Porsche 928 GT1991, Owner'S Manual

Page: 85 / 154

Tires/Wheels
WARNING
Tire wear
The original equipment tires on your Porsche
comply with all applicable Federal Motor
Vehicle Safety Standards.
For your driving safety remember the follow-
ing:
• Wheel rims and wheel bolts are matched
to fit your Porsche.
• If you intend to use other than original
equipment wheels, be sure that they con-
form to Porsche specifications for your
model.
• The use of wheel rims and wheel bolts
that do not meet specifications of the
original factory installed equipment will
affect the safe operation of your vehicle.
• Before you plan on exchanging wheels,
or snow tires already mounted on wheel
rims, consult your Porsche dealer. He has
the technical information necessary to
advise you which wheel rims and wheel
bolts are compatible with the original fac-
tory installations.
Tire pressures
The tire pressures are monitored by the tire
pressure warning system.
Incorrect tire pressures cause increased
tire wear and adversely affect road holding
of the vehicle, leading to loss of control.
Tire traction
WARNING
When driving on wet or slushy roads, a
wedge of water may build up between the
tires and the road. This phenomenon is
known as aquaplaning and may cause par-
tial or complete loss of traction, vehicle
control or stopping ability. Reduce speed
on wet surface.
Tire life
Tire life depends on various factors, i.e.,
roads, traffic and weather conditions, driv-
ing habits, type of tires and tire care.
Inspect your tires at least every 2000 miles
or 3000 km for wear and damage. If you
notice uneven or substantial wear, wheels
might need alignment or tires should be ba-
lanced or replaced.
Tires must always remain on same side
of vehicle.
After changing, adjust tire pressure and tor-
que wheel nuts diagonally to 94 ftlb (130
Nm). See "Changing wheels".
The original equipment tires on your Porsche
have built-in wear indicators. They are
molded into the bottom of the tread grooves
and will appear as approximately 1/2 in (12
mm) bands when the tire tread depth is
down to 1/16 of an in (1.6mm).
When the indicators appear in two or more
adjacent grooves, it is time to replace the
tires. We recommend, however, that you do
not let the tires wear down to this extent.
Worn tires cannot grip the road surface prop-
erly and are even less effective on wet roads.
In the United States, state laws may govern
the minimum tread depth permissible. Fol-
low all such laws.
WARNING
Do not drive with worn tires or tires show-
ing cuts or bruises as they may lead to sud-
den deflation.
If you notice that tires are wearing unevenly,
consult your Porsche dealer. Uneven wear
may not always be due to improper wheel
alignment. It can be the result of individual
driving habits such as cornering at high
speeds. If the tire pressure is not checked
and adjusted regularly, abnormal tire wear
can also occur.
84