2008 Saturn Astra Owner's Manual - Page 237

Vehicle Service and Care 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 matches the recommended pressure on the Tire and Loading Information label, no further adjustment is necessary. If the inflation pressure is low, add air until you reach the recommended amount. If you overfill the tire, release air by pushing on the metal stem in the center of the tire valve. Re-check 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. 9-47 High-Speed Operation { CAUTION Driving at high speeds, 100 mph (160 km/h) or higher, puts an additional strain on tires. Sustained high-speed driving causes excessive heat build up and can cause sudden tire failure. You could have a crash and you or others could be killed. Some high-speed rated tires require inflation pressure adjustment for high speed operation. When speed limits and road conditions are such that a vehicle can be driven at high speeds, make sure the tires are rated for high speed operation, in excellent condition, and set to the correct cold tire inflation pressure for the vehicle load. If the vehicle has P205/55R16 size tires, additional air pressure is required when driving the vehicle at speeds of 99 mph (158 km/h) or higher. Set the cold tire inflation pressure to the maximum inflation pressure shown on the tire sidewall, or 32 psi (220 kPa), whichever is lower. See the example following. Example: The maximum load and inflation pressure is molded on the tire's sidewall, in small letters, near the rim flange. It reads something like this: Maximum load 710 kg (1565 lbs) 350 kPa (51 psi) Max. Press. For this example, the cold tire inflation pressure for high-speed driving should be set at 32 psi (220 kPa).