Wasn't it established that offset is how far the wheel mounting space was from the center of the wheel? If the wheel has 0 offset, and it is 7" wide, then the backspacing is 3.5". Stock backspacing is 4", and a stock wheel is only 5.5" wide. So, if my calculations are correct, your new wheels will stick out 2.5" further than the stock wheels plus however much farther the tires stick out.