Bridgestone Corporation

Yasutaka Enoki

Shigeo Makino

Yasutoshi Aoki

Akihito Goto

Toru Tsuda

Tetsuhito Tsukagoshi

Shinji Murase

A tread of a heavy-duty pneumatic radial tire comprises a pair of upper and lower rubber layers having mutually different moduli of elasticity and a small-width groove formed in the upper rubber layer in such manner as to be substantially continuous in a circumferential direction of the tire. The dimension between a boundary surface bordering the two rubber layers and a bottom of the groove is set to be 1 mm or more. Accordingly, the arrangement prevents the occurrence of cracks due to a deforming stress acting in the groove bottom occurring when the tire rolls or rides on a curbstone.

Tread of heavy duty pneumatic radial tire

A heavy duty pneumatic tire including in its tread at least one circumferential main groove and shoulder rib grooves spaced from the circumferential main groove and arranged in the proximity of tread ends to define shoulder rib grooves. The shoulder rib grooves are formed to fulfill relationships of Rw/W=0.28-0.42, Rs/W=0.05-0.12 and Rd/W=0.07-0.19, where a distance from an equatorial plane to the tread end of the tire is W mm, a distance from the tread end to the shoulder rib groove is Rw mm, a width of the shoulder rib groove is Rs mm and a depth of the shoulder rib groove is Rd mm. Angles .alpha. and .beta. made by normal lines to surfaces of the tread and opposite walls of the shoulder rib grooves are in relations -7.degree..ltoreq..alpha. and .beta..ltoreq.7.degree., respectively.

Heavy duty pneumatic tire having tread with shoulder ribs

In a heavy duty pneumatic tire, a protrusion is disposed in an intersect portion between circumferential groove and transverse groove in a tread of block pattern, whereby stone capturing is prevented. Furthermore, blind sipe is formed in each block of at least center and second block rows, whereby heel and toe wear as well as shoulder wear are prevented.

Heavy duty pneumatic tires

Automobile tire

The uneven wear produced in the tread side rib in the heavy duty pneumatic radial tire is prevented by arranging a peripheral fine groove on a particular region of the side face of the tread portion in a particular form.

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Sayama, Japan

Yasutaka Enoki