| 摘要 |
PURPOSE:To aim at lowering noise from a tire having a tread surface formed therein circumfer ential rag grooves opened to right and left shoulder sides of the tire, by setting the actual forward edge clutch ratio of the tread forward edge section to a specified value when the tire is new one, which is different from a specific value when the tire is worn up to 50%. CONSTITUTION:Rag grooves 6 opened to both shoulder 2a, 2b sides are formed in the periph eral surface of a rag tire at equal or unequal intervals within the areas of both right and left sides of the tire tread surface (m). In the above-mentioned tire, as to the ground gripping contour of the tire which is obtained when the tire grips the ground under such a condition that the tire pneumatic pressure is set to a JIS standard value and the load thereof is a normal double wheel load, variations in the actual tread length of the tread forward edge section which is forward in the advancing direction, in accordance with the rotation of the tire, is set to be less than a value that is 0.22 times as large as the overall tread length of the tread forward edge section, which is the sum of an actual tread section and the groove section when the tire is new and therefore no grooves are present, but it is set to be less than a value which is 0.70 times as large as the overall tread length when the tire is worn up to 50%. Further, the crossing angle alpha between the tread forward edge line 10 and the rag groove contour line 11 is less than 3 deg. over more than 95% part of the groove contour line 11. |
