Porsche 928 S 1984 Owner's Manual page 76

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 properly and are
even less effective on wet roads.
WARNING
Do not drive with worn tires or tires show-
ing cuts or bruises as they may lead to
sudden 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.
Tire care
WARNING
• Avoid damaging tires and wheel rims.
If you must drive over a curb or other
obstacle, drive slowly and at an obtuse
angle. Frequently check tires for uneven
wear and damage.
• Remove imbedded material.
• Replace worn or damaged tires imme-
diately.
• Replace missing valve dust caps.
• Keep oil; fuel, brake fluid, etc. away from
tires.
• Keep tires inflated correctly.
Tire replacement
In the interest of maximum safety and best all-
around car handling, always buy replacement
tires that have the same specifications with
regard to tire size, design load carrying capa-
city, tread pattern, tread depth, etc. This also
applies to Porsche-recommended alternate
replacement tires.
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 ther-
mal 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 is replaced it should be noted
that the difference in tread depth on one axle
must not be more than 30 %.
Tire specifications are imprinted on the side-
wall of the tires. If in doubt, check with your
Porsche dealer.
When replacing tubeless tires, always install
new valve stems. When replacing tires requir-
ing an inner tube, always install new tubes.
New tires do not possess maximum trac-
tion. They tend to be slippery. Break new
tires in by driving at moderate speed for
the first 60 - 120 miles or 100 - 200 km.
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 ba-
lanced from time to time. Unbalanced wheels
may affect car handling and tire life.
When balancing light alloy wheels, use only
adhesive balancing weights supplied through
the Porsche parts service.
Wheels
If you intend to use other than original equip-
ment wheels, be sure that they conform to
Porsche specifications for your model.
Check with your Porsche dealer regarding the
correct wheel specifications for type and mo-
del year.
73