Test fit Vision 18" wheel today

so I test the wheels in the front yesterday. well, 18's definitely clear pretty much everything and even with 6 inches of backspacing I can say that the rim does not hit the stock upper control arm. BUT, I guestimated that with 26" tall tires the tire will be rubbing against the frame rail. :( I don't know how you guys with deep backspacing do it and not hit the frame rail. :(