Bridgestone Corporation

Tadashi Yamazaki

Hisao Ushikubo

A pneumatic tire having improved high-speed running performances is manufactured by conducting vulcanization of a green tire with a mold provided at a position corresponding to a given position between neighborhood of shoulder portion and neighborhood of bead portion with at least one protrusion which protrudes inside the mold and continuously extends in the circumferential direction of the mold and consists of a first arc segment having a center of curvature located outside from the inner surface of the mold and second arc segments each having a center of curvature located inside from the inner surface of the mold and smoothly connecting to the first arc segment at upper and lower ends in the radial direction of the mold.

Pneumatic radial tires

Method of making pneumatic radial tires

A heavy duty pneumatic tire is disclosed, which comprises a plurality of main grooves extending in a tire circumferential direction, shoulder land portions formed between the main grooves on the shoulder portions and edges of a tread, and a plurality of lateral grooves extending axially inwardly and outwardly in a tire axial direction on the shoulder land portions from the tread edges and spaced at an interval in the tire circumferential direction. The lateral grooves include the tread edges, and consist of two kinds of lateral grooves having different axial distances W.sub.1 and W.sub.2 from the tread edge to axially inward ends of the bottoms of the lateral grooves. An amplitude of the shoulder main grooves is varied corresponding to positions of the respective lateral grooves such that distances L.sub.1 and L.sub.2 from the radially inner ends of the lateral grooves to the axially outermost walls of the shoulder main grooves on the sides of the shoulder land portions adjoining the respective lateral grooves may be substantially equal to each other or in a range from (L.sub.1 -L.sub.2)/TW.ltoreq.0.06.

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Kodaira, Japan

Tadashi Yamazaki