Porsche 928 ST1991 Owner's Manual page 90

Tire pressure increases by approx. 0.1 bar
(1.5 psi) for every 10° C (18° F) increase in the
temperature of the air inside the tire. There-
fore, the correct pressure in tires that have
been driven until warm is always above the
specified pressure. Never reduce tire pres-
sure while the tires are warm.
Brief test of the tire pressure warning
system
Please conduct this test every time a wheel
or tire is changed. The car need travel no
more than some 20 meters (66 ft) at a speed
of at least 5 km/h (3 mph) with the tires in-
flated as follows:
1. Tire pressure 0.5 bar (8 psi) beneath
specified pressure: front 2.0 bar (28
psi), rear 2.5 bar (36 psi)
While driving, observe the instrument-
cluster display.
The arrows concerned must flash.
If an arrow indicates steadily instead of
flashing, one pressure-operated switch
in the wheel concerned is defective and
must be replaced.
Do not exceed 50 km/h (30 mph). At
speeds above 50 km/h (30 mph), the dis-
play always flashes.
2. Tire pressure 0.5 bar (8 psi) above
specified pressure: front 3.0 bar (44
psi), rear 3.5 bar (52 psi)
While driving, observe the instrument-
cluster display.
There should be no fault messages.
A fault message indicates that there is a
system malfunction.
In the event of a fault message, contact
your authorized Porsche dealer.
3. Do not forget to correct tire pressures
to the specified settings after the brief
test.
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