Tire Pressure Monitor System - Chevrolet 2007 Optra Owner's Manual

How to Check
Use a good quality pocket-type gage to check
tire pressure. You cannot tell if your tires are
properly inflated simply by looking at them. Radial
tires may look properly inflated even when they
are under-inflated. 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.
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.
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Tire Pressure Monitor System

The Tire Pressure Monitor System (TPMS) uses
radio and sensor technology to check tire pressure
levels. If your vehicle has this feature, sensors
are mounted onto each tire and wheel assembly,
except for the spare tire. The TPMS sensors
monitor the air pressure in your vehicle's tires and
transmit tire pressure readings to a receiver
located in the vehicle.
Each tire, including the spare (if provided), should
be checked monthly when cold and inflated to
the inflation pressure recommended by the vehicle
manufacturer on the vehicle placard or tire
inflation pressure label. (If your vehicle has tires of
a different size than the size indicated on the
vehicle placard or tire inflation pressure label,
you should determine the proper tire inflation
pressure for those tires.)