| 摘要 |
PURPOSE: To reduce the noise of a tread by dividing a main tread into central, intermediate and end part areas, smoothly linking respective sections to each other by setting an angle of a main groove to the axial direction of the main groove in a specific value, and continuing end parts with the areas by squeezing a width from the intermediate area having the largest width. CONSTITUTION: Main grooves 2 and land parts 3 which extend in a V shape to the ends E of a main tread 11 by inclining in the axial direction from a central part of a tread part 1 and continue in an auxiliary tread 12 , are provided. The main tread 11 has a central area A corresponding to 20% of a main tread width W with an equatorial surface O as the center, intermediate areas B corresponding to 30% of W on its both sides and end part areas C being an area between the areas B and the ends E. In the main grooves 2, the respective areas are smoothly continued with each other by setting an angle to the axial direction in the areas A, B and C at 70 to 120 deg., 45 to 85 deg. and 30 to (-)30 deg., and are continued by squeezing a width to a width C of the area C from a width (b) of the widest area B. Therefore, pitching sound of a tire and a pattern noise can be reduced. |
