We present a new method for planning motion around obstacles for a mobile robot system configured as a car pulling many trailers with non-standard kingpin hitching. In our method, we need only plan for the front car and the trailers will follow without hitting obstacles. We assume there are no back-ups in the trajectory. By setting the distance between an axle and its neighboring kingpin to be the same for all axles, by showing exponential convergence of the distance between the path followed by a trailer and the path followed by a car, and by showing there exists a bound on this distance, we propose an obstacle avoidance algorithm for a multi-trailer system using any existing path planner for the front car only. Examples are given for a car pulling a single trailer and three trailers.