The 100 series Land Cruiser can handle a 33″ spare tire in the stock location. Steps need to be taken in order to get it tucked up and out of harms way though.
The most common tires size people go to on the 100 series Land Cruiser is the 285/75r16 or 275/70r18. Both of these are a 33″ tire and will fit in the stock spare tire location. The problem is these tires are fatter than the factory spare and can hang down in harms way. Luckily there is an easy way to get your spare up another inch or so out of harms way.
If you crawl under your truck you will notice the spare tire crossmember can be raised quite a bit. 1998-2002 guys have a little more room to work with since their charcoal canister is under the hood instead of down here like the 2003-2007 guys.
I need to count again but I was able to squeeze 11 or 12 5/8″ washers under the crossmember to get it raised a little over an inch.
The 2003+ guys will have to use a dremmel to cut the bolt pictured above. From the factory it sticks up about a 1/2″ above the nut and will rub on the charcoal canister if you do this mod. Trimming it down to the nut ensures maximum clearance.
One more thing of note, there is one more bar that is not pictured here that mounts to the rear of the vehicle. It has 4 bolts and needs to be angled up to allow the tire to be placed as far as possible towards the rear to avoid the panhard bar. This can be down by bending it or placing 3 washers under the bottom most bolts.
When you are all done you will have a spare tire that is hopefully above your hitch for maximum protection.