JP4461746B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire. In particular, the present invention relates to a pneumatic tire capable of improving uneven wear resistance while exhibiting high turning performance even when traveling under high severity conditions.

  A conventional pneumatic tire has a plurality of grooves formed in the tread portion, for example, in order to improve steering stability during rainy weather traveling. However, the block portion surrounded by the grooves is deformed obliquely with respect to the road surface during cornering. For this reason, only the tread end side tread of the tread edge side of the block portion comes into contact with the road surface, and the contact pressure of this portion increases, so the tread surface on the equator line side of the pneumatic tire of the same block portion floats. . When running in such a situation, the grounded tread surface, that is, the tread end tread only, wears out, and there is a step between the tread end side and the equatorial line side of the same tread surface. And uneven wear occurs. When uneven wear occurs in this way, the contact pressure differs between the worn part and the unworn part of the tread, and the entire tread cannot be used as an effective ground contact area. Steering stability such as turning performance due to the grip force will decrease. Further, the portion remaining due to uneven wear also caused deterioration of pattern noise.

  Therefore, there is a chamfer formed at an edge portion around the block portion, that is, a portion where the tread surface and the groove intersect (see, for example, Patent Document 1). By forming chamfers in this way, even if the block part is deformed during cornering, the crest part on the tread end side is provided, so the ground pressure on the tread end side tread does not increase, and the same block part Since the tread on the equator line side is also grounded, uneven wear can be prevented.

JP-A-2-179508

  However, at the time of high severity such as during circuit running, the force in the lateral direction on the tread surface, that is, the input in the tire width direction increases, and there is a tendency for uneven wear to increase. In order to prevent uneven wear when the input in the tire width direction is large in this way, it is effective to increase the chamfering of the edge part, but when the chamfering is increased, the area of the tread decreases. End up. When the area of the tread surface decreases, the frictional force between the tread surface and the road surface decreases, and steering stability such as turning performance decreases.

  Then, this invention is made | formed in view of the above, Comprising: While improving turning performance, it aims at providing the pneumatic tire which can improve uneven wear resistance.

In order to solve the above-described problems and achieve the object, a pneumatic tire according to the present invention is a pneumatic tire having a block portion defined by a groove formed in a tread portion, the wall surface of the groove and the tread. A chamfer is formed at a portion where the tread surface of the portion intersects, and the chamfer is formed on the tread end direction wall surface of the groove and the chamfered portion at a portion where the equatorial line wall surface of the groove and the tread surface intersect. The feature is that the chamfered portion of the portion where the tread surface intersects is formed larger .

  In the present invention, a groove is provided in the tread portion of the pneumatic tire, and a portion defined by the groove and surrounded by the groove is formed as a block portion. Further, the tread surface (the surface of the block portion) that is a portion that contacts the road surface of the pneumatic tire is formed on the outer peripheral surface of the pneumatic tire, and the surface of the block portion is the outer side in the tire radial direction. Is formed. A chamfer is formed at an edge portion where the tread surface and the wall surface of the groove intersect. Furthermore, the size of the chamfer is set to be different depending on the position where the chamfer is formed. In this way, by forming the chamfer with different sizes, when an external force is input to the tread from the large chamfering direction and the block portion is deformed, the chamfered portion is also deformed so as to be grounded to the road surface. In the block portion, it is possible to prevent the tread surface in the vicinity of the edge portion on the distal end side in the input direction of the external force from separating from the road surface. In other words, in the block portion, the edge portion where the large chamfer is formed and the tread surface near the opposite edge portion along the input direction can be prevented from leaving the road surface. Accordingly, even if the block portion is deformed in a predetermined direction by the frictional force between the tread surface and the road surface, any part of the tread surface can be grounded to the road surface. Further, since only a part of the chamfer is formed large, the area of the tread can be secured to a sufficient size. As a result, it is possible to prevent uneven wear of the tread while improving the turning performance by a sufficient frictional force between the tread and the road surface.

  Further, in the pneumatic tire according to the present invention, the chamfer size is such that the tread end direction wall surface of the groove and the tread surface are larger than the chamfer of the portion where the equatorial line wall surface of the groove and the tread surface intersect. A feature is that the chamfered portion of the intersecting portion is formed larger.

  The wall surface in the tread end direction is a vertical groove formed in the tread portion of the pneumatic tire, which is the wall surface on the equator line side among the opposing wall surfaces constituting the vertical groove, and further includes a horizontal groove in the tread portion. In the case of being formed, a wall surface that faces the tread end direction at least is included among the wall surfaces constituting the lateral groove. In the vertical groove formed in the tread part of a pneumatic tire, the equatorial wall is the wall on the tread end side of the opposing wall that forms this vertical groove, and a lateral groove is further formed in the tread. In the case where the horizontal groove is formed, a wall surface facing the equatorial line direction is included among the wall surfaces constituting the lateral groove. For example, when the block section defined by two vertical grooves and two horizontal grooves has a parallelogram shape, the tread end direction wall surface is the tread edge on the side surface of the block section formed in the tire circumferential direction. In the side surface in the direction and the side surface of the block portion formed in the tire width direction, it refers to the side surface that is slightly directed toward the tread end direction. On the other hand, the side surface in the equator line direction refers to the side surface facing the equator line direction even slightly on the side surface in the equator line direction on the side surface of the block part formed in the tire circumferential direction and the side surface of the block part formed in the tire width direction. Say.

  In this invention, in one block portion, the chamfer of the portion where the tread end direction wall surface and the tread surface intersect is formed larger than the chamfer of the portion where the equatorial line wall surface and the tread surface intersect. Therefore, even if an external force is applied to the tread from the tread end direction toward the inside in the tire width direction, even if the block is deformed, any part of the tread can be grounded to the road surface. For this reason, even if the vehicle to which the pneumatic tire is mounted travels on a circuit and the block portion is greatly deformed at the time of high severity such as turning, any part of the tread should be in contact with the road surface. Can do. In addition, as described above, the chamfer on the equator line side of the block portion is formed smaller than the chamfer on the tread end side, so that any part of the tread on the road surface at the time of high severity as described above. Even when grounding, the area of the tread surface of the block portion is not reduced, so that the frictional force between the tread surface and the road surface can be increased. As a result, the turning performance can be enhanced by a sufficient frictional force between the tread and the road surface, and even during high severity, the tread does not tilt and contact with the ground, so uneven wear on the tread can be prevented. .

  In the pneumatic tire according to the present invention, the chamfering size of the portion where the equatorial line direction wall surface and the tread surface intersect is Rco, and the tread end direction wall surface and the tread surface size is chamfered. When the thickness is Rei, the relationship between Rco and Rei is 1.5 ≦ Rei / Rco ≦ 3.0 and 1.0 mm ≦ Rco.

  In the present invention, the chamfer size (Rco) of the portion where the equator line direction wall surface and the tread surface intersect is set to 1 mm or more, and the tread edge direction wall surface size (Rei) is set to 1.5 mm with respect to the chamfer size. About 3 times. As described above, by forming Rco with a thickness of 1 mm or more, the above-described effects due to chamfering can be more reliably obtained. Further, by setting Rei to be larger than Rco, even if the block is deformed by a large external force from the tread end direction toward the tire width direction inward on the tread surface as described above, any part of the tread surface will be on the road surface. Can be grounded. At the same time, since Rco is formed smaller than Rei, the area of the tread can be sufficiently secured, and the frictional force between the tread and the road surface can be increased. As a result, turning performance can be enhanced by sufficient frictional force between the tread and the road surface, and the tread is inclined even at high severity, such as when a large external force is applied to the tread inward in the tire width direction. Since there is no grounding, uneven wear on the tread can be prevented.

  In the pneumatic tire according to the present invention, the chamfer is characterized in that a chamfer at least at a portion where the wall surface in the tread end direction intersects with the tread is formed in a curved shape.

  In the present invention, at least a portion of the chamfer where the wall surface in the tread end direction and the tread surface intersect is formed in a curved shape, that is, R chamfering is performed. Therefore, there is no corner portion at the boundary between the chamfer and the tread surface, and the corner portion does not exist even when the block is deformed by a large external force from the tread end direction toward the inner side in the tire width direction as described above. Therefore, there is no resistance at the time of deformation, and it deforms smoothly. In this way, even if the block portion is deformed and the ground contact state of the tread changes to the road surface, it smoothly changes without resistance. Therefore, when the block portion is deformed, any part of the tread is reliably grounded to the road surface. be able to. As a result, even at the time of high severity as described above, it is possible to more reliably prevent the tread from tilting and grounding, so that uneven wear of the tread can be reliably prevented.

  In the pneumatic tire according to the present invention, the chamfer is characterized in that at least a chamfer at a portion where the wall surface in the tread end direction intersects with the tread is formed in a linear shape.

  In the present invention, at least a portion of the chamfer where the wall surface in the tread end direction intersects with the tread surface is formed in a linear shape, that is, chamfered by a normal plane. Chamfering can be easily performed by forming the chamfering by chamfering with such a flat surface. Since many block portions for chamfering are formed in the tread portion, the total length of all the chamfers in one tire is considerably long. By forming the chamfer by chamfering using a flat surface that can be easily formed as described above, the chamfer forming operation is greatly facilitated. As a result, the production time can be shortened and the cost can be reduced.

  The pneumatic tire according to the present invention forms a chamfer at an edge portion where a wall surface of a groove provided in a tread portion and a tread surface of a block portion surrounded by the groove intersect. Furthermore, the size of the chamfer is larger for the chamfer formed at the portion where the tread end direction wall surface and the tread surface intersect than at the portion where the equatorial line wall surface and the tread surface intersect. Form. By forming the chamfer in this way, even if the block is greatly deformed at the time of high severity in which a large external force is applied to the tread from the tread end direction toward the inside in the tire width direction, any part of the tread Can also be grounded to the road surface. Further, since the chamfer on the equator line side of one block portion is formed smaller than the chamfer on the tread end side, the area of the tread is sufficiently secured even if the chamfering is performed, The frictional force between the tread surface and the road surface can be increased. As a result, the turning performance can be enhanced by sufficient frictional force between the tread and the road surface, and the tread does not incline and come into contact with the ground even at high severity, thereby preventing uneven wear on the tread. Play.

  Below, the example of the pneumatic tire concerning the present invention is described in detail based on a drawing. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

  In the following description, the tire width direction refers to a direction parallel to a virtual rotation axis of the pneumatic tire. Further, the tire radial direction refers to a direction orthogonal to the rotation axis. The tire circumferential direction is a circumferential direction with the rotation axis as a central axis. The pneumatic tire to which the present invention is applied may be a radial tire or a bias tire. FIG. 1 is a plan view showing a main part of a pneumatic tire according to the present invention. The pneumatic tire 1 is provided with a groove portion 3 in a tread portion 2 which is the outermost side in the tire radial direction. The groove portion 3 includes a vertical groove 4 and a horizontal groove 5, and the vertical groove 4 is formed in the tire circumferential direction. Further, the lateral grooves 5 are formed substantially in the tire width direction, and the tread pattern of the pneumatic tire 1 is formed by the longitudinal grooves 4 and the lateral grooves 5. A portion surrounded by the vertical grooves 4 and the horizontal grooves 5 is formed as a block portion 8.

  2 is a partial cross-sectional view of the pneumatic tire of FIG. A portion of the block portion 8 that contacts the road surface is formed as a tread surface 9. The tread surface 9 is also a portion located on the outermost side in the tire radial direction of the pneumatic tire 1. The vertical groove 4 and the horizontal groove 5 are provided with a bottom surface 6 facing outward in the tire radial direction and two for each groove, and are opposed to the bottom surface 6 so as to sandwich the bottom surface 6. It is formed from orthogonal wall surfaces 7. The block portion 8 is formed by the wall surface 7 and the tread surface 9, and the wall surface 7 is formed as a side surface of the block portion 8.

  A chamfer 11 is formed at an edge portion 10 where the wall surface 7 and the tread surface 9 intersect. Since the chamfer 11 is formed on all the portions where the wall surface 7 and the tread surface 9 intersect as described above, in other words, the chamfer 11 is formed on the entire circumference of the block portion 8. The chamfer 11 is different in size depending on the portion of the chamfer 11 formed on one block portion 8 where the chamfer 11 is formed.

  Specifically, the chamfer 11 at the portion where the wall surface 7 of the vertical groove 4 and the tread surface 9 intersect is the equator which is the wall surface 7 formed on the tread end 16 side which is the end portion in the tire width direction of the tread portion 2. The tread end direction wall surface, which is the wall surface 7 formed on the equator line 15 side of the pneumatic tire 1, and the tread surface 9 cross each other than the inner chamfer 13 which is the chamfer 11 of the portion where the linear wall surface and the tread surface 9 intersect. The outer chamfer 12 that is the chamfer 11 of the portion to be formed is formed larger. That is, when the chamfers 11 of the portion where the wall surface 7 of the vertical groove 4 and the tread surface 8 intersect each other in one block portion 8 are compared, the size of the chamfer 11 is the chamfer 11 on the equator line 15 side. The outer chamfer 12 that is the chamfer 11 on the tread end 16 side is formed larger than the inner chamfer 12.

  Further, the lateral grooves 5 are not formed only in the tire width direction, but are also formed in the tire circumferential direction while being formed in the tire width direction in consideration of improving drainage and reducing pattern noise. It is formed in an oblique direction. For this reason, the wall surface 7 of the lateral groove 5 faces either the equator line 15 direction or the tread end 16 direction. The chamfer 11 where the wall surface 7 and the tread surface 9 of the lateral groove 5 intersect is an inner chamfer 11 which is a chamfer 11 where the equatorial line direction wall surface which is the wall surface 7 facing the equator line 15 direction and the tread surface 9 intersect. The outer chamfer 12, which is a chamfer 11 at a portion where the tread end direction wall surface that is the wall surface 7 facing the tread end 16 direction and the tread surface 9 intersect, is formed larger than the chamfer 13.

  In addition, the specific sizes of the chamfers 11 are compared with each other when 1.5 ≦ Rei / Rco ≦ 3.0 when the size of the inner chamfer 13 is Rco and the size of the outer chamfer 12 is Rei. It has become. That is, Rei is formed with a size of 1.5 times or more and 3.0 times or less of Rco. Furthermore, Rco, that is, the size of the inner chamfer 13 is formed with a size of 1.0 mm or more.

  When the pneumatic tire 1 is mounted on a vehicle and travels, the pneumatic tire 1 rotates to advance the vehicle by the frictional force between the tread surface 9 and the road surface. Further, when cornering, the direction of the front wheel, that is, the steering wheel By changing the direction of the pneumatic tire 1, a lateral force is generated by the frictional force between the tread surface 9 and the road surface to change the direction of the vehicle. Since the pneumatic tire 1 acts as described above, an external force is relatively input to the tread surface 9 from the road surface.

  3 is a detailed view of the block portion when an external force is applied to the tread surface of the pneumatic tire of FIG. As for the input to the tread 9, the force in the tire circumferential direction is mainly inputted when going straight, but the input in the tire width direction is also added in addition to the external force in the tire circumferential direction at the cornering. Further, during high severity such as cornering during circuit running, the input from the road surface 20 to the tread surface 9 is substantially only in the tire width direction. During such cornering, a force is exerted on the vehicle toward the outside of the turn due to the centrifugal force at the time of turning, so the input direction from the road surface 20 to the tread surface 9 is relatively inward of the turn. At the time of high severity such as during circuit driving, the force in this direction is large, so that the block portion 8 on which the tread surface 9 is formed is deformed. The deformation direction is deformed so as to incline toward the inside of the turn. For this reason, the tread surface 9 tends to tilt obliquely in the direction in which the inner side of the turn is away from the road surface 20, but the block part 8 has a shoulder end side of the block part 8, that is, an edge part 10 in the outer side direction of the turn. A large outer chamfer 12 is formed. As a result, the block portion 8 is deformed, and the portion of the inner chamfer 13 comes in contact with the road surface 20.

  Further, when the tread surface 9 is considered in two ranges on both sides centered on the equator line 15 in the tire width direction, the size of the chamfer 11 formed in each block portion 8 is the tread belonging to the same range. With reference to the end 16 and the equator line 15, Rei is formed to be 1.5 times or more and 3.0 times or less of Rco as described above. That is, the outer chamfer 12 is formed larger than the inner chamfer 13. As described above, when a high turning G is applied like cornering at the time of circuit driving, among the treads 9 of one pneumatic tire 1, the treads 9 in the outward direction of the turn from the road surface 20 as described above. However, since the chamfer 11 is formed with the equator line 15 as the center as described above, the tread surface 9 is reliably provided on the road surface 20 in the left and right cornering as described above. To ground.

  Hereinafter, the performance evaluation test performed on the conventional pneumatic tire 1 and the pneumatic tire 1 of the present invention will be described. The evaluation condition is that a 235 / 45R17 pneumatic tire 1 is mounted on a wheel with a rim size of 17 × 8 JJ, the air pressure is 220 kPa on the front and 190 kPa on the rear, and the displacement is 2000 cc, mounted on a domestic passenger car with a turbo, Performance evaluation of steady circular rotation G and uneven wear resistance was performed. As a test method for performance evaluation, the steady circular turning G was compared by the maximum lateral acceleration when the steady circular turning was performed with a radius of 30R. For uneven wear resistance, a figure 8 turn (turn G = 0.76 G) was performed, and the remaining amounts of the block portion on the equator line 15 side and the tread end 16 side were compared. These results are shown as an index with the conventional pneumatic tire 1 as 100. This value indicates that the larger the maximum lateral acceleration of the steady circular turn G is, the smaller the degree of uneven wear is. Table 1 shows the results obtained by the performance evaluation test.

  In the evaluation test, an example in which the chamfer 11 is formed by R chamfering is used as an example of a conventional pneumatic tire 1. The Rei and the Rco are represented by the size of the radius (unit: mm). In this conventional example, Rei = 1.5, Rco = 1.5, and Rei / Rco = 1.0. The steady circular turning G and uneven wear resistance when an evaluation test is performed on this conventional product is set to 100 as described above, and the steady circular turning G and uneven wear resistance of this conventional example are used as a reference.

  In Example 1 which is an example of the present invention, Rei = 1.75 and Rco = 1.25 are formed, and Rei / Rco = 1.4. In Example 1, Rei is larger than that of the conventional example, and Rco is 1 mm or more. Therefore, the performance of both steady circular turning G and uneven wear resistance is improved compared to the conventional example. However, since Rei / Rco = 1.4, it is not formed with 1.5 ≦ Rei / Rco ≦ 3.0 as described above. For this reason, the degree of performance improvement from the conventional example is small, and steady circular turning G = 103 and uneven wear resistance = 103.

  In Example 2 which is an example of the present invention, Rei = 1.8 and Rco = 1.2 are formed, and Rei / Rco = 1.5. In Example 2, Rei is larger than that in the conventional example, and Rco is 1 mm or more. Therefore, both the steady circular turning G and the uneven wear resistance are improved as compared with the conventional example. In addition, since Rei / Rco = 1.5, the above-described 1.5 ≦ Rei / Rco ≦ 3.0 is also satisfied. As a result, the performance of the conventional example is greatly improved, and steady circular turning G = 105 and uneven wear resistance = 106.

  In Example 3 which is an example of the present invention, Rei = 2.0 and Rco = 1.0 are formed, and Rei / Rco = 1.0. In Example 3, Rei is larger than that of the conventional example, and Rco is 1 mm or more. Therefore, both the steady circular turning G and the uneven wear resistance are improved as compared with the conventional example. Further, since Rei / Rco = 2.0, the above-described 1.5 ≦ Rei / Rco ≦ 3.0 is also satisfied. As a result, the performance of the conventional example is greatly improved, and steady circular turning G = 108 and uneven wear resistance = 112.

  In Example 4 which is an example of the present invention, Rei = 2.25 and Rco = 0.75 are formed, and Rei / Rco = 3.0. In the fourth embodiment, Rei is larger than that in the conventional example, and Rei / Rco = 3.0. Therefore, the above-described 1.5 ≦ Rei / Rco ≦ 3.0 is also satisfied, and the steady circular turning G In addition, both uneven wear resistance and performance are improved compared to conventional products. However, since Rco = 0.75, it is formed with less than 1 mm. For this reason, the degree of improvement in performance from the conventional example is small, and steady circular turning G = 106 and uneven wear resistance = 107.

  In Example 5 which is an example of the present invention, Rei = 2.4 and Rco = 0.6, and Rei / Rco = 4.0. In Example 5, since Rei is larger than that in the conventional example, the performance of both steady circular turning G and uneven wear resistance is improved as compared with the conventional example. However, since Rco = 0.6, it is formed with less than 1 mm, and since Rei / Rco = 4.0, it is not formed with 1.5 ≦ Rei / Rco ≦ 3.0. For this reason, the degree of performance improvement from the conventional example is small, and steady circular turning G = 104 and uneven wear resistance = 103.

  As is clear from the above test, when Rei is larger than Rco, both steady circular turning G and uneven wear resistance can be improved. Further, when Rco is formed with a size of 1 mm or more and Rei is larger than Rco, particularly when the condition of 1.5 ≦ Rei / Rco ≦ 3.0 is satisfied, these performances Can be further improved. When the chamfer 11 is formed as described above, the block portion 8 is greatly deformed when an external force in the tire width direction is input from the road surface 20 to the tread surface 9 at the time of high severity such as cornering in circuit driving. In this case, the outer chamfer 12 contacts the road surface 20. For this reason, even if the block portion 8 is greatly deformed as described above, the edge portion 10 is not formed on the input side of the external force from the road surface 20. Since no reaction force in the direction of separating the Rco side tread surface 9 from the road surface 20 is generated and the tread surface 9 in the vicinity of the inner chamfer 13 can be prevented from separating from the road surface 20, any part of the tread surface 9 is grounded to the road surface 20. Can do. As a result, uneven wear of the tread surface 9 can be prevented.

  In addition, the above-mentioned performance is most effective in Example 3, and as a result of comparing the remaining amounts of the block portion 8 on the equator line 15 side and the tread end 16 side, the uneven wear ratio of the conventional example is 1.27. On the other hand, in Example 3, since it was 1.13, the improvement of about 12% was seen. Moreover, since Rco is formed smaller than Rei, the area of the tread surface 9 can be formed larger, and the frictional force between the tread surface 9 and the road surface 20 can be increased even during high severity such as cornering during circuit driving. Can be bigger. As a result, the turning performance of the vehicle equipped with the pneumatic tire 1 can be improved.

  On the other hand, when the difference between Rei and Rco is small and Rei / Rco is less than 1.5, when the block portion 8 is deformed with high severity as described above, the wall surface 7 that forms the outer chamfer 12 and Since the force to maintain the shape of the tread surface 9 is increased, the block portion 8 is deformed while the positional relationship between the wall surface 7 and the tread surface 9 is maintained, and the tread surface 9 near the inner chamfer 13 is easily separated from the road surface 20. Become. For this reason, when Rei / Rco is less than 1.5, the wear on the tread surface 9 tends to be greater on the outer chamfer 12 side than on the inner chamfer 13 side, and the degree of improvement in uneven wear resistance is 1. It becomes lower than the case where the condition of 5 ≦ Rei / Rco ≦ 3.0 is satisfied.

  Further, when the chamfer 11 on the Rco side is small and Rco is less than 1 mm, the substantial size of Rei is not ensured even if the condition of 1.5 ≦ Rei / Rco ≦ 3.0 is satisfied. When the block portion 8 is deformed with such high severity, the tread surface 9 near the inner chamfer 13 may be separated from the road surface 20. For this reason, when Rco is less than 1 mm, the wear on the tread surface 9 may be greater on the outer chamfer 12 side than on the inner chamfer 13 side. In this case, the improvement in uneven wear resistance is as follows. As described above, it is slightly lower than the case where the condition of 1.5 ≦ Rei / Rco ≦ 3.0 is satisfied.

  As described above, the relationship between Rco which is the size of the inner chamfer 13 and Rei which is the size of the outer chamfer 12 is 1.5 ≦ Rei / Rco ≦ 3.0 and 1.0 mm ≦ Rco. In this case, the turning performance can be greatly improved by a sufficient frictional force between the tread surface 9 and the road surface 20, and the tread surface 9 is not inclined and touches even during high severity. It is possible to greatly improve the uneven wear resistance.

  In the above embodiment, the chamfer 11 formed on the edge portion 10 which is a portion where the tread surface 9 and the wall surface 7 intersect is formed by R chamfering, but it is formed linearly or planarly. Chamfer 11 may be used. Even if the chamfer 11 is formed in such a shape, uneven wear of the tread surface 9 can be prevented while improving the turning performance as described above. Furthermore, the chamfer 11 can be easily formed by forming the chamfer 11 linearly or planarly. Furthermore, since the groove portion 3 of the tread portion 2 is a single tire and a plurality of vertical grooves 4 and horizontal grooves 5 are formed, the total length of the chamfer 11 is long. Since the chamfer 11 can be easily formed as described above, the forming operation of the chamfer 11 is greatly facilitated. As a result, the manufacturing time of the pneumatic tire 1 can be shortened, the chamfer 11 can be easily formed, and the manufacturing time can be shortened to reduce the cost.

  As described above, the pneumatic tire 1 according to the present invention is effective for improving turning performance while preventing uneven wear, and is used particularly in the case of high severity such as when cornering the circuit at high speed. Suitable for cases.

It is a top view which shows the principal part of the pneumatic tire which concerns on this invention. It is a partial cross section figure of the pneumatic tire of FIG. FIG. 3 is a detailed view of a block portion when an external force is applied to the tread surface of the pneumatic tire of FIG. 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Groove part 4 Vertical groove 5 Horizontal groove 6 Bottom surface 7 Wall surface 8 Block part 9 Tread surface 10 Edge part 11 Chamfering 12 Outer side surface chamfer 13 Inner side surface chamfer 15 Equatorial line 16 Tread edge 20 Road surface

Claims (4)

In a pneumatic tire having a block portion defined by grooves formed in a tread portion,
A chamfer is formed in a portion where the wall surface of the groove and the tread surface of the tread portion intersect,
The chamfer is formed such that the chamfer of the portion where the tread end direction wall surface of the groove intersects the tread surface is larger than the chamfer of the portion where the equatorial line wall surface of the groove intersects the tread surface . Pneumatic tire characterized by. When the chamfering size of the portion where the equator line direction wall surface and the tread surface intersect is Rco, and the chamfering size of the portion where the tread edge direction wall surface and the tread surface intersect is Rei, the Rco and 2. The pneumatic tire according to claim 1 , wherein the relationship with Rei is 1.5 ≦ Rei / Rco ≦ 3.0 and 1.0 mm ≦ Rco. The chamfer pneumatic tire according to claim 1 or 2, characterized in that the chamfering of the portion with the at least the tread edge direction wall tread intersect is formed in a curved shape. The chamfer pneumatic tire according to claim 1 or 2 chamfered portion and the at least the tread edge direction wall tread intersect is characterized in that it is formed in linear shape.

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