Aluminum plates simplify setting of toe-in and toe-out. Plates fit against outside edges of tires. Using two tape measures (sold separately), measure the distance front and rear, between plates. The difference in tape readings is the toe setting. Deluxe plates have radiused edges, slots for narrow and wide tape measures and are 9" tall x 23" wide to work with vehicles with smaller wheel openings. Standard plates are 1/2" thick, 11" tall x 32" wide and work well for vehicles with larger wheels and wheel openings.