After we mini tubbed my dart we took measurements using the stock width A body rear end. To run a 15x10 tire would have required a 7 1/2 inch backspace wheel. That's fine if you want to run modern wheels, but that wasn't the look I was going for. I had Strange build me a custom width S60 that is four inches narrower than stock on each end, which allows me to run a 3 1/2 inch backspace wheel.