a rim having a rim size of 15 × 6 J, and the internal pressure was set to 230 kPa and mounted on a test vehicle. Next, after the tire is worn until the amount of wear in the tread reaches 50%, an acceleration test is performed from a speed of 50 km / h on a test course at a depth of 10.0 mm, and the speed at which hydroplaning occurs (hydroplaning generation speed) ) Was measured. The index was evaluated with the hydroplaning generation speed of the tire of Comparative Example 1 as 100. In the table, the larger the index, the greater the hydroplaning generation rate and the better the drainage.

  From Table 1, it can be seen that the tires of Examples 1 to 3 have a smaller wear amount difference between the center of the tread portion and the shoulder portion and a smaller wear amount ratio than the tire of Comparative Example 1. Therefore, in the tires of Examples 1 to 3, it can be seen that the occurrence of uneven wear can be suppressed and the decrease in tire life can be suppressed. Moreover, it turns out that the tire of Examples 1-3 is excellent in drainage.

  According to the present invention, it is possible to provide a pneumatic tire that can sufficiently suppress the occurrence of uneven wear.

DESCRIPTION OF SYMBOLS 1 Tread part tread 2 Main groove 3 Horizontal groove 4, 4 'Shoulder block land part 5 Shoulder block land part row 6 Inclined groove 7 Block land part row 8 Inclined groove 9 Block land part row 41, 41A, 41B, 41C Reduced width part 42 Enlarged part

Claims (4)

At least one main groove extending in the tire circumferential direction and a plurality of lateral grooves extending in the tire width direction between the main groove and the tread end are disposed on the tread portion tread located between both tread ends, A pneumatic tire in which a shoulder block land portion row composed of a plurality of shoulder block land portions is partitioned between the main groove and the tread end,
The tire circumferential direction of the tire radial direction outer part located in the range from a shoulder block land part tread to 1/3 of a shoulder block land part height in the tire circumferential direction sectional view at least in a part of the shoulder block land part The pneumatic tire is characterized in that a reduced width portion is formed in which the average dimension of the tire is larger than the average dimension in the tire circumferential direction of the tire radial inner portion located inward of the tire radial direction than the tire radial outer portion. tire.   The dimension of the tire circumferential direction of the reduced width portion is the same or less as viewed from the tread surface side of the reduced width portion toward the inner side in the tire radial direction in a sectional view in the tire circumferential direction. The described pneumatic tire. Mount the tire on the applicable rim and apply the specified internal pressure and load to the grounding condition.
The pneumatic tire according to claim 1, wherein a ground contact end of the tire is located between a tire width direction outer end and a tire width direction inner end of the reduced width portion. The mounting direction for the vehicle is specified,
The said reduced width part is formed in the shoulder block land part which comprises the shoulder block land part row | line | column located inside a vehicle at the time of tire mounting to a vehicle, The one in any one of Claims 1-3 characterized by the above-mentioned. Pneumatic tires.

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