Hey Man, I measured for rims and tires about 50 times on my setup to get all I could get. I even replaced the missing fender braces with slightly longer homemade braces and gained about 1/4-1/2" extra. Still think a 275 will be too close for comfort on a hard rear squat. Is there any chance you could give us a photo of what the 255's look like in your fenders. I don't want to do this twice. Are yours 26" or 28" tall?