Patent ID: 8079839

Claim:
A bladder for vulcanization of tires, comprising: a bladder body made from a flexible material, the bladder body which is disposed inside an unvulcanized tire in a vulcanizing mold during vulcanization and expands so that the unvulcanized tire becomes pressure contact with the inner surface of the vulcanizing mold; a plurality of first air-release grooves provided on the outer surface of the bladder body and arranged with first predetermined intervals with each other in the tire-circumferential direction, each of the first air-release grooves formed so as to extend from one to the other of the tire circumferential direction and extend toward one side of the tire-width direction; and a plurality of second air-release grooves provided on the outer surface of the bladder body and arranged with second predetermined intervals with each other in the tire-circumferential direction, the second interval is a distance equal to or more than 1.2 times and equal to or less than 4.5 times relative to the first interval, each of the second air-release grooves formed so as to extend from one to the other of the tire circumferential direction and extend toward the other side of the tire-width direction, each of the second air-release grooves intersecting two or more first air-release grooves.