Is there a reason why you never see any tanks in Fallout? For a civilization constantly at war and so heavy on the weapons development they seem to focus on infantry all the time.
You could argue this was because of the fuel being scarce but there are so many nuclear cars around this seems a tad void (since military always comes before civilian toys). The closest thing to a tank is the Chinese chimera tank, which is a converted oil drill/rig.
All I've ever met in my travels are army trucks, and once a Jeep. I doubt I missed them so is there any reason for the lack of military vehicles?