A rear-wheel steering control system for a vehicle/trailer combination that adaptively changes an open-loop feed-forward command signal for different trailers or the same trailer with different configurations based only on vehicle parameters. The system includes a hand-wheel sensor for providing a hand-wheel angle signal of a hand-wheel position of the vehicle, a vehicle speed sensor for providing a vehicle speed signal of the vehicle, and a vehicle yaw rate sensor for providing a measured vehicle yaw rate signal of the vehicle. The system also determines if a vehicle yaw rate has reached a steady state and uses the steady-state yaw rate signal to calculate the rear-wheel steering command. In one embodiment, the system updates feed-forward rear/front values for a plurality of predetermined vehicle speeds when determining the proper rear-wheel steering command.