| 摘要 |
A vehicle wheel bearing apparatus has an outer member (2), an inner member (1) and double row ball groups. A pitch circle diameter (PCDo) of the outer side ball group is larger than a pitch circle diameter (PCDi) of the inner side ball group. Ribs (17) are formed on a surface of the inner side of the wheel mounting flange (6). Each rib (17) is formed by an outline including straight portions (17a), radially extending outwardly from the base of the wheel mounting flange (6), and a rounded tip portion (17b), having a predetermined radius of curvature (r) centered on the axial center (O) of hub bolt (6a). The rounded tip substantially corresponds to a distance between the axial center (O) and the outermost periphery of the wheel mounting flange (6).
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