This paper deals with the analysis of the effects of inaccuracies in the knowledge of the inertia properties of a dynamic driving simulator on the performances of its motion control. Dynamic motion simulators aim to reproduce the motion of a vehicle with a high degree of fidelity. The simulators are moved by actuators up to relatively high frequencies. Special algorithms are used to scale the motion of the actual vehicle in order to comply with the travel allowed by the simulator while maintaining the more significant motion characteristics. Such algorithms are fine tuned to reproduce the feeling of each vehicle and suit the expectations of each user. Therefore, the motion controllers of the driving simulators must be able to accomplish the desired motion. Errors in the knowledge of the inertia parameters of the driving simulator can reduce the performances of the controller and increase the tracking error with respect to the desired trajectory.