"Kevin Kubiak" wrote in message The problem apparently was that
some of the steel cord must have popped up through the tires sidewall and
punctured the tub. If you rub your hand over the inside you can feel the
steel
wire protruding through the sidewall. Does this kind of thing happen
frequently.

It doesn't happen frequently, but it does happen. I learned the hard way
that replacing the valve stem along with the tube is cheap insurance. I also
learned that many flats are the result of the tube being folded back on
itself during installation, causing a pinch or a crease in the tube which
quickly rubs a hole.

Did I over react by shutting down
the engine, but I was really did not want to add a prop strike
to ruin my day?

You did the right thing. Taxiing with a flat tire can cause a lot of damage.
No sense in adding unneccessary risk.

Also, what would happen if the tire went flat
during flight? I guess I would know the minute the nose settled on the
runway.
If that happened, all I could do is hold the nose off by pulling back on
the yolk.

Landing with a flat can cause problems because of the severe vibrations. I
landed a C-337 with a flat main tire. It was controllable throughout but the
vibrations were so bad that the brake pads departed the gear. A Cessna 400
series won't taxi at slow speeds with a flat nose tire. The tire just cocks
to the side and that's the end.

D.