Also, tanks put about as much pressure on the ground as a walking man, if I remember correctly. Not much more. The problem is when part of it ends up in the air that normally shouldn't be.
I remember my brother once told me a 1 foot thick layer of ice on top of a frozen lake is enough to support a tank in stationary position.
That would be enough for a small car or a light truck as 8 inches can support about 2000 LB, you would need about 30 inches before it would able to support a 60+ ton Abrams. Beyond that I think its just water on the ground.