okay people, i know that the normal size for 17's are 235/45's, BUT i just got a set of the 17x7 altima 5-lugs and the widest that will fit is 225. i went to order some 225/45s from tirerack.com over the phone and the guy told me they couldn't. he said that the required size is 225/50 and that 225/45s don't have the proper load. load i could see being a reason, but won't having a 50 profile tire throw off my speedo? anyone else heard of this? i was hoping someone on here with some 17x7s would know. help please