[Pearls Before Swine]

If inflated in the factory at 75°F and then played on the field at a substantially lower temp, then the 13 psi would be slightly less..........

That's why weighing would be the appropriate method of measurement. The air inside the ball doesn't go anywhere, even if it's pressure is lowered due to the temperature. Not to mention, sloppy insertion of a needle for measurement could allow air to leak.

[Red Badger]

Do they even possess a scale accurate enough to detect the difference in weight in a slightly deflated ball? It would have to be a pretty fine scale..................

[Red Badger]

And are the balls inflated with just common air or dry nitrogen? That would cause a difference in weight as well...............