We have a 1992 4 Door XLT and have had a few sized spares over the last year or so..
30" spare fits no problem
31" spare fits, but tight
32" spare fits, must lower tire pressure to 10psi
The 30" was a BFG
The 31" was a Yokohama Geolander MT and a BFG AT
The 32" is a BFG AT
None of the tires had full tread, but they have well over 1/2 of the tread left