In this paper it is proposed the extension of an efficient method employed for non-holonomic mobile robots to the path tracking of tractors with a trailer. The main advantage of this pure geometric technique is that no kinematic model of the vehicle is needed, which is an interesting property when working in irregular terrain or with tracks instead of wheels. The differences of applying this method to the combined system appear when avoiding collisions of the vehicle with the trailer and while moving in reverse direction. This technique has been successfully implemented and tested in the outdoor mobile robot Auriga-α.