Patent ID: 7651275

Claim:
A vehicle wheel bearing apparatus comprising: an outer member formed with double row outer raceway surfaces on its inner circumference; an inner member formed, on its outer circumference surface, with double row inner raceway surfaces arranged oppositely to the double row outer raceway surfaces; double row ball groups freely rollably contained between the outer raceway surfaces and inner raceway surfaces, respectively, of the outer member and the inner members; the outer member is made of medium carbon steel including carbon of 0.40˜0.80% by weight, it is hardened by high frequency induction quenching so that each of the outer raceway surfaces is formed with a hardened layer having surface hardness of 58˜64 HRC; and an effective depth of the hardened layer is set at at least 2 mm and the minimum wall thickness of the outer member at these outer raceway surfaces is set at at least 4 mm.