spacewrangler

i'm currently running 32x11.50x15's on an aftermarket 15" wheel. it works pretty good with the stock suspension but the tires are a pain to balance....so i was considering changing to a 16" wheel and running 265x75x16's. my thinking is that the 265's will balance easier since they are a bit narrower than the 32's. ..my question is what would be the optimal backspacing for such a set up? i don't want the tires to stick way out past the fenders. ..just enough to avoid rubbing. i'm thinking either 4.0 or 4.5 ....but i'm not sure which one

thanks in advance!