i use 5/16" spacers on the rear of mine when i put tires on it that are a little too big and rub somewhere inside. the spacers are just enough to fix it. You wont be able to go much wider than that with the stock wheel studs.
you dont need the whole wheel to stick out a lot. What you need is some beefy tires on there. Atleast 255mm wide. anything less would be uncivilized.
