That's so odd I have a 7 1/4 rear end and I measured my back spacing and it's coming out to 3 1/2" I'm so confused because everybody I see says 4.25 as well for back spacing would you mind taking a look at my post in this forum on my question I has small bolt pattern when I bought the car. I converted to disc brakes in the front brining the bolt pattern in the front only to 4 1/2". I still have small bolt pattern in the rear with a 7 1/4" rear end. I had stock steelies 14" on the car with f70-14 tires. I measured the back spacing and show 3 1/2" for both front and rear wheels. I have to get 15" wheels and tires to clear the front disc brakes. I am keeping my 7 1/4 rear end with small bolt pattern in the rear for now. I have no clue what size back spacing to get for 15" wheels for the rear or front. Can you help at all. I ordered front wheels and got 15 5x4.5 with 3.75" back spacing. Will this work? And if so what size tires as far as the rear goes what size wheels and tires do I get for a 7 1/4 small bolt pattern and what size tires?