Bridgestone Corporation

Hiroyuki Katsuno

Takayuki Kurata

Yoshio Kaji

Shinsaku Katayama

Eisuke Seta

Ataka Takei

Masafumi Koide

Satoshi Ishikawa

Shoichi Tanaka

Masakazu Amano

Koichi Ota

Yoshikage Sato

Masahiro Katayama

Ryoichi Watabe

A pneumatic tire (), which has, in the surface of the tread (), lug grooves () on one side extending from one axial edge towards the axial center of the tire in such a manner as to intersect with the circumferential direction of the tire and lug grooves () on the other side extending in a symmetrically opposite direction from the axial center towards the other axial edge of the tire, has at least one circumferential groove () extending circumferentially around the tire. Also, circumferential grooves () are so formed as to satisfy a relationship of '1&#x2264;(S/L)&#x2264;3' where L is the axial length of the central region, which is the region enclosed by two straight parallel lines each passing through the center between the contact width center (CL) and the contact edge with the shoulder regions being the regions axially outside of the parallel lines, and S is the total of the groove areas of the circumferential grooves () disposed in the central region. Therefore, the pneumatic tire () not only secures the steering stability performance on wet road surfaces, but also improves the steering stability and wear resistance performance on dry road surfaces.

Pneumatic tire having lug grooves forming a direction tread pattern

A pneumatic tire () has, in the surface of the tread (), a central circumferential groove () located at the center of the contact patch width and extending circumferentially around the tire, a plurality of longitudinal grooves (()) formed on the axially outside of the central circumferential groove (), lug grooves (), and blocks ((to)) defined by the central circumferential groove (), the longitudinal grooves (), and the lug grooves (). Each of the lug grooves () is formed such that its width in the shoulder region is greater than its width in the central region, and the sum of the groove area of the central circumferential groove () and the groove area of the longitudinal grooves () is smaller than the area of the lug grooves (). As a result, the pneumatic tire () not only secures the wet braking performance and wear resistance performance on paved roads, but also improves the acceleration performance and braking performance and the steering stability performance on snowy roads.

Pneumatic tire

A pneumatic tire, comprising: a tread surface; a plurality of grooves formed in the tread surface, including a plurality of widthwise grooves each extending from a corresponding tread end on the inner side in the tread width direction and a plurality of circumferential grooves each extending in the tread circumferential direction to intersect the widthwise grooves; blocks demarcated by the plurality of grooves; and a chamfered portion formed at a corner, on the trailing edge side and on the outer side in the tread width direction, of each block.

The tread surface of a tire according to the present invention is molded with a tire mold having a tread molding surface, and at least a portion of the tread molding surface is formed by projecting spherical projection material having a predetermined sphericity and causing the spherical projection material to collide.

Tire mold, tire, and tire manufacturing method

Tread portion of an automobile tire

A pneumatic tire largely improves the run-flat durability while preventing the deterioration of the ride comfort to the input of vibrations to the tire at a normal state and comprises a reinforcing rubberarranged inside a sidewall portionand having a crescent form at its cross section, in which one cord reinforcing layerhaving a rubberized structure of steel cords is arranged along a turnup portionof a carcass plyaround a bead coreand an interval between the steel cords in the cord reinforcing layer is within a range of 2.5-20 times a diameter of the cord.

Pneumatic radial tire

Growing community of inventors

Kodaira, Japan

Hiroyuki Katsuno