| 摘要 |
PROBLEM TO BE SOLVED: To improve wet performance, noise performance and dry-gripping performance. SOLUTION: Two longitudinal grooves 9, 9 at both sides of a tire equator, extending to the peripheral direction, are provided in a tread surface, whereby the tread surface is parted into a shoulder portion 10 outside the longitudinal groove 9 and a central portion 11 between the longitudinal grooves 9, 9. In the cross section of a tire meridian in a standard non-loaded condition, each longitudinal groove 9 has an inside wall face 9i, ranging from the inside bottom edge of the groove to the edge Ce of the tread surface at the central portion in the axial direction of a tire, substantially linearly formed at a small angleαto the side of the tire equator C. An outside wall face 9o of each longitudinal groove 9 includes a large circular portion 14 protruded outside to the radial direction of the tire. The large circular portion 14 has a radius of curvature Ra being 10-40% of a ground width TW. Each longitudinal groove 9 has a maximum groove width of 35 mm or more in the axial direction of the tire, measured on a ground plane. |
