JP2005153654A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving drainability when the tire is new and improving acceleration, brake performance and maneuvering stability on a dry road surface without replacing the tire by increasing actual grounding area of the tire and the road surface according to the state of the road surface when the road surface begins to dry. <P>SOLUTION: A plurality of lateral main grooves 14 inclined from a grounding end 12E in a tire peripheral direction are provided on both sides of tire equatorial plane of a tread 12. A zigzag center main groove 26 is formed at the center of the tread 12 by connecting a tire equatorial plane side end part of the lateral main groove 14 on one side in relation to the tire equatorial plane to a longitudinal direction intermediate part of the lateral main groove 14 on the other side in relation to a tire equatorial plane and connecting a tire equatorial plane side end part of the lateral main groove 14 on the other side to a longitudinal direction intermediate part of the lateral main groove 14 on the one side. A chamfering part 28 which does not reach a groove bottom of the lateral main groove 14 is formed at a block edge part facing to the zigzag center main groove 26. A wide peripheral main groove 32 is integrally formed in the zigzag center main groove 26 by interposing the zigzag center main groove 26. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire, and in particular, when it is new, it improves wet drainage, and when the road surface begins to dry, the tire is replaced by increasing the actual contact area between the tire and the road surface according to the road surface condition. The present invention relates to a pneumatic tire that has improved acceleration, braking performance, and handling stability on a dry road surface without having to.

  Conventionally, in order to improve wet drainage on wet road surfaces, methods such as increasing the negative rate, expanding the width of the circumferential main groove continuous in the circumferential direction, and increasing the inclination angle of the inclined lateral groove (for example, Patent Documents 1 to 9).

  However, since the actual contact area with respect to the road surface of the tire is greatly reduced in any of the above means, as the road surface dries, the block rigidity is small with respect to the reaction force increase from the road surface, and therefore, uneven wear occurs on the outside of the block, There was a problem that acceleration performance, brake performance and steering stability deteriorated.

  Conventionally, in order to improve steering stability on a dry road surface with little rainfall, the negative main body is reduced, the width of the circumferential main groove continuous in the circumferential direction is reduced or the circumferential main groove is removed, and the inclination angle of the inclined lateral groove is increased. The method of reduction etc. was taken.

However, the above-described means has a problem that the drainage performance of the tread tread surface portion is deteriorated, the rainfall is large, and the drainage performance on the wet road surface and the steering stability are lowered.
JP 54-38005 JP-A-60-197409 JP-A-61-92902 JP-A-7-186628 JP-A-7-195911 JP 2000-177321 A WO9727070 Patent 3046818 Patent 3046810

  The present invention has been made to solve the above-mentioned problems. When new, the wet drainage is improved, and when the road surface starts to dry, the actual contact area between the tire and the road surface is increased in accordance with the road surface condition. Accordingly, it is an object of the present invention to provide a pneumatic tire that can improve acceleration, braking performance and steering stability on a dry road surface without exchanging the tire.

  According to the first aspect of the present invention, a plurality of treads are arranged on both sides of the tire equatorial plane at intervals in the tire circumferential direction and extend from the tread grounding end toward the tire equatorial plane, and at the end of the tire equatorial plane side. A pneumatic tire having a horizontal main groove that is inclined with respect to the tire circumferential direction so as to come into contact with the tire from the tire equatorial plane, the tire equatorial plane side end of the horizontal main groove on one side with respect to the tire equatorial plane Is connected to the longitudinal intermediate portion of the transverse main groove on the other side, and the tire equatorial plane side end of the transverse main groove on the other side is connected to the longitudinal intermediate portion of the transverse main groove on the one side. Thus, a plurality of short portions between the tire equatorial plane side end portion of the horizontal main groove and the connecting portions of the horizontal main grooves are connected in the tire circumferential direction at the center in the width direction of the tread. Zigzag central main groove extending in a zigzag shape The zigzag central main groove has a plurality of blocks arranged on the both sides in the tire width direction, and the first chamfered portion that does not reach the groove bottom of the horizontal main groove is disposed in the zigzag central main groove. By forming the edge of the block on both sides of the tire equatorial plane facing the groove, the first chamfered portion is used as a groove wall and the chamfered depth is the groove depth, and the tire is formed via the zigzag central main groove. A wide circumferential main groove extending continuously in the circumferential direction is formed integrally with the zigzag central main groove.

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

  When running on a wet road with new tires, water between the tread tread and the road is drained outside the tread tread through the horizontal main groove, and the water near the center of the tread tread is wide. It flows into the main groove and zigzag central main groove and is drained outside the tread surface.

  Since the tread pattern of this pneumatic tire is a directional pattern due to the horizontal main groove, when running on a wet road surface, a water flow is always generated in the horizontal main groove from the central region of the tread to both side regions. Thus, the water in the tread surface can be always drained outside the tread surface, and high wet performance can be obtained.

  The wide circumferential main groove formed at the edge of the block on both sides of the tire equatorial plane has the first chamfered portion that does not reach the bottom of the horizontal main groove as the groove wall and the chamfering depth is the groove depth. For example, the drainage performance is improved from the beginning of new wear to the beginning of wear where the circumferential main groove exists, and the wide circumferential main groove disappears. For example, the negative rate decreases after the middle wear of the tread (actual ground contact area increases), and the dry Steering stability can be improved.

  In addition, since the first chamfered portion that does not reach the groove bottom of the horizontal main groove is formed at the edge of the block on both sides of the tire equatorial plane facing the zigzag central main groove, the rigidity of the block forming the chamfered portion increases. In addition, the driving stability on the dry road surface is improved, and the uneven wear property at the substantially central portion in the tire axial direction of the tread surface is improved.

  In the pneumatic tire according to claim 1, with the above configuration, when the tire is new, the wet performance is emphasized, and as the tire wears, the wet performance is decreased and the dry performance is emphasized. In particular, a process in which the road surface before the completely dry road surface dries from the situation where the water level on the road surface is relatively large due to the climatic conditions (for example, from rainy weather to sunny weather) This is suitable for continuous use without exchanging tires in such an unstable situation change that changes to (2). In such a case, stable steering stability can always be exhibited.

  When the road surface dries in competition running, the wet tire is usually replaced with a dry tire at a certain point. However, with the pneumatic tire of the present invention, the performance from the wet emphasis to the dry emphasis is one. Since it changes, there is no need to change tires, and there is no time loss required for changing tires, so the running time can be greatly reduced.

  According to a second aspect of the present invention, in the pneumatic tire according to the first aspect, at least a pair of both-side circumferential mains extending on the both sides of the zigzag central main groove and extending along the tire circumferential direction while intersecting the lateral main groove. A groove is disposed, and the angle of the surface of the groove wall on the outer side in the tire axial direction with respect to the normal line standing on the tread surface is set within a range of 0 ° to 25 °, and the tire shaft with respect to the normal line The angle at the tread tread surface opening portion of the groove wall on the inner side in the direction is larger than the angle of the surface of the groove wall on the outer side in the tire axial direction, and is set in the range of 20 ° to 80 °.

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

  When running on a wet road surface, water in the region between the zigzag central main groove and the tread ground contact end is discharged to the outside of the tread surface by the two circumferential main grooves, so that the wet performance is further improved.

  Here, the circumferential groove on both sides is a groove on the inner side in the tire axial direction with respect to the normal line by setting the angle of the surface of the groove wall on the outer side in the tire axial direction to the normal line standing on the tread surface. The angle at the tread tread opening portion of the wall is set larger than the angle of the surface of the groove wall on the outer side in the tire axial direction and within the range of 20 ° to 80 °. It can be minimized.

  In addition, when the angle of the surface of the groove wall on the outer side in the tire axial direction with respect to the normal is smaller than 0 °, the block rigidity on the outer side in the tire axial direction is greatly reduced, the cornering performance is deteriorated, and the uneven wear property is deteriorated. It is.

  When the angle of the surface of the groove wall on the outer side in the tire axial direction with respect to the normal is larger than 25 °, the groove volume of the circumferential main grooves on both sides is insufficient, and the drainage of the region between the zigzag central main groove and the tread ground contact edge I can't expect any improvement.

  When the angle at the tread tread surface opening portion of the groove wall on the inner side in the tire axial direction with respect to the normal line is less than 20 °, the block rigidity on the inner side in the tire axial direction of the circumferential main grooves on both sides is lowered, and the dry steering stability is lowered.

  On the other hand, if the angle at the tread tread opening portion of the groove wall on the inner side in the tire axial direction with respect to the normal exceeds 80 °, the groove volume of the circumferential main grooves on both sides is insufficient, and the region between the zigzag central main groove and the tread ground contact edge I cannot expect improvement of drainage.

  The invention according to claim 3 is the pneumatic tire according to claim 2, wherein the circumferential main grooves are substantially parallel to the tire circumferential direction at the edge of the groove wall on the inner side in the tire axial direction. The edge of the groove wall on the outer side in the tire axial direction is inclined in the same direction as the adjacent horizontal main groove, and the inclination angle with respect to the tire circumferential direction is set to be smaller than the inclination angle of the horizontal main groove, and kicks more than the stepping side. A feature is that the groove width on the delivery side is set large.

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

  In both circumferential main grooves, the edge of the groove wall on the inner side in the tire axial direction is substantially parallel to the tire circumferential direction, and the edge of the groove wall on the outer side in the tire axial direction is inclined in the same direction as the adjacent horizontal main groove. In addition, by setting the inclination angle with respect to the tire circumferential direction smaller than the inclination angle of the horizontal main groove and further setting the groove width on the kicking side larger than the stepping side, water is efficiently supplied to the adjacent horizontal main groove It can flow.

  According to a fourth aspect of the present invention, in the pneumatic tire according to the second or third aspect, the both-side circumferential main grooves disappear when 85 ± 5% of the tread is worn.

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

  In the pneumatic tire according to claim 4, when the tread is 85% ± 5% worn, the main grooves on both sides disappear, the negative rate of the tread is reduced, and the dry performance is improved.

  Here, in the present invention, the time of 100% wear of the tread means the time when the horizontal main groove disappears (the groove depth is zero).

  According to a fifth aspect of the present invention, in the pneumatic tire according to any one of the second to fourth aspects, the zigzag central main groove and the circumferential main grooves on both sides are provided at least on one side of the tire equatorial plane. An intermediate circumferential main groove extending along the tire circumferential direction is provided therebetween, and the intermediate circumferential main groove has an angle of the surface of the groove wall on the outer side in the tire axial direction with respect to a normal line standing on the tread surface between 0 ° and 25 °. The angle at the tread tread surface opening portion of the groove wall on the inner side in the tire axial direction with respect to the normal is larger than the angle of the surface of the groove wall on the outer side in the tire axial direction, and 20 ° to 80 °. The groove wall on the inner side in the tire axial direction is substantially parallel to the tire circumferential direction, the groove wall on the outer side in the tire axial direction is inclined in the same direction as the adjacent horizontal main groove, and The inclination angle with respect to the direction is the inclination of the horizontal main groove Angle smaller set than further, the groove width of the side out kicking than leading side is set larger, it is characterized in that.

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

  When running on a wet road surface, water in the region between the zigzag central main groove and both side peripheral main grooves is discharged out of the tread surface by the intermediate peripheral main groove, so that the wet performance is further improved.

  Here, the intermediate circumferential main groove is a groove on the inner side in the tire axial direction with respect to the normal line by setting the angle of the surface of the groove wall on the outer side in the tire axial direction to the normal line standing on the tread surface. The angle at the tread tread opening portion of the wall is set larger than the angle of the surface of the groove wall on the outer side in the tire axial direction and within the range of 20 ° to 80 °. It can be minimized.

  In addition, when the angle of the surface of the groove wall on the outer side in the tire axial direction with respect to the normal is smaller than 0 °, the block rigidity on the outer side in the tire axial direction is greatly reduced, the cornering performance is deteriorated, and the uneven wear property is deteriorated. It is.

  When the angle of the surface of the groove wall on the outer side in the tire axial direction with respect to the normal line is larger than 25 °, the groove volume of the intermediate circumferential main groove is insufficient, and the region between the zigzag central main groove and the both side circumferential main grooves Improve drainage performance.

  When the angle at the tread tread surface opening portion of the groove wall on the inner side in the tire axial direction with respect to the normal is less than 20 °, the block rigidity on the inner side in the tire axial direction of the intermediate circumferential main groove is lowered, and the dry steering stability is lowered.

  On the other hand, if the angle at the tread tread surface opening portion of the groove wall on the inner side in the tire axial direction with respect to the normal exceeds 80 °, the groove volume of the intermediate circumferential main groove is insufficient, and the gap between the zigzag central main groove and the circumferential main grooves on both sides is insufficient. The drainage of the area cannot be improved.

  The invention according to claim 6 is the pneumatic tire according to any one of claims 1 to 5, wherein the wide circumferential main groove has a smaller amplitude than the zigzag central main groove. It is said.

  Next, the operation of the pneumatic tire according to claim 6 will be described.

  If the amplitude of the wide circumferential main groove is smaller than the amplitude of the zigzag central main groove, there will be a see-through groove continuous in the circumferential direction near the tire surface of the wide circumferential main groove, and the width of the see-through groove will be further increased. As a result, the drainage at the center of the tread is further improved.

  The invention according to claim 7 is the pneumatic tire according to any one of claims 1 to 6, wherein the surface shape of the first chamfered portion is a change in the zigzag shape of the zigzag central main groove. It is characterized by the fact that it has a substantially triangular shape with the vertices at the vertices.

  Next, the operation of the pneumatic tire according to claim 7 will be described.

  When the surface shape of the first chamfered portion has a substantially triangular shape with the zigzag inflection point of the zigzag central main groove as a vertex, water in the wide circumferential main groove flows smoothly along the tire circumferential direction. The drainage of the tread center is improved.

  The invention according to claim 8 is the pneumatic tire according to claim 7, wherein the ridge line between the first chamfered portion and the tread surface is set substantially parallel to the tire circumferential direction, The wide circumferential main groove extends in a straight line in the tire circumferential direction.

  Next, the operation of the pneumatic tire according to claim 8 will be described.

  When the ridge line between the first chamfered portion and the tread surface is set substantially parallel to the tire circumferential direction, and the wide circumferential main groove extends straight in the tire circumferential direction, Water flows more smoothly along the tire circumferential direction, and the drainage of the tread center is further improved.

  According to a ninth aspect of the present invention, in the pneumatic tire according to any one of the first to eighth aspects, the tire equator extends from the tread ground contact edge between the lateral main grooves adjacent to each other in the tire circumferential direction. A transverse sub-groove that extends toward the surface and is not connected to the transverse main groove is provided.

  Next, the operation of the pneumatic tire according to claim 9 will be described.

  When running on a wet road surface, water between the horizontal main grooves is discharged to the tread grounding end side through the horizontal sub-grooves, and the wet performance is further improved.

  According to a tenth aspect of the present invention, in the pneumatic tire according to any one of the first to ninth aspects, a second chamfered portion is formed at a stepped-side tip portion of the block. It is a feature.

  Next, the operation of the pneumatic tire according to claim 10 will be described.

  By forming the second chamfered portion at the stepped-side tip of the block, the block rigidity of the stepped-side tip of the block can be improved, and the steering stability and uneven wear on the dry road surface can be improved.

  According to an eleventh aspect of the present invention, in the pneumatic tire according to any one of the first to tenth aspects, the groove wall of the zigzag central main groove has an angle with respect to a normal line standing on the tread surface. It is characterized by being set within the range of ° to 85 °.

  Next, the operation of the pneumatic tire according to claim 11 will be described.

  In the pneumatic tire according to claim 11, the angle of the surface of the groove wall of the zigzag central main groove is set to 30 ° to 85 °, which is set larger than the angle of the surface of the groove wall of a general groove. The increase in the actual contact area with the road surface in the central region of the tread due to the progress of the wear is remarkably increased as compared with the conventional case, and the steering stability, acceleration performance, and brake performance are further improved by the wear of the tread.

  The invention according to claim 12 is the pneumatic tire according to any one of claims 1 to 11, wherein the tread has a negative rate in the range of 45% to 55% when new, 50% The negative rate at the time of wear is set within a range of 25 to 35%, and the negative rate at the time of 80% wear is set within a range of 15% to 25%.

  Next, the operation of the pneumatic tire according to claim 12 will be described.

  When the negative rate at the time of new article is set within the range of 45% to 55%, the negative rate at the time of 50% wear is set within the range of 25 to 35%, and the negative rate at the time of 80% wear is set within the range of 15% to 25%. Since the negative rate is relatively large at the initial stage of tire use, high wet drainage is obtained.

  Continued running, the amount of water on the road surface decreases, and the tread tread surface wears rapidly. When the negative rate of the entire tread tread portion decreases, the actual contact area with the road surface increases and the block rigidity increases. In addition, stable steering stability, grip, acceleration performance, and braking performance can be exhibited.

  In addition, when the negative rate at the time of a new tire is smaller than 45%, the groove volume of the whole tread is insufficient and the wet drainage is insufficient.

  If the negative rate when the tire is new is greater than 60%, the actual contact area with the road surface of the entire tread is insufficient, the grip with the road surface is insufficient, and the steering stability is lowered.

  When the negative rate at the time of 50% wear is smaller than 25%, the groove volume of the entire tread is insufficient, and wet drainage is reduced.

  Further, when the negative rate at 50% wear is larger than 35%, the actual contact area with the road surface of the entire tread is insufficient, the grip with the road surface is insufficient, and the steering stability is lowered.

  When the negative rate at 80% wear is less than 15%, wet drainage is insufficient.

  When the negative rate at 80% wear is larger than 25%, the actual contact area with the road surface of the entire tread is insufficient, the grip with the road surface is insufficient, and the steering stability is lowered.

  The pneumatic tire according to claim 13 is provided on the tread with at least a pair of both-side circumferential main grooves disposed on both sides of the tire equatorial plane and extending along the tire circumferential direction, and spaced in the tire circumferential direction on both sides of the tire equatorial plane. Are arranged to extend from the tread grounding end toward the tire equatorial plane so as to intersect the both-side circumferential main grooves and to be grounded from the end side on the tire equatorial plane side. And a horizontal main groove having a groove depth deeper than the both-side circumferential main grooves, and is defined by the both-side circumferential main grooves and the horizontal main grooves on the outer side in the tire width direction of the both-side circumferential main grooves. A pneumatic tire in which a plurality of blocks are arranged, wherein the angle of the surface of the groove wall on the outer side in the tire axial direction with respect to the normal line standing on the tread surface is within the range of 0 ° to 25 ° Set and tire against said normal The angle in the tread tread surface opening portion of the groove wall on the inner side in the axial direction is larger than the angle of the surface of the groove wall on the outer side in the tire axial direction, and is set in a range of 20 ° to 80 °. .

  Next, the operation of the pneumatic tire according to claim 13 will be described.

  When running on a wet road with new tires, water between the tread tread and the road is drained outside the tread tread through the horizontal main groove, and the water near the center of the tread tread is wide. It flows into the main groove and zigzag central main groove and is drained outside the tread surface.

  Since the tread pattern of this pneumatic tire is a directional pattern due to the horizontal main groove, when running on a wet road surface, a water flow is always generated in the horizontal main groove from the central region of the tread to both side regions. Thus, the water in the tread surface can be always drained outside the tread surface, and high wet performance can be obtained.

  Since the circumferential groove on both sides is shallower than the transverse main groove, if the wear of the tread progresses, the transverse main groove remains but the circumferential main grooves on both sides disappear, and the negative rate decreases and dry handling stability is reduced. Can be improved.

  Here, the circumferential groove on both sides is a groove on the inner side in the tire axial direction with respect to the normal line by setting the angle of the surface of the groove wall on the outer side in the tire axial direction to the normal line standing on the tread surface. The angle at the tread tread opening portion of the wall is set larger than the angle of the surface of the groove wall on the outer side in the tire axial direction and within the range of 20 ° to 80 °. It can be minimized.

  The pneumatic tire according to claim 13 has the above-described configuration, so that the wet performance is emphasized when it is new, and the dry performance is emphasized by decreasing the wet performance as it wears. In particular, a process in which the road surface before the completely dry road surface dries from the situation where the water level on the road surface is relatively large due to the climatic conditions (for example, from rainy weather to sunny weather) This is suitable for continuous use without exchanging tires in such an unstable situation change that changes to (2). In such a case, stable steering stability can always be exhibited.

  When the road surface dries in competition running, the wet tire is usually replaced with a dry tire at a certain point. However, with the pneumatic tire of the present invention, the performance from the wet emphasis to the dry emphasis is one. Since it changes, there is no need to change tires, and there is no time loss required for changing tires, so the running time can be greatly reduced.

  In addition, when the angle of the surface of the groove wall on the outer side in the tire axial direction with respect to the normal is smaller than 0 °, the block rigidity on the outer side in the tire axial direction is greatly reduced, the cornering performance is deteriorated, and the uneven wear property is deteriorated. It is.

  When the angle of the surface of the groove wall on the outer side in the tire axial direction with respect to the normal is larger than 25 °, the groove volume of the circumferential main grooves on both sides is insufficient, and the drainage of the region between the zigzag central main groove and the tread ground contact edge I can't expect any improvement.

  When the angle at the tread tread surface opening portion of the groove wall on the inner side in the tire axial direction with respect to the normal line is less than 20 °, the block rigidity on the inner side in the tire axial direction of the circumferential main grooves on both sides is lowered, and the dry steering stability is lowered.

  On the other hand, if the angle at the tread tread opening portion of the groove wall on the inner side in the tire axial direction with respect to the normal exceeds 80 °, the groove volume of the circumferential main grooves on both sides is insufficient, and the region between the zigzag central main groove and the tread ground contact edge I cannot expect improvement of drainage.

  The invention according to claim 14 is the pneumatic tire according to claim 13, wherein the circumferential main grooves are substantially parallel to the tire circumferential direction at the edge of the groove wall on the inner side in the tire axial direction. The edge of the groove wall on the outer side in the tire axial direction is inclined in the same direction as the adjacent horizontal main groove, and the inclination angle with respect to the tire circumferential direction is set to be smaller than the inclination angle of the horizontal main groove, and kicks more than the stepping side. A feature is that the groove width on the delivery side is set large.

  Next, the operation of the pneumatic tire according to claim 14 will be described.

  In both circumferential main grooves, the edge of the groove wall on the inner side in the tire axial direction is substantially parallel to the tire circumferential direction, and the edge of the groove wall on the outer side in the tire axial direction is inclined in the same direction as the adjacent horizontal main groove. In addition, by setting the inclination angle with respect to the tire circumferential direction smaller than the inclination angle of the horizontal main groove and further setting the groove width on the kicking side larger than the stepping side, water is efficiently supplied to the adjacent horizontal main groove It can flow.

  According to a fifteenth aspect of the present invention, in the pneumatic tire according to the thirteenth or fourteenth aspect, the both-side circumferential main grooves disappear when 85 ± 5% of the tread is worn.

  Next, the operation of the pneumatic tire according to claim 15 will be described.

  In the pneumatic tire according to claim 15, when the tread is worn by 85 ± 5%, the circumferential main grooves on both sides disappear, the negative rate of the tread is reduced, and the dry performance is improved.

  According to a sixteenth aspect of the present invention, in the pneumatic tire according to any one of the thirteenth to fifteenth aspects, at least one side of the tire equator plane is between the tire equator plane and both circumferential main grooves. An intermediate circumferential main groove extending along the tire circumferential direction is provided, and the intermediate circumferential main groove has an angle of the surface of the groove wall on the outer side in the tire axial direction with respect to the normal line standing on the tread surface of 0 ° to 25 °. The angle at the tread tread surface opening portion of the groove wall on the inner side in the tire axial direction with respect to the normal is greater than the angle of the surface of the groove wall on the outer side in the tire axial direction, and is in the range of 20 ° to 80 °. The edge of the groove wall on the inner side in the tire axial direction is substantially parallel to the tire circumferential direction, and the edge of the groove wall on the outer side in the tire axial direction is inclined in the same direction as the adjacent horizontal main groove. And the inclination angle with respect to the tire circumferential direction is Horizontal main grooves is set smaller than the inclination angle of the further, the groove width of the side out kicking than leading side is set larger, it is characterized in that.

  Next, the operation of the pneumatic tire according to claim 16 will be described.

  When running on a wet road surface, water in the region between the tire equator and the circumferential main grooves on both sides is discharged to the outside of the tread surface by the intermediate circumferential main groove, so that the wet performance is further improved.

  Here, the intermediate circumferential main groove is a groove on the inner side in the tire axial direction with respect to the normal line by setting the angle of the surface of the groove wall on the outer side in the tire axial direction to the normal line standing on the tread surface. The angle at the tread tread opening portion of the wall is set larger than the angle of the surface of the groove wall on the outer side in the tire axial direction and within the range of 20 ° to 80 °. It can be minimized.

  In addition, when the angle of the surface of the groove wall on the outer side in the tire axial direction with respect to the normal is smaller than 0 °, the block rigidity on the outer side in the tire axial direction is greatly reduced, the cornering performance is deteriorated, and the uneven wear property is deteriorated. It is.

  When the angle of the surface of the groove wall on the outer side in the tire axial direction with respect to the normal line is larger than 25 °, the groove volume of the intermediate circumferential main groove is insufficient, and the region between the zigzag central main groove and the both side circumferential main grooves Improve drainage performance.

  When the angle at the tread tread surface opening portion of the groove wall on the inner side in the tire axial direction with respect to the normal is less than 20 °, the block rigidity on the inner side in the tire axial direction of the intermediate circumferential main groove is lowered, and the dry steering stability is lowered.

  On the other hand, if the angle at the tread tread surface opening portion of the groove wall on the inner side in the tire axial direction with respect to the normal exceeds 80 °, the groove volume of the intermediate circumferential main groove is insufficient, and the gap between the zigzag central main groove and the circumferential main grooves on both sides is insufficient. The drainage of the area cannot be improved.

  According to a seventeenth aspect of the present invention, in the pneumatic tire according to any one of the thirteenth to sixteenth aspects, the tread has a negative rate in the range of 45% to 55% when new, 50% The negative rate at the time of wear is set within a range of 25 to 35%, and the negative rate at the time of 80% wear is set within a range of 15% to 25%.

  Next, the operation of the pneumatic tire according to claim 17 will be described.

  When the negative rate at the time of new article is set within the range of 45% to 55%, the negative rate at the time of 50% wear is set within the range of 25 to 35%, and the negative rate at the time of 80% wear is set within the range of 15% to 25%. Since the negative rate is relatively large at the initial stage of tire use, high wet drainage is obtained.

  If the negative rate of the entire tread tread decreases as the amount of water on the road continues to decrease and the tread tread wears rapidly, the groove depth of the main grooves on both sides that continue in the tire circumferential direction While gradually decreasing and suppressing uneven wear, the actual contact area with the road surface increases, the block rigidity increases, and stable steering stability, grip, acceleration performance, and braking performance can be exhibited.

  In addition, when the negative rate at the time of a new tire is smaller than 45%, the groove volume of the whole tread is insufficient and the wet drainage is insufficient.

  If the negative rate when the tire is new is greater than 60%, the actual contact area with the road surface of the entire tread is insufficient, the grip with the road surface is insufficient, and the steering stability is lowered.

  When the negative rate at the time of 50% wear is smaller than 25%, the groove volume of the entire tread is insufficient, and wet drainage is reduced.

  Further, when the negative rate at 50% wear is larger than 35%, the actual contact area with the road surface of the entire tread is insufficient, the grip with the road surface is insufficient, and the steering stability is lowered.

  When the negative rate at 80% wear is less than 15%, wet drainage is insufficient.

  When the negative rate at 80% wear is larger than 25%, the actual contact area with the road surface of the entire tread is insufficient, the grip with the road surface is insufficient, and the steering stability is lowered.

  The invention according to claim 18 is a pneumatic tire having a plurality of grooves in a tread, wherein the tread has a negative rate in the range of 45% to 55% when new and a negative rate at 50% wear. Is set in the range of 25 to 35%, and the negative rate at the time of 80% wear is set in the range of 15% to 25%.

  Next, the operation of the pneumatic tire according to claim 18 will be described.

  When the negative rate at the time of new article is set within the range of 45% to 55%, the negative rate at the time of 50% wear is set within the range of 25 to 35%, and the negative rate at the time of 80% wear is set within the range of 15% to 25%. Since the negative rate is relatively large at the initial stage of tire use, high wet drainage is obtained.

  Continued running, the amount of water on the road surface decreases, and the tread tread surface wears rapidly. When the negative rate of the entire tread tread portion decreases, the actual contact area with the road surface increases and the block rigidity increases. In addition, stable steering stability, grip, acceleration performance, and braking performance can be exhibited.

  In the pneumatic tire according to claim 18, with the above configuration, when the tire is new, the wet performance is emphasized, and as the tire wears, the wet performance is decreased and the dry performance is emphasized. In particular, a process in which the road surface before the completely dry road surface dries from the situation where the water level on the road surface is relatively large due to the climatic conditions (for example, from rainy weather to sunny weather) This is suitable for continuous use without exchanging tires in such an unstable situation change that changes to (2). In such a case, stable steering stability can always be exhibited.

  When the road surface dries in competition running, the wet tire is usually replaced with a dry tire at a certain point. However, with the pneumatic tire of the present invention, the performance from the wet emphasis to the dry emphasis is one. Since it changes, there is no need to change tires, and there is no time loss required for changing tires, so the running time can be greatly reduced.

  In addition, when the negative rate at the time of a new tire is smaller than 45%, the groove volume of the whole tread is insufficient and the wet drainage is insufficient.

  If the negative rate when the tire is new is greater than 60%, the actual contact area with the road surface of the entire tread is insufficient, the grip with the road surface is insufficient, and the steering stability is lowered.

  When the negative rate at the time of 50% wear is smaller than 25%, the groove volume of the entire tread is insufficient, and wet drainage is reduced.

  Further, when the negative rate at 50% wear is larger than 35%, the actual contact area with the road surface of the entire tread is insufficient, the grip with the road surface is insufficient, and the steering stability is lowered.

  When the negative rate at 80% wear is less than 15%, wet drainage is insufficient.

  When the negative rate at 80% wear is larger than 25%, the actual contact area with the road surface of the entire tread is insufficient, the grip with the road surface is insufficient, and the steering stability is lowered.

  In the present invention (Claims 3, 5, 8, 14, and 16), “substantially parallel” includes ± 10 ° or less with respect to the tire circumferential direction.

  As described above, since the pneumatic tire according to claim 1 has the above-described configuration, when it is new, the wet drainage is improved, and when the road surface starts to dry, the tire and the road surface are matched to the road surface condition. By increasing the actual ground contact area, there is an excellent effect that acceleration on a dry road surface, braking performance and steering stability can be improved without exchanging tires.

  Since the pneumatic tire according to claim 2 has the above configuration, it has an excellent effect that the wet performance can be further improved.

  Since the pneumatic tire according to claim 3 has the above-described configuration, it has an excellent effect that the wet performance can be further improved.

  Since the pneumatic tire according to claim 4 has the above-described configuration, it has an excellent effect that the dry performance is improved when the tread is worn by 85% ± 5%.

  Since the pneumatic tire according to claim 5 has the above configuration, it has an excellent effect that the wet performance can be further improved.

  Since the pneumatic tire according to claim 6 has the above-described configuration, it has an excellent effect that the drainage performance at the center portion of the tread is further improved.

  Since the pneumatic tire according to claim 7 has the above configuration, it has an excellent effect that the wet performance can be further improved.

  Since the pneumatic tire according to claim 8 has the above-described configuration, it has an excellent effect that the wet performance can be further improved.

  Since the pneumatic tire according to claim 9 has the above-described configuration, it has an excellent effect that the wet performance can be further improved.

  Since the pneumatic tire according to claim 10 has the above-described configuration, it has an excellent effect that it is possible to improve steering stability and uneven wear performance on a dry road surface.

  Since the pneumatic tire according to claim 11 has the above-described configuration, it has an excellent effect that steering stability, acceleration performance, and braking performance are further improved by wear of the tread.

  Since the pneumatic tire according to claim 12 has the above-described configuration, high wet drainage is obtained in the initial use of the tire, and after wear, the actual contact area with the road surface increases, the block rigidity increases, and the stability is increased. It has an excellent effect that it can exhibit the steering stability, the grip, the acceleration performance, and the braking performance.

  Since the pneumatic tire according to claim 13 has the above-described configuration, when it is new, the wet drainage is improved, and when the road surface starts to dry, the actual contact area between the tire and the road surface increases according to the road surface condition. As a result, acceleration on a dry road surface, braking performance, and steering stability can be improved without changing tires.

  Since the pneumatic tire according to claim 14 has the above-described configuration, it has an excellent effect that the wet performance can be further improved.

  Since the pneumatic tire according to claim 15 has the above-described configuration, it has an excellent effect that dry performance is improved when 85% ± 5% of the tread is worn.

  Since the pneumatic tire of the sixteenth aspect has the above-described configuration, it has an excellent effect that the wet performance can be further improved.

  Since the pneumatic tire according to claim 17 has the above-described configuration, high wet drainage is obtained in the initial use of the tire, and after wear, the actual contact area with the road surface increases, the block rigidity increases, and the stability is increased. It has an excellent effect that it can exhibit the steering stability, the grip, the acceleration performance, and the braking performance.

  Since the pneumatic tire according to claim 18 is configured as described above, when it is new, the wet drainage is improved, and when the road surface starts to dry, the actual contact area between the tire and the road surface is increased in accordance with the road surface condition. As a result, acceleration on a dry road surface, braking performance, and steering stability can be improved without changing tires.

[First Embodiment]
Hereinafter, a pneumatic tire 10 according to a first embodiment of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the tread 12 of the pneumatic tire 10 according to the present embodiment has a tire equator surface on both sides of the tire equator surface CL from a ground contact end (the outermost end portion in contact with the road surface) 12E of the tread 12. The tire axial direction (arrow IN direction (vehicle inward direction when mounted on the vehicle)) and arrow OUT direction (vehicle outward direction when mounted on the vehicle) so as to extend toward CL and to contact from the end of the tire equatorial plane CL A plurality of lateral main grooves 14 inclined with respect to the tire circumferential direction (in the direction of arrow A (the direction of rotation of the tire) and in the direction opposite to the direction of arrow A) are arranged at intervals.

  A tire equatorial plane side end of the lateral main groove 14 on one side with respect to the tire equatorial plane CL is coupled to a longitudinal intermediate portion of the lateral main groove 14 on the other side with respect to the tire equatorial plane CL, and is connected to the tire equatorial plane CL. On the other hand, the tire equatorial plane side end portion of the other lateral main groove 14 is connected to the longitudinal middle portion of the lateral main groove 14 on the one side with respect to the tire equatorial plane CL. The land is demarcated.

  Further, a lateral sub-groove 16 extending from the ground contact end of the tread 12 toward the tire equatorial plane CL is formed between the lateral main groove 14 and the lateral main groove 14 adjacent to each other in the tire circumferential direction. .

  The transverse sub-groove 16 is inclined in the same direction as the transverse main groove 14 adjacent in the tire circumferential direction, and the tire equatorial plane CL side terminates in the land portion without being connected to other grooves.

  Further, the tread 12 is formed with both circumferential main grooves 18 extending in the circumferential direction between the tire equatorial plane CL and the ground contact end of the tread 12.

  The both-side circumferential main grooves 18 of the present embodiment intersect with the horizontal main grooves 14 and the horizontal auxiliary grooves 16, and the groove depth is set to be shallower than the horizontal main grooves 14 and the horizontal auxiliary grooves 16.

  In addition, it is preferable that the both-side circumferential main grooves 18 disappear when the tread 12 is worn by 85 ± 5%. In this embodiment, the groove depth of the horizontal main groove 14 is 8 mm, and the groove depth of the both-side circumferential main groove 18 is 7 mm, and the both-side circumferential main groove 18 disappears when the tread 12 is 87.5% worn.

  As shown in FIG. 2, the both-side circumferential main groove 18 has an asymmetric groove cross-sectional shape.

  The groove wall 18A on the outer side in the tire axial direction (on the ground contact end 12E side) of the circumferential main grooves 18 on both sides is inclined at a constant angle in this embodiment, but the angle may be changed.

  The angle θ1 of the surface of the groove wall 18A on the outer side in the tire axial direction with respect to the normal line HL standing on the tread 12 is set within a range of 0 ° to 25 ° (average value when not inclined at a constant angle). Is preferred. In the present embodiment, the angle θ1 is set to 15 °.

  On the other hand, the groove wall 18B on the inner side in the tire axial direction (the tire equatorial plane CL side) of the circumferential main grooves 18 on both sides is formed in an arc shape (curvature radius R2) having the center of curvature on the outer side of the tire in this embodiment. It may be inclined at a certain angle.

  The surface angle θ2 (angle of the tangent to the groove wall surface at the opening end) of the groove wall 18B on the inner side in the tire axial direction with respect to the normal line HL standing on the tread 12 is 20 ° to 80 °. It is preferable to set within the range. In the present embodiment, the angle θ2 is set to 60 °.

  In addition, although the groove wall 18B of this embodiment is circular arc shape which has a center of curvature on the tire outer side as shown in FIG. 2, it may be linear. When the groove wall 18B has a linear shape, the groove wall 18B extends to a predetermined depth with the angle θ2 and is connected to a bottom surface parallel to the tread surface.

  As shown in FIG. 1, the width of the circumferential main grooves 18 on both sides is such that the width between the horizontal main grooves 14 and the horizontal auxiliary grooves 16 is from the stepping side (tire rotation direction side: arrow A direction side) to the kicking side (tire rotation). The groove wall 18B on the inner side in the tire axial direction extends linearly along the tire circumferential direction when the tread 12 is viewed in a plan view. The angle of the surface of the groove wall 18A on the outer side with respect to the tire circumferential direction gradually increases.

  Hereinafter, in the present embodiment, the land portion defined by the both-side circumferential main groove 18, the lateral main groove 14, and the lateral sub-groove 16 outside the both-side circumferential main groove 18 in the tire axial direction is defined as the shoulder block 20, the both-side circumferential main groove. The land portion defined by the inner circumferential direction groove 18 and the lateral main grooves 18 on the inner side in the tire axial direction is referred to as a center block 22.

  A chamfered portion 24 having a substantially triangular shape is formed at the corner of the tread surface at the front end portion of the shoulder block 20 on the stepping side.

  In the present embodiment, a plurality of short portions between the end portion of the lateral main groove 14 on the tire equatorial plane side and the connecting portion between the lateral main grooves are subsequently connected in the tire circumferential direction at the center in the width direction of the tread 12. Accordingly, a portion extending in a zigzag shape in the tire circumferential direction is referred to as a zigzag central main groove 26.

  The center block 22 is formed with a substantially triangular chamfered portion 28 at a block edge facing the zigzag central main groove 26.

  The ridgeline 28A between the chamfered portion 28 and the tread surface has an arc shape with a radius of curvature R1 in this embodiment, but may be a curve or a straight line other than the arc.

  As shown in FIG. 3, the chamfered portion 28 is formed so as not to reach the groove bottom of the horizontal main groove 14.

  Here, in the present embodiment, the chamfered portion 28 is a groove wall, the chamfered depth D2 of the chamfered portion 28 is a groove depth, and extends continuously in the tire circumferential direction along the zigzag central main groove 26. This groove portion is called a wide circumferential main groove 32.

  The wide circumferential main groove 32 preferably has a smaller amplitude than the zigzag central main groove 26.

  FIG. 4 shows a road surface contact portion (the shape of the tread of each block) of the tread 12.

  As shown in FIG. 4, the amplitude of the wide circumferential main groove 32 is the groove width of the wide circumferential main groove 32 measured at the tread portion (the ridge line 28A between the chamfered portion 28 and the tread surface is connected in the tire circumferential direction). Measured at the center line HCL of the edge of the horizontal main groove 14 (the opening portion of the lateral main groove 14 does not actually have the ridge line 28A, and this portion extends the adjacent real ridge line 28A to become the virtual ridge line 28FA). To do.

  Further, the amplitude of the zigzag central main groove 26 is measured at the center line ZCL in the width direction of the zigzag central main groove 26 as shown in FIG.

  As shown in FIG. 1, a substantially triangular chamfered portion 30 is formed at the edge of the block at the tip end portion of the center block 22 (the zigzag inflection point of the zigzag central main groove 26).

The tread 12 has a negative rate of 45% to 55% when new, a negative rate of 25% to 35% at 50% wear, and a negative rate of 15% to 25 at 80% wear. % Is set within the range.
(Function)
Next, the effect | action of the pneumatic tire 10 of this embodiment is demonstrated.

  When a new pneumatic tire 10 is run on a wet road surface, water between the tread tread portion and the road surface has a horizontal main groove 14, a lateral sub-groove 16, both side circumferential main grooves 18, a zigzag central main groove 26, and It is discharged to the outside of the tread tread portion through the wide circumferential main groove 32.

  Here, the water in the vicinity of the center portion of the tread tread portion flows into the wide circumferential main groove 32 and the zigzag center main groove 26, flows along the tire circumferential direction, and is drained out of the tread tread portion.

  Further, water between the tire equatorial plane CL and the ground contact end 12E flows along the tire circumferential direction via the both-side circumferential main grooves 18 and is drained out of the tread tread portion.

  Since the tread pattern of the pneumatic tire 10 is a directional pattern by the lateral main groove 14 and the lateral sub-groove 16, when the vehicle runs on a wet road surface, it is always in the lateral main groove 14 and the lateral sub-groove 16. A water flow is generated from the tread central region toward both side regions, and the water in the tread tread portion can always be drained out of the tread tread portion, and high wet performance can be obtained.

  Since the circumferential main grooves 18 are shallower than the lateral main grooves 14, when the wear of the tread 12 progresses, the lateral main grooves 14 remain but the circumferential main grooves 18 become extinct (the negative rate decreases). ), The shoulder block 20 and the center block 22 that have been completely separated until now are integrated, and the rigidity of the dry operation is improved by increasing the block rigidity.

  Incidentally, FIG. 5 is a plan view of the tread 12 at 50% wear, and FIG. 6 is a plan view of the tread 12 at 75% wear.

  Since the wide circumferential main groove 32 has a shallower depth than the zigzag central main groove 26, the drainage performance is improved from the beginning of wear, for example, when the wide circumferential main groove 32 is new, and the wide circumferential main groove 32 disappears. For example, after the middle stage of wear of the tread 12, the negative rate decreases (actual contact area increases), and dry handling stability improves.

  In addition, the amplitude of the wide circumferential main groove 32 is smaller than the amplitude of the zigzag central main groove 26 at the initial stage of wear, and gradually increases as it wears and approaches the amplitude of the zigzag central main groove 26. There is a see-through groove continuous in the circumferential direction in the vicinity of the tire surface of the groove 32, and the width of the see-through groove is further increased, so that the drainage of the tread central portion is further improved.

  Further, in the center block 22, the chamfered portion 28 is formed at the edge facing the zigzag central main groove 26, and the chamfered portion 30 is formed at the front end portion of the stepping side. Therefore, the chamfered portion 28 and the chamfered portion 30 are not formed. As compared with the above, the rigidity of the center block 22 is increased, the steering stability on the dry road surface is improved, and the uneven wear property of the center block 22 is improved.

  Similarly, since the chamfered portion 24 is formed at the front end portion of the shoulder block 20, the shoulder block 20 is more rigid than the case where the chamfered portion 24 is not formed, and the steering stability on the dry road surface is improved. In addition, the uneven wear of the shoulder block 20 is improved.

  Further, the pneumatic tire 10 has a negative rate of 45% to 55% when new, a negative rate of 25% to 35% at 50% wear, and a negative rate of 15% to 80% wear. Since it is set within the range of 25%, the wet performance is emphasized when it is new, and the wet performance decreases with wear and the dry performance is emphasized.

  For this reason, when this pneumatic tire 10 is mounted on a racing vehicle and used continuously in a process where the road surface before the completely dry road surface dries out from a relatively large amount of water on the road surface, stable handling stability is always obtained. Can be demonstrated.

  In addition, the angle of the surface of the groove wall on the outer side in the tire axial direction of both circumferential main grooves 18 is set within a range of 0 ° to 25 °, and the angle at the tread tread surface opening portion of the groove wall on the inner side in the tire axial direction is set in the tire axial direction. Since the angle was set larger than the angle of the surface of the outer groove wall and within a range of 20 ° to 80 °, it was possible to minimize the decrease in block rigidity while ensuring drainage.

  In addition, when the angle of the surface of the groove wall on the outer side in the tire axial direction of both circumferential main grooves 18 is smaller than 0 °, the block rigidity on the outer side in the tire axial direction is greatly reduced, the cornering performance is deteriorated, and the uneven wear property is deteriorated. It is inappropriate.

  When the angle of the surface of the groove wall on the outer side in the tire axial direction of the circumferential main grooves 18 on both sides is larger than 25 °, the groove volume of the circumferential main grooves 18 on both sides is insufficient, and the zigzag central main groove 26 and the tread ground contact end Improve drainage in the area between.

  When the angle at the tread tread surface opening portion of the groove wall on the inner side in the tire axial direction of both circumferential main grooves 18 is less than 20 °, the block rigidity on the inner side in the tire axial direction of both circumferential main grooves 18 decreases, and the dry steering stability decreases. To do.

  On the other hand, when the angle at the tread tread surface opening portion of the groove wall on the inner side in the tire axial direction of both circumferential peripheral grooves 18 exceeds 80 °, the groove volume of both circumferential circumferential main grooves 18 becomes insufficient, and the zigzag central main groove 26 and the tread grounding end It is not possible to improve drainage in the area between.

  In the circumferential main grooves 18 on both sides, the groove wall on the inner side in the tire axial direction is substantially parallel to the circumferential direction of the tire, the groove wall on the outer side in the tire axial direction is inclined in the same direction as the adjacent horizontal main groove 14, and The inclination angle with respect to the direction is set smaller than the inclination angle of the horizontal main groove, and the groove width on the kicking side is set larger than the stepping side, so that water can flow efficiently to the adjacent horizontal main groove 14. .

  In the pneumatic tire 10, when the tread is worn by 80%, the both-side circumferential main grooves 18 disappear, the negative rate of the tread 12 is reduced, and the dry performance is improved.

  Since the surface shape of the chamfered portion 28 has a substantially triangular shape with the zigzag inflection point of the zigzag central main groove as a vertex, water in the wide circumferential main groove 32 flows smoothly along the tire circumferential direction, The drainage of the tread central area is improved.

  The angle of the surface of the groove wall of the zigzag central main groove 26 is set within a range of 30 ° to 85 °, and is set to be larger than the angle of the surface of the groove wall of a general groove. The increase in the actual contact area with the road surface in the central region is remarkably increased as compared with the prior art, and the handling stability, acceleration performance, and brake performance are further improved by wear of the tread 12.

  In addition, when the negative rate at the time of a new tire is smaller than 45%, the groove volume of the whole tread is insufficient and the wet drainage is insufficient.

  If the negative rate when the tire is new is greater than 60%, the actual contact area with the road surface of the entire tread is insufficient, the grip with the road surface is insufficient, and the steering stability is lowered.

  When the negative rate at the time of 50% wear is smaller than 25%, the groove volume of the entire tread is insufficient, and wet drainage is reduced.

  Further, when the negative rate at 50% wear is larger than 35%, the actual contact area with the road surface of the entire tread is insufficient, the grip with the road surface is insufficient, and the steering stability is lowered.

  When the negative rate at 80% wear is less than 15%, wet drainage is insufficient.

When the negative rate at 80% wear is larger than 25%, the actual contact area with the road surface of the entire tread is insufficient, the grip with the road surface is insufficient, and the steering stability is lowered.
[Second Embodiment]
Next, a pneumatic tire 10 according to a second embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected about the same structure as 1st Embodiment, and the description is abbreviate | omitted.

  As shown in FIG. 7, in the pneumatic tire 10 of the present embodiment, the shape of the chamfered portion 28 of the center block 22 is different from that of the first embodiment, and the ridgeline 28A between the chamfered portion 28 and the tread tread surface. Is set in parallel to the tire circumferential direction, and the wide circumferential main groove 32 extends in a straight line with a constant width in the tire circumferential direction (that is, the amplitude of the wide circumferential main groove 32 is zero).

Therefore, the water inside the wide circumferential main groove 32 flows more smoothly in the tire circumferential direction than in the first embodiment, and the drainage of the tread central region is improved.
[Third Embodiment]
Next, a pneumatic tire 10 according to a third embodiment of the present invention will be described with reference to FIGS. 8 and 9. In addition, the same code | symbol is attached | subjected about the same structure as embodiment mentioned above, and the description is abbreviate | omitted.

  As shown in FIG. 8, in the pneumatic tire 10 of the present embodiment, the zigzag central main groove 26 and the wide circumferential main groove 32 are slightly on the inner side (arrow IN direction side) when the vehicle is mounted than the tire equatorial plane CL. An intermediate peripheral main groove extending in the tire circumferential direction between the tire equatorial plane CL and both side peripheral main grooves 18 on the outer side (arrow OUT direction side) when the vehicle is mounted than the tire equator plane CL. 34 is provided.

  In the tread 12, a second block 36 is defined by the lateral main groove 14, the both-side circumferential main groove 18, and the intermediate circumferential main groove 34. The other end of the second block 36 is connected to other blocks. Similarly, a chamfered portion 38 is formed.

  The groove shape of the intermediate circumferential main groove 34 and the angle of the surface of the groove wall are preferably set in the same manner as the circumferential circumferential main groove 18.

  That is, as shown in FIG. 9, the angle θ4 of the groove wall 34A on the outer side in the tire axial direction with respect to the normal line HL standing on the tread surface is set within the range of 0 ° to 25 °, and the inner side in the tire axial direction with respect to the normal line HL. The angle θ3 at the tread tread surface opening portion of the groove wall 34B is set to be larger than the angle θ4 of the groove wall 34A on the outer side in the tire axial direction and within a range of 20 ° to 80 °, and as shown in FIG. The groove wall 34B on the inner side in the direction is substantially parallel to the tire circumferential direction, the groove wall 34A on the outer side in the tire axial direction is inclined in the same direction as the adjacent horizontal main groove 14, and the inclination angle with respect to the tire circumferential direction is lateral. The inclination angle of the main groove 14 is set smaller than that, and the groove width on the kicking side is set larger than that on the stepping side.

  Incidentally, the groove wall on the outer side in the tire axial direction of the intermediate circumferential main groove 34 (on the ground contact end 12E side) is inclined at 15 ° with respect to the normal line HL standing on the tread 12 tread surface. Further, the groove wall on the inner side in the tire axial direction (the tire equatorial plane CL side) is inclined at 60 ° with respect to the normal line HL raised on the tread surface of the tread 12.

Thus, since the groove shape of the intermediate circumferential main groove 34 and the angle of the surface of the groove wall are set, water can be efficiently allowed to flow to the adjacent horizontal main groove 14, and the tire equatorial plane CL and both side circumferential main grooves 14 The drainage of the area between the grooves 18 is improved.
[Fourth Embodiment]
Next, a pneumatic tire 10 according to a fourth embodiment of the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected about the same structure as embodiment mentioned above, and the description is abbreviate | omitted.

  As shown in FIG. 10, in the pneumatic tire 10 of the present embodiment, intermediate circumferential main grooves 34 are provided on both sides of the tire equatorial plane CL.

  Therefore, the drainage performance of the region between the tire equatorial plane CL and the side circumferential main grooves 18 is improved on both sides of the tire equatorial plane CL.

Incidentally, FIG. 11 is a plan view of the tread 12 at 50% wear, and FIG. 12 is a plan view of the tread 12 at 75% wear.
(Test example)
In order to confirm the effect of the present invention, one type of conventional tire and four types of tires according to the embodiments of the present invention were prepared, hydroplaning, wet circuit lap time, wet grip, uneven wear, and dry circuit wear. After lap time was examined.
Example 1: The pneumatic tire described in the first embodiment.
Example 2: The pneumatic tire described in the second embodiment.
Example 3: The pneumatic tire described in the third embodiment.
Example 4: The pneumatic tire described in the fourth embodiment.
Conventional example: a pneumatic tire having a tread pattern shown in FIG. In addition, the code | symbol described in FIG. 13 has shown the structure corresponding to the structure of embodiment. 14 shows a tread when 50% wear of the conventional example, and FIG. 15 shows a tread when 75% wear of the conventional example.
・ Hydroplaning: Using a new tire, run on a wet road surface with a depth of 2 mm and measure the hydroplaning speed. The evaluation was expressed as an index with the hydroplaning generation speed of the conventional example as 100. The larger the index value, the higher the hydroplaning rate and the better the wet drainage.
-Wet circuit lap time: Measures the lap time when a new tire runs around a wet road surface (circuit course) with a water depth of 2 mm. The evaluation was expressed as an index with the lap time of the conventional example as 100. The smaller the index value, the shorter the lap time and the better the wet circuit running performance.
-Wet grip: Feeling evaluation by a test driver when running around a wet road surface (test course) with a water depth of 2 mm. The evaluation was expressed as an index with the conventional example being 100. The larger the index value, the better the wet grip.
-Uneven wear: Measures the amount of heel-and-toe wear steps that occur on the block after running around a wet road surface (test course) with a water depth of 2 mm. The evaluation was represented by an index with the level difference of the conventional example as 100. The smaller the numerical value of the index, the smaller the level difference and the better the uneven wear.
-Lap time after dry circuit wear: After running around a wet road surface (test course) with a water depth of 1 mm or less until the amount of wear reaches 50%, measure the lap time when driving around the dry road surface (test course). The evaluation was expressed as an index with the lap time of the conventional example as 100. The smaller the index value, the shorter the lap time, and the better the dry circuit running performance after wear.
Tire size Front wheel: RAR 180 / 550R13 (tread width 188mm)
Rear wheel: RAR 240 / 570R13 (tread width 254mm)
・ Test vehicle wheel alignment Front wheel: Toe angle (toe-out side) 1 mm, negative camber angle 4 °
Rear wheel: Toe angle (toe-in side) 1 mm, negative camber angle 3 °

ジグザグ中央主溝２６のオフセット量ＯＦ１※：車両のホイールアライメントにより異なるタイヤ実接地形状の中心線（タイヤ接地中心線）のタイヤ中心線（タイヤ赤道面）とのズレ（間隔）のことを示す。

Offset amount OF1 * of the zigzag center main groove 26: Indicates a deviation (interval) between the tire center line (tire ground center line) and the tire center line (tire equatorial plane) of the actual tire ground contact shape depending on the vehicle wheel alignment.

  As shown in the test results of Table 1 above, the tires of the examples to which the present invention was applied were compared with the tires of the conventional examples, hydroplaning, wet circuit lap time, wet grip, partial wear, and lap time after dry circuit wear. It can be seen that the performance is improved for all items.

  In the pneumatic tire 10 of the above embodiment, the tread pattern is a directional pattern, but at least the negative rate when the tread 12 is new is within a range of 45% to 55%, and the negative rate when 50% is worn. If the negative rate at the time of 80% wear is set in the range of 25% to 35% and in the range of 15% to 25%, the tread pattern may not necessarily be a directional pattern.

It is a top view of the tread (at the time of a new article) of the pneumatic tire concerning a 1st embodiment. It is sectional drawing of a both-sides circumference main groove. It is sectional drawing of a center block. It is explanatory drawing which shows the shape of the road surface contact part (tread surface shape of each block) of a tread. It is a top view of the tread of the pneumatic tire concerning a 1st embodiment at the time of 50% wear. It is a top view of the tread of the pneumatic tire concerning a 1st embodiment at the time of 75% wear. It is a top view of the tread of the pneumatic tire concerning a 2nd embodiment. It is a top view of the tread of the pneumatic tire concerning a 3rd embodiment. It is sectional drawing of an intermediate periphery main groove. It is a top view of the tread of the pneumatic tire concerning a 4th embodiment. It is a top view of the tread of the pneumatic tire concerning a 4th embodiment at the time of 50% wear. It is a top view of the tread of the pneumatic tire concerning a 4th embodiment at the time of 75% wear. It is a top view of the tread (at the time of a new article) of the pneumatic tire concerning a conventional example. It is a top view of the tread (at the time of a new article) of the pneumatic tire concerning the conventional example at the time of 50% wear. It is a top view of the tread (at the time of a new article) of the pneumatic tire concerning the conventional example at the time of 75% wear.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Pneumatic tire 12 Tread 12E Grounding end 14 Lateral main groove 16 Lateral subgroove 18 Both-sides circumferential main groove 18A Groove wall 18B Groove wall 20 Shoulder block 22 Center block 24 Chamfered portion 26 Zigzag center main groove 28 Chamfered portion 30 Chamfered portion 32 Wide width Circumferential main groove 34 Intermediate peripheral main groove 34A Groove wall 34B Groove wall 36 Second block 38 Chamfered portion CL Tire equatorial plane

Claims (18)

A plurality of treads are arranged on both sides of the tire equatorial plane at intervals in the tire circumferential direction, extend from the tread grounding end toward the tire equatorial plane, and contact with the tire equatorial plane end in the tire circumferential direction. A pneumatic tire having a transverse main groove inclined with respect to the tire;
A tire equatorial plane side end portion of the lateral main groove on one side with respect to the tire equator plane is connected to a longitudinal intermediate portion of the lateral main groove on the other side with respect to the tire equator plane, and the lateral main portion on the other side A tire equatorial plane side end of the groove is connected to a longitudinal middle portion of the lateral main groove on the one side, so that the tire equatorial plane side end of the horizontal main groove and the horizontal main A zigzag central main groove extending in a zigzag shape in the tire circumferential direction is formed by connecting a plurality of short portions between the coupling portions of the grooves in the tire circumferential direction,
A plurality of blocks that are partitioned by the plurality of transverse main grooves are arranged on both sides in the tire width direction of the zigzag central main groove,
By forming a first chamfered portion that does not reach the groove bottom of the lateral main groove at the edge of the block on both sides of the tire equatorial plane facing the zigzag central main groove, the first chamfered portion is defined as a groove wall. In addition, the chamfering depth is the groove depth, and the wide circumferential main groove extending continuously in the tire circumferential direction through the zigzag central main groove is integrally formed with the zigzag central main groove.
A pneumatic tire characterized by that. On both sides of the zigzag central main groove, at least a pair of both-side circumferential main grooves that intersect the lateral main groove and extend along the tire circumferential direction are arranged,
The both circumferential circumferential main grooves are configured such that the angle of the surface of the groove wall on the outer side in the tire axial direction with respect to the normal line standing on the tread surface is set within a range of 0 ° to 25 °, and the groove wall on the inner side in the tire axial direction with respect to the normal line The angle at the tread tread opening portion is larger than the angle of the surface of the groove wall on the outer side in the tire axial direction, and is set within a range of 20 ° to 80 °.
The pneumatic tire according to claim 1. The circumferential main grooves on both sides are substantially the same as the lateral main grooves in which the edge of the groove wall on the inner side in the tire axial direction is substantially parallel to the tire circumferential direction and the edge of the groove wall on the outer side in the tire axial direction is adjacent. The inclination angle with respect to the tire circumferential direction is set smaller than the inclination angle of the lateral main groove, and the groove width on the kicking side is set larger than the stepping side. Pneumatic tire described in 2. 4. The pneumatic tire according to claim 2, wherein the circumferential main grooves on both sides disappear when 85 ± 5% of the tread is worn. 5. At least one side of the tire equatorial plane is provided with an intermediate circumferential main groove extending along the tire circumferential direction between the zigzag central main groove and both circumferential main grooves,
The intermediate circumferential main groove is configured such that the angle of the surface of the groove wall on the outer side in the tire axial direction with respect to the normal line standing on the tread surface is set within a range of 0 ° to 25 °, and the groove wall on the inner side in the tire axial direction with respect to the normal line The angle at the tread tread opening portion of the tire is set to be larger than the angle of the surface of the groove wall on the outer side in the tire axial direction and within a range of 20 ° to 80 °, and the groove wall on the inner side in the tire axial direction is Are substantially parallel, and the groove wall on the outer side in the tire axial direction is inclined in the same direction as the adjacent horizontal main groove, and the inclination angle with respect to the tire circumferential direction is set smaller than the inclination angle of the horizontal main groove, The pneumatic tire according to any one of claims 2 to 4, wherein a groove width on a kick-out side is set larger than a step-on side. The pneumatic tire according to any one of claims 1 to 5, wherein the wide circumferential main groove has an amplitude smaller than that of the zigzag central main groove. 7. The surface shape of the first chamfered portion is a substantially triangular shape having a zigzag inflection point of the zigzag central main groove as an apex. 8. The pneumatic tire according to item. The ridge line between the first chamfered portion and the tread surface is set substantially parallel to the tire circumferential direction, and the wide circumferential main groove extends in a straight line in the tire circumferential direction. The pneumatic tire according to claim 7. A transverse sub-groove extending from the tread grounding end toward the tire equatorial plane and not connected to the transverse main groove is provided between the transverse main grooves adjacent to each other in the tire circumferential direction. The pneumatic tire according to any one of claims 1 to 8. The pneumatic tire according to any one of claims 1 to 9, wherein a second chamfered portion is formed at a stepped side tip portion of the block. The groove wall of the zigzag central main groove has an angle with respect to a normal line standing on the tread tread within a range of 30 ° to 85 °. The pneumatic tire according to item. The tread has a negative rate of 45% to 55% when new, a negative rate of 25% to 35% at 50% wear, and a negative rate of 15% to 25% at 80% wear. The pneumatic tire according to any one of claims 1 to 11, wherein the pneumatic tire is set inside. The tread is disposed on both sides of the tire equatorial plane and is disposed at least a pair of both side circumferential main grooves extending along the circumferential direction of the tire, and a plurality of tires are arranged on both sides of the tire equatorial plane at intervals in the circumferential direction of the tire. Inclined with respect to the tire circumferential direction so as to extend toward the equator plane and intersect with the circumferential grooves on both sides of the tire and to contact from the end side on the tire equator plane side, and the groove depth is greater than the circumferential grooves on both sides. A pneumatic tire in which a plurality of blocks partitioned by the both-side circumferential main grooves and the lateral main grooves are arranged outside the both-side circumferential main grooves in the tire width direction. There,
The both circumferential circumferential main grooves are configured such that the angle of the surface of the groove wall on the outer side in the tire axial direction with respect to the normal line standing on the tread surface is set within a range of 0 ° to 25 °, and the groove wall on the inner side in the tire axial direction with respect to the normal line The pneumatic tire is characterized in that an angle at an opening portion of the tread surface of the tire is set to be larger than an angle of a surface of the groove wall on the outer side in the tire axial direction and within a range of 20 ° to 80 °. The circumferential main grooves on both sides are substantially the same as the lateral main grooves in which the edge of the groove wall on the inner side in the tire axial direction is substantially parallel to the tire circumferential direction and the edge of the groove wall on the outer side in the tire axial direction is adjacent. The inclination angle with respect to the tire circumferential direction is set smaller than the inclination angle of the lateral main groove, and the groove width on the kicking side is set larger than the stepping side. Pneumatic tire described in 2. The pneumatic tire according to claim 13 or 14, wherein the both-side circumferential main grooves disappear when 85 ± 5% of the tread is worn. At least one side of the tire equatorial plane is provided with an intermediate circumferential main groove extending along the tire circumferential direction between the tire equatorial plane and both circumferential circumferential main grooves,
The intermediate circumferential main groove is configured such that the angle of the surface of the groove wall on the outer side in the tire axial direction with respect to the normal line standing on the tread surface is set within a range of 0 ° to 25 °, and the groove wall on the inner side in the tire axial direction with respect to the normal line The angle at the tread tread opening portion is larger than the angle of the surface of the groove wall on the outer side in the tire axial direction and is set within a range of 20 ° to 80 °, and the edge of the groove wall on the inner side in the tire axial direction is the tire. It is substantially parallel to the circumferential direction, the edge of the groove wall on the outer side in the tire axial direction is inclined in the same direction as the adjacent horizontal main groove, and the inclination angle with respect to the tire circumferential direction is the inclination angle of the horizontal main groove The pneumatic tire according to any one of claims 13 to 15, wherein the pneumatic tire is set to be smaller, and the groove width on the kicking side is set to be larger than that on the stepping side. The tread has a negative rate of 45% to 55% when new, a negative rate of 25% to 35% at 50% wear, and a negative rate of 15% to 25% at 80% wear. The pneumatic tire according to any one of claims 13 to 16, wherein the pneumatic tire is set inside. A pneumatic tire having a plurality of grooves in a tread, wherein the tread has a negative rate in the range of 45% to 55% when new, and a negative rate in the range of 25 to 35% at 50% wear, A pneumatic tire, wherein a negative rate at the time of 80% wear is set in a range of 15% to 25%.

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