Subaru 2004 Impreza Owner's Manual page 431

Maintenance and service
Check the tire pressures when the tires are cold. Use
a pressure gauge to adjust the tire pressures to the
values shown on the tire placard. The tire placard is lo-
cated on the door pillar on the driver's side.
Driving even a short distance warms up the tires and
increases the tire pressures. Also, the tire pressures
are affected by the ambient temperature. It is best to
check tire pressure outdoors before driving the vehi-
cle.
When a tire becomes warm, the air inside it expands,
causing the tire pressure to increase. Be careful not to
mistakenly release air from a warm tire to reduce its
pressure.
11-46
NOTE
" The air pressure in a tire increases by approxi-
mately 4.3 psi (30 kPa, 0.3 kg/cm
becomes warm.
" The tires are considered cold when the vehicle
has been parked for at least three hours or has
been driven less than one mile (1.6 km).
Do not let air out of warm tires to adjust press-
rue. Doing so will result in low tire pressure.
Incorrect tire pressures detract from controllability and
ride comfort, and they cause the tires to wear abnor-
mally.
2
) when the tire