[Smokin' Joe]

PV/T=P'V'/T'

Basic gas laws.

Volume remains constant.

[lepton]

Volume remains constant.

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Unless the leather gets wet.1/32” in change of radius could relieve the pressure roughly .5 PSI.

4/3 PI times the radii in each axis.

[babygene]

“Volume remains constant.”

You are confused...

Lets suppose the ambient temperature is 250 degrees. The ball is filled with 50% water vapor and 50% air. With the absolute (gauge) pressure at 12.5 PSI.

You now reduce the temperature to 150 degrees... The water vapor now condenses to liquid H2O. What’s the pressure in the ball?

Got it? It’s close to 6.5 PSI... Of course the volume remains more or less constant, but the pressure doesn’t. It conforms to Dalton’s law of partial pressures.