MBT stats are slightly physically impossible

[jp10]

I find your "Let's double that for the rest of the tank." to be in extreme contrast to the preciseness of the other calculations.
The numerical weight of steel per cubic meter is 7850 kg/cubic meter, not 100 tons. One cubic meter of Chobham armor is not solid steel. It is an arrangement of steel and ceramic plates A fully loaded Abrams weights around 73-75 tons.