FWIW I had a sidewall tear very similar in appearance and location to the one pictured above by biker128pedal. This was on a LB hookless rim running a Specialized Sawtooth 38c tire setup tubeless. I think it happened from running low pressure - which became unavoidable as we were in the middle of nowhere and I could not get the leak to stop and had the wrong size tubes with me. And this was the rear tire on a tandem, so lots of stress on the sidewall.