Just read in the 2012 F150 Quick Reference guide, the following:
"Location of spare tire
A temporary spare tire is located under the vehicle,
just forward of the rear bumper. The temporary spare
is designed for emergency use only and should be
replaced as soon as possible."
I hope this is not the case with the off road package. If it is, I hope there is room for it to be replaced with a real Spare. Maybe that is how they were able to put a 36 gallon tank under the 5.5 box. That may not seem like a problem in the populated areas, but in the high desert of AZ/UT it is a concern. May have to throw a real wheel/tire in the back of the 5.5 bed.