The drag of an isolated rotating wheel sub-system including its accessories (tire, suspension, A-arms and fender) of a tricycle vehicle was studied numerically using the Star CCM+. The purpose of the present work is to optimize the wheel subsystem through drag analysis. The numerical model is validated by comparison to the wind tunnel experimental drag and pressure coefficient. Two aerodynamic shapes of A-arms are designed to perform drag reduction. Numerical simulations show a sensitive drag decrease up to 19.9% of the original wheel subsystem.