Out back, the stock wheel size is 20x9 with a 275/40 ZR20 Pirelli PZero tire (28.5-inch diameter, 10-inch tread). Rear wheel and tire weight comes in at 68 pounds each (136 pounds for the pair). The rear rotors are slightly larger than the fronts at 14.5 inches. The rotor and caliper weight loss at each corner was 9 pounds. We'd like to note here that in our drag test after the installation of the Mast Motorsport heads, we used Nitto 275/40R20 drag radials mounted on the stock wheels.