| 摘要 |
PROBLEM TO BE SOLVED: To facilitate rim assembly without catching on the rim flange, prevent the bead toe portions from breaking off, and improve air filling performance before and after running. SOLUTION: The bottom surface 5 of a bead portion directly below a bead core 1 on the longitudinal cross-section of a tire is composed of a non-protrusive arc 51 formed with a convex curvature. An angleα, forming a straight line L which connects a point of origin A on the side of the bead toe 31 of the arc 51 and a point of origin B on the side of the bead heal 41 and the rotational axis, forms an angle that strictly follows the rim. Assuming that the center point of the arc 51 where a vertical line bisecting the straight line L, which connects the point of origin A on the side of the bead toe 31 of the arc 51 and the point of origin B on the side of the bead head 41, intersects with the arc 51 is designated a point C, the point C which is then center point of the arc 51 is located within the range of the bead core maximum width W that falls vertical to the rotational axis of the tire from both ends of the bead core maximum width W.
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