2009 MERCEDES-BENZ SLR brakes

236 OperationDriving instructionsPower assistance
Brakes
Refer to the description of the Brake Assist
System (BAS) (
page 84).
Warning!
G
The brake system requires electrical energy
for operation.
A malfunction in the vehicle’s power supply
or electrical system may impair brake sys-
tem operation and switch it into its emer-
gency operation mode. In such a case, the
red brake warning lamp (
page 307) and
warning messages (
page 319) in the in-
strument cluster come on while driving. To
brake, the driver must then apply signifi-
cantly greater brake pedal pressure and de-
press the pedal much further to obtain the
expected braking effect. If necessary, apply
full pressure to the brake pedal. Brakes are
only applied to the front wheels. Stopping
distance is increased! If there is a malfunc-
tion in the electro-hydraulic brake system,
we recommend that the vehicle be trans-
ported with all wheels off the ground using
flatbed or appropriate wheel lift/dolly
equipment.
A tow bar must be used if circumstances do
not permit the use of the recommended
towing methods and the vehicle requires
towing with all four wheels on the ground.
Towing the vehicle with all four wheels on
the ground is only permissible for distances
up to 30 miles (50 km) and at a speed not to
exceed 30 mph (50 km/h). For more infor-
mation, see “Towing the vehicle”
(page 373).
With the engine not running, there is no
power assistance for the brake and steering
systems. In this case, it is important to keep
in mind that a considerably higher degree of
effort is necessary to brake and steer the
vehicle.
i
The brake system is designed to decelerate
your SLR from high speeds at the best possible
rate. Depending on the applied brake force,
speed, and ambient conditions, the brake sys-
tem may produce a squeak-type noise when you
apply the brakes at a moderate rate, e.g. at city
traffic. If you experience this noise, you should
occasionally test the effectiveness of the brakes
by applying above-normal braking pressure at
high speeds. Please perform this braking proce-
dure three times. This will also enhance the grip
of the brake pads. If the noise continuous,
contact an authorized Mercedes-Benz Center.Warning!
G
Make sure not to endanger any other road
users when carrying out these braking
maneuvers.

237 Operation
Driving instructions
Downhill grades
Continuous or hard braking
After hard braking, it is advisable to drive
on for some time, rather than to park im-
mediately, so the air stream will cool down
the brakes faster.Wet roads
The first time the brakes are applied after
a long period of driving in heavy rain with-
out braking, it is possible that:


there will be a delayed braking re-
sponse


you will need to depress the brake ped-
al more firmly
You should therefore maintain a greater
distance from the vehicle in front.To help prevent brake disk corrosion after
driving on wet road surfaces (particularly
salted roads), it is advisable to brake the
vehicle with considerable force prior to
parking. The heat generated serves to dry
the brakes.
Salty roads
!
When driving down long and steep grades,
relieve the load on the brakes by shifting into a
lower gear to use the engine’s braking power.
This helps prevent overheating of the brakes and
reduces brake pad wear.
Warning!
G
Resting your foot on the brake pedal will
cause excessive and premature wear of the
brake pads.
It can also result in the brakes overheating
thereby significantly reducing their effec-
tiveness or in the total loss of braking per-
formance. It may not be possible to stop the
vehicle in sufficient time to avoid an
accident.
Warning!
G
After driving in heavy rain for some time
without applying the brakes or through wa-
ter deep enough to wet brake components,
the first braking action may be somewhat
reduced and increased pedal pressure may
be necessary to obtain expected braking
effect. Maintain a safe distance from
vehicles in front.
Warning!
G
A layer of salt on the brake discs and the
brake linings may cause a delay in the brak-
ing effect, resulting in a significantly in-
creased braking distance, which could lead
to an accident.


238 OperationDriving instructions
Brake service
If the parking brake is released and the red
brake warning lamp in the instrument clus-
ter stays on, there is a malfunction in the
electro-hydraulic brake system
(page 307) or the brake fluid level in the
reservoir is too low.
Brake pad wear or a leak in the system may
be the reason for low brake fluid in the
reservoir.
Observe additional messages that may
appear in the multifunction display
(page 335).Have the brake system inspected
immediately. Contact an authorized
Mercedes-Benz Center.
All checks and service work on the brake
system should be carried out by qualified
technicians only. Contact an authorized
Mercedes-Benz Center.
Only install brake pads and brake fluid
recommended by Mercedes-Benz.
To avoid this danger, you should:

occasionally brake carefully when you
are driving on salted roads, so that any
layer of salt that may have built up on
the brake discs and the brake linings is
removed without putting other road us-
ers at risk


maintain a greater distance to the vehi-
cle ahead and drive with particular care


carefully apply the brakes at the end of
a trip and immediately after commenc-
ing a new trip, so that salt residues are
removed from the brake disc
!
Because the ESP
® operates automatically,
the engine must be shut off (SmartKey in starter
switch position 0 or1) when the parking brake is
being tested on a brake test dynamometer.
Active braking action through the ESP
® may
otherwise seriously damage the brake system
which is not covered by the Mercedes-Benz
Limited Warranty.
Warning!
G
If other than recommended brake pads are
installed, or other than recommended brake
fluid is used, the braking properties of the
vehicle can be degraded to an extent that
safe braking is substantially impaired. This
could result in an accident.
Be certain to read and observe the warning
notices on brake pad replacement
(page 89).


239 Operation
Driving instructions
High performance driving
The rate of wear of individual brake system
components, such as brake pads or disks,
depends on your driving style and the con-
ditions under which you operate the vehi-
cle.
It is therefore not possible to give a gener-
ally applicable service life. High perfor-
mance driving, such as driving on closed
circuit race tracks or an aggressive driving
style, will cause the brakes to wear more
quickly.
Driving off
Apply the brakes to test them briefly after
driving off. Perform this procedure only
when the road is clear of other traffic.
Warm up the engine smoothly. Do not
place full load on the engine until the
operating temperature has been reached
(page 311).
i
Please contact your PLM or any authorized
Mercedes-Benz Center before operating the
vehicle under such demanding operating condi-
tions for more information.
Warning!
G
Repetitive excessive load on the brake
system may particularly cause the brake
system to overheat and can thus reduce the
braking power, or even cause brake system
components to fail due to increased wear.
You could lose control of the vehicle and
cause an accident. Installation and examina-
tion of brake system assemblies requires
specialist knowledge. Therefore, after high
performance driving, have the brake system
checked and maintained by an authorized
Mercedes-Benz Center.
!
When driving off on a slippery surface, do
not allow a drive wheel to spin for an extended
period with the ESP
® switched off. Doing so may
cause serious damage to the drivetrain which is
not covered by the Mercedes-Benz Limited
Warranty.
!
Simultaneously depressing the accelerator
pedal and applying the brakes reduces engine
performance and causes premature brake and
drivetrain wear.

241 Operation
Driving instructions
The treadwear indicator appears as a solid
band across the tread.Specified tire inflation pressures must be
maintained. This applies particularly if the
tires are subjected to high loads (e.g. high
speeds, heavy loads, high ambient
temperatures).
For more information, see “Tires and
wheels” (
page 259).
Hydroplaning
Depending on the depth of the water layer
on the road, hydroplaning may occur, even
at low speeds and with new tires. Reduce
vehicle speed, avoid track grooves in the
road and apply brakes cautiously in the
rain.Tire traction
The safe speed on a wet, snow covered or
icy road is always lower than on a dry road.
You should pay particular attention to the
condition of the road whenever the outside
temperatures are close to the freezing
point.
Warning!
G
Although the applicable federal motor
vehicle safety laws consider a tire to be
worn when the treadwear indicators (TWI)
become visible at approximately
1/16in
(1.6 mm), we recommend that you do not
allow your tires to wear down to that level.
As tread depth approaches
1/8in (3 mm),
the adhesion properties on a wet road are
sharply reduced.
Depending upon the weather and/or road
surface (conditions), the tire traction varies
widely.
Have worn tires replaced in pairs (front pair
or rear pair). Otherwise the driving stability
of the vehicle will be adversely affected.
Warning!
G
Do not drive with a flat tire. A flat tire affects
the ability to steer or brake the vehicle. You
may lose control of the vehicle. Continued
driving with a flat tire or driving at high
speed with a flat tire will cause excessive
heat build-up and possibly a fire.!
A wheel change should only be carried out
at an authorized Mercedes-Benz Center. Other-
wise there is a danger of damaging the vehicle by
jacking it up incorrectly.
Warning!
G
If ice has formed on the road, tire traction
will be substantially reduced. Under such
weather conditions, drive, steer and brake
with extreme caution.

259 Operation
Tires and wheels
Tires and wheels
For safety reasons, only use tires and rims
which have been tested and approved by
Mercedes-Benz for use on SLR vehicles.
Contact an authorized Mercedes-Benz
Center for information on tested and
recommended rims and tires for summer
and winter operation. They can also offer
advice concerning tire service and
purchase.
Important guidelines

For the first 100 miles (160 km) avoid
high-speed cornering. Do not exceed a
speed of 125 mph (200 km/h).
1


Only use sets of tires and rims of the
same type and make.


Tires must be of the correct size for the
rim.


Regularly check the tires and rims for
damage. Dented or bent rims can
cause tire inflation pressure loss and
damage to the tire beads.


If vehicle is heavily loaded, check tire
inflation pressure and correct as
required.
Warning!
G
Replace rims or tires with the same designa-
tion, manufacturer and type as shown on the
original part. Contact an authorized
Mercedes-Benz Center for further informa-
tion. If incorrectly sized rims and tires are
mounted:

The wheel brakes or suspension
components can be damaged.


The operating clearance of the wheels
and the tires may no longer be correct.
Warning!
G
Worn, old tires can cause accidents. If the
tire tread is badly worn, or if the tires have
sustained damage, replace them.
Have worn or damaged tires replaced in
pairs (front pair or rear pair) an make sure
the tires rotate in the direction specified
(page 262). Otherwise, the driving stabili-
ty of the vehicle will be adversely affected,
especially when driving at high speeds.
When replacing rims, only use genuine
Mercedes-Benz wheel bolts specified for the
particular rim type. Failure to do so can
result in the bolts loosening and possibly an
accident.
Retreaded tires are not tested or recom-
mended by Mercedes-Benz, since previous
damage cannot always be recognized on re-
treads. The operating safety of the vehicle
cannot be assured when such tires are used.
!
A wheel change should only be carried out
at an authorized Mercedes-Benz Center. Other-
wise there is a danger of damaging the vehicle by
jacking it up incorrectly.
1Please always drive carefully and obey applicable
speed limits.

272 OperationTires and wheelsThe TPMS only functions on wheels that
are equipped with the proper electronic
sensors. It monitors the tire inflation pres-
sure, as selected by the driver, in all four
tires. A warning is issued to alert you to a
decrease in pressure in one or more of the
tires.
Tire pressure inquiries are made using the
multifunction display. The present inflation
pressures are displayed only after a few
minutes’ travel time.
Switch on the ignition (
page 40).

Press buttonj or k on the mul-
tifunction steering wheel until the cur-
rent inflation pressures for each tire
appear in the multifunction display.
i
Possible differences between the readings
of a tire pressure gauge of an air hose, e.g. gas
station equipment, and the vehicle’s control
system can occur. Usually the readings issued by
the control system are more precise.
i
When the vehicle has been parked for longer
than 20 minutes, the message
Tire pressure
displayed after driving for a few
minutes.
appears in the multifunction display.
Warning!
G
It is the driver’s responsibility to calibrate
the TPMS on the recommended cold infla-
tion pressure. Underinflated tires affect the
ability to steer or brake the vehicle. You
might lose control over the vehicle.i
With a spare wheel mounted, the system
may still indicate the tire inflation pressure of the
removed road wheel for some minutes. If this
happens, keep in mind that the indicated value
where the spare wheel is mounted does not re-
flect the actual spare tire inflation pressure.
Warning!
G
The TPMS does not indicate a warning for
wrongly selected inflation pressures. Always
adjust tire inflation pressure according to
the Tire and Loading Information placard on
the driver’s door B-pillar or, if available, the
supplemental tire inflation pressure infor-
mation on the inside of the fuel filler flap.
The TPMS is not able to issue a warning due
to a sudden dramatic loss of pressure (e.g.
tire blowout caused by a foreign object). In
this case bring the vehicle to a halt by care-
fully applying the brakes and avoiding
abrupt steering maneuvers.

286 OperationTires and wheelsTire ply material
1Plies in sidewall
2Plies under tread
This marking tells you about the type of
cord and number of plies in the sidewall
and under the tread.
Tire and loading terminology
Accessory weight
The combined weight (in excess of those
standard items which may be replaced) of
automatic transmission, power steering,
power brakes, power windows, power
seats, radio, and heater, to the extent that
these items are available as
factory-installed equipment (whether
installed or not).
Air pressure
The amount of air inside the tire pressing
outward on each square inch of the tire.
Air pressure is expressed in pounds per
square inch (psi), or kilopascal (kPa) or
bars.
Aspect ratio
Dimensional relationship between tire
section height and section width
expressed in percentage.Bar
Another metric unit for air pressure. There
are 14.5038 pounds per square inch (psi)
to 1 bar; there are 100 kilopascals (kPa)
to 1 bar.
Bead
The tire bead contains steel wires wrapped
by steel cords that hold the tire onto the
rim.
Cold tire inflation pressure
Tire inflation pressure when your vehicle
has been sitting for at least three hours or
driven no more than 1 mile (1.6 km).
Curb weight
The weight of a motor vehicle with stan-
dard equipment including the maximum
capacity of fuel, oil, and coolant, and, if so
equipped, air conditioning and additional
optional equipment, but without passen-
gers and cargo.
i
For illustration purposes only. Actual data
on tires are specific to each vehicle and may vary
from data shown in above illustration.