Patent EP-1752314-A1 (EP)
Inventor: FUKUNAGA TAKAYUKI
IPC: B60C11/13
Filed: 2005-05-27
Abstract: The present invention provides a pneumatic tire which can obtain a high wet drainage performance, roadholding ability, and wear-resistant property without sacrificing other capabilities A directional pattern is formed by a circumferential wide major groove 14, a first narrow circumferential minor groove 16, a second narrow circumferential minor groove 18, a first transverse groove 20, a second transverse groove 22, and a third transverse groove 24. The circumferential wide major groove 14 is provided in a center region in a tire width direction of a tread 12. The first narrow circumferential minor groove 16 is arranged on the outside in a tire axis direction of the circumferential wide major groove 14. The second narrow circumferential minor groove 18 is arranged on the outside in the tire axis direction of the first narrow circumferential minor groove 16. The first transverse groove 20 is extended from a tread end 12E and coupled to the circumferential wide major groove 14. The second transverse groove 22 is arranged between the first transverse grooves 20, and the second transverse groove 22 is extended from the tread end 12E and terminated while not coupled to the circumferential wide major groove 14. The third transverse groove 24 is arranged between the first transverse groove 20 and the second transverse groove 22, and the third transverse groove 24 is extended from the tread end 12E and terminated between the first narrow circumferential minor groove 16 and the second narrow circumferential minor groove 18. Therefore, in wet road surface driving, the water between the pneumatic tire and a road surface flows efficiently into each groove to obtain high wet performance. Because the high wet performance is obtained while an increase in negative ratio is suppressed, a wheel tread area of a block is secured to improve a wear-resistant property. A circumferential length of a second block 28 becomes a substantial half of a first block 26, and circumferential lengths of a stepping-on side third block 30 and a kickout side third block 32 become a substantial half of the second block 28. Therefore, a wet drainage property can be improved on both sides of the tread while block rigidity is increased on a tread central region to improve traction performance, brake performance, and cornering performance. Furthermore, when the pneumatic tire of the invention is used in a front wheel, handling performance is improved by increasing the block rigidity in a central region in the tire axis direction. Widths and depths of the first narrow circumferential minor groove 16 and second narrow circumferential minor groove 18 are decreased from a kickout side toward a stepping-on side of the block in a range where the block is zoned by the first and second narrow circumferential minor grooves 16 and 18. Therefore, the block rigidity is increased on the stepping-on side of the blocks located on both sides of the first and second narrow circumferential minor grooves 16 and 18, and thereby the traction performance, brake performance, and cornering performance are improved.