I put some new tires on my 89 bird this weekend. I mount and balance my own tires. So I have time to figure out what will fit and what won't. With a minimal amount of rubbing I am running:

255/60R15's on the front
275/60R15's on the back

With an ~4.5" backspaced factory wheel.

I had to beat out the rear inner fender well slightly to make the tire fit. They come out with ~1" of clearance around the tire. The front tires do rub at full turn, but so far I'm yet to rub on the street. I'm running a coupe with air conditioning intact, but the spart removed from the car.