All steel, matte black powder coat. Image shown is 17x8. Note: 18" wheels DO NOT have windows as seen in the 17". Outside nubs for caps on 5-lug wheels measure 10 1/8", nubs on 6-lug wheels measure 11 5/8". Additional 6 & 8-lug options for this wheel style are available on our Truck tab. Image shown with lug nuts, not included. Please check proper fitment before mounting.