I believe stock wheels are 4+2 front and 5+3 rear. Based on that an aftermarket 5+2 wheel on the front sits inboard an additional inch as compared to stock. I have a set of 5+2 wheels on mine but have also always had 2" spacers so can't comment on the fitment, but have heard people say that they usually clear fine. There shouldn't be any problem in the rear. Based on that you usually don't "need" wheel spacers but many people, including myself, run them to make the overall machine wider. Also a typical lift makes the machine a little more narrow (just geometry changes as the a-arms are at a higher angle with reduces the overall width some) so they use spacers to widen it back out. Some people also say that spacers on the front help clear larger tires....again, not real sure on this but have never actually measured or viewed mine with and without spacers.....if the tires are rubbing a full lock sometimes wheel spacers just make it worse and the tire swings or arches more. I have a set of 4+3 wheels coming so if I get motivated might pull off one of the front spacers and see how it does with and without spacers.