Bridgestone Corporation

Namito Aoki

Yasufumi Ichiki

Chishiro Tanabe

A pneumatic tire includes a plurality of blocks, each having a narrow area interposed between one set of two sipes which extend substantially in a transverse direction of the tire and wide areas positioned respectively at both sides of the narrow area across the sipes. An average distance H2 from a tire tread surface of the narrow area to bottom portions of the sipes is less than an average distance H1 from tire tread surfaces of the wide areas to the bottom portions of the sipes. Expanded portions may be provided at the bottom portions of the two sipes. A ratio W2/W1 of a length W2 of the narrow area in the transverse direction of the tire to a length W1 of the wide areas in the transverse direction of the tire may satisfy 0.50.ltoreq.W2/W1.ltoreq.0.95. A length, in the circumferential direction of the tire, of at least one side end portion of the narrow area may be longer than a length, in the circumferential direction of the tire, of a central portion of the narrow area. In a vulcanization mold for forming a green tire, a pair of blades for forming a pair of sipes are provided at a bottom portion of a concave portion for forming a block portion. A vent hole is also provided at a bottom portion of an area between the blades. A method of manufacturing a pneumatic tire using the mold is provided.

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Kokubunji, Japan

Namito Aoki