Porsche 928 S 1986 Driver Manual page 72

Tyre damage
Examine tyres at regular intervals for foreign
matter, nicks, cuts, cracks and bulges (side-
walls). In case of tyre damage where it is un-
certain whether there is a break in the ply with
all its consequences or tyre damage caused
by thermal or mechanical overloading due to
a loss of pressure or any other prior damage,
we recommended that the tyre be replaced
for safety reasons.
If one faulty tyre is replaced it should be
noted that the difference in tread depth on
one axle must not be more than 30 %.
Visual inspection.
Tyre replacement
When buying new tyres, only buy tyres with
the same specification and replace at least
both the tyres on one axle.
At the current time there is still no binding stan-
dard as regards the permitted top speed for
VR tyres above 210 km/h.
Therefore use only the makes and types of
tyre tested by Porsche.
68
Please ask your Porsche dealer about the
latest release situation before fitting your ve-
hicle with new tyres. If you have any doubts
you can of course always directly consult the
After-Sales Service Department of Porsche
AG.
The makes and types of tyres expressly quoted
in your vehicle registration papers are binding.
If a change is made to other tyres in the Federal
Republic of Germany, this must be registered
by an officially authorized expert (from the TÜV,
for example).
In all other countries the applicable regulations
should be observed. If you have any questions,
please consult your Porsche dealer or the
Porsche importer for your country.
New tyres should be fitted on the front axle
because
a) the rear axle is more critical from a stability
point of view and
b) in wet conditions it is the front wheels which
hit deep water first, while the rear wheels
run mostly in the track of the front ones.
Make sure that new valves are fitted whenever
the tyres are changed. During their initial break-
in period new tyres do not have their full grip.
It is therefore necessary to run them at only
moderate speeds during the first 100 - 200 km
(60 - 1 2 0 miles). Never use different types of
tyres. Have tyres fitted by a specialist.
Curbs
Hard impact against curbs (traffic islands too)
is dangerous. It can result in hidden tyre dam-
age which only becomes noticeable later on
(risk of high speed failure); tyres have a me-
mory!
For this reason you should only drive over
curbs slowly and preferably at right angles.
Take care when parking at or on curbs.
Tyre storage
Always store tyres in a cool, dry and dark
place. Tyres not on rims should be stood up.
Avoid any contact with fuel, oil or grease.