I have the same dilemma. Bought 15x8 with 4.5" backspace. Mounted 255/70's but it's tight, I can just get my fingers in. Haven't driven yet but will probably go to a 235/70. I didn't move the springs inboard for the same reason, tailpipes. Should be fun with a 511" wedge and street tires.
An association of men who will not quarrel with one another is a thing which has never yet existed, from the greatest confederacy of nations down to a town meeting or a vestry.
Thomas Jefferson
with a 511" wedge and street tires. 
