| 摘要 |
PROBLEM TO BE SOLVED: To reduce the damage occurrence of cut scars or the like at least at a tensile body burial corresponding part in the width direction in the projection areas of mandrels on a ground plane. SOLUTION: A peripheral tensile body 3 is buried in a main body 2, blocks 7 divided by grooves 5 in the nearly peripheral direction and grooves 6 in the nearly width direction are formed on the ground plane 4, and the blocks 7 are divided only by the grooves 5 in the nearly peripheral direction at least at the tensile body burial corresponding part t in the width direction in the projection areas A of mandrels 8 on the ground plane 4.
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