I would think a lot has to do with the style of the wheel, if there is any meat to drill and tap once the outer lip is machined off. My current set of 17s I am sure there isn't enough material there as it is rather thin being that is pretty much the dish part of the wheel. That could be fixed by welding in material, but not all aluminums will weld correctly. At this point it would make better sense to just get custom one off wheels exactly like I want. Expensive, but probably cheaper then all the work to make the wrong wheel into the right wheel.