wheels and tires

have an 800 xc and thinking about another set of wheels and tires so i can run 50 inch trails. ive read here that sti makes a 6 1 offset wheel that will keep me 50 inch question is what tire size will i use? if anybody is running the sti setup on your machine please chime in. dont want to make a 1000 dollar mistake. thanks. 14 inch wheels is what i want.