thinner

As most of you may know, the OEM tyres on an LCR are 225/40/18 which to my knowledge fits 7.5" - 8.5" wheels comfortably but I was wondering, what would be the difference, in any aspect, of fitting a size smaller, width wise, 215/40/18? As far as I know, this tyres size will accomodate a 7" - 8"...