I'd stay away from the thornbirds,they make plenty of tires that will fit a stock KJ,but you''l' need to drop to a 15x6 rim(those will fit on a KJ),they have TSL,SSR's,and TSL radials that are 29" or less.They make alot more that will fit a KJ with a lift in both the 15" and 16" sizes.There are others also like the MT/R's,Maxxis BigHorn radials,and even the BFG MT's that will fit a non-lifted and lifted KJ for 16" rims.
If I was unlifted and wanted a set of rims/tires just for offroad I would get a set of 15x6 "wagon wheel" steel rims(paint them black) and mount some Super Swamper TSL's(29x8.50-15's)on them and would have some killer offroad tires.Probally cost less then $600 for the tires and rims mounted(no use balancing TSL's).