I don't have any experience on my car with different width rims. However I am stuffing 225s onto 13x6" wheels, but mainly because the 225/45-13 gives me (I think) the OD that I want. To be honest, it is quite possible that a 7" wheel would perform better, or course it ain't easy finding either size in a 13.

As much as anything, I am doing this to try something different and learn something that makes the car faster...or not. Either way valuable info.