Patent ID: 6807996
Filing Date: 2004-10-26
Classification: B60C,Y10T

Abstract:
A pneumatic tire comprisinga tread portion, a pair of sidewall portions, a pair of bead portions each with a bead core and a bead apex therein, a carcass comprising a ply of cords extending between the bead portions through the tread portion and sidewall portions and turned up around the bead core in each said bead portion from the inside to the outside of the tire so as to form a pair of turned up portions and a main portion therebetween, said bead apex made of hard rubber disposed between the main portion and turned up portion and extending radially outwards from the bead core, a length (LA) of the bead apex between the radially inner end and radially outer end thereof being in a range of from 0.1 to 0.25 times the section height (H) of the tire, a reinforcing cord layer composed of a single ply of cords disposed along the axially inside of each said turned up portion, the reinforcing cord layer having a radially outer end (FU) which is positioned radially outside the radially outer end (BU) of the bead apex but radially inside the maximum tire section width point (M), and a radially inner end (FD) which is positioned radially outside the radially outer end of the bead core but radially inside the radially outer end (BU) of the bead apex so that the reinforcing cord layer comprises a main portion disposed between the bead apex and carcass ply turned up portion, and a protruding portion protruding radially outwardly from the radially outer end (BU) of the bead apex, and the protruding portion adjoins the carcass ply main portion and turned up portion to form a triangle cord arrangement, a length (LB) of the reinforcing cord layer between the radially inner end and the radially outer end thereof being in a range of from 1.2 to 2.0 times said length (LA) of the bead apex, a length (alpha) of the protruding portion being in a range of not less than 10.0 mm, the sidewall portions having a minimum thickness (Wmin) being in a range of not more than 0.5 times a maximum thickness (Wmax) of a region where the reinforcing cord layer exists, wherein said minimum thickness (Wmin) occurs between the radially outer end (FU) of the reinforcing cord layer and the maximum tire section width point (M) and between the radially outer end (FU) of the reinforcing cord layer and the radially outer end of the turned up portion, and said maximum thickness (Wmax) occurs near the radially outer end (BU) of the bead apex.