If you are going to have a set custom made then you might as well go up to a 16" rim. You'll find way more tire choices. As for the rear back spacing you might be able to get away w/ 5" factory is 4.5" I have 15x9 w/ 5 inches of backspace and the fit. 275/60/15 The taller bigger tire might "bulge" some so be careful.