Kodebuster, what you described is pretty much what happens to a "low profile" tire that has been driven while deflated.
Being a low profile tire, it can be driven for quite some time "Flat" and not display the usual flat tire obligatory noise......(flappity flappity flappity flappity) that is common with tires that have a larger aspect ratio, such as 60, or 70 series tires do when they go flat.
Since you can't hear any tell tale noise, most drivers only sense a minor sway that's not unlike driving in the ruts made by the big rigs.
While the tire is rotating, the uninflated tire's side wall will still fold under the edge of the rim, and it systematically slices the side wall (little by little) every revolution. That's why the tread can stay intact, but give the illusion of a catastrophic side wall failure.
Green-ghost, many Mercedes have staggered tire applications, and come with a doughnut spare. We don't have a LSD on our Crossfires so it shouldn't cause too much of a problem. Not sure how the ETC would react. If you're still concerned with a rear tire failure, you could always replace the rear tire with a front one, and put the doughnut on the front. There are more than a few here on the forum that carry a doughnut, and I don't think any of them are LEO's.
Zahanma, I think Firestoned experienced a "ply separation problem" before the tire went flat.

In other words, pretty much what John and JC said above. (Thanks to Very slow typing skills).