Dave, So the interesting thing is 1 US TON = 2000 lbs ... You're right on the MAX gross weight being around that 220,000 lbs on the prototypes.
That being said, if I take 220,000 / 2000 = 110 Tons and not 70 Tons
So I'm wondering why on the newer/shopped prototypes I've seen recently they've stamped 36" wheels on the ends?