well some 15's won't fit and having a half inch less of sidewall is not that big of a deal, that is if you run 16's. I ran 16's and aired down to 10psi all the time in mine with 33's with no issues. Some guys run 17-18 and bigger but I'm not down for that on something I'll air down unless the tires are fairly large (Like a 35" tire on a 18" rim would be the same as a 33" tire on a 16" rim as far as sidewall essentially)