Originally Posted by
BlazingPedals
A tire with a tube in it could have blown off the same way, given the same... whatever did it. Which is to say there's nothing special about tubed tires that would have prevented a blow-off. I guess you can rule out pinched tube, at least.
While a tubed tire can blow off, the mechanism is a bit different.
Originally Posted by
MattTheHat
You know, that's an excellent point. Pressure is pressure.
-Matt
While pressure is pressure, not all pressure
vessels are the same. A tubed tire is less likely to blow off the rim, hence the higher pressure rating, because of the way that a tube, rim and tire interact vs the way a tubeless tire and the rim interact. With a tube, there is another, lighter pressure vessel pushing on the bead of the tire to keep it in place. This increases the friction between the tire and the rim which allows it to run higher pressures.
Without a tube, i.e. tubeless, only the air pressure is keeping the tire in place. Without that extra friction, the pressure required for the tire to slip and blow off the rim is lower. The tire has to be made so that it fits more tightly to the rim but it still lacks the friction that a tube provides. And, because the tubeless
can't hold as much pressure, the friction between the tire and the rim is reduced.
Additionally, sealant may not be your friend. If there is a leak between the bead and the rim...folded bead, poorly seated bead, damaged bead, damaged rim from running too little pressure, etc...sealant will get pushed into that gap and lubricate the rim/tire interface. Now your friction is far lower than it would be dry and the bead can scoot right off.