are 18 x 7.5's ok with 245 rears?
 

I have a performance model that comes stock with 18 x8's and 225 45 18 up front and 245 45 18 rear. I have found a set of rims I like, but they are only 18 x 7.5's. I have been told that this half an inch less in width will not affect performance or appearance. Is that accurate? Has anyone installed 18 x 7.5's with the stock 18 inch rubber? Any problems? Can you post pics?

Any help would be much appreciated/