If it's going on a K5, and you are talking about a body lift, you'll need to take off a bit at the rear of the wheel well at the least. As they said, it depends on the wheel width and backspacing. I have 15x10 wheels with 4" backspacing, and my 33's rub occasionally when the wheel is cranked to one side all of the way and I enter a parking lot. I have a 3" body-lift on a '91 K5.