This paper presents a methodology to optimize the drive forces and steering angles for achieving accurate path tracking by a four wheel steer and four wheel drive (4WS4WD) vehicle. The 7-order Bézier curves are applied in path planning and online tracking, and used to obtain the kinematic and dynamic profiles for the guidance of vehicle. The 8-input dynamic model is developed and applied in an objective function, which is optimized by PSO algorithm to obtain the optimal driving and steering motions for tracking the planned path precisely. The slip angles and lateral forces are also considered in the dynamic model, and the vehicle motion optimization can be implemented in real time. Note that this paper does not address the implementation of the force and steering controllers at the wheels. Simulation results are provided to validate the proposed method.