A method for determining a trailer angle for a trailering assist system of a vehicle includes providing a rearward facing camera at a rearward portion of a vehicle and a control that processes image data captured by the camera. Responsive to processing by the processor of captured image data, a location of a portion of the trailer relative to the vehicle and a trailer angle of the trailer relative to a longitudinal axis of the vehicle are determined. During a reversing maneuver, a rearward trajectory of the trailer is determined and a graphic overlay may be generated to overlay displayed images to indicate the determined rearward trajectory. During forward travel, a degree of swing of the trailer may be determined and a threshold level of swing may be adjusted based at least in part on a speed of the vehicle and trailer and/or a load of the trailer.