Originally Posted by
chaadster
I don’t agree with that, and the statement from Vittoria which I posted upthread supports the idea that if high temp induced tube failure is the problem, then eliminating the tube by going tubeless will eliminate the problem and greatly reduce the risk of tire blow-off.
In that statement, Vittoria say their tires are tested to 200% of maximum pressure, so if we assume a 100psi max tire inflated to 90psi at 70ºF cold, then brake heated to 284ºF— the top end of the range which Vittoria said would “destroy” the tube— then the Ideal Gas law tells us the pressure at 284º would be 132.3psi, well below the tire failure pressure.
Also, because tubeless supports lower pressure, it provides an additional level of overheat protection.
If the increase in air pressure inside the tire due to nR(delta)T/V is what is causing the tire to blow off the rim, I guess I would agree with them. But the OP calls it "heat related deflation", which suggests something less dramatic, and the opposite of what one expects for increased pressure due to temperature increase. In any case, rubber/bead deformation due to a heated rim, rather than expanding gas, is likely the culprit (if indeed the tire is becoming unseated, which isn't clear.)
Whatever the mechanism, disc brakes will be the safest option.
FWIW, Vittoria tires (tubed) are the only ones I have ever experienced blowing off rims, and the pressure was well under the stated max (it was about 70 psi for 28mm). Thankfully, this happened in my garage, and it did not involve a temperature change.
Also, FWIW, P(2) = 125 psi (assuming the volume does not change).