On my fj62 the largest i can fit is a 31x10.5. As i can see there is no way to fit a larger tire. You could probably fit a wider tire 12.5 14.5 but then you would lose more ground clearance. You can put it on the roof (top heavy), rear tire carrier (too much money in my opinion), put it inside (what i would do if i had a full size spare... probably upright to save space), just not have one (not good if you get a flat), or run a small spare (31x 10.5... may make steering difficult blabla bla...)
33x9.5 fits in the stock location on a 60 or 62, no mods. I imagine a 33x10.5 or maybe even a 33x12.5 would fit but I haven't tried. Same deal on a fj80, except on the 80 you can raise(use a spacer and replace bolts) the carrier up an inch+ to gain more clearence.
I fit a 33 x 12.5 tire under mine, only cause I got to :'(
It fit's fine, but it does look like it's taking a crap.
I keep it under there, then if I'm goin wheeling, I just throw it in the back. Not ideal situation, but it works. Only problem is, it takes me forever to put it back under. Only when I'm driven completely insane by it bouncing around back there do I bother.
On my 87 FJ60 I'm holding a 33 x 10.5 under there... Looking forward to putting it on the swing away on the rear bumper when more important things are paid off... (I have a stock bumper and no trailer hitch).
My 33x10.50 spare fits well under my 62. It hangs a little low for my liking. So it'll sit in the back when I'm wheeling. Otherwise it fits great! Even with the new 2 1/2" exhaust and greasable shackles.
My 33x9.5 fits perfectly. It just touches the hitch and edge of one of the shackles. I had the option of putting it on my swing out but chose not too. I wanted to keep center of gravity down and have less weight further back.
That is not a bad idea. I have had two serious tire issues this year, both resulting in having to buy new tires to replace the damaged one. Once the spare is on, the fun sort of has to slow down because of the risk of getting another.