Bridgestone Corporation

Bridgestone Corporation 10-1

Mamoru Mamada

Kenichi Motomura

Hiroshi Ogawa

Hikaru Tansei

Yukimasa Yamada

Masao Nakamura

Mitsuhisa Yahagi

In order to improve the wandering performance of a radial tire, that is, to increase the camber thrust, the camber torque and the self-alignment effort of the tire without degrading various performances required for the radial tire, the radial tire is formed with a plurality of main zigzag wide grooves extending in the circumferential direction of the tire; at least one auxiliary straight narrow groove disposed on the shoulder rib and extending in a circumferential direction of the tire; and a plurality of sipes arranged outside the auxiliary groove at regular intervals along the outermost circumferential edge of the tire and extending in the lateral direction of the tire from the outermost end of the tire to the auxiliary groove. The width W.sub.a of the auxiliary groove is 1 to 4% of that of the main grooves W.sub.m ; the outward inclination angle .theta..sub.a is 10 to 60 degrees with respect to a normal line perpendicular to the tread outer surface; the position of the auxiliary groove is such that a distance S.sub.a from an outermost edge of the tread thereto is 20 to 80% of a distance S.sub.m from the same outermost edge to the main grooves.

Pneumatic radial tire tread for reducing wandering

A pneumatic tire comprising a tread divided into at least three ribs by at least two main wide grooves extending substantially in a circumferential direction of the tire, wherein a shoulder rib arranged at an outermost end portion of the tread is divided in an axial direction parallel to an axis of rotation of the tire into at least two shoulder rib portions; and between two adjacent shoulder rib portions of said at least two shoulder rib portions, an outer surface of an outer shoulder rib portion is radially inwardly disposed with respect to an extension line of an outer surface of an inner shoulder rib portion arranged inwardly of the outer rib portion. A plurality of sipes may be formed in the vicinity of an outer end of at least one shoulder rib portion other than an outermost shoulder rib portion. Further, a plurality of sipes are formed in the vicinities of outer ends of at least two rib portions other than an outermost rib portion, the quantity of siping being gradually reduced in the axial direction.

Pneumatic tire tread with divided shoulder

A pneumatic tire comprising a tread divided into at least three ribs by at least two main wide grooves substantially extending in a circumferential direction of the tire, wherein a shoulder rib of the ribs arranged at an outermost end portion of the tread is divided in an axial direction parallel to an axis of rotation of the tire into at least two rib portions; and between two adjacent rib portions of the rib portions, an inner end of an outer surface of an outer rib portion is connected through an outer surface of a circumferentially extending sloped portion to an outer end of an outer surface of an inner rib portion so that the outer end of the outer surface of the outer rib portion is lower than the inner end of the outer surface of the inner rib portion.

Pneumatic tire tread with recessed shoulder portion

Growing community of inventors

Kodaira, Japan

Mamoru Mamada