[GZG] AFV ground pressure ( was Re: New to the list, and 2 questions: lift/jump infantry)

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I trust the Internets:
M109 SPH
Ground Pressure: 11.2 psi (not stated as combat weight or other)
Combat Weight: 52461 lbs.
Tread: 15" wide, 156" contact length (the math bears out)
source: http://afvdb.50megs.com/usa/155mmsphm109.html

An explanation of continous tracks and ground pressure is:
http://en.wikipedia.org/wiki/Continuous_track

If I believe them (I'm a bit skeptical), tire pressure in a car = ground
pressure. I'm skeptical because I find it hard to imagine my car can run
anywhere from 28 - 35 PSI bearing the same weight of car on slightly
different performance tires of the same general dimensions... I didn't
think
the contact patch changed that much.

But by this logic, I could pile 3 M109s stacked vertically and still
only
equal my car's ground pressure.

OTOH, when my car takes a corner, the wheels turn all the way around. I
don't lock one track and spin the other, which probably has some
deleterious
effects on road surfaces. I've also seen tanks driving through small
European towns in the 1980s (M1s) knocking corners off of buildings
while
trying to navigate narrow streets, so from that angle, most armour has
poorer fine handling and probably (no first hand experience, just a
guess)
less driver visibility than normal vehicles.

Still, ground pressure for tracklayers, even an M1, is better
distributed.
The only real concern would be bridges, where aggregate load matters as
much
as anything. Some small bridges may not handle 25 tons or the heavier
weights of modern MBTs.

I recall in High School (in Southern Alberta) seeing a picture of a car
destroyed a Suffield by a Challenger. The driver of the track hadn't
known
his buddy had parked his car behind the track and reversed up on top of
it
before he realizes his mistake and could stop. This is the sort of thing
that gets people concerned about AFVs and normal traffic. A collision
between two cars of roughly equal mass results in roughly equal damage.
The
collision between an AFV and a car... well, the AFV is likely to be the
winner....

This is a total threadjack about ground pressure and AFVs.

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