2009 PORSCHE 911 service

Practical Tips, Emergency Service
235
Tires/Wheels The original equipment tires and wheel rims on
your Porsche comply with all applicable Federal
Motor Vehicle Safety Standards.
For your safety remember the following:
– Wheel rims and wheel bolts are matched to fit
your Porsche.
– If you intend to use other than original equip-
ment wheels, be sure that they conform to
Porsche specifications for your model.
Only tires with the same make and with the
same specification code (e.g. “N0”, “N1”...)
can be mounted.
– The use of wheel rims and wheel bolts that do
not meet specifications of the original factory
installed equipment will affect the safe opera-
tion of your vehicle.
– Before you plan on exchanging wheels, or
snow tires already mounted on the wheel rims,
consult your authorized Porsche dealer. Your
dealer has the technical information necessary
to advise you which wheel rims and wheel bolts
are compatible with the original factory instal-
lations.
Danger!
Risk of loss of control and serious personal
injury or death.
fIf while driving, your vehicle experiences a sud-
den vibration or ride disturbance, and/or you
suspect that possible damage to your tires or
vehicle has occurred, you should immediately
reduce your speed without excessive use of
the brakes.
fStop the vehicle as soon as possible, and in-
spect the tires.
If you cannot determine the cause for the dis-
turbance, have your vehicle towed to the near-
est Porsche or tire dealer to have your vehicle
or tire(s) inspected.
fContinuing to operate the vehicle without cor-
rection could result in a loss of control and serious personal injury.
ExampleUniform Tire Quality GradingQuality grades can be found where applicable on
the tire sidewall between tread shoulder and max-
imum section width.
All passenger car tires must conform to Federal
Safety Requirements in addition to these grades.
Tr e a d w e a r
The treadwear grade is a comparative rating
based on the wear rate of the tire when tested
under controlled conditions on a specific govern-
ment test course.
For example, a tire graded 150 would wear one

236
Practical Tips, Emergency Service and a half (1-1/2) times as well on the government
course as a tire graded 100.
The relative performance of tires depends upon
the actual conditions of their use, however, and
may depart significantly from the norm due to var-
iations in driving habits, service practices and dif-
ferences in road characteristics and climate.
Traction AA, A, B, C
The traction grades, from highest to lowest, are
AA, A, B, and C and they represent the tire’s ability
to stop on wet pavement as measured under con-
trolled conditions on specified government test
surfaces of asphalt and concrete.
A tire marked C may have poor traction perform-
ance.
Warning!
The traction grade assigned to this is based on
braking (straight-ahead) traction tests and does
not include cornering (turned) traction, accelera-
tion, hydroplaning or peak traction characteris-
tics.
Temperature A, B, C
The temperature grades are A (the highest), B and
C, representing the tire’s resistance to the gener-
ation of heat and its ability to dissipate heat when
tested under controlled conditions on a specified
indoor laboratory test wheel.
Sustained high temperatures can cause the mate-
rial of the tire to degenerate and reduce tire life,
and excessive temperature can lead to sudden tire failure.
The grade C corresponds to a level of perform-
ance which all passenger car tires must meet un-
der the Federal Motor Vehicle Safety Standard No.
109.
Grades B and A represent higher levels of per-
formance on the laboratory test wheel than the
minimum required by law.
Warning!
The temperature grade for this tire is established
for a tire that is properly inflated and not overload-
ed.
Excessive speed, underinflation, or excessive
loading, either separately or in combination, can
cause heat buildup and possible tire failure, result-
ing in serious personal injury or death. Tire pressures
Warning!
Incorrect tire pressure causes increased tire
wear and adversely affects road handling.
This could lead to tire failure, resulting in loss
of control, leading to serious personal injury
or death.
fAlways use an accurate tire pressure gage
when checking inflation pressures.
fDo not exceed the maximum tire pressure list-
ed on the tire sidewall.
Please see the chapter “TIRE PRESSURE PLA-
TE” on Page 285.fCold tire inflation pressure means: all tires
must be cold, ambient temperature maximum
(68 °F/20 °C)
, when adjusting the inflation
pressure.
Avoid sunlight striking the tires before measur-
ing cold pressures, since the pressures would
rise from temperature influence.
fValve caps protect the valve from dust and dirt,
and thus from leakage.
Always screw caps tightly down.
Replace missing caps immediately.
fUse only plastic valve caps.
fDo not use commercially available sealant or
tire inflating bottles. Only use Porsche
approved tire sealant.
fPlease see the chapter “TIRE PRESSURES FOR
COLD TIRES (68 °F / 20 °C)” on Page 289.

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237
Each tire, should be checked every 2 weeks when
cold (68 °F/20 °C) and inflated to the inflation
pressure recommended in this Owner's Manual or
on the tire-pressure plate.
If your vehicle has tires of a different size than the
size indicated in this Owner's Manual or on the tire-
pressure plate, you should determine the proper
tire inflation pressure for those tires.
As an added safety feature, your vehicle has been
equipped with a tire pressure monitoring (TPM)
that illuminates a low tire pressure message when
one or more of your tires is significantly under-in-
flated. Accordingly, when the low tire pressure
message illuminates, you should stop and check
your tires as soon as possible, and inflate them to
the proper pressure. Driving on a significantly un-
der-inflated tire causes the tire to overheat and
can lead to tire failure. Under-inflation also reduc-
es fuel efficiency and tire tread life, and may affect
the vehicle’s handling and stopping ability.
Please note that the TPM is not a substitute for
proper tire maintenance, and it is the driver’s re-
sponsibility to maintain correct tire pressure, even
if under-inflation has not reached the level to trig-
ger illumination of the TPM low tire pressure mes-
sage.
fOn vehicles with tire pressure monitoring:
Please see the chapter “TPM TIRE PRESSURE
MONITORING” on Page 143.
When tires are warm, the tire pressure is
increased.fNever let air out of hot tires.
This could cause the tire pressure to fall below
the prescribed value.
Insufficient tire filling pressure can cause tires to
overheat and thus be damaged – even invisibly.
Hidden tire damage is not eliminated by subse-
quently correcting the tire pressure.
Overloading
Danger!
Risk of damage to vehicle parts, loss of con-
trol and serious personal injury or death.
fDo not overload your vehicle. Be careful about
the roof load.
fIf loading the vehicle also correct the tire pres-
sure. Tire pressure for loaded vehicle can be
found on the tire pressure plate and in the
chapter technical data.
fNever exceed the specified axle load.
Overloading can shorten the service life of the
tires and car, as well as lead to dangerous ve-
hicle reactions and long braking distances.
Damage due to overloading is not covered by the vehicle warranty.
fPlease see the chapter “LOADING INFORMA-
TION” on Page 246.
fPlease see the chapter “TIRE PRESSURES FOR
COLD TIRES (68 °F / 20 °C)” on Page 289.
Example of a tire pressure plateTire pressure plateInformation on the tire pressure plate
A Seating capacity
Maximum number of vehicle occupants, inclu-
ding the driver.

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Practical Tips, Emergency Service B Vehicle load limit
Is the maximum total weight limit specified of
the load (passengers and cargo) for the vehi-
cle. This is the maximum weight of passengers
and cargo that can be loaded into the vehicle.
Please see the chapter “LOADING INFORMA-
TION” on Page 246.
C Tire size for the front axle
Check with your authorized Porsche dealer
about the current release status.
D Recommended tire pressure for the front axle
These values are for cold tires (68 °F/20 °C).
E Tire size for the rear axle
Check with your authorized Porsche dealer
about the current release status.
F Recommended tire pressure for the rear axle.
These values are for cold tires (68 °F/20 °C).
G In vehicles with collapsible spare wheel:
Size and tire pressure of the spare wheel.
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 “hydroplane” and may cause par-
tial or complete loss of traction, vehicle
control or stopping ability.
fReduce speed on wet surface to prevent this. Tire life Tire life depends on various factors, i. e., road
surfaces, traffic and weather conditions, driving
habits, type of tires and tire care.
fInspect your tires for wear and damage before
driving off. If you notice uneven or substantial
wear, wheels might need alignment or tires
should be balanced or replaced.
Tire wear The original equipment tires on your Porsche have
built-in tire 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.
(1.6 mm).
When the indicators appear in two or more adja-
cent 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.
Snow tires lose their traction capability when their
tread depth falls below 5/32 in. (4 mm).
In the United States, state laws may govern the
minimum tread depth permissible. Follow all such
laws.

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239
Danger!
Driving on worn tires can result in loss of con-
trol of the vehicle and could cause serious
personal injuries or death.
fDo not drive with worn tires or tires showing
cuts or bruises as they may lead to sudden
deflation and loss of control which could cause
severe personal injury.
fSpecialized high performance tires on high
performance sports cars exhibit more wear
than those on a family sedan, or even a high
performance sedan.
Therefore, it is important to check your tire
pressure and condition at least every two weeks.
If you notice that tires are wearing unevenly, con-
sult 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 fAvoid damaging tires and wheel rims.
fIf you must drive over a curb or other obstacle,
drive slowly and at an obtuse angle.
fCheck tires for uneven wear and damage
before driving off.
fRemove imbedded material.
fReplace worn or damaged tires immediately.
fKeep oil, fuel, brake fluid, etc. away from tires.
fReplace missing valve stem caps.
fKeep tires inflated correctly.
fWash tires when washing the vehicle. Also
clean inner side of wheels.
fDo not use abrasive cleaners when washing
the wheels.
fCheck wheel rims for corrosion.
fRemove road salt, if driving in winter.
Tire damage, puncture High-pressure cleaning units can damage the
tires.
fPlease see the chapter “HIGH-PRESSURE
CLEANING UNITS, STEAM CLEANERS” on
Page 224.
fCheck tires for imbedded material, cuts, punc-
tures, cracks and bulges (side wall) before driv-
ing off.
In case of tire damage, where it is uncertain wheth-
er there is a break in the ply with all its conse-
quences or tire damage caused by thermal or me-
chanical overloading due to 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
exceed 30%.
Handling inconsistencies may result.
fPerform a visual inspection if necessary.

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Practical Tips, Emergency Service
Danger!
Risk of serious personal injury or death.
Driving the vehicle with low tire pressure
increases risk of a tire failure and resulting
loss of control. Furthermore, low tire pres-
sure increases rate of wear of the affected
tires.
fCheck tires – including sidewalls – regularly for
foreign bodies, nicks, cuts, cracks and bulges.
fAfter driving off road, examine tires for signs
of damage such as cuts, tears, bulges or for-
eign objects stuck in the tread. Replace a dam-
aged tire if necessary.
fCross curb edges slowly and at right angles if
possible.
Avoid driving over steep or sharp curbs.
fIn cases of doubt, have the wheel (particularly
the inner side) checked by an authorized Porsche dealer.
Tire replacements If in doubt, contact your Porsche dealer.
Use only tire makes and types approved by
Porsche.
If you do not use a Porsche recommended
replacement tire, make sure that you
purchase your new tires from a reputable tire
dealer and that the dealer complies with all
manufacturers warnings for those tires.
Only tires with the same make and with the
same specification code (e.g. “N0”, “N1”...)
can be mounted.
Before mounting new tires, check with your
Porsche dealer about the current release
status.
Use tires with “ZR” quality standards. There
are currently no standards concerning tire
strength at speeds above 150 mph (240 km/h).
Tires should be replaced no less than on one axle
at the time.
Only tires of the same make and type must be
used. Mixed tires are not permissible.
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). If new tires are installed only on one axle, a notice-
able change in handling occurs due to the different
tread depth of the other tires.
This happens especially if only rear tires are re-
placed. However, this condition disappears as the
new tires are broken in.
fPlease adjust your driving style accordingly.
Installation of new tires should only be done by a
qualified tire technician.
Valves
Rubber valve stems must be replaced every time
a tire is replaced.
For metal valves, the installation and replacement
instructions must be observed.
fUse only genuine Porsche metal valves.
fProtect the valve inserts against soiling with
valve caps.
Soiled valve inserts can cause a gradual loss
of air.
fUse only plastic valve caps.

Practical Tips, Emergency Service
241
Parking at the curb
Warning!
Hard impacts against curbs (or traffic
islands) are dangerous and may cause hid-
den tire damage which is not noticeable until
later. Such damage can result in accidents at
high speeds causing serious personal injury
or death.
Depending on the force of impact, the edge
of the rim can also be damaged.
fIf you are in doubt, have the wheel checked by
an expert, particularly if you suspect damage
on the inside.
fIf you must drive over a curb or other obstacle,
drive slowly and at an obtuse angle. Exercise care when parking along curbs.
Wheel alignment, wheel balancing As a precaution, have wheels with summer tires
balanced in the spring, and those with mud and
snow tires before winter.
Unbalanced wheels may affect car handling and
tire life.
Only the specified weights may be used for wheel
balancing.
Self-adhesive weights must not come into contact
with cleaning agents, since they could drop off.
Uneven tread wear indicates wheel imbalance. In
this event, the vehicle should be checked at an au-
thorized Porsche dealer.
Warning!
If, during a trip, uneven running or vibrations
occur that could be caused by damage to
tires or the car, the speed must be reduced
immediately, but without braking sharply.
If you continue your trip without having the
cause of the fault remedied, you might lose
control of your vehicle which could cause se-
rious personal injury or death.
fStop the vehicle and check the tires.
fIf no cause for the fault can be found, drive
carefully to the nearest authorized Porsche dealer.
Wheels with Tire Pressure Monitoring
(TPM) sensorsBefore changing wheels, make sure that the
wheels are compatible with your vehicle's TPM.
fCheck this with your authorized Porsche
dealer.Removing and storing tires fAfter changing, adjust tire pressure and torque
wheel bolts diagonally to 94 ftlb (130 Nm).
Tires must always remain on the same side of
the vehicle.
When wheels are removed, the direction of
rotation and position of each wheel should be
marked.
Example
FR (front right), FL, RR and RL.
Wheels must always be fitted in accordance with
their marking.
The perception that tire durability and perform-
ance are immune to the effects of storage and
age is unfounded.
Chemical additives, which make the rubber elas-
tic, lose their effectiveness in the course of time
and the rubber becomes brittle and cracks.
Therefore, the tires should be inspected from
time to time.

242
Practical Tips, Emergency Service Note
Under no circumstances should tires older than 6
years be used on your Porsche.
The age of the tire can be obtained from the “DOT”
code number. If, for example, the last four num-
bers read 1208, then the tire was produced in the
12th week of 2008.
fStore tires in a cool and dry place.
Snow tires For a better grip on snow and ice, use radial M+S
tires with studs.
Check with your local Motor Vehicle Bureau for
possible restrictions.
Danger!
Risk of loss of control and damage to the
vehicle as well as serious personal injury or
death.
The standard tires profile and rubber mixture
are optimized for wet and dry driving condi-
tions, and may not prove favorable for snow
conditions.
fTherefore install M+S tires before driving in such conditions. Before mounting snow tires, consult with
your Porsche dealer. He has the technical
information necessary to advise you on
wheel and tire compatibility.
Snow tires should have the same load capacity as
original equipment tires and should be mounted on
all four wheels.
Snow tires with studs should be run at moderate
speeds when new in order to give the studs time
to settle.
Danger!
Tires with badly worn treads and studs are
very dangerous and could cause accidents
resulting in serious personal injuries or
death.
fMake sure they are replaced immediately.
fDo not drive a vehicle equipped with snow tires
at prolonged high speed.
Snow tires do not have the same degree of
traction on dry, wet or snowfree roads as a
normal tire.
Furthermore, snow tires wear rapidly under
these conditions.
Comply with all state and local laws
governing snow tire and tread depth
requirements.
Danger!
Risk of accident and serious personal injury
or death due to excessive speed.
fAlways check the maximum speed rating on
the tire sidewall on any tire on the vehicle.
fNever exceed the maximum speed rating of the tires.
fFit winter tires to both axles well before the
cold season begins.
Your authorized Porsche dealer will be pleased
to advise you.
Maintenance note
We recommend fitting snow tires on the vehicle at
temperatures below 45 °F (7 °C) since the driving
performance of summer tires is reduced at low
temperatures. Summer tires may be permanently
damaged at extremely low temperatures.
Winter tires lose their traction capability when their
tread depth falls below 5/32 in. (4 mm).