largest tire

26" fit with plenty of room to spare, not sure how much bigger you can go. I would say at least 27".

i know robb and maby a couple others are running 29.5" outlaws on there foreman 500's without a lift. if they can fit them im sure you can fit what you want. they proubly did have to cut a little bit though. on my rubicon i had a 1.5" lift with 27s and when i would turn real sharp sometimes they would rub on the fender supports in the front fender supports.
-Aaron

thanku for advice

I fit 27" gators with no lift no problem

how good r the gators

I was never stuck with my gators. They rode well in the trails too for me. My laws are rough as **** but would never get rid of them.