Bridgestone Tire Company Limited

Noboru Sugimura

Shigeo Makino

Hideki Matsuda

A combination radial tire for heavy load vehicles comprising a thread portion consisting of a combination of a belt composed of at least two metal cord layers and a carcass composed of at least two organic textile cord plies. In the lower half region of the carcass located at a bead portion, at least one additional reinforcing layer is interposed between the carcass plies and/or another additional reinforcing layer is interposed between the carcass ply and rubber stocks sandwiched between the carcass ply and its turn-up portion, these additional reinforcing layers being extended in parallel with the carcass ply cords and including organic textile cords.

Combination radial tire for heavy load vehicles

A heavy duty pneumatic low-sectional radial tire having an aspect ratio of not more than 0.8 is disclosed, which comprises a pair of bead portions, a pair of side portions, a tread portion extending across the side portions, and a reinforcement for a tire casing composed of at least one carcass ply extending across two bead cores and turning up around the bead core and containing cords embedded therein in a substantially radial direction of the tire, each cord having a modulus of not less than 4,000 kg/mm.sup.2, and a belt of at least two layers, each layer containing metal cords embedded therein, superimposed around a crown portion of the carcass and crossing with each other at a relatively small angle with respect to the equatorial line of the tire. In this tire, a carcass line of the tire casing at a temporarily mounted posture on a normal rim under an internal pressure of 0.5 kg/cm.sup.2 depicts a bow-shaped profile in tire section defined by a curved line, whose curvature being smaller with distance from a chord PQ at the outside thereof, where the PQ is a line segment connecting a point P to a point Q, the point P is an intersection of the carcass line and a normal line of the carcass line passing an alienating point of the bead portion from a rim flange or an inflection point of the carcass line when the intersection is located inside the inflection point and the point Q is an intersection of the carcass line and a radial line of the tire passing the point P. The bow-shaped profile of the carcass line is substantially symmetrical with respect to a substantially perpendicular bisector of the chord PQ as a symmetrical axis inside and outside thereof.

Heavy duty pneumatic low-sectional radial tire

A pneumatic radial tire for heavy load vehicles comprising a body reinforcement and a bead portion reinforcement, in which the bead portion reinforcement substantially continuously covers the carcass ply wound around a bead core up to the inside of the tire, the upper end of the turn-up portion of the carcass ply and the outside upper end of the bead portion reinforcement covering the upper end of the carcass ply are arranged at an area other than a bead portion flexible region defined by two segments BC and AD as shown in attached FIG. 3, the bead portion reinforcement makes use of a cord having a modulus which corresponds to 15 to 60% of that of the ply cord of the carcass, and a tension at 100% elongation of a soft stiffener corresponds to 5 to 30% of that of a hard stiffener, the soft and hard stiffeners being disposed on the bead core one upon the other.

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Kodaira, Japan

Noboru Sugimura