Originally Posted by Mike

yes, there is a reason. Our wheels use an acorn style lugnut. the clamping force is on the washer area. most other factory wheels, and most aftermarket use conical tapered lugs, but the mounting point on our wheel is flat, not tapered. If you use aftermarket lugnuts, you will get a ring of about 1/16" of an inch that is the only contact area between the lugnut and the wheel.