Bones Wheels presents: ' X-Formula is another industry leading innovation from the Bones Wheels factory. X-Formula rolls over rough terrain like softer wheels do, but slides much like a harder wheel will. X- Formula™ was originally only offered in 97A, also known as X97.  Now available in 99A/X99 in the V6 cut. Wheels are recessed in a way so you cannot grind down your axle nuts anymore! No more rethreading your truck axles with these amazing X formula wheels!