The paper deals with the dynamic modeling of wheeled planetary rovers operating on rough terrain. The dedicated model here presented, although kept as simple as possible, includes the effect of nonlinearities and models the suspensions in a realistic, albeit simplified, way. It can be interfaced with a model of the control system so that different control strategies can be studied in detail and, in case of teleoperated rovers, it can be used as a simulator for training the operators. Different implementations, with different degrees of complexity, are presented and compared with each other so that the user can simulate the dynamics of the rover making a tradeoff between simulation accuracy and computer time. The model allows to study the effects of the terrain characteristics, of the ground irregularities and the operating speed on the behavior of the rover. Some examples dealing with rovers with different configurations conclude the paper.