You need 1 inch bolt on adaptors that have new studs on them to adjust teh backspacing on these wheels from 5.72 to 4.72.
The 255 40 17 will fit in the rear (that's what I runon my 65) with a rolled fender lip. They will will be wide in the front I beleive (not to mention a bugger with manual steering). I run 235s and while I have not rolled the fender, I have done the shelby drop and run a very aggressive alignment spec which is why they fit so well