I assume an F100, correct? (I have 20s and 22.5s on some of my trucks, but they are F600s)

As long as your overall diameters and widths are not too far from stock you should be OK. I have seen F100s with 7.00 x 16 tires, and there was still quite a bit of room in the wheel wells, so diameter wise you may be OK. be careful on width. If you lower too much you might get interference with the fender lip when turning.