All steel with gloss white powder coat. Outside nub for 5-lug cap is 10 1/8". 8-lug options for this wheel style are available on our Truck tab. Part numbers ending in "R" are reverse rim. Lug nuts not included. Please check proper fitment before mounting. NOTE: 15" wheels have windows (see Series 657 image), 16" & 17" wheels do not have windows.