Bearing apparatus for a wheel of vehicle

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
• said inner member comprises a wheel hub having a wheel mounting flange and an inner ring press fit onto the wheel hub;
• all surfaces of the inner member on which the wheel mounting flange is formed are thermally refined by tempering after forging of the inner member to change the metallographic structure;
• the surface of the inner member where the inner ring is fit onto the wheel hub is formed with a surface hardened layer by high frequency induction hardening after said thermal refining of said inner member;
• said inner raceway surfaces are hardened by quenching after said thermal refining of said member;
• and
• said inner raceway surfaces are hardened by quenching after said thermal refining of said inner member;
• and
• said outer raceway surface are hardened by quenching of said outer member.