I've got 6 boat trailers in my backyard. They all have their stock sized tire and whell as far as I know. They all have a Ford wheel bolt pattern, 5 on a 4.5" bolt circle. They all have 14" X 6" wheels on them. They all have 18575R14 tires on them. The only difference that I found was that some of them were made with reversed rims and some were made with stock offset rims. Stock wheel backspacing is about 3.5", reversed back spacing is about 2.5". The offset of the wheel decides where the tire is going to sit within the fender. If you have a welder and a handheld grinder the fender is extremely easy to move and re-install. Hope some of this helped. BTW, all trailers that I have but one came from jet boats and the other one came from a walk-through with an outboard on it.