I've heard 31", 32",33" are all fine after a few years.....
On the flip side I've also heard 31", 32", 33" bend after a couple weeks/months/years.
Just make sure it's nice and tight and nothing is loose and it SHOULD be ok on a 31" (but no guarantees lol). Mines had a 32" for awhile and down to a 31. The spare area looks ok but there is slight damage to the door but I believe it's from something else as there is other damage near the tailgate damage.
If you want to be absolutely safe, get a tire mount for the bumper (in my plans). Otherwise tighten it up and just keep an eye on it.
1995 wrangler 4 cyl 5 1" poly body lift,2.5 ome 3/4" shackle, 32" swampers lock right in the d-30
1.25 motor mount lift full cage hi line fendered
98 TJ 2.5 5 speed 2.5 rc lift 1" poly body lift rancho 5000s
I had 32x11.5 on mine and over time the hinges began to sag, I had to lift up on the door to close it. I now have 35x12.5 tires on a swing away carrier on my new bumper, works much better with the weight off the tailgate.
If it were me I would get the full size spare. Then hang it on the tailgate and keep a close eye on it. If the tailgate or hinges start showing any signs of damage I would take the spare off. And once you get the tires, I suggest start saving for a bumper/tire carrier.
The spare on the tailgate should be ok for months at least.
"No matter what anyone says, it's YOUR Jeep, do what YOU want"
I have a 31" on mine and the hinges are holding up well. However, the PO obviously closed the tailgate by pushing the tire and now the tailgate is bent inwards. Someday, I'll fix that.
Back to your question ... no problem, just be sure to push on the tailgate (not the tire) when closing.
It's a Jeep Thing ... I do understand!
1993 Jeep Wrangler - 2.5" RC Suspension Lift, 31" Mud Tires, powered by 4 angry squirrels
31" on mine as well with no issues so far! Been on there about 8 months
1995 Jeep Wrangler YJ Rio Grande, 2.5L, 5-Speed, 31x10.50x15's on Pacer's, Stock Suspension, 2" BL, 12000lb Rough Country Winch, 6 KC's for Night Wheelin', Hi-Lift on the Hood, Smittybuilt XRC Front Bumper, and Hopefully More to Come!