I sure was Simon. Black Civic Si in the blue group when I was not instructing. Seems like I remember you name on the entry list. I assume you were there too?

A little further investigation also reveals that the tires were on the overinflated side, although still seemingly withing Toyos advised values. Also, there was some scuffing on the inner sidewall that reminded me I ALMOST went over the back of the curbing at turn 10A earlier in the weekend, which, if you are familiar with it, is a BIG drop off. So it's possible that the combination led to the failure.

The biggest curiosity is that I had the same failure with a different tire when the car was configured completely differently. Things that make you go Hmmmmm.