I've had two blow outs at high speed. the first one was on a tandem going over 45mph. I hit rock and the front tire popped. but I only lost 50% pressure...I run two innertubes on my tandem (I drilled a second hole for the additional innertube). I pulled over, checked the tire and inflated the one innertube that still had air and left the flat innertube in place, changed it after the ride. the second blowout was at about 35 mph coming down mt. tam and hit a potpole...the tubular went flat and I grabbed my rear brake...came to a stop just in time.