| 摘要 |
PURPOSE:To improve tire characteristics by forming a tire as a composite structure having surface layer rubber bounded without surface waveness by a rotation surface of a segment of a line extending linearly in parallel to a rotation axis of the tire with respect to internal layer rubber. CONSTITUTION:A tire has a tread part 1, surface layer rubber 12, internal layer rubber 1b, and a main groove 2, which is yielded by extending a tread raw material 3 through a dual extruder so as to provide an almost flat shape in its outer contour appearance along its transversal cross section. The surface layer rubber of the tire is adapted to be a composite structure bounded, without surface waviness, by a rotation surface of a segment of a linearly extending line substantially in parallel to a rotation axis of the tire with respect to the internal layer rubber. Since the tire is such constructed that a boundary between the surface layer rubber and the internal layer rubber does not present surface waviness on the transversal cross section of the tire, it has less variance in a thickness ratio of both the rubbers widthwise of the tread and thus it is also available for composite tire performance expected on the basis of predetermined thickness proportion therebetween. |
