Three Piece Forged Wheel Using 6061 T-6 Aluminum Alloy Wheel Size: 17" 18" 19" 20" 21" 22" Outer Rim: 1.5J ~ 8.5J Inner Rom: 5J ~ 8.5J Center Disc: Normal / Concave / Ultra Concave Bolts: Stainless Steel / Titanium Cap: Aluminum Alloy Valve: TPMS Compatibal The Design Department of QIYU consists of a group of skilled and experienced designers who have great understanding of wheel history and fashion. Each of the designers has the background of aesthetics and engineering science, which founds the basis of making the most attractive wheels.