as some of you may know i have an 86 iroc, and it has 15in rims with p235/60r15 tires on it, would a p235/75r15 fit on this rim but just throw off the speedometer? i think stock iroc rims are 16in, however the ones on it now are 15in, and im about 99% postive the previous owner didnt recalibrate it after that. so would i be able to fit those guys on it?