Tires, Wheels, and Brakes - Beware the wet thumb
If you top off your tires at a service station, check to see if there's moisture coming from the air pump. Simply depress the pin inside the inflator valve with your thumbnail. If your thumb gets wet, advise the station manager that his tanks need to be drained and go to a different station. Moisture, trapped inside a tire, can cause pressure variations and corrode rims.