Back in High School I told the jerky kid across the street that he needed to change his tires over to 'Summer Air'. I told him that since he had 'Winter Air' in his tires he'd never get an accurate pressure reading and that he needed to 'drain' the more dense 'Winter Air' and refill his tires with the current less dense air. I lectured him at length about cooler gases being more dense etc. Like most good B.S. there were just enough points in it he thought he understood to get him to buy it hook line and sinker.
The best part is he used one of the really cheap 12V cig lighter powered ones and it took probably 20 minutes per tire.