The front I'd say 235/60-15 and the rear 255/60-15. Some people run 275/60-15's on 15x7 wheels, but they really need to be on 15x8's. The 235 on the front may rub a little though, it's the same height as the 215/56, but about an inch wider. The 255/60 is about an inch taller and about an inch/inch and a half wider. They look good on these cars.
A 275/60/15 tire on a 15 x 8 rim will fit fine without rubbing issues. I've clearanced (rolled) my fender lips but that's more for the 10" wide slick I run when racing the car. The 275/60/15 tire will work fine on a 15 x 7 rim as well, but it looks better on the 8" rim IMHO. Pics are on my webshots page in the link in my sig.