The Yokohama Rubber Co., Ltd.

Kenichi Shirai

Toshihiko Suzuki

Hiroshi Tokizaki

Izumi Kuramochi

Masahiro Ishida

Tetsuya Kuze

Sadakazu Takei

Hisaya Morishita

Riichiro Mama

Automobile tire

Pneumatic radial tire including main grooves and sub-grooves

A pneumatic tire in which sub-grooves extending at least in the widthwise direction of the tire are provided in a center portion of a tread surface and shoulder portions thereof on both sides of the center portion at a predetermined pitch, both the width and depth of the sub-grooves in the two shoulder portions being set larger than those of the sub-grooves in the center portion, a ratio of the area of the sub-grooves in the two shoulder portions to that of the tread surface being set larger than a ratio of the area of the sub-grooves in the center portion to that of the tread surface. This tire can be used with the air pressure therein set higher under the on-road travelling condition, and lower under the off-road travelling condition.

Pneumatic tire having V-shaped subgrooves

A pneumatic tire having a tread pattern formed on a tread surface and comprising a plurality of main grooves extending in the center region of the tread surface towards the circumferential direction of the tire and a plurality of subgrooves extending so as to cross the plurality of main grooves, wherein the percentage groove area of the whole grooves including said main grooves and said subgrooves relative to the area of the whole tread surface is 20 to 30% and the number of pitches at which the circumferential direction of the tire is divided by the plurality of subgrooves is 30 to 45. The pneumatic tire is characterized in that the subgrooves each have a groove portion bent in a wedge form in shoulder regions respectively located outside the outermost main grooves.

Pneumatic tire tread with symmetrical grooves having a bent shoulder

Growing community of inventors

Hiratsuka, Japan

Kenichi Shirai