Saris' Spare Tire Plate is for use with their spare tire racks. Grab the Spare as an extra or replacement part.
Use the spare tire plate to ensure a proper fit with your vehicle's external spare tire. If the wheel depth (distance from spare tire mounting plate to outside of tire) is between 5" and 7-3/4" you must use Base Plate 996B. If the wheel depth is between 2-1/2" and 5-¼", use Base Plate 996A.