This paper gives the mechanical response of a simplified model of a trailer when its tow point moves along a certain prescribed path. The type of path considered here is described by a constant forward velocity on which is superimposed a low-velocity-amplitude, sidewise, periodic motion. In this investigation analytical expressions proposed by Huber (3) were used for the forces and moments on the tires. The equations of motion are studied for small slip angles. The analysis leads to a prediction of the natural frequency of the trailer and shows that the damping of the system due to slip of the tires is inversely proportional to the forward velocity of the trailer.