| 摘要 |
PURPOSE: To lower the noise by chamfering at least a prescribed area (given in terms of percentage of a pitch in the circumferential direction of a directional, low, inclined groove) of the surface of a letter-V-shaped center block in such a manner that the depth of chamfering becomes shallower from the convergent tip part of the letter-V toward wide width part before the tire is inflated by internal pressure, thereby making the level of the chambered surface become equal to that of the surrounding surface when the tire is inflated. CONSTITUTION: Before a tire is inflated by internal pressure, the surface of a letter-V-shaped center block is chamfered, ranging over an area 4 of more than 40% (preferably 70%) of a large pitch (P), or a circumferential space of a directional, low, inclined groove 1. The depth of chamfering becomes gradually shallower from the convergent tip end of the letter-V toward wide width part. When the tire is inflated by internal pressure after the tire is assembled with a rim, the level of the chamfered surface of the letter-V-shaped center block 3 becomes almost equal to that of the surface of the surrounding block, as shown by a double-dot-and-dash line of an A-A section. With this, the uniformity level is drastically improved, and moreover the tire noise can be lowered. |
