Patent ID: 6109320
Filing Date: 2000-08-29
Classification: B60C,Y10T

Abstract:
A heavy duty radial tire for mounting on a standard 15 degree center drop rim comprisinga pair of bead portions, each with a bead core therein,a radial carcass made of steel cords extending between the bead portions and turned up around the bead cores from axially inside to the outside thereof to form a pair of turnup portions and a main portion disposed therebetween,a hard rubber bead apex disposed between the main portion and each turnup portion and extending radially outwardly from the bead core,a bead reinforcing layer comprising a ply of reinforcing cords disposed axially outside each turnup portion and extending radially outwardly from a position radially inward of the bead core,a rubber strip disposed between each turnup portion and the bead reinforcing layer,the rubber strip extending at least from the lower radially outer end of the turnup portion or the bead reinforcing layer, whichever is lower, to the upper radially outer end of the turnup portion or the bead reinforcing layer, whichever is higher,the rubber strip having a thickness such that the minimum distance between the carcass cords and the bead reinforcing cords measured at the radially outer end of the turnup portion or the bead reinforcing layer, whichever is lower, is in the range of from 2.5 to 5.0 times the diameter of the carcass cords,the rubber strip having a JIS-A hardness of 70 to 90 degrees and larger than the JIS-A hardness of the bead apex by not less than 10 degrees, andthe difference B-D of the inside diameter B of the bead cores from the rim diameter D of the rim being in the range of from -4 to 1 mm.