225/50/15's are too tall. 225/45/15 (Hoosiers) are the only tire I'm aware of in a 225 that will fit on an R. Even then you'll have to roll the rear fenders. That said, a good 205 (street or competition) tire will be more than enough for an R especially with 7-8 wide wheels.

SSR Compeitions are good choice for the R. Look good and are 7.5 inches wide and are about 10lbs. They are more expensive that other options, but are lighter and wider than most 15 inch wheels