Patent ID: 7452136

Claim:
A vehicle wheel bearing apparatus comprising: an outer member formed with double row outer raceway surfaces on an inner peripheral surface; an inner member formed with double row inner raceway surfaces arranged opposite to the double row outer raceway surfaces; double row rolling elements freely rollably contained between the outer and inner raceway surfaces, respectively, of the outer and inner members; and a wheel mounting flange integrally formed with either one of the outer or inner members which are thermally refined, at least one of the outer and inner members on which the wheel mounting flange is formed and is quenched after being thermally refined on a base portion on an outboard side of the mounting flange to increase strength and durability against rotary bending fatigue, said thermally refining hardening said outboard side base portion of the mounting flange at said outer or inner member to a first surface hardness, and hardening said raceway surfaces by quenching to a second predetermined surface hardness wherein the second surface hardness is greater than the first surface hardness.