The 2002-2004 X's can fit up to 32's w/o a lift (The Lift to fit larger tires on an X is a Body Lift btw...).
You simply snip off the plastic ledge the front mud flaps used to screw to, to avoid the rub on turns mentioned above.
Its soft plastic, and takes ~ 5 minutes.
If we knew your rim size, it would be easier to recommend a tire size.
With 15" rims, a 32 x 11.5/15
If 16" a 265/75/16
etc.
The BFG AT ko's are an excellent choice as well...as already mentioned.
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- TJ
2001 Xterra '03 VG33, SE 5 spd, 305/70/16's, Revolvers, UBSkidderz, Doubled AAL's, 3"SL/2"BL, winch/bumpers, skids, sliders, OBA, Snorkel, pine stripes....
Friends don't let friends drive stock.
http://www.gifsoup.com/view/501230/tj-tackling-crawlers-ridge-o.gif