| 摘要 |
PURPOSE:To reduce a belt separation so as to obtain durability of the belt by connecting the contour parts of tread/crown parts together by means of the crown radial of large diametr and small diameter and connecting the radius part of the small diameter crown to both end parts of the tread by its extension line so as to form a square shoulder. CONSTITUTION:Cross belts B1 to B6 are laminated at an angle of 15 to 30 deg. so that the directions of rubber covered cords of the cross belts are opposite to one another. When it is assumed that a point at which a line passing the end of the cross belt layer intersects a tread crown part is P0, and that a point at which a line passing the end of the belt layer B6 of the maximum width is P1, a crown radius R0 in which a fall height h0 at P0 is 0.45 to 0.55% of the outside diameter D of a tire is selected. When it is assumed that a fall height at a point where the line passing the belt layer B6 of the maximum width intersects a virtual extension line of the crown radius R0 is h2, a crown radius R1 in which a fall height h1 at P1 is 135 to 200% of h2 is selected. The, the crown radius R1 is extended to both the ends E of the tread and connected to a buttless line so as to form a square shoulder. |
