Saturn 2004 Ion - Manual (Page 297)

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.
Check the tire’s inflation pressure when the tires are cold.
Cold means your vehicle has been sitting for at least
three hours or driven no more than 1 mile (1.6 km).
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. 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.
High Speed Operation (Red Line)
{ 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 your vehicle has 215/45ZR17 size tires, set the cold
tire inflation pressure to 33 psi (227 kPa) for the
front and rear tires, when operating your vehicle under
high-speed conditions. When you end high-speed
driving, return the tires to the cold inflation pressure
shown on the tire and loading information label.
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