A method for providing backup assistance includes providing a rear backup camera and a processor at a vehicle, and storing a plurality of mathematical formulas in memory, with each stored formula associated with a respective vehicle wheelbase configuration. A wheelbase configuration input is provided that is representative of the wheelbase configuration of the vehicle. Responsive at least in part to the input, a mathematical formula is selected from the stored formulas. Responsive to a steering angle input, the processor selects a value to be input into the selected mathematical formula. During the reversing maneuver of the vehicle, a predicted vehicle trajectory overlay is generated by calculating, via the selected mathematical formula and using the selected value, an overlay representative of the predicted vehicle trajectory of the vehicle. The predicted vehicle trajectory overlay is superimposed over displayed video images for viewing by the driver of the vehicle during the reversing maneuver.