Porsche 928 ST1991 Owner's Manual page 86

Tire care
WARNING
• Avoid damaging tires and wheel rims. If
you must drive over a curb or other obs-
tacle, drive slowly and at an obtuse
angle. Frequently check tires for uneven
wear and damage.
• Remove imbedded material.
• Replace worn or damaged tires im-
mediately.
• Replace missing valve dust caps.
• Keep oil, fuel, brake fluid, etc. away
from tires.
• Keep tires inflated correctly.
Tire damage
Regularly check tires for imbedded material,
cuts, punctures, cracks and bulges (side
wall).
In case of tire damage, where it is uncertain
whether there is a break in the ply with all its
consequences or tire damage caused by
thermal or mechanical overloading due to a
loss of pressure or any other prior damage,
we recommend that the tire be replaced for
safety reasons.
If one faulty tire on an axle is replaced it
should be noted that the difference in tread
depth on one axle must not exceed 30 %.
Performe visual inspection.
Parking at the curb
Hard impacts against curbs (or traffic is-
lands) are dangerous and may cause hidden
tire damage which is not noticeable until
later. (Danger of accidents at high speeds).
Tires have a memory!
WARNING
It you must drive over a curb, drive slowly
and, if possible, at right angles. Exercise
care when parking along curbs.
Tire replacement
The tire makes and types specifically
mentioned in your vehicle papers are
binding, when changing to different tires,
be sure to observe the applicable regula-
tions in your country. If in doubt, contact
your Porsche dealer or Porsche importer
of your country.
If you do not use a Porsche recom-
mended replacement tire, make sure that
you purchase your new tires from a repu-
table tire specialty dealer and that the
dealer complies with all manufacturers
warnings for those tires.
Before mounting new tires, check with
your Porsche dealer about the current re-
lease status.
For tires with ZR quality standard, there are
currently no final standards concerning tire
strength at speeds above 240 km/h.
For this reason, only use tire makes and
types tested by Porsche.
Tires should be replaced at least on one axle
at a time. As a matter of principle, only tires
of the same make and type should be com-
bined. Mixed tires are not permissible.
Whenever you replace tires, make certain
that you install new valves. Initially, new tires
do not have their full traction. You should
therefore drive at moderate speeds during
the first 60 - 120 miles (100 - 200 km).
Have new tires mounted by an expert only.
Wheel balancing
A wheel should always be balanced after a
tire repair. Even with regular use a wheel can
get out of balance, and should, therefore, be
balanced from time to time. Unbalanced
wheels may affect car handling and tire life.
When fitting tires already mounted on rims,
ensure that the colored wheel bolt is closest
to the valve. Always screw the lockable
wheel nut onto this bolt. When removing,
mark the direction of rotation on each wheel,
e.g. FR, FL, RR and RL. This precaution en-
sures that the wheels will be remounted in
the same position, thus obviating the risk of
imbalance.
When balancing light alloy wheels, use only
adhesive balancing weights
through the Porsche parts service.
supplied
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