Reusing tire after driven while flat?

[Chris Newbold]

Anyone have any opinions or guidelines for reusing or discarding a tire
that's been driven while flat? It's not known exactly when the tire went
flat, but it was driven 10 miles or less at low speeds, under 40MPH.

Other than not being able to find the cause of the air loss, the tire
looks fine (e.g. side walls not shredded, etc.) but there is a
pronounced bluish band of wear around both sidewalls where they
collapsed. Despite being removed from the car, the carcass doesn't
really want to pop back into it's original shape, either, remaining
visibly flattened at one point with the sidewalls a little deformed.

My instinct says just chuck it and buy another, but maybe it would pop
back into shape and be fine with air pressure...

Obligitory Audi content: fortunately this happened on my VW Golf and not
the S4 :-)

-Chris
2001 S4 Avant 6spd
(1993 90CS 5spd)