The old rule of thumb we used for tube type tires on multi-piece rims was if the pressure of a tire was more than 10% below the recommended pressure, we did not attempt to air them up- - - -break it down and find the leak! Attempting to add air to a low tire could possibly cause an explosive rim separation. My employees knew that was a good way to get fired.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!