Porsche Cayenne Turbo Driver Manual page 286

In the case of the following tyre damage, the tyre
must be replaced for safety reasons:
– Tyre damage where the possibility of a ply
fracture cannot be ruled out.
– If the tyre has been thermally and mechanically
overloaded following a loss of pressure or
other previous damage.
286
Minor Repairs
Maintenance note
Tyre repairs are not permissible under any circum-
stances.
f After driving off-road, examine tyres for signs
of damage such as cuts, tears, bulges or
foreign objects stuck in the tread and replace
if necessary.
Kerbs
Heavy or sharp-angled impacts against kerbs or
sharp-edged objects (e.g. stones) can cause non-
visible tyre damage which only shows up later.
Depending on the strength of the impact, the rim
flange may also be damaged.
Storing wheels
f Always store wheels in cool, dry, dark condi-
tions. Tyres without wheels should be stored in
a standing position.
f Avoid contact with petrol, oil and grease.
In no case should tyres be more than 6 years
old.
The idea that tyres become more wear-resistant
with storage and age has no foundation.
Chemical additives that make the rubber elastic
lose their effect in the course of time and the
rubber becomes brittle. The age of a tyre can be
seen from the DOT code on the tyre sidewall.
If, for example, the last four digits are 1206, this
means: the tyre was manufactured in the twelfth
week of 2006.
Tread
The less tread, the greater the danger of
aquaplaning.
f For safety reasons, replace the tyres before
the wear indicators appear (webs in the tyre
grooves, 1.6 mm high).
f Check tyre tread regularly, particularly before
and after long journeys.
Wheel balancing
f As a precaution, have wheels with summer
tyres balanced in the spring, and those with
mud and snow tyres before winter.
Only specified weights may be used for wheel
balancing.
Self-adhesive weights must not come into contact
with cleaning agents, since they could drop off.
Wheel change
f When wheels are removed, mark the direction
of rotation and position of each wheel.
Example:
FR (front right), FL, RR and RL.
f Always fit the wheels in accordance with their
marking.