High speed heavy duty tire and rim assembly whose tire includes a buffer

Abstract

A pneumatic tire for high speed and heavy duty use, in which durability of the bead and lower sidewall region is improved. The tire includes: a carcass comprising a radial ply of cords turned up around bead cores from the axially inside to the outside, the carcass cords rubberized with a topping rubber having a 100% modulus of 40 to 70 kg/cm.sup.2, an elongation at rupture of 200 to 350%, and a stress at rupture of 150 to 300 kg/cm.sup.2 ; a rubber bead apex disposed between the carcass main portion and each turned up portion; a buffer cord layer interposed between the carcass main portion and each turned up portion, the buffer cord layer extending radially inwardly to the bead portion to form an axially inner portion and then turned up around the bead core to form an axially outer portion, the axially inner portion having a radially outer edge located radially outward of the radially outer edge of the carcass turned up portion and radially inward of the maximum tire section width point, the axially outer portion having a radially outer edge located radially inward of the middle height position of the bead apex; in a normal pressure condition, at least 60%, in number, of the spacings of reinforcing cords existing in a tire side portion defined between two points (P1 and P2) are in the range of 0.25 to 2.0 times the thickness (D) of the carcass cords, the reinforcing cords including the carcass cords and the buffer cords.