The difference in tape readings is the toe setting.
FeaturesAluminum Toe PlatesPrecise manufacturing and high-grade materialsPack of 2 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. Aluminum plates simplify setting of toe-in and toe-out. Standard plates are 1/2" thick, 11" tall x 32" wide and work well for vehicles with larger wheels and wheel openings.