A fellow 'bolter, Bill Jesse, in Canada told me that a tire in the close vacinity of 30" dia. is what you want in order to fill the wheelwell. I would have considered going to a P235/80R15 for height but it wasn't available. Don't know if they make it or not, but the 75R is close enough for me.
I know many 'bolters want to go bias ply for that original look and ride, but I opted for radials that track true and ride smooth even on uneven or grooved roads. They sure are nice and I'm happy with the look.
Spot