im guessing the tire was not fully inflated. An underinflated tire at speeds over 40-50mph will it heat up and eventually shred. i see that kinda thing some some frequency in the shop. Not quite to that degree, but i see it often. Michelin's are notorious for blowing out like that. I dont deal with enough continentals to know if they do that frequently.
is there a bunch of tire "dust" stuck in there still?