70
Controls, Instruments
Operation of the ABS systemA wheel speed sensor is mounted to each of the
four wheels. If wheel lock-up of either of the front
wheels or the rear wheels is sensed during brak-
ing, the brake pressure is adjusted automatically
until the wheel no longer slips. The brake pressure
is regulated for each front wheel individually and
for both of the rear wheels together.
On a road surface which is slippery on only one
side, the rear wheel which is braking on the slip-
pery surface determines the brake pressure which
will be applied equally to both rear wheels. This en-
sures that directional stability is maintained. How-
ever, if braking forces approach the wheel lock-up
point for all wheels (panic braking) the ABS system
will intervene to provide a rapid rythmic braking.
The proper operation of ABS is perceived by the
driver as a pulsating brake pedal in conjunction
with audible noise and perhaps some vibration.
fIf you experience these sensations while driv-
ing or a road surface with questionable trac-
tion, reduce vehicle speed appropriate for the
prevailing road conditions.
The functional readiness of all the main electrical
components of the ABS is checked by an
electronic monitoring system both before and
while you drive. 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!
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.
Warning light USA
Warning light Canada
Controls, Instruments
109
TPC
Tire pressure monitoringPlease observe the chapter “TIRE PRESSURES” on
Page 232.
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
Safety notes!
Despite the advantages offered by the tire
pressure monitoring, it is still the driver’s
responsibility to update the corresponding
settings 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 the tire pressure monitoring is defective (e.g.
defective wheel transmitter), contact an
authorized Porsche dealer immediately and
have the damage repaired.
The tire pressure will not be monitored by a
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 monitoring cannot warn you
about tire damage that occurs suddenly (e.g.
flat tire due to abrupt external effects).
Controls, Instruments
111
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 “TPC” 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 “TPC” with the operating lever.
fPush operating lever forward.
The display changes to the Tire pressure
menu.fSelect “Set” with the operating lever.
fPush the operating lever forward.
fSelect desired tire type:
summer or winter.
fPush operating lever forward.
A display for confirming the selected type of
tire appears.
f f f
234
Practical Tips, Emergency Service
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.
In the United States, state laws may govern the
minimum tread depth permissible. Follow all such
laws.
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.
236
Practical Tips, Emergency Service
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.
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 severe personal injury.
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.
240
Practical Tips, Emergency Service
Example of InscriptionInscription on radial tireATire size
Example: P 295/30 ZR 19 100 Y
–P - The tire is designed for Passenger vehicle.
This information is not included on all tires.
–295 - Indication of tire width in mm
–30 - Indication of tire height to tire width ratio
in percent–ZR - code letter for radial tires for speeds
above 150 mph / 240 km/h
There are currently no standards concerning
tire strength at speeds above 150 mph
(240 km/h).
–R - Belt type code letter for radial
–19 - Indication of rim diameter in inches
–100 - Load capacity coefficient
–Y - Speed code letter
–XL (Extra Load) - Tire with increased load rat-
ing
B TIN (Tire Identification Number)
Example: DOT xx xx xxxx xxxx
–DOT
The DOT symbol indicates that the tires com-
ply with the requirements of the US Depart-
ment of Transportation and provides informa-
tion about:
– first two-digit code means manufacture’s iden-
tification mark.
– second two-digit code means tire size.
– third four-digit code means tire type code.
– fourth four-digit code means date of manufac-
ture.
If, for example, the last four numbers read
0204, the tire was produced in the 2nd week
of 2004.
C Tire ply composition and material
The number of layers in the tread and sidewalls
and their material composition.
D Maximum permissible inflation pressure
The maximum permissible cold inflation pressure
to which a tire can be inflated.
fDo not exceed the permissible inflation pres-
sure.
288
Technical Data
Tires, Rims, Tracks 911 Carrera, 911 Carrera S
Tire Rim Rim offset Track
Summer tires*front 235/40 ZR 18 (91Y) 8 J x 18 H2 57 mm 58.5 in./1486 mm
rear 265/40 ZR 18 (101Y) XL 10 J x 18 H2 58 mm 60.4 in./1534 mm
orfront 235/35 ZR 19 (87Y) 8 J x 19 H2 57 mm 58.5 in./1486 mm
rear 295/30 ZR 19 (100Y) XL 11 J x 19 H2 67 mm 59.7 in./1516 mm
orfront 235/35 ZR 19 (87Y) 8.5 J x 19 H2 55 mm 58.7 in./1490 mm
rear 305/30 ZR 19 (102Y) XL 11.5 J x 19 H2 67 mm 59.7 in./1516 mm
Snow tiresfront 235/40 R 18 91V M+S 8 J x 18 H2 57 mm 58.5 in./1486 mm
rear 265/40 R 18 97V M+S** 10 J x 18 H2 58 mm 60.4 in./1534 mm
orfront 235/35 R 19 87V M+S 8 J x 19 H2 57 mm 58.5 in./1486 mm
rear 295/30 R 19 100V XL M+S 11 J x 19 H2 67 mm 59.7 in./1516 mm
The load capacity coefficient (e.g. “91”) and maximum speed code letter (e.g. “Y”) are minimum requirements.
Snow chainsCan be mounted only on the rear wheels; maximum speed 30 mph (50 km/h).
Use only Porsche authorized fine-link cross-type or edge chains.
Snow chain clearance can be guaranteed only on the tire + rim combination marked** without spacers.
Tire and rim sizesExtensive tests are performed before specific tires and wheels are approved by Porsche. Your Porsche dealer has informa-
tion about approved tires and wheels and is happy to assist you.
If aftermarket tires and/or wheels are installed which are not approved by Porsche, the vehicle’s roadability and handling
characteristics might be impaired. Since Porsche has no data on such combinations, Porsche cannot stand behind the safe-
ty or durability of these aftermarket combinations.
* 911 Carrera S: Summer tires 19-inch only
Technical Data
289
Tires, Rims, Tracks 911 Carrera 4, 911 Carrera 4S
Tire Rim Rim offset Track
Summer tires* front 235/40 ZR 18 (91Y) 8 J x 18 H2 57 mm 58.6 in./1488 mm
rear 295/35 ZR 18 (99Y) 11 J x 18 H2 51 mm 60.9 in./1548 mm
or front 235/35 ZR 19 (87Y) 8 J x 19 H2 57 mm 58.6 in./1488 mm
rear 305/30 ZR 19 (102Y) XL 11 J x 19 H2 51 mm 60.9 in./1548 mm
or front 235/35 ZR 19 (87Y) 8.5 J x 19 H2 55 mm 58.7 in./1492 mm
rear 305/30 ZR 19 (102Y) XL 11.5 J x 19 H2** 67 mm 61.0 in./1550 mm
Snow tires front 235/40 R 18 91V M+S 8 J x 18 H2 57 mm 58.6 in./1488 mm
rear 295/35 R 18 99V M+S*** 11 J x 18 H2 51 mm 60.9 in./1548 mm
or front 235/35 R 19 87V M+S 8 J x 19 H2 57 mm 58.6 in./1488 mm
rear 295/30 R 19 100V XL M+S*** 11 J x 19 H2 51 mm 60.9 in./1548 mm
The load capacity coefficient (e.g. “91”) and maximum speed code letter (e.g. “Y”) are minimum requirements.
Snow chains Can be mounted only on the rear wheels; maximum speed 30 mph (50 km/h).
Use only Porsche authorized fine-l ink cross-type or edge chains.
Snow chain clearance can be guaranteed on ly on the tire + rim combination marked***.
Tire and rim sizes Extensive tests are performed before specific tires and wheels are approved by Porsche. Your Porsche dealer has information
about approved tires and wheels and is happy to assist you.
If aftermarket tires and/or wheels are in stalled which are not approved by Porsche, the vehicle’s roadability and handling cha-
racteristics might be impaired. Since Porsche has no data on such combinations, Porsche cannot stand behind the safety or
durability of these af termarket combinations.
* 911 Carrera 4S: Summer tires 19-inch only ** Only approved together with 17 mm spacers