The army also had a 10-ton tractor that pulled a special low-bed trailer. It carried battle tanks (M-60s) as well as armored personnel carriers. I drove one in Germany back in the 60s. It was a monster rig that called for two drivers. 10 speeds (5 shifts with a hi-lo transfer case). The assistant driver worked the transfer case up and down while the driver went through the gears double clutching all the way. Top speed was 42 mph (2800 rpm governed).
The rear of the trailer was right at 13 feet wide. We drove in convoy with jeep escorts. Gross weight was right at 80 tons. I was 21 years old when I qualified to drive the thing. Makes a fiver seem like a toy in comparison. 'Course, pulling with a pick-up truck makes the fiver a monster, too. :)