To address the uncertainty in determining the optimal spherical base curvature radius ( SR) for tapered roller bearings, this study develops dynamic and friction torque models under combined loading conditions to evaluate three SR configurations (0.85 ρ p, 0.90 ρ p, and 0.95 ρ p, where ρ p denotes the inner rib’s curvature radius) in terms of load capacity, friction losses, and operational precision. The results demonstrate that: (1) the 0.85 ρ p configuration minimizes friction by optimizing the contact zone’s fV parameter under combined loads, making it ideal for low-friction applications; (2) the 0.95 ρ p design achieves superior operational accuracy; while (3) the intermediate 0.90 ρ p value provides an optimal compromise between friction torque reduction and operational precision. These findings establish quantitative guidelines for SR selection based on specific bearing performance requirements.