In this study, the effect of a passenger car radial tire rim width on its force and moment characteristics (behavior) and subsequently on a vehicle dynamic performance is investigated. The study on the sensitivity of tire behavior to changing its rim width was carried out using the finite element method with the help of Abaqus. For this purpose, the finite element models of a 185/65R14 tire with two rim widths of 5.5″ and 6″ were created and compared in terms of steady-state longitudinal, steady-state lateral, transient longitudinal, and transient lateral behavior, by simulation of stiffness measuring and slip tests. To investigate the effect of rim width on vehicle dynamic performance, several road tests were simulated using a full vehicle dynamic model from CarSim. In each test, at least one of the parameters associated with the discussion of vehicle dynamic performance evaluation including brake distance, understeer gradient, vehicle slip angle, lateral deviation, and roll angle is measured. The vehicle model used is one of the B class instant vehicle models from CarSim, for which this tire size is appropriate. For all subsystems except tires, the same default values were used. For tires, the Pacejka 5.2 tire model is used. Numerical values of the coefficients of this tire model are calculated by fitting the curves of the tire forces and moments obtained from the finite element simulation of required tire tests. The results of the road test simulations have shown that the vehicle with the narrower rim has the better braking ability, but its other behavioral aspects are weaker.