Don Terrill’s Speed-Talk

I know this isn't in the right section, but I think it might get the best answer here.

What could have caused that explosion on Paul Menard's car at Homestead? It blew the floorboard loose and curled up the hood even with the hood flaps. It also blew the entire hub, brake rotor, axle and wheel off. The tire changer said he would have been killed if he hadn't hesitated.

https://www.youtube.com/watch?v=NpEObbJ-hhQ

Tire got hot and blew?

Then possibly with the fire under the rear of car from the rubber, it caught the fuel on fire?

The tire itself did not blow up, it was blown off. A shockwave appears (to me) to come out of the axle housing and is reflected out of the wheel well on the driver's side. So far, no one has said anything about a fuel fire that I am aware of.

Gear oil !! There is a pump to pump oil in the rear end to keep it cool. His rotor came apart and tore off brake line then probably caught brake fluid on fire, He was losing parts from that side all around the track. Axle got hot enough to burn out seal and pump pushed out hot oil fueling fire til tire blew.

Way too much pressure to just be gear oil fire. First guess a high pressure chamber built into the rear end housing. For what ?

Classic tire explosion.

Look at it at 1:50 or so, you can see that it is massively overpressured from heat.

The mechanism is, the heat from the fire made rubber inside the tire start to smolder. I was under the impression that they ran nitrogen in the tires, but even without oxygen present for a flame the outgassing would still raise pressures considerably, which raises heat, in a positive feedback loop.

Here's an interesting video with pressure and temperature gauges attached.

https://www.youtube.com/watch?v=uScd7nFzfQE

And an OSHA safety video:

https://www.youtube.com/watch?v=pNZ4siYGkag

Would a shock filled with nitrogen have that much force/volume? Do they use steel or alum shocks? A gas steel shock could have over pressurized from heat, alum would fail before that much pressure from a rotor fire heat issue, I would think. There was little fire I saw from the actual blast. The fire on track until stopped, did have enough time to heat up a lot of surrounding items in that area, I would have guessed a RR tire blow out on first glance..