| 摘要 |
PURPOSE:To aim at the equalization of wear in checking any partial abrasion to be produced in time of traveling by sorting a tread surface into a tread center part and a tread shoulder part with a pair of longitudinal main grooves, and installing a specified longitudinal sub-groove in this tread center part. CONSTITUTION:A tread width of 15 to 25% separates from a tire equator C to the tire axial both sides while a pair of longitudinal main grooves 3 or 0.05 to 0.08 times over the tread width in groove depth are installed in a tread surface 2 which is therefore sorted into a tread center part 4 and a tread shoulder part 5 respectively. In this tread center part 4, each longitudinal sub groove 6 is installed in a position setting apart as far as a distance L of 0.02 to 0.05 times over the tread width WT from a groove edge toward the tire equator C of the longitudinal main groove 3, and this groove depth is set to be 0.7 to 1.0 times over the depth of the longitudinal groove 3 and groove width to 1.5 to 2.5mm, respectively. Accordingly, any partial abrasion to be produced in both center and shoulder areas of the tread surface 2 is refrained from occurring and simultaneously durability is enhanced and thus primary service life of the tire is well improvable. |
