I don't know if the wheel well for the Sierra's are different from the Silverado's, but you can run 35s with just a 4" BDS. I saw 4.5" of lift and have no rubbing issues and didn't have to trim. I did however go 35x11.5 and not the usual 35x12.5 but BDS claims you can clear them too. I just don't like too wide a tire. This is all on stock 20's of course. Hope that helps. This is the second time i go with a 4" lift; it's the ideal lift for me.