i like to fill my wheel wells, so I use a 255/70/15 or 275 / 60 /15 on the rear and a 225/ 70/15 on the front all with 7 , 8 and 8 1/2 sometimes 10 inch wheels.
here is a 255/70/15 on an 8 1/2 inch wide wheel. I do not use the 50 series tires because they have short side walls