hyper inflation: let's cut to the chase

[CapriRacer]

Originally Posted by slowmover

I suppose a more serious question has to do with internal tire temperatures. On another site I/we could find no information in re the point where delamination begins to occur (tire pressure monitors with a pre-set alarm of 157F). My pickup runs 127F externally when GVWR is close in hot Texas conditions.

In the same way here . . does anyone know risks in overinflation? Links? Anyone run an internal temp monitor and can recite differences in pressure vs temps? (Tire/wheel weight rating + actual weight on that pair; external factors, etc, etc).

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First, inflation pressure is subject to the Ideal Gas Law: PV = nRT, where P = pressure, V = the volume of the inside of the tire (stays the same), n = number of moles of the gas, R = a constant (same regardless of the gas), and T = Temperature.

If you rearrange this formula you'll get the P/T = P/T, so anytime you know the starting conditions (pressure and temperature), you only need to know one to get the other. BTW, both pressure and temperature are expressed as absolute (add 14.7 psi to the gauge pressure and 460° to the ambient temp in Farenheit.)

For a passenger car tire, 3 psi is considered a reasonble build up, with 5 psi build up a maximum. You can do the math to see what the internal temperature would be.

But trying to connect this to delamination is problematic.

Rubber, like many things, is subject to the Arrhenius Law: The rate at which chemicals react doubles for every 10°C increase in temperature.

This is partially what is going on with the rubber degradation. Not only does this say that temperature is a factor, but so is time.

Second, the stresses involved are also factors. Clearly high speeds are more stressful than low speeds as would be high load / low pressures be more stressful than the opposite.

And we haven't even mentioned the differences in tires. Things like cap plies, and the actual rubber chemistry are all going to impact how this works.

There is way too much going on to simplify it down to a single parameter - which is why you couldn't find any info on it.