Patent ID: 6478064
Filing Date: 2002-11-12
Classification: B60C,Y10T

Abstract:
A heavy duty radial tire comprisinga tread portion, a pair of sidewall portions, a pair of bead portions with a bead core therein, a carcass comprising a ply of cords extending between the bead portions and turned up around a bead core in each bead portion from the inside to outside of the tire so as to form a pair of turnup portions and a main portion therebetween, and so that the minimum rubber thickness T4 between the bottom of the bead portion and the carcass cords is in the range of from 1.0 to 5.0 mm, a bead apex rubber disposed between each of the turnup portions and the main portion, each of the turnup portions extending radially outwardly beyond a radially outer end of the bead apex to adjoin the main portion, a chafer rubber having a 100% modulus of from 55 to 75 kgf/sq.cm and disposed along at least an axially outer surface of each of the bead portions so as to define at least a flange-contacting part for contacting with a flange of a wheel rim, the flange-contacting part being devoid of a concave profile, a sidewall rubber disposed in each bead portion and spliced to said chafer rubber to define a boundary between the chafer rubber and sidewall rubber, when the tire is mounted on a standard rim and inflated to a standard inner pressure but loaded with no tire load, the height of the radially outer end of the bead apex being in the range of from 7 to 35% of the height of the carcass at the tire equator, and being less than the height of the radially outer end of the chafer rubber, a rubber thickness measured axially from the outer surface of the tire to the carcass becoming maximum near the radially outer end of the bead apex, and at the radially outer end of the bead core, an axial thickness TC of the chafer rubber being in the range of from 0.7 to 1.5 times the maximum section width BW of the bead core, said boundary between the chafer rubber and the sidewall rubber having a radially inner end P2 positioned at a height L4 of from 1.2 to 2.5 times a radial height L5 of a flange of the rim, a sidewall lower part defined between the radially outer end P3 of the flange-contacting part and the maximum tire width point P1 having a smoothly curved convex profile.