| 摘要 |
Tread comprises (i) two wide main circumferential grooves having axial grooves extending therebetween divide the tread portion into at least three rows of blocks; (ii) a series of 1st sipes, narrower than the circumferential and axial grooves, are provided in the tread surface, (iii) the depth of the axial grooves is 0.2 0.5 times the depth of the circumferential grooves, (iv) each axial groove has in its bottom face a 2nd sipe having a width of 0.2 to 1.1mm, (v) each 2nd sipe extends centrally in the axial groove, has a length between 0.7 and 1.0 times the groove length and terminates, within the groove, and the total of the depths of the axial groove and the second sipe is not more than 0.7 times the depth of the circumferential grooves. The axial grooves may be inclined at not more than 30 deg. w.r.t. the tyre axial direction. A pair of narrow zigzag circumferential grooves (3a) may be provided between the wide straight circumferential grooves (3b). The central portion of the axial grooves may comprise narrow grooves (6a) alternating with wider grooves (7a), the wider grooves (7a) having the same depth (P) as the adjacent circumferential groove (3a), and the narrow grooves (6a) being shallower than this depth (P).
|
