A technique for reducing the likelihood of fatigue damage to a wheel rim assembly (11) of the type having an annular wheel rim (13) with a first bead flange (19), a second separable bead flange (15, 21), and a retaining ring (17) disposable within a groove (35) in the wheel rim to secure the separable bead flange to the wheel rim includes forming the retaining ring to have an annular bead (41), a portion of which has an arcuate cross-sectional configuration by shaping the annular bead, in cross-section, as at least two tangentially joined circular segments (43, 45) of unequal radii (27, 29). Contact between the retaining ring and the wheel rim is limited to the arcuate portion as the sole contact region between retaining ring and wheel rim. The separable bead flange is formed to have a concave retaining ring engaging annular surface (25) which, in cross section has a finite radius of curvature (59) and the retaining ring is formed to have a separable bead flange engaging convex annular surface (23) which, in cross-section, has a finite radius of curvature (61). Each radius of curvature (59, 61) is constant throughout the respective engaging surfaces.