2009 PORSCHE BOXSTER four wheel drive

Operation, Safety
59
ABS Brake System
(Antilock Brake System)The ABS system represents a major contribution
to the enhancement of active safety in your vehi-
cle. This system prevents the wheels from locking
in a panic stop on almost all road surfaces.
With the ABS system in your vehicle, the
following areas are enhanced:
Steering, vehicle remains steerable under all
braking forces when ABS is engaged.
Good directional control , no swerving caused
by locking of wheels under braking conditions.
Shorter stopping distance , stopping distances
are usually reduced because controlled braking is
maximized.
Prevention of wheel lock up , no brake- induced
sliding and thus no localized tire wear from emer-
gency braking.
The crucial advantage of the ABS system over a
conventional brake system is in the area of main-
taining directional control and maneuverability of
the car in emergency situations.
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
physics cannot be overcome, even with ABS.
The risk of accidents due to inappropriate
speed cannot be reduced, even by the ABS.
The driver bears the responsibility for all
driving maneuvers.
f Adapt your driving style to the prevailing road
and weather conditions.
f Obey all traffic laws.
Other vehicles not equipped with the ABS
system may not be able to maintain control,
especially on wet or poor road surfaces and
thus may be more likely to impact you from
behind.
f To minimize that risk, use your ABS system to
increase your ability to maneuver to avoid dan-
gerous situations and not merely to try to stop in the shortest distance possible.
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.
If braking forces approach the wheel lock-up point
for all wheels (panic brak ing) 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 au-
dible noise and perhaps some vibration.
f If you experience these sensations while driv-
ing or a road surface with questionable trac-
tion, reduce vehicle speed appropriate for the
prevailing road conditions.
f If full braking should be necessary, press the
brake pedal all the wa y down throughout the
entire braking procedure, regardless of the pul-
sating pedal. Do not ease up on pressure ap-
plied to the pedal.
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.

Instruments, On-Board Computer, Warnings
147
TPM
Tire Pressure MonitoringfPlease see the chapter “TIRE PRESSURE FOR
COLD TIRES (68 °F/20 °C)” on Page 277.
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. f
The 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 ti re 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!
f Despite 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.
f When 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.
f Do not by any means continue to drive with
damaged tires.
f Sealing 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). f
Do 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.
f Damaged tires must be immediately replaced
by an authorized Porsche dealer.
Tire repairs are not permissible under any
circumstances.
f If a fault occurs in the Tire Pressure Monitoring
(e.g. defective wheel tr ansmitter), 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.
f Tires 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.
f The 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).

148
Instruments, On-Board Computer, Warnings
Tire pressure function of the on-board
computer
The tire pressure function of the on-board
computer
displays the tire pressures (actual
pressure) dependent on temperature in the four
wheels.
You can watch the tire pressure rise as the
temperature increases while driving.
This display is only for information.
f Under no circumstances should the tire
pressures be changed based on this display.
Warning!
This display is for informational purposes
only. Under no circumsta nces should the tire
pressures be changed based on this display.
Changing the tire pressure to incorrect
pressures could adversely affect the perfor-
mance, driving character istics, and safety of
your vehicle.
f Maintain tire pressures according to the units
indicated on the tire pressure plate, located on the drivers side door of the vehicle.
Displaying the tire pressure function of the
on-board computer
f Push operating lever up or down until the tire
pressure function of the on-board computer
appears.
(The selection field must be switched off.)Pressure info in tire pressure menu
In accordance with physical principles, the air
pressure changes as the temperature changes.
The tire pressure increases or decreases by
around 1.5 psi (0.1 bar) for every 18 °F (10 °C)
change in temperature.
The Tire Pressure Monitoring takes this relation-
ship between tire pressure and temperature into
account.
f
Please see the chapter “PRESSURE INCREASE
AS THE RESULT OF TEMPERATURE
INCREASE” on Page 156.
You can read the tire pressures to be
corrected in this display.

230
Practical Tips, Emergency Service
Note
Under no circumstances sh
ould 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 ti re was produced in the
12th week of 2008.
f Store 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 seri ous personal injury or
death.
The standard tires prof ile and rubber mixture
are optimized for wet and dry driving condi-
tions, and may not prove favorable for snow
conditions.
f Therefore 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.
f Make sure they are replaced immediately.
f Do 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 se rious personal injury
or death due to excessive speed.
f Always check the maximum speed rating on
the tire sidewall on any tire on the vehicle.
f Never exceed the maximum speed rating of the tires.
f Fit 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).

Practical Tips, Emergency Service
269
TowingCertain state statutes and local ordinances prohib-
it towing with a chain, rope or even a tow bar.
In addition, damage to your vehicle may result
from improper procedures.
Consult your authorized Porsche dealer for de-
tails. Vehicle towing Flat bed towing is the preferred type of towing to
be used on Porsche vehicles.
Under certain circumstances, wheel lifts may be
used when the vehicle will not roll.
The vehicle must be towed with all four
wheels off the ground, otherwise damage to
the vehicle may result.
PDK selector lever emergency releaseIn the event of an electronics failure, the selector
lever must be released for towing.
1. Lift up the rubber mat in the oddments tray.
2. Insert a screwdriver in the opening and press down until you feel it reach the limit position.
The selector lever ca n now be moved to
position N .
Towing hook The towing hook A is contained in the tool box in
the luggage compartment.
Caution!
Risk of damage to the vehicle.
f Use the towing hook only for an emergency to
remove the vehicle off the road. The towing
hook is to be used only to pull the vehicle onto
the flat bed, tractor or towing aparatus if the
vehicle will roll freely. Under no circumstances
is the vehicle to be secured using the towing
hook.
f Never use the towing hook to tow this or any
other vehicle.
f Bear in mind the limited ground clearance of your car on uneven surfaces.