If you talk to an attendant he will assist you and feeling up the air volume of your tires. It shouldn't be that hard but those machines can sometimes be tricky. You want to make sure you know the air Valium prior to filling your tires. Check before you fill your tires and after. A visual inspection of the tires after air has been added never hurts.
Generally you need something (a gage) to measure pressure. Basically you let the air in, check the pressure, and repeat until you get the PSI you want. The machine that generates the air pressure doesn't measure the pressure in the tire.
Sorry, I haven't used the tire air there. im sure the attendant will help you, very friendly staff.
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