Bridgestone Corporation

Bridgestone Americas Tire Operations, LLC

Takayuki Kurata

Shinsaku Katayama

Yoshio Kaji

Eisuke Seta

Kohei Sahashi

Naoyuki Sone

Masakazu Amano

Hiroyuki Katsuno

Ataka Takei

Masafumi Koide

Satoshi Ishikawa

Koichi Ota

Yoshikage Sato

Keiichi Hasegawa

David O Stalnaker

The bead portion of the tire has an inner bead provided inside the tire width direction of a carcass ply and an outer bead provided outside the tire width direction of the carcass ply. The inner bead and the outer bead have a bead core portion including a bead cord formed of a metal material, and a filler portion provided outside the tire radial direction of the bead core portion and formed of a resin material. The inner bead and the outer bead sandwich a carcass ply.

Tire

Tire tread

By forming a ground contact edge side of lug grooves such that the groove depth becomes shallower in groove depth from the tire equatorial plane side toward the ground contact edge, and by setting an average angle of inclination formed between a tread face and a groove bottom to be not more than 5&#xb0;, water expulsion is performed smoothly in the vicinity of the ground contact edge while securing the rigidity of land portions in the vicinity of the ground contact edge. This enables a high degree of both wet performance and dry performance to be achieved.

Pneumatic tire

Taking a groove side-wall to a position at &#xbd; a groove depth from a tread face of lug groove as a tread-in side first inclined portion, and taking a groove side-wall from the position at &#xbd; groove depth to a groove bottom as a tread-in side second inclined portion, then the following Ais set less than the following B. When viewed in cross-section orthogonal to a length direction of the lug groove: Ais an area of a region enclosed by an imaginary line passing through an end portion on a tread face side of the tread-in side first inclined portion and perpendicular to the tread face, by an imaginary line passing through an end portion on a groove bottom side of the tread-in side first inclined portion and orthogonal to the imaginary line, and by the tread-in side first inclined portion; and Bis an area of a region enclosed by an imaginary line passing through an end portion on a tread face side of the tread-in side second inclined portion and perpendicular to the tread face, by an imaginary line passing through the deepest portion of the lug groove and parallel to the tread face, and by the tread-in side second inclined portion.

A pneumatic tire, having a plurality of sipes formed in land portions of a tread thereof so as to each extend in the tire width direction, characterized in that: in a cross section of the land portion orthogonal to the sipe extending direction, provided that an imaginary sipe main line links two ends in the tire radial direction of each sipe, at least two of the sipes are 'inclined sipes' each having the sipe main line inclined with respect to the tire radial direction; each inclined sipe has inner bent portions each protruding with respect to the sipe main line with peaks positioned deeper than 20% of the sipe depth; and the sipe main line(s) of at least one of the inclined sipes are inclined in a direction opposite, with respect to the tire radial direction, to the sipe main line of any of the other inclined sipes.

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.

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.

In a tire according to the present invention, the shape of the outermost reinforcing layer in the tire radial direction is optimized.

Growing community of inventors

Tokyo, Japan

Takayuki Kurata