2009 PORSCHE 911 tire size

62
Operation, Safety When the ignition is switched on the ABS warning
light will light up while the system is electronically
interrogated and goes out when the engine is
started if the check is not yet complete.
If the ABS warning lamp fails to go out, this indi-
cates that ABS has been deactivated due to a
fault. If the warning lights in the instrument panel
and on-board computer light up while you are driv-
ing, this indicates that a fault has occurred. In both
cases, normal braking, as in vehicles without ABS,
is still retained.
The ABS system should, however, be examined at
an authorized Porsche dealer immediately to pre-
vent the occurrence of further faults.
fIf the ABS system becomes inoperative, take
your vehicle to your authorized Porsche dealer
immediately.
Warning!
Risk of an accident, resulting in serious per-
sonal injury or death.
The control unit of the ABS brake system is
set for standard tire size. If non-standard
tires are installed, the control unit may mis-
interpret the speed of the vehicle, because of
the variant data it receives from the sensors
on the axles.
fUse only tire makes and types tested by Porsche.
Clutch Pedal The clutch pedal must be depressed fully
before the starter will engage.
Warning!
Risk of an accident, resulting in serious per-
sonal injury or death.
fAlways check the movement of the clutch ped-
al before driving and make sure that it is not
obstructed by a floor mat or any other object.
fSecure the floor mat to prevent it from sliding
into positions that could interfere with the safe
operation of your vehicle.
Your Porsche dealer will be glad to offer you
nonskid floor mats of the correct size.
To avoid damage to the clutch and transmis-
sion:
fAlways depress the clutch pedal fully when
changing gears.
fDo not hold the car on a steep grade with the clutch pedal partially depressed.
Should the free travel of the clutch pedal suddenly
become larger, it could mean a malfunction of the
clutch.
fSee your Porsche dealer for correction.
Warning light USA
Warning light Canada

Operation, Safety
63
Porsche Traction Management
(PTM)With PTM, the engine power is variably distributed
to the front and rear wheels.
Power distribution between the front and rear ax-
les is performed by a map-conrolled multiple-disc
clutch.
Distribution of the engine power also depends on
the difference in wheel speed between the two ax-
les.
The multiple-disc clutch always delivers sufficient
drive power to the front wheels to ensure optimum
propulsion even on an unfavorable road surface.
In combination with the Porsche Stability Manage-
ment (PSM), the PTM ensures optimum handling
and high driving stability.
Warning!
The increased control that is provided should
not induce you to take greater risks with your
safety. The limits dictated by the laws of phy-
sics cannot be overcome, even with PTM.
The risk of accidents due to inappropriate
speed cannot be reduced, even by PTM.
The driver bears the responsibility for all dri-
ving maneuvers.
fAdapt your driving style to the prevailing road
and weather conditions.
fObey all traffic laws.
Dynamometer testing procedure Some U.S. states and Canadian provinces con-
duct emissions inspection/maintenance testing in-
volving the use of two-wheel dynamometer.
A two-wheeled dynamometer is a treadmill type
device upon which a single axle of the car, the dri-
ving axle of the vehicle, rotates to simulate vehicle
operation on the road while the vehicle remains
stationary.
Your vehicle has a full-time four-wheel drive system
which cannot be disabled. Severe damage to the
powertrain can result if tested on a two-wheel dy-
namometer.
Warning!
Risk of severe powertrain damage and a pos-
sible unexpected movement of the vehicle.
fDo not test your vehicle on a two-wheel dyna-
mometer.
fAdvise the emission station of this warning be-fore testing the vehicle.
Brake testsBrake tests must be performed only on plate-type
test stands or roller test stands.
The ignition must be off.
The following limit values must not be exceeded
on roller test stands:
– Testing speed 5 mph (8 km/h)
– Test duration 20 seconds Handbrake tests Handbrake tests on the roller test stand must only
be carried out with the ignition switched off. Balancing wheels on the vehicle During finish balancing of the wheels, the vehicle
must be hoisted and all the wheels able to rotate
freely. Towing fPlease see the chapter “TOWING” on
Page 280.Wheels/TiresThe PTM control unit is adapted to the approved
tire sizes. The use of non-approved tire sizes may
lead to deviations in wheel speeds and it may influ-
ence handling or result in the PTM switching off.

Instruments, On-Board Computer, Warnings
143
TPM
Tire Pressure MonitoringfPlease see the chapter “TIRE PRESSURES FOR
COLD TIRES (68 °F / 20 °C)” on Page 289.
The Tire Pressure Monitoring continuously
monitors tire pressure and tire temperature on all
four wheels and warns the driver when the tire
pressure is too low.
The display as well as the settings for the Tire
Pressure Monitoring take place on the on-board
computer.
However, you must still adjust the tire pressure on
the wheel.fThe driver is responsible for filling the tires
correctly and making the correct settings on
the on-board computer.
The Tire Pressure Monitoring offers the following
functions:
– Display of the actual tire pressure while the
vehicle is in motion.
– Display of the deviation from the required
pressure (refilling pressure).
– Display of currently set tire size and type.
– Tire pressure warnings in two stages.
Warning!
fDespite the advantages offered by the Tire
Pressure Monitoring, it is still the driver’s re-
sponsibility to update the corresponding set-
tings in the on-board computer and maintain
the pressure in the tires.
Low tire pressure reduces the road safety of
the vehicle and destroys the tire and wheel.
fWhen a flat tire has been displayed, immedi-
ately stop in a suitable place and check the
tires for damage. If necessary, remedy the
damage with a tire sealant.
fDo not by any means continue to drive with
damaged tires.
fSealing the tire with tire sealant is only an
emergency repair, so you can drive to the next
authorized Porsche dealer. The maximum per-
mitted speed is 50 mph (80 km/h).fDo not drive with tires whose tire pressure
drops again in a short period of time. In cases
of doubt, have tires checked by an authorized
Porsche dealer.
fDamaged tires must be immediately replaced
by an authorized Porsche dealer.
Tire repairs are not permissible under any
circumstances.
fIf a fault occurs in the Tire Pressure Monitoring
(e.g. defective wheel transmitter), contact an
authorized Porsche dealer immediately and
have the damage repaired.
The tire pressure will not be monitored at all or
will be monitored only partially by defective
Tire Pressure Monitoring.
fTires lose air over time without a tire defect
being present. A tire pressure warning will then
appear in the on-board computer display.
Correct the tire pressure at the next oppor-
tunity.
fThe Tire Pressure Monitoring gives a warning
about tire damage due to natural pressure loss
as well as about a gradual loss of pressure due
to foreign objects.
The Tire Pressure Mnitoring cannot warn you
about tire damage that occurs suddenly (e.g.
flat tire due to abrupt external effects).

Instruments, On-Board Computer, Warnings
145
The tire pressure to be corrected (refill pressure)
is indicated on the displayed wheel.
Example: If “ –1.5 psi (–0.1 bar)” is displayed,
1.5 psi (0.1 bar) must be added to this tire.
Note
The tire pressure menu can only be called up when
the vehicle is stationary.
Calling up the “Info pressure” display
fPush operating lever forward in order to switch
on the selection field.
fSelect “TPM” with the operating lever.
fPush operating lever forward.
The display changes to the tire pressure menu.
fSelect “Info pressure” with the operating lever.
fPush operating lever forward.
Note
After the ignition is switched on, it can take up to
approx. 1 minute before all tire pressures are
displayed. Dashes (“-.-”) appear instead of the tire
pressures. Tire type info in Tire pressure menu
Information about the currently set tires:
– Tire type: Summer tires, winter tires
– Tire size: 18, 19 inch
“Info tires” shows the current tire settings.
Calling up the “Info tires” display
fPush operating lever forward in order to switch
on the selection field.
fSelect “TPM” with the operating lever.
fPush operating lever forward.
The display changes to the tire pressure menu.fSelect “Info tires” with the operating lever.
fPush operating lever forward.
Tire selection in the “Set” menu
fPush operating lever forward in order to switch
on the selection field.
fSelect “TPM” with the operating lever.

Instruments, On-Board Computer, Warnings
147
fSelect “Continue” and push the operating lever
forward.fSelect the appropriate tire size (18 or 19 inch)
and push operating lever forwards. A display
for confirming the selected tire size appears.
Note
This menu is displayed only if the tire pressures
are different for the approved tire sizes.fSelect “Continue” and push the operating lever
forward.

148
Instruments, On-Board Computer, Warnings The tire selection has only been successfully
completed when the message “Process
complete” is displayed by the on-board computer.
fSelect arrow (Back) and push the operating
lever forward. The display returns to the tire
pressure menu.
The on-board computer additionally displays
the message “System learning”.Note
The message “Process aborted” appears if the
setting process is interrupted. All entries made up
to this point are lost, and the original settings
remain in effect.
Only if the message “Process complete” appears
after the settings have been made will the Tire
Pressure Monitoring re-learn the wheels.
fPlease see the chapter “SYSTEM LEARNING”
on Page 150.
Before fitting tires with sizes which are not stored
in the on-board computer, the missing information
should be supplemented in the on-board
computer.
fPlease consult your authorized Porsche
dealer.
fUse only tires approved by Porsche.
The available items in the tire pressure menu
depend on the tires on your vehicle. For this
reason it is possible that some of the items shown
here are not available on your on-board
computer’s display.
fMake sure that tire pressures correspond to
the on-board computer settings. Correct the
tire pressure if necessary.
fPlease see the chapter “TIRE PRESSURES FOR
COLD TIRES (68 °F / 20 °C)” on Page 289.Load
fPush operating lever forward in order to switch
on the selection field.
fSelect “TPM” with the operating lever.
fPush operating lever forward.
The display changes to the tire pressure menu.
fSelect “Load” with the operating lever.

Practical Tips, Emergency Service
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.

238
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.