JP4639859B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire. In particular, the present invention relates to a pneumatic tire that can achieve both improved uneven wear resistance and improved drainage without reducing steering stability.

  In a conventional pneumatic tire, in order to improve running stability on a wet road surface, an improvement in drainage is an important factor, so by forming a straight main groove formed along the tire circumferential direction, The drainage was improved. However, since the straight main groove is difficult to suppress air column resonance noise, it has been difficult to reduce noise. In view of this, some conventional pneumatic tires achieve both performances by providing a plurality of main grooves having different shapes. For example, in Patent Document 1, the straight main groove is arranged at the center in the tire width direction, and arc-shaped grooves that are formed along the tire circumferential direction and curved in the tire width direction are formed on both sides of the straight main groove in the tire width direction. An arc-shaped curved main groove formed continuously and repeatedly in the tire circumferential direction is disposed. As a result, noise performance was improved while ensuring drainage.

JP 2004-168142 A

  However, in the conventional pneumatic tire described above, the main groove is arranged in the center portion in the tire width direction, so that the block rigidity in the vicinity of the center portion in the tire width direction is lowered, so that drainage performance and noise performance are improved. However, it has been difficult to improve the handling stability. In addition, depending on the position where each main groove is arranged, the width in the tire width direction of each land portion located between the main grooves varies greatly, and there is a possibility that uneven wear may occur due to a difference in block rigidity of each land portion. It was.

  This invention is made | formed in view of the above, Comprising: It aims at providing the pneumatic tire which can improve both drainage property and uneven wear resistance, ensuring steering stability.

  In order to solve the above-described problems and achieve the object, a pneumatic tire according to the present invention is a pneumatic tire in which a plurality of land portions are partitioned by a plurality of groove portions formed in a tread surface that is a surface of a tread portion. In the center portion of the tread surface in the tire width direction, a center land portion of the plurality of land portions is located, and among the plurality of groove portions, at both ends of the center land portion in the tire width direction. The adjacent groove portions are formed as arc-shaped curved main grooves formed so that arc-shaped grooves formed along the tire circumferential direction are continuously curved in the tire circumferential direction while being curved in the tire width direction. Among the land portions, the land portion adjacent to the outer side in the tire width direction of the arc-shaped curved main groove is formed as a second land portion, and the tire width direction of the second land portion among the plurality of groove portions. Next to the outside The groove portion is formed with a groove width equal to the groove width of the arc-shaped curved main groove, and is formed as a second main groove formed along the tire circumferential direction, and among the plurality of land portions The land portion adjacent to the outer side in the tire width direction of the second main groove is formed as a shoulder land portion formed from the second main groove to an end portion in the tire width direction of the tread surface, In the shoulder land portion, a ground contact end that is an end portion in the tire width direction of a ground contact portion that is a portion that is filled with air at a normal internal pressure and is loaded with a normal load is located on the tread surface. The width in the tire width direction of the center land portion, the width in the tire width direction of the second land portion, and the tire width direction from the end of the shoulder land portion on the second main groove side to the ground contact end The width in Wherein the difference when compared with the ratio between relative contact width is the width in the tire width direction of the land portion is formed to be 5% or less.

  In the present invention, since the center land portion is disposed at the center portion of the tread surface, the block rigidity of the center portion of the pneumatic tire at the time of ground contact is high. The center portion of the tread surface is located at the center portion in the tire width direction of the portion that is in contact with the ground when the vehicle is running, and is a portion where the contact load tends to increase. For this reason, the stability at the time of vehicle travel can be acquired by improving the rigidity of this part. In addition, the main grooves formed along the tire circumferential direction among the plurality of groove portions are each formed with two arcuate curved main grooves and two second main grooves. That is, since four main grooves are formed, the water located between the road surface and the tread surface can be effectively drained by the four main grooves.

  Further, the land portion includes the center land portion, a second land portion adjacent to the outer side in the tire width direction of the center land portion via the arc-shaped curved main groove, and a tire of the second land portion via the second main groove. A shoulder land portion adjacent to the outside in the width direction is formed, and the difference in the ratio of the width of each land portion in the tire width direction to the contact width is 5% or less. For this reason, since the difference in the block rigidity of each land part becomes small, the difference in the amount of wear of each land part when the pneumatic tire is mounted on the vehicle and travels becomes small. Thereby, the amount of uneven wear is less likely to occur. As a result, it is possible to improve both drainage and uneven wear resistance while ensuring steering stability.

  Further, the pneumatic tire according to the present invention is formed from the arcuate curved main groove adjacent to the second landed part through the second land part among the plurality of grooved parts, and the arcuate curved main groove. The groove part connected to the second main groove is formed as a second land part lug groove part, the second land part lug groove part is adjacent to the second land part, and the arc shape The groove width at the end portion on the second main groove side is narrower than the groove width at the end portion on the curved main groove side.

  In the present invention, by forming the second land portion lug groove portion connected to the arc-shaped curved main groove and the second main groove, when traveling on a wet road surface, the arc-shaped curved main groove and the second main groove are In order to improve drainage, water is allowed to flow. Further, since the groove width of the second land portion lug groove portion is narrower on the second main groove side than on the arcuate curved main groove side, the second land in contact with the second land portion lug groove portion is formed. The size of the portion can be made larger on the second main groove side than on the arcuate curved main groove side. Thereby, the block rigidity of the second land portion can be made higher on the outer side in the tire width direction than on the inner side in the tire width direction. When cornering when the vehicle is running, a load is easily applied to the outer side in the tire width direction. However, as described above, the block rigidity of the second land portion is more outward in the tire width direction than inward in the tire width direction. By making the side higher, when a load is applied to the outer side in the tire width direction such as cornering, the load can be received with high rigidity. Thereby, the stability at the time of cornering can be improved. As a result, drainage performance and steering stability can be further improved.

  The pneumatic tire according to the present invention is characterized in that the second land portion lug groove portion is formed to be inclined in the tire circumferential direction with respect to the tire width direction.

  In the present invention, since the second land lug groove portion is inclined in the tire circumferential direction with respect to the tire width direction, water flows more reliably between the arc-shaped curved main groove and the second main groove. can do. That is, the pneumatic tire contacts the road surface while rotating, but the water flowing between the arc-shaped curved main groove and the second main groove moves in the tire width direction. For this reason, when water flows between the arc-shaped curved main groove and the second main groove, the water moves in an oblique direction with respect to the traveling direction of the vehicle. By making it incline as mentioned above, this water that passes through the second land portion lug groove portion can be made easier to flow. As a result, drainage can be improved more reliably.

  Further, in the pneumatic tire according to the present invention, the second land portion lug groove portion is formed with a groove width Wka of an end portion on the arc-shaped curved main groove side in a range of 2 to 8 mm, and the arc shape The relationship between the groove width Wka at the end on the curved main groove side and the groove width Wkb at the end on the second main groove side is in the range of 0.25 ≦ (Wkb / Wka) ≦ 0.9. It is characterized by.

  In this invention, since the groove width Wka of the end of the second land portion lug groove portion on the arcuate curved main groove side is in the range of 2 to 8 mm, the steering stability is more reliably ensured. It is possible to improve drainage performance. That is, when the groove width Wka of the second land portion lug groove portion is less than 2 mm, the groove width is too narrow, so that a small amount of water flows in the second land portion lug groove portion. In addition, when the groove width Wka of the second land portion lug groove portion is less than 8 mm, the second land portion becomes small because the groove width of the second land portion lug groove portion is too wide, and the second land portion The block rigidity will decrease. Therefore, by forming the second land portion lug groove portion so that the groove width Wka is within a range of 2 to 8 mm, water can easily flow into the second land portion lug groove portion, and the size of the second land portion. By securing the block rigidity of the second land portion can be ensured. Thereby, since it becomes easy for water to flow in the 2nd land part lug groove part, drainage nature improves, and since block rigidity of the 2nd land part is secured, steering stability can be secured. As a result, the drainage can be improved while ensuring the steering stability more reliably.

  The relationship between the groove width Wka of the end of the second land lug groove on the arcuate curved main groove side and the groove width Wkb of the end of the second land lug groove on the second main groove side is 0.25. By making it within the range of ≦ (Wkb / Wka) ≦ 0.9, the drainage performance can be improved while ensuring the steering stability more reliably. That is, when (Wkb / Wka) is less than 0.25, the groove width Wkb at the end of the second land portion lug groove portion on the second main groove side is too narrow. Becomes difficult to flow. Further, when (Wkb / Wka) is larger than 0.9, there is a possibility that the size of the second land portion on the outer side in the tire width direction becomes too small, which causes the block rigidity of the second land portion to be too small. There is a risk of lowering. Therefore, the relationship between the groove width Wka of the end of the second land lug groove on the arcuate curved main groove side and the groove width Wkb of the end of the second land lug groove on the second main groove side is 0.25. ≦ (Wkb / Wka) ≦ 0.9 By ensuring that water flows effectively in the second land portion lug groove portion, the size of the second land portion is secured. Block rigidity can be secured. Thereby, while improving drainage, steering stability can be ensured by ensuring the block rigidity of a 2nd land part. As a result, the drainage can be improved while ensuring the steering stability more reliably.

  In the pneumatic tire according to the present invention, the arc-shaped curved main groove is formed as a see-through in the tire circumferential direction.

  In the present invention, the resistance to drainage when water flows into the arcuate curved main groove is reduced by forming the arcuate curved main groove into a see-through shape. Thereby, the water on the road surface easily flows in the arc-shaped curved main groove. As a result, drainage can be improved more reliably.

  In the pneumatic tire according to the present invention, both the arc-shaped curved main groove and the second main groove are formed so that the groove width is within a range of 3 to 10% with respect to the ground contact width. It is characterized by.

  In the present invention, the arcuate curved main groove and the second main groove are both formed so that the groove width is within the range of 3 to 10% with respect to the ground contact width, thereby ensuring the steering stability more reliably. While improving drainage. That is, when the groove width of these main grooves is less than 3% with respect to the ground contact width, the groove width is too narrow, so that it is difficult for water to flow, and drainage performance may be deteriorated. Further, when the groove width of these main grooves is larger than 10% with respect to the ground contact width, the land width becomes too small due to the groove width becoming too wide, and the block rigidity of the land portion becomes low. There is a fear. Thus, when the block rigidity of a land part becomes low, there exists a possibility that steering stability may fall. Therefore, by forming both the arc-shaped curved main groove and the second main groove so that the groove width is within a range of 3 to 10% with respect to the ground width, water can easily flow in each main groove. The size of the land portion can be secured, and the block rigidity of the land portion can be secured. Thereby, drainage improves and steering stability improves. As a result, the drainage can be improved while ensuring the steering stability more reliably.

  Further, in the pneumatic tire according to the present invention, the arc-shaped curved main groove has an arc-shaped pitch length in the tire circumferential direction of each arc-shaped groove forming the arc-shaped curved main groove. It is characterized by being formed within a range of 2 to 5% of the length.

  In this invention, by forming the length in the tire circumferential direction of each arc-shaped groove forming the arc-shaped curved main groove so as to be in the range of 2 to 5% of the total circumferential length of the arc-shaped curved main groove, It is possible to reliably ensure steering stability and reduce noise. That is, when the length of the arc-shaped groove in the tire circumferential direction is less than 2% of the total circumferential length of the arc-shaped curved main groove, the length in the tire circumferential direction of the portion adjacent to the arc-shaped curved main groove in the land portion is reduced. In this case, the block rigidity of this portion may decrease, and the steering stability may decrease due to the decrease in block rigidity. In addition, the arc-shaped curved main groove is formed so as to wave in the tire width direction by repeatedly forming the arc-shaped groove. By forming the main groove in this way, the arc-shaped curved main groove is generated in the groove portion when the vehicle is running. Since the frequency of the sound to be distributed is dispersed, the air column resonance sound is hardly generated. However, when the length of the arc-shaped groove in the tire circumferential direction is longer than 5% of the total circumferential length of the arc-shaped curved main groove, the frequency of sound generated in the arc-shaped curved main groove is not dispersed, There is a risk that it is difficult to reduce the occurrence of column resonance noise. Therefore, by forming the length of each arc-shaped groove forming the arc-shaped curved main groove in the tire circumferential direction so as to be within a range of 2 to 5% of the total circumferential length of the arc-shaped curved main groove, Since the block rigidity can be secured, the steering stability can be secured, and the air column resonance can be more reliably reduced by dispersing the frequency of the sound generated in the arc-shaped curved main groove. As a result, it is possible to more reliably ensure steering stability and reduce noise.

  In the pneumatic tire according to the present invention, among the second land portion lug groove portions, the interval between the second land portion lug groove portions adjacent in the tire circumferential direction is the second land portion lug groove portion pitch length. And the said 2nd land part lug groove part is arrange | positioned by the said 2nd land part lug groove part pitch length from which length differs, respectively, The said tire part lug groove part adjoins in the tire circumferential direction among the said shoulder part lug groove parts The interval between the shoulder lug grooves is the shoulder lug groove pitch length, and the shoulder lug groove portions are arranged with a plurality of shoulder lug groove pitch lengths different from each other. Features.

  In the present invention, the plurality of second land portion lug groove portions are arranged with a plurality of second land portion lug groove portion pitch lengths, and the plurality of shoulder portion lug groove portions are arranged with a plurality of shoulder portion lug groove portion pitch lengths. Yes. For this reason, when the pneumatic tire rolls, the interval when the second land portion or the shoulder land portion is in contact with the road surface or when it is separated from the road surface is an interval of a plurality of lengths in one circumference of the pneumatic tire. become. As a result, it is possible to suppress the generation of a sound having a specific frequency strongly due to a plurality of types of frequencies that are not generated due to the specific frequency when contacting or leaving the road surface. As a result, pattern noise can be reduced.

  In the pneumatic tire according to the present invention, the second land portion lug groove portion is provided such that a plurality of the second land portion lug groove pitch lengths having different lengths are periodically repeated in the tire circumferential direction. The shoulder lug groove portions are provided such that a plurality of shoulder lug groove pitch lengths having different lengths are periodically repeated in the tire circumferential direction.

  In this invention, since the 2nd land part lug groove part pitch length and the shoulder part lug groove part pitch length are repeated periodically, the frequency of the sound generated at the time of rolling of a pneumatic tire can be set up easily. As a result, pattern noise can be more reliably reduced.

  Further, in the pneumatic tire according to the present invention, the second land portion lug groove portion and the shoulder portion lug groove portion adjacent to the second land portion or the shoulder land portion adjacent to each other through the second main groove are: One having a part where the position in the tire circumferential direction is the same as the second land part located within the range of one or a plurality of continuous second land lug groove part pitch lengths. Alternatively, a plurality of the land portion patterns are formed by using the shoulder land portions located within a range of a plurality of continuous shoulder portion lug groove portion pitch lengths as one land portion pattern. To do.

  In the present invention, since the second land portion and the shoulder land portion form one land portion pattern, it can be set more easily when setting the frequency of the sound generated when the pneumatic tire rolls. . As a result, pattern noise can be more reliably reduced.

  The pneumatic tire according to the present invention is characterized in that the shoulder lug groove is connected to the second main groove.

  In this invention, since the shoulder lug groove portion is connected to the second main groove, the water flowing in the second main groove can flow to the shoulder lug groove portion when traveling on a wet road surface, and it is easy to drain. can do. As a result, drainage can be improved more reliably.

  The pneumatic tire according to the present invention has an effect that both drainage and uneven wear resistance can be improved while ensuring steering stability.

  Embodiments of a pneumatic tire according to the present invention will be described below in detail with reference to the drawings. 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. Further, pneumatic tires having grooves formed in a direction along the tire circumferential direction include pneumatic tires having a rib pattern, a rib lug pattern, etc., but in the following description, an air having a rib-based tread pattern The entering tire will be described.

(Embodiment)
In the following description, the tire width direction refers to a direction parallel to the rotation axis of the pneumatic tire, the inner side in the tire width direction refers to the direction toward the equator in the tire width direction, and the outer side in the tire width direction refers to the tire. The direction opposite to the direction toward the equator in the width direction. Further, the tire radial direction refers to a direction orthogonal to the rotation axis, and the tire circumferential direction refers to a direction rotating around the rotation axis as a center of rotation. FIG. 1 is a view showing a tread portion of a pneumatic tire according to the present invention. The pneumatic tire 1 shown in the figure has a tread portion 4 formed on the outermost side in the tire radial direction, and the surface of the tread portion 4, that is, a vehicle (not shown) on which the pneumatic tire 1 is mounted travels. In this case, the portion in contact with the road surface is formed as a tread surface 5. A plurality of groove portions are formed on the tread surface 5, and a plurality of land portions are defined on the tread surface by the plurality of groove portions.

  Of the plurality of groove portions, a groove portion having a predetermined width and formed substantially along the tire circumferential direction is formed as a main groove 10. A plurality of the main grooves 10 are formed, and four of the plurality of main grooves 10 are formed substantially in parallel with the same groove width. Further, the positions of these main grooves 10 are arranged at approximately symmetrical positions, two on each side of the equator plane 40 with the equator plane 40 as the center. Note that these main grooves 10 may not be formed accurately along the tire circumferential direction. Each main groove 10 only needs to be formed substantially in the tire circumferential direction, and may be formed in a case where it is formed obliquely in the tire width direction or in a curved line.

  A center rib 21 that is a center land portion of the plurality of land portions is located in a central portion of the tread surface 5 in the tire width direction, that is, a portion where the equator surface 40 is located. The center rib 21 is formed in the tire circumferential direction along the equator plane 40 at the center of the tread surface 5 in the tire width direction.

  Center-side main grooves 11 of the main grooves are disposed adjacent to the center ribs 21 at both ends of the center rib 21 in the tire width direction. The center-side main groove 11 is formed as an arc-shaped curved main groove formed such that a plurality of arc-shaped grooves 14 are continuously repeated in the tire circumferential direction. The arc-shaped groove 14 has a shape formed along the tire circumferential direction while being curved to be convex inward in the tire width direction. The center-side main groove 11 is formed as an arc-shaped curved main groove in which the arc-shaped groove 14 is continuously formed in the tire circumferential direction, so that the center-side main groove 11 is formed in the tire width direction while being formed along the tire circumferential direction. An arc-shaped groove that is convex and curved is formed repeatedly. Further, in the center side main groove 11, a portion to which the arc-shaped groove 14 is connected, that is, a portion protruding outward in the tire width direction is a trough portion 15. The two center-side main grooves 11 positioned at both ends of 21 are formed such that the positions of the valley portions 15 are different in the tire circumferential direction.

  Further, the center side main groove 11 formed in such a shape is see-through in the tire circumferential direction. That is, the groove wall 16 on the outer side in the tire width direction of the center side main groove 11 is in the tire width direction with respect to all the portions of the groove wall 16 on the inner side in the tire width direction of the center side main groove 11. Located outside.

  As described above, the center-side main groove 11 is formed so that the arc-shaped grooves 14 are continuously repeated in the tire circumferential direction, but the arc-shaped pitch length L in the tire circumferential direction of each arc-shaped groove 14, that is, The length L in the tire circumferential direction from the adjacent valley 15 to the valley 15 in the tire circumferential direction is formed within a range of 2 to 5% of the total circumferential length of the center side main groove 11. Is preferred.

  A second rib 22 that is a second land portion of the plurality of land portions is formed outside the center-side main groove 11 in the tire width direction. The second rib 22 is located between the center-side main groove 11 and the shoulder-side main groove 12 that is the second main groove of the main groove 10 that is located outward of the center-side main groove 11 in the tire width direction. It is adjacent to these main grooves 10.

  Further, between the center side main groove 11 and the shoulder side main groove 12 which are adjacent to each other via the second rib 22, a second rib communication inclined groove 32 which is a second land portion lug groove portion formed therebetween is arranged. Has been. The second rib communication inclined groove 32 is connected to the center side main groove 11 and the shoulder side main groove 12 and is adjacent to the second rib 22 in the tire circumferential direction. Further, since the second rib communication inclined groove 32 is formed between the center side main groove 11 and the shoulder side main groove 12, it is formed substantially in the tire width direction. Inclined in the tire circumferential direction with respect to the direction.

  The plurality of second rib communication inclined grooves 32 formed in this way are provided in the tire circumferential direction, and the second rib closing inclined groove 33 adjacent to the second rib 22 is provided between the second rib communication inclined grooves 32 in the tire circumferential direction. Is formed. The second rib closing inclined groove 33 is connected to the shoulder side main groove 12 and is formed inwardly in the tire width direction from the shoulder side main groove 12. The second rib closing inclined groove 33 is formed from the second rib closing inclined groove 33. Unlike the communication inclined groove 32, it is not connected to the center side main groove 11. For this reason, the end of the second rib closing inclined groove 33 on the inner side in the tire width direction is located on the outer side in the tire width direction with respect to the center side main groove 11, and the second rib closing inclined groove 33 and the center side main groove are The second rib 22 is located between the second rib 22 and the second rib 22. Further, the second rib closing inclined groove 33 is formed to be inclined with respect to the tire circumferential direction or the tire width direction at an inclination angle similar to the inclination angle of the second rib communication inclined groove 32. The second rib closing inclined grooves 33 are also provided in the tire circumferential direction similarly to the second rib communicating inclined grooves 32, and the second rib closing inclined grooves 33 and the second rib communicating inclined grooves 32 are alternately arranged in the tire circumferential direction. Has been.

  A shoulder rib 23 that is a shoulder land portion adjacent to the shoulder side main groove 12 is formed outside the shoulder side main groove 12 in the tire width direction. The shoulder rib 23 is formed from the shoulder side main groove 12 to the end of the tread surface 5 in the tire width direction.

  Further, a shoulder rib inclined groove 34 that is a shoulder lug groove formed from the shoulder side main groove 12 toward the outer side in the tire width direction is formed at a position on the outer side in the tire width direction from the shoulder side main groove 12. Has been. The shoulder rib inclined groove 34 is connected to the shoulder-side main groove 12 and is formed to the outer end in the tire width direction of the shoulder rib 23 while being adjacent to the shoulder rib 23. Inclined in the tire circumferential direction with respect to the direction. Further, a plurality of the shoulder rib inclined grooves 34 are provided in the tire circumferential direction in the same manner as the second rib communication inclined grooves 32.

  Among the shoulder rib inclined grooves 34, the interval between the shoulder rib inclined grooves 34 adjacent to each other in the tire circumferential direction is a shoulder rib inclined groove pitch length N which is the shoulder portion lug groove portion pitch length. The shoulder rib inclined grooves 34 are arranged in the tire circumferential direction by a plurality of shoulder rib inclined groove pitch lengths N each having a different length, and the plurality of shoulder rib inclined groove pitch lengths N having different lengths are arranged around the tire circumference. It is provided to be repeated periodically in the direction. Similarly, among the second rib communicating inclined grooves 32, the interval between the second rib communicating inclined grooves 32 adjacent in the tire circumferential direction is the second rib communicating inclined groove pitch length M which is the second land portion lug groove portion pitch length. Yes. The second rib communicating inclined grooves 32 are arranged in the tire circumferential direction by a plurality of second rib communicating inclined groove pitch lengths M having different lengths, and a plurality of second rib communicating inclined groove pitch lengths M having different lengths. Are periodically repeated in the tire circumferential direction.

  Further, the second rib 22 or the shoulder rib 23 adjacent to each other via the shoulder side main groove 12 has a block pattern which is a predetermined land pattern by the second rib communication inclined groove 32 or the shoulder rib inclined groove 34 adjacent to the second rib 22 or the shoulder rib 23. Is provided. That is, two continuous rib rib groove pitches having a second rib 22 located within the range of one second rib communicating inclined groove pitch length M and a portion where the second rib 22 and the position in the tire circumferential direction are the same position. The shoulder rib 23 positioned within the range of the length N is one block pattern. The second rib communication inclined groove 32 and the shoulder rib inclined groove 34 are arranged with a plurality of lengths of the second rib communication inclined groove pitch length M and a plurality of lengths of the shoulder rib inclined groove pitch length N. The block pattern by the ribs 22 and the shoulder ribs 23 is formed in a plurality of types of shapes.

  Thus, when the pneumatic tire 1 on which the tread pattern is formed is grounded, the ground contact end 8 that is an end portion of the ground contact portion in the tire width direction is located in the shoulder rib 23. Further, the width from the ground contact edge 8 to the inner end of the shoulder rib 23 in the tire width direction, the width of the center rib 21 in the tire width direction, and the width of the second rib 22 in the tire width direction are approximately the same. It has become. Specifically, the width of the center rib 21 in the tire width direction is W1, the width of the second rib 22 in the tire width direction is W2, and the portion of the shoulder rib located on the inner side in the tire width direction from the ground contact end 8 is shown. When the width in the tire width direction is W3, the difference in the ratio of W1, W2, and W3 to the contact width W that is the width in the tire width direction of the contact portion is 5% or less. That is, the center rib 21, the second rib 22, and the shoulder rib 23 are formed such that the difference between (W1 / W), (W2 / W), and (W3 / W) is 5% or less. These W1, W2, and W3 are the widths of the widest portion of the widths of the center rib 21, the second rib 22, and the shoulder rib 23 in the tire width direction, respectively.

  Further, the contact width W here means that the pneumatic tire 1 is in contact with the road surface when the pneumatic tire 1 is assembled to a regular rim, filled with a regular internal pressure and a regular load is applied. The width in the tire width direction. Here, the regular rim is “standard rim” defined by JATMA, “Design Rim” defined by TRA, or “Measuring Rim” defined by ETRTO. The normal internal pressure is “maximum air pressure” defined by JATMA, the maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO. However, in the case of the pneumatic tire 1 for passenger cars, it is 180 kPa. The normal load is “maximum load capacity” defined by JATMA, the maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “LOAD CAPACITY” defined by ETRTO. However, in the case of the pneumatic tire 1 for passenger cars, these loads are 88%.

  Further, the groove width of the center side main groove 11 and the groove width of the shoulder side main groove 12 are both formed within a range of 3 to 10% of the ground contact width W. That is, when the groove width in the tire width direction of the center side main groove 11 is Wa and the groove width in the tire width direction of the shoulder side main groove 12 is Wb, (Wa / W) and (Wb / W) are Both are within the range of 3 to 10%. The groove width Wa of the center side main groove 11 and the groove width Wb of the shoulder side main groove 12 are the groove widths of the widest portions of the groove widths of the main grooves 10.

  FIG. 2 is a detailed view of part A of FIG. Further, the second rib communication inclined groove 32 has a shoulder side end portion 36 which is an end portion on the shoulder side main groove 12 side rather than a groove width of the equatorial plane side end portion 35 which is an end portion on the center side main groove 11 side. The groove width is narrower. The second rib communicating inclined groove 32 is formed within a range where the groove width of the equatorial plane side end 35 is 2 to 8 mm, and the groove width of the equatorial plane side end 35 is Wka, and the shoulder side end When the groove width of 36 is set to Wkb, it is preferable that these relationships are formed so as to be in the range of 0.25 ≦ (Wkb / Wka) ≦ 0.9.

  When the pneumatic tire 1 according to the above embodiment is mounted on a vehicle and travels, the tread surface 5 contacts the road surface. At that time, although the ground load tends to be large in the central portion in the tire width direction, that is, in the vicinity of the equator plane 40, the center rib 21 is arranged in this portion. For this reason, the rigidity in the vicinity of the equator plane 40 is high, and the vicinity of the center of the tread surface 5 in the tire width direction is hardly deformed. Thereby, the stability at the time of driving the vehicle can be obtained.

  In addition, the main groove 10 formed along the tire circumferential direction includes two center side main grooves 11 and two shoulder side main grooves 12, for a total of four. When the vehicle travels, water may be present on the road surface such as in rainy weather, but even when traveling on such a wet road surface, the main groove 10 formed in the tire circumferential direction as described above. Since four are formed, the water located between the road surface and the tread surface 5 can be effectively drained by the four main grooves 10.

  Further, a center rib 21, a second rib 22, and a shoulder rib 23 are disposed on the tread surface 5, and the widths in the tire width direction are set to the same width. That is, the difference between the ratio of the width W1 of the center rib 21 to the ground width W, the ratio of the width W2 of the second rib 22 to the ground width W, and the ratio of the width W3 in the ground portion of the shoulder rib 23 to the ground width W. Is set to 5% or less. As a result, the difference in block rigidity between the land portions is reduced, so that the difference in the wear amount of the center rib 21, the second rib 22 and the shoulder rib 23 when the vehicle equipped with the pneumatic tire 1 travels is reduced. Thereby, the amount of uneven wear is less likely to occur. As a result, it is possible to improve both drainage and uneven wear resistance while ensuring steering stability.

  Further, since the center side main groove 11 is formed so that the arc-shaped groove 14 is continuously repeated in the tire circumferential direction, even when the tread surface 5 is grounded during traveling of the vehicle, the center side main groove 11 is grounded in the center side main groove 11. Since the frequency of the sound that is sometimes generated is dispersed, air column resonance is less likely to occur. As a result, it is possible to reduce noise during travel of the vehicle equipped with the pneumatic tire 1. Further, since the center side main groove 11 is formed in the shape as described above, the length of the portion where the groove wall 16 of the center side main groove 11 and the tread surface 5 intersect, that is, the center rib 21 and the second rib. 22, the length in the direction along the center-side main groove 11 of the end portion on the center-side main groove 11 side of the portion that actually contacts the road surface is such that the main groove 10 is formed in a straight shape. It is long compared. This part is formed as an edge because the tread surface 5 and the center side main groove 11 intersect, but this edge becomes longer, so the amount of edge increases and grips even when traveling on a wet road surface. It becomes easy. As a result, it is possible to improve the handling stability when traveling on a wet road surface.

  Further, since the center side main groove 11 has a see-through shape, when water flows into the center side main groove 11 to drain water between the tread surface 5 and the road surface, the center side main groove 11 The drainage resistance of the water flowing through can be reduced. Thereby, the water on the road surface is easily drained through the center-side main groove 11. As a result, drainage can be improved more reliably.

  The arc-shaped pitch length L in the tire circumferential direction of each arc-shaped groove 14 forming the center-side main groove 11 or the length L from the valley 15 to the valley 15 adjacent in the tire circumferential direction is the center. Since it is formed so as to be within a range of 2 to 5% of the entire circumferential length of the side main groove 11, it is possible to more reliably ensure steering stability and to reduce noise. That is, the center rib 21 and the second rib 22 adjacent to the center side main groove 11 are formed so that the side adjacent to the center side main groove 11 has irregularities in the tire width direction. By forming the length L up to 2% or more of the total circumferential length of the center-side main groove 11, it is possible to prevent the tire circumferential pitch of the unevenness from becoming too small. Thereby, the block rigidity of the part located in the center side main groove 11 vicinity in the center rib 21 or the second rib 22 can be ensured, and steering stability can be ensured. Further, by forming the length L from the valley portion 15 to the valley portion 15 to be 5% or less of the total circumference of the center-side main groove 11, it is generated in the center-side main groove 11 when the vehicle is traveling. It is possible to more reliably disperse the sound frequency and to suppress air column resonance more reliably. As a result, by forming the length L from the valley 15 to the valley 15 of the center side main groove 11 to be in the range of 2 to 5% of the total circumferential length of the center side main groove 11, more It is possible to reliably ensure steering stability and reduce noise.

  Further, since the groove width Wa of the center side main groove 11 and the groove width Wb of the shoulder side main groove 12 are both formed within a range of 3 to 10% with respect to the grounding width W, it is more reliable. In addition, it is possible to improve drainage while ensuring steering stability. That is, by forming these groove widths Wa and Wb to be 3% or more of the ground contact width W, it is possible to secure a groove width for easily draining water. In addition, by forming the groove widths Wa and Wb to be 10% or less of the ground contact width W, the groove width becomes too wide, so that each land portion adjacent to the center side main groove 11 or the shoulder side main groove 12 is. It can be suppressed that the size of the block becomes too small and the block rigidity is lowered. Accordingly, by forming the groove width Wa of the center-side main groove 11 and the groove width Wb of the shoulder-side main groove 12 so as to be within a range of 3 to 10% with respect to the ground contact width W, drainage performance is improved. It is possible to improve more reliably, and it is possible to obtain steering stability by suppressing a decrease in the block rigidity of the land portion. As a result, the drainage can be improved while ensuring the steering stability more reliably.

  In addition, since the second rib communication inclined groove 32 connected to both is provided between the center side main groove 11 and the shoulder side main groove 12, the center side main groove 11 and the shoulder side main groove 12 are arranged between the center side main groove 11 and the shoulder side main groove 12. Water can be flowed, and drainage can be improved more reliably. Further, since the groove width of the shoulder side end portion 36 of the second rib communication inclined groove 32 is narrower than the groove width of the equatorial plane side end portion 35, the second rib adjacent to the second rib communication inclined groove 32 is provided. The block rigidity on the outer side in the tire width direction in 22 can be improved. Thus, even when a load is applied outward in the tire width direction, such as during cornering, the load can be received with high rigidity. Thereby, the stability at the time of cornering can be improved. As a result, drainage performance and steering stability can be further improved.

  Further, since the second rib communication inclined groove 32 is inclined in the tire circumferential direction with respect to the tire width direction, the pneumatic tire 1 rotates between the center side main groove 11 and the shoulder side main groove 12. When the water flows through the second rib communication inclined groove 32, the water easily flows in the second rib communication inclined groove 32. That is, when water flows between the center side main groove 11 and the shoulder side main groove 12 while the pneumatic tire 1 rotates, the water proceeds simultaneously in the tire circumferential direction and the tire width direction. This water flows in an oblique direction with respect to the traveling direction of the vehicle. For this reason, the water flowing in the second rib communication inclined groove 32 can be made to flow easily by inclining the second rib communication inclined groove 32 in the tire circumferential direction with respect to the tire width direction. As a result, drainage can be improved more reliably.

  Further, since the groove width Wka of the equatorial plane side end portion 35 of the second rib communicating inclined groove 32 is formed within the range of 2 to 8 mm, the drainage performance is improved while ensuring the steering stability more reliably. Can be made. That is, by forming the groove width Wka of the equatorial plane side end portion 35 of the second rib communication inclined groove 32 to be 2 mm or more, water can easily flow into the second rib communication inclined groove 32. . Moreover, by forming the groove width Wka of the equatorial plane side end portion 35 of the second rib communication inclined groove 32 to be 8 mm or less, it is possible to suppress the groove width of the second rib communication inclined groove 32 from being excessively widened. It can be suppressed that the second rib 22 becomes too small and the block rigidity becomes too low due to the groove width of the rib communication inclined groove 32 becoming too wide. Accordingly, by forming the groove width Wka of the equatorial plane side end portion 35 of the second rib communication inclined groove 32 within the range of 2 to 8 mm, the drainage can be improved more reliably, The block rigidity of the rib 22 can be ensured. As a result, the drainage can be improved while ensuring the steering stability more reliably.

  The relationship between the groove width Wka of the equatorial plane side end portion 35 of the second rib communication inclined groove 32 and the groove width Wkb of the shoulder side end portion 36 is within the range of 0.25 ≦ (Wkb / Wka) ≦ 0.9. Therefore, the drainage performance can be improved while ensuring the steering stability more reliably. That is, by forming so that (Wkb / Wka) is 0.25 or more, it is possible to suppress the groove width Wkb of the shoulder side end portion 36 from becoming too narrow, and water can easily enter the second rib communication inclined groove 32. Can be made to flow. Further, by forming the (Wkb / Wka) to be 0.9 or more, the groove width of the shoulder side end portion 36 of the second rib communication inclined groove 32 becomes too wide. It is possible to suppress the block rigidity on the outer side in the tire width direction from becoming too low. Therefore, the relationship between the groove width Wka of the equatorial plane side end portion 35 of the second rib communication inclined groove 32 and the groove width Wkb of the shoulder side end portion 36 is within the range of 0.25 ≦ (Wkb / Wka) ≦ 0.9. By forming so that it becomes, drainage property can be improved more reliably and the block rigidity of the second rib 22 can be ensured. As a result, the drainage can be improved while ensuring the steering stability more reliably.

  The second rib communication inclined grooves 32 are arranged with a plurality of second rib communication inclined groove pitch lengths M each having a different length, and the shoulder rib inclined grooves 34 are formed with a plurality of shoulder rib inclined groove pitch lengths having different lengths. N. For this reason, when the pneumatic tire rolls, the interval when the second rib 22 or the shoulder rib 23 contacts the road surface or leaves the road surface is the second rib communication inclined groove pitch length M or the shoulder rib inclined groove pitch length. It depends on the length of N. Thereby, in the 1 round of the said pneumatic tire 1, the space | interval of the ground contact etc. to the road surface of the 2nd rib 22 or the shoulder rib 23 becomes a space | interval of several length. As described above, when the second rib 22 and the shoulder rib 23 are in contact with the road surface or separated from the road surface, a sound is generated. However, this sound has the same height when the intervals such as the ground contact are the same. , That is, a sound of the same frequency. Therefore, by setting the intervals such as the ground contact of the second rib 22 and the shoulder rib 23 to a plurality of lengths, a sound at the time of grounding to the road surface is not generated at a specific frequency, and a plurality of types of frequencies are generated. It is possible to suppress the generation of a sound having a specific frequency. As a result, pattern noise can be reduced.

  Further, the second rib communicating inclined groove 32 is formed so as to periodically repeat the second rib communicating inclined groove pitch length M, and the shoulder rib inclined groove 34 is configured to periodically repeat the shoulder rib inclined groove pitch length N. Is formed. Thereby, the frequency of the sound generated when the pneumatic tire rolls can be easily set. As a result, pattern noise can be more reliably reduced.

  Further, the second rib 22 and the shoulder rib 23 form one block pattern, and a plurality of lengths of the second rib communication inclined groove pitch length M and a plurality of lengths of the shoulder rib inclined groove pitch length N By forming the block pattern so as to have a plurality of shapes, the frequency of the sound generated when the pneumatic tire 1 rolls can be set more easily. As a result, pattern noise can be more reliably reduced.

  Further, since the shoulder rib inclined groove 34 is connected to the shoulder side main groove 12, the water flowing in the shoulder side main groove 12 when running on a wet road surface is caused to flow into the shoulder rib inclined groove 34, so that the shoulder rib inclined Water can be drained from the groove 34 in the outward direction in the tire width direction. Thereby, it is possible to easily drain water flowing in the shoulder side main groove 12. As a result, drainage can be improved more reliably.

  FIG. 3 is a diagram illustrating a modified example of the pneumatic tire according to the embodiment. In the pneumatic tire 1 described above, the center rib 21 is disposed at the center of the tread surface 5 in the tire width direction, and a groove or the like is formed on the center of the tire width direction or on the equator surface 40. However, if the opening area is small and the depth is shallow, the center rib 21 may be formed with a groove or a recess. For example, as shown in FIG. 3, the center rib 21 may be disposed at the center of the tread surface 5 in the tire width direction, and the auxiliary groove 50 formed along the tire circumferential direction may be provided in the center rib 21. The auxiliary groove 50 here has a groove depth that is 1.6 mm or more shallower than the groove depth of the main groove 10, and the groove width is the main groove having the widest groove width among the plurality of main grooves 10. A groove of 40% or less of the groove width of 10 Even when such an auxiliary groove 50 is formed in the center rib 21, the groove depth is shallow and the groove width is narrow. Therefore, the block rigidity of the center rib 21 is hardly lowered, and thus steering stability can be ensured. That is, if the groove or dent has substantially no influence on the block rigidity of the center rib 21, the center rib 21 may form such a groove or dent.

  Further, the second rib communication inclined groove 32 and the shoulder rib inclined groove 34 are not provided such that the second rib communication inclined groove pitch length M and the shoulder rib inclined groove pitch length N are periodically repeated, and the second ribs having different lengths are provided. The communication inclined groove pitch length M and the shoulder rib inclined groove pitch length N may be provided at random. Further, the second rib communication inclined groove 32 and the shoulder rib inclined groove 34 are related to each other by the second rib communication inclined groove pitch length M and the shoulder rib inclined groove pitch length N. The second rib communicating inclined groove pitch length M of the second rib communicating inclined groove 32 and the shoulder rib inclined groove pitch length N of the shoulder rib inclined groove 34 may be independent of each other without forming a block pattern. Good. Even when the second rib communication inclined groove 32 and the shoulder rib inclined groove 34 are formed as described above, the plurality of second rib communication inclined groove pitch lengths M having different lengths and the shoulder rib inclined groove pitches having different lengths are used. By forming with a length N, pattern noise can be reduced.

  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 performance evaluation test was conducted on three items: steering stability, uneven wear resistance, and drainage.

  The test method is as follows. The 205 / 50R16 size pneumatic tire 1 is assembled to a 16 × 6.5JJ rim, the internal pressure is set to 180 kPa, and the vehicle is mounted on a rear-wheel drive vehicle with an engine displacement of 1800 cc. Made by letting. The evaluation method of each test item is as follows. Regarding the steering stability, the vehicle runs on a paved road including a wet road surface, and the steering stability at that time is evaluated by the feeling of the driver. The steering stability of Comparative Example 3 was evaluated with an index of 100. The larger the index, the better the steering stability. The uneven wear resistance was evaluated by an index in which the uneven wear resistance of Comparative Example 2 described later was set to 100, after traveling 8000 km on the paved road with the above vehicle and measuring the amount of uneven wear. The larger the index, the better the uneven wear resistance. The drainage is evaluated by straight-forward hydroplaning performance. Specifically, the vehicle enters the hydro pool having a water depth of 10 mm ± 1 mm at high speed, and the speed is compared when the tire slip rate reaches 10%. This result was evaluated by an index with the drainage of Comparative Example 3 described later as 100. The larger the index, the better the drainage.

  The pneumatic tire 1 to be tested is tested by the above method for six types of the present invention and four types of comparative examples to be compared with the present invention. Among each evaluation test, the comparative example 1 and this invention 1 are compared in the evaluation test about steering stability. In the evaluation test for uneven wear resistance, Comparative Example 2 and Inventions 2 and 3 are compared. Moreover, in the evaluation test about drainage, the comparative examples 3 and 4 and this invention 4-6 are compared, and also in this test, the steering stability at the time of drive | working on the wet road surface is also evaluated. Yes.

  Among the pneumatic tires 1 that perform the evaluation test as described above, the pneumatic tires 1 of the present invention 1 to 6 include a center side main groove 11, a shoulder side main groove 12, a second rib communication inclined groove 32, and a shoulder rib inclination. A groove 34 is formed. The groove width of each of these groove portions is 9.2 mm for the center side main groove 11, 8.9 mm for the shoulder side main groove 12, and the equatorial plane side end of the second rib communicating inclined groove 32. The groove width Wka of the portion 35 is 4 mm, and the groove width Wkb of the shoulder side end portion 36 of the second rib communication inclined groove 32 is 1.5 mm. The groove depth of each groove portion is 8 mm for both the center side main groove 11 and the shoulder side main groove 12, and both the second rib communication inclined groove 32 and the shoulder rib inclined groove 34 are 6.3 mm. Further, the inclination angle of the second rib communication inclined groove 32 and the shoulder rib inclined groove 34 in the tire width direction with respect to the tire circumferential direction is 55 ° for the second rib communication inclined groove 32 and 72 ° for the shoulder rib inclined groove 34. Yes. Each of these numerical values is a numerical value in the pneumatic tire 1 subjected to the evaluation test, and each numerical value of the pneumatic tire 1 according to the present invention is not limited to these numerical values.

  Further, the pneumatic tire 1 of Comparative Example 1 for performing the steering stability evaluation test is provided with a center groove in the tire width direction of the tread surface 5 or a center groove formed on the equator surface 40 along the tire circumferential direction. It has been. On the other hand, in the first aspect of the present invention, no center groove is formed in the center portion in the tire width direction, and the center rib 21 is disposed in this portion.

  Moreover, the comparative example 2 which performs the evaluation test of uneven wear resistance and the pneumatic tire 1 of the present invention 2 and 3 are provided with a center rib 21, a second rib 22 and a shoulder rib 23. However, the ratio of the width in the tire width direction of these land portions to the ground contact width is different. The ratio of the width of these land portions is (W1 in the comparative example 2 when the width of the center rib 21 is W1, the width of the second rib 22 is W2, the width of the shoulder rib 23 is W3, and the ground contact width is W. / W) is 10%, (W2 / W) is 18%, and (W3 / W) is 15%. On the other hand, in the present invention 2, (W1 / W) is 16%, (W2 / W) is 15%, and (W3 / W) is 15%. In the present invention 3, (W1 / W) Is 12%, (W2 / W) is 17%, and (W3 / W) is 15%.

  In addition, the pneumatic tires 1 of Comparative Examples 3 and 4 that perform the drainage and steering stability evaluation tests on wet road surfaces are provided with a plurality of main grooves 10 as in the pneumatic tires 1 to 6 of the present invention. Is formed. The plurality of main grooves 10 are different in the ratio of the groove width in the tire width direction to the contact width W for each pneumatic tire 1. Further, in the pneumatic tire 1 of Comparative Example 3, in addition to the center side main groove 11 and the shoulder side main groove 12, a center groove is formed at the center in the tire width direction.

  The ratio of the groove width of the main groove 10 to the ground width W is defined as Wa for the center-side main groove 11 and Wb for the shoulder-side main groove 12, and the groove width of the center groove of Comparative Example 3 Is Wc, in Comparative Example 3, (Wc / W) is 8%, (Wa / W) is 7%, and (Wb / W) is 1%. In Comparative Example 4, (Wa / W) is 6% and (Wb / W) is 6%. On the other hand, in the present invention 4, (Wa / W) is 6% and (Wb / W) 6%, and in the present invention 5, (Wa / W) is 8% and (Wb / W) 4. In the sixth aspect of the present invention, (Wa / W) is 6% and (Wb / W) is 6%. In Comparative Example 3 and Inventions 4 to 6, the arc-shaped groove 14 is formed in the main groove 10, but in Comparative Example 4, the arc-shaped groove 14 is not formed in the main groove 10. Furthermore, in the comparative example 3 and the present inventions 4 and 5, the main groove 10 in which the arc-shaped groove 14 is formed is see-through, but in the present invention 6, the main groove 10 in which the arc-shaped groove 14 is formed is a see-through. It is not.

  These comparative examples 1 to 4 and pneumatic tires 1 of the present invention 1 to 6 are subjected to an evaluation test by the above method, and the obtained results are shown in Tables 1 to 3. Table 1 shows the test results of Comparative Example 1 and Invention 1, Table 2 shows the test results of Comparative Example 2 and Inventions 2 and 3, and Table 3 shows the Comparative Example. 3 and 4 and the test results of the present invention 4 to 6 are displayed.

  As is apparent from the above test results shown in Table 1, when a groove formed in the tire circumferential direction is provided in the center portion of the tread surface 5 in the tire width direction, the rigidity in the vicinity of the tire center portion decreases. Therefore, good steering stability cannot be obtained (Comparative Example 1). Further, as apparent from the test results shown in Table 2, when the width in the tire width direction of each land portion formed on the tread surface 5 is greatly different for each land portion, the land portion is accordingly accompanied. Since the block rigidity is greatly different, uneven wear is likely to occur (Comparative Example 2).

  Further, as is clear from the test results shown in Table 3, when there is a main groove whose groove width is significantly narrower than the other main grooves 10 among the plurality of main grooves 10, Since the amount of drained water is reduced, drainage cannot be improved (Comparative Example 3). Further, when the arc-shaped groove 14 is not formed in the main groove 10, the length of the edge, which is a portion where the wall surface of the main groove 10 and the tread surface 5 intersect, does not become long. The steering stability cannot be improved (Comparative Example 4).

  On the other hand, steering stability can be improved by not providing a groove | channel in the center part in a tire width direction but providing the center rib 21 as mentioned above (Invention 1). Further, the width in the tire width direction of the plurality of land portions formed on the tread surface 5 is all the same, specifically, the difference in the ratio with respect to the contact width W is 5% or less. Therefore, uneven wear can be suppressed (inventions 2 and 3). In addition, the groove widths in the tire width direction of the plurality of main grooves 10 formed are all the same, specifically, the ratio of the ratio to the ground contact width W is within the range of 3 to 10%. In addition, by forming the arc-shaped groove in the main groove 10, it is possible to improve the steering stability when traveling on a wet road surface (Inventions 4 to 6). Furthermore, by making the main groove 10 having the arc-shaped groove 14 see-through, the drainage can be more reliably improved (Inventions 4 and 5).

  Therefore, a center rib 21 is provided at the center of the tread surface 5 in the tire width direction, and the difference in the width of the plurality of land portions in the tire width direction compared with the ratio of the width of the land portion to the ground contact width W is different. By forming the arc-shaped groove 14 in the main groove 10 so as to be 5% or less, stability during traveling of the vehicle can be ensured and uneven wear can be reduced, and water flows into the main groove 10. Can be made easier. As a result, it is possible to improve both drainage and uneven wear resistance while ensuring steering stability.

  In the above description, the pneumatic tire 1 having a rib-based tread pattern is described as an example of the pneumatic tire 1. However, the pneumatic tire 1 to which the present invention is applied may be other than the rib-based tread pattern. For example, a rib lug pattern or a block pattern may be used. The pattern shape of the tread surface 5 is not limited as long as the tread pattern has a plurality of main grooves 10 formed at least along the tire circumferential direction.

  As described above, the pneumatic tire according to the present invention is mainly useful for a pneumatic tire to be mounted on a vehicle traveling on a paved road, and in particular, when handling stability, drainage, and uneven wear resistance are both achieved. Suitable for

It is a figure which shows the tread part of the pneumatic tire which concerns on this invention. FIG. 2 is a detailed view of part A in FIG. 1. It is a figure which shows the modification of the pneumatic tire of embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 4 Tread part 5 Tread surface 8 Grounding end 10 Main groove 11 Center side main groove 12 Shoulder side main groove 14 Arc-shaped groove 15 Valley part 16 Groove wall 17 Groove wall 21 Center rib 22 Second rib 23 Shoulder rib 32 Second rib Communication inclined groove 33 Second rib closed inclined groove 34 Shoulder rib inclined groove 35 Equatorial plane side edge 36 Shoulder side edge 40 Equatorial plane 50 Auxiliary groove

Claims (8)

In a pneumatic tire in which a plurality of land portions are partitioned by a plurality of groove portions formed on a tread surface which is a surface of a tread portion,
A center land portion of the plurality of land portions is located at a center portion in the tire width direction of the tread surface,
Among the plurality of groove portions, the groove portions adjacent to both ends of the center land portion in the tire width direction have arc-shaped grooves formed along the tire circumferential direction while being curved in the tire width direction. It is formed as an arc-shaped curved main groove formed to repeat,
Among the plurality of land portions, the land portion adjacent to the outer side in the tire width direction of the arc-shaped curved main groove is formed as a second land portion,
Of the plurality of groove portions, the groove portion adjacent to the outer side in the tire width direction of the second land portion is formed with a groove width equal to the groove width of the arc-shaped curved main groove, and along the tire circumferential direction. Formed as a formed second main groove,
Of the plurality of land portions, the land portion adjacent to the outer side in the tire width direction of the second main groove is a shoulder land portion formed from the second main groove to an end portion in the tire width direction of the tread surface. Is formed as
Of the plurality of groove portions, the arc-shaped curved main groove adjacent to the second land portion is formed from the arc-shaped curved main groove to the second main groove, and the arc-shaped curved main groove and the second main groove are connected to each other. The groove is formed as a second land lug groove,
The second land portion lug groove portion is adjacent to the second land portion, and the groove width of the end portion on the second main groove side is larger than the groove width of the end portion on the arcuate curved main groove side. Is narrower,
Of the plurality of grooves, the groove formed from the second main groove outward in the tire width direction is formed as a shoulder lug groove,
In the shoulder land portion, a ground contact end that is an end portion in the tire width direction of a ground contact portion that is a portion that is filled with air with a normal internal pressure and is loaded with a normal load is located in the tread surface. And
The width in the tire width direction of the center land portion, the width in the tire width direction of the second land portion, and the width in the tire width direction from the end on the second main groove side of the shoulder land portion to the ground contact end Is formed so that the difference when compared with the ratio to the contact width that is the width in the tire width direction of the contact portion is 5% or less ,
Among the second land portion lug groove portions, the interval between the second land portion lug groove portions adjacent in the tire circumferential direction is the second land portion lug groove portion pitch length, and the second land portion lug groove portion is , Each of the second land portion lug groove portion pitch length different from each other is arranged,
Among the shoulder portion lug groove portions, the interval between the shoulder portion lug groove portions adjacent in the tire circumferential direction is a shoulder portion lug groove portion pitch length, and the shoulder portion lug groove portions each have a plurality of different lengths. It is arranged by the shoulder part lug groove part pitch length,
The second land portion lug groove portion and the shoulder portion lug groove portion adjacent to the second land portion or the shoulder land portion adjacent via the second main groove,
The second land portion located within one or a plurality of continuous second land portion lug groove pitch lengths;
The said shoulder land part located in the range of the said some shoulder part lug groove part pitch length which has the part from which the position in the tire circumferential direction and the said 2nd land part becomes the same position as said one land part pattern A pneumatic tire, wherein a plurality of land portion patterns are provided . 2. The pneumatic tire according to claim 1 , wherein the second land portion lug groove portion is formed to be inclined in a tire circumferential direction with respect to a tire width direction. The second land portion lug groove portion has a groove width Wka at the end on the arcuate curved main groove side within a range of 2 to 8 mm, and a groove width Wka at the end on the arcuate curved main groove side. according to claim 1 or 2 relationship between the groove width WKB end of the second main groove side, characterized in that it is in the range of 0.25 ≦ (Wkb / Wka) ≦ 0.9 and Pneumatic tires. The arcuate curved main grooves are pneumatic tire according to any one of claims 1 to 3, characterized in that it is formed by a see-through in the tire circumferential direction. Wherein A arcuate curved main grooves and the second main groove, either both groove width of claims 1-4, characterized in that it is formed in a range of 3-10% with respect to the contact width The pneumatic tire according to claim 1. In the arc-shaped curved main groove, the arc-shaped pitch length in the tire circumferential direction of each arc-shaped groove forming the arc-shaped curved main groove is in the range of 2 to 5% of the total circumferential length of the arc-shaped curved main groove. the pneumatic tire according to any one of claims 1 to 5, characterized in that it is formed Te. The second land portion lug groove portion is provided such that a plurality of the second land portion lug groove portion pitch lengths having different lengths are periodically repeated in the tire circumferential direction,
The shoulder portion lug groove, either one of claims 1 to 6, a plurality of the shoulder portion lug groove pitch lengths having different respective lengths, characterized in that it is provided as periodically repeated in the tire circumferential direction The pneumatic tire according to item 1 . The pneumatic tire according to any one of claims 1 to 7 , wherein the shoulder lug groove portion is connected to the second main groove.

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