2004 Chevrolet Astro Owner's Manual - Page 281
2004 Chevrolet Astro Manual
Page 281 highlights
When to Check Check your tires once a month or more. Also, check the tire pressure of the compact spare tire. It should be at 60 psi (420 kPa). Remove the valve cap from the tire valve stem. Press the tire gage firmly onto the valve to get a pressure measurement. If the cold tire inflation pressure is low, add air until you reach the recommended pressure on the Certification/Tire label or the Tire and Loading Information label. If you overfill the tire, release air by pushing on the metal stem in the center of the tire valve. Recheck the tire pressure with the tire gage. Be sure to put the valve caps back on the valve stems. They help prevent leaks by keeping out dirt and moisture. How to Check Use a good quality pocket-type gage to check tire pressure. You can't tell if your tires are properly inflated simply by looking at them. Radial tires may look properly inflated even when they're underinflated. 5-67