I was wondering what is the largest tire you can put on a stock X? i've heard people say 30 and 31? i think 31 sounds more right . i had 31's on my pathfinder.

Hope you've got asbestos pants on.! :p

If anyone bothers to answer you will be told to do a search as this is a very regular question.

31/10.5/15 or 265/75/16 I think is the answer with trimming to your mud flaps.

I will admit that having searched many times I am often left confused as there are always exceptions that prove 'the rule' to be wrong.

The 265/75/16s will rub the fuel filler cover on the passenger side. My Trxus in this size rub BOTH sides in the rear when fully stuffed (opposite tire off the ground). I seem to have slightly bent the rear fender under the well molding a bit on the passenger side also. Dont know how it happened- not noticeable...
My 2002 has the mudflaps removed, and the fenders are pre-trimmed from the factory. Trimming is easy to do if you need to.

You can fit up to a 32" tire w/ just trimming the mud-flaps/fenders. Swampwrecker is running 33" tires with a T-Bar tweak up front. (Granted, the Super Swampers are narrow. Mehdi needed a 2" Body Lift to accomodate the 33" BFG M/Ts)