2008 MERCEDES-BENZ SL55AMG run flat

312 Operation
Tires and wheels
Potential problems associated with
underinflated and overinflated tires
Underinflated tires
Underinflated tires can:

cause excessive and uneven tire wear

adversely affect fuel economy

lead to tire failure from being
overheated

adversely affect handling
characteristicsOverinflated tires
Overinflated tires can:

adversely affect handling
characteristics

cause uneven tire wear

be more prone to damage from road
hazards

adversely affect ride comfort

increase stopping distance
MOExtended system*
The MOExtended system allows you to
continue driving your vehicle even if there
is a total loss of pressure in one or more
tires.
You may only use the MOExtended system
in conjunction with the Run Flat Indicator*
(Canada vehicles) (
page 303), TPMS
(U.S. vehicles) (
page 305), or Advanced
TPMS* (Canada vehicles) (
page 308).
For information on driving in case of pres-
sure loss in one or more tires (emergency
mode), see the “Practical hints” section
(
page 425).Warning!G
Follow recommended tire inflation
pressures.
Do not underinflate tires. Underinflated tires
wear excessively and/or unevenly,
adversely affect handling and fuel economy,
and are more likely to fail from being
overheated.
Warning!G
Follow recommended tire inflation
pressures.
Do not overinflate tires. Overinflated tires
can adversely affect handling and ride
comfort, wear unevenly, increase stopping
distance, and result in sudden deflation
(blowout) because they are more likely to
become punctured or damaged by road
debris, potholes etc.

361 Practical hints
What to do if …
Text messages
Left displayRight displayPossible cause/consequencePossible solution
Check tires,
then restart
Run Flat Indicator
.
There was a warning message about a
loss in the tire inflation pressure and
the Run Flat Indicator has not been
restarted yet.Make sure that the correct tire inflation
pressure is set for each tire.
Then restart the Run Flat Indicator.
Tire Pressure
Check TiresThe Run Flat Indicator indicates that
the pressure is too low in one or more
tires.Carefully bring the vehicle to a halt, avoid-
ing abrupt steering and braking maneu-
vers. Observe the traffic situation around
you.
Check and adjust tire inflation pressure as
required (
page 302).
If necessary, change the wheel
(
page 417).
Restart the Run Flat Indicator after adjust-
ing the tire inflation pressure values
(
page 304).
ABCMalfunction
Stop CarYou have started driving although the
vehicle level is still too low.
The vehicle is being raised. The ABC
message goes out after a few seconds.Stop your vehicle in a safe location or as
soon as it is safe to do so.
Wait until the message disappears from
the multifunction display.
You may then drive off.

372 Practical hints
What to do if …
Left displayRight displayPossible cause/consequencePossible solution
PGear Selector
Lever To PYou have tried to start the engine with
the KEYLESS-GO* start/stop button
with the gear selector lever not in
position P.Place the gear selector lever in position P.
You have tried to turn off the engine
with the KEYLESS-GO* start/stop
button with the gear selector lever not
in position P.
Run Flat IndicatorInoperativeThe Run Flat Indicator is
malfunctioning.Have the Run Flat Indicator checked by an
authorized Mercedes-Benz Center.
The Run Flat Indicator has been
switched off due to an error.

402 Practical hints
Where will I find ...?
Storing the spare wheel after use
If you wish to store the spare wheel after
use, carry out the following steps. Other-
wise, the spare wheel may not fit the spare
wheel well.
Unscrew the valve cap from the valve
of the collapsible tire.
Take the valve extractor from the
vehicle tool kit (
page 400).
Unscrew the valve insert from the valve
and allow the air to escape.
Screw the valve insert back into the
valve.
Screw the valve cap back onto the
valve.
Store the spare wheel by carrying out
the steps described in “Removing the
spare wheel” (
page 401) in reverse
order.
Compressing the collapsible tire
(vehicles with 19" spare wheel only)
The collapsible tire on a 19" spare wheel
must be compressed with two tensioning
straps before you can store it back in the
trunk.
Extend the tensioning strap by pulling
the slider.
Place tensioning strap around spare
wheel rim and collapsible tire with the
buckle facing the inside of the rim.
Close the buckle.
Pull the loose end of the tensioning
strap.
The tensioning strap must be pulled as
tight as possible.
!Make sure the spare wheel is dry before
storing it.
iIt may take a few minutes for the collapsible
tire to deflate completely.
iVehicles with 19" spare wheel only: Before
storing the spare wheel in trunk fasten tension-
ing straps, see “Compressing the collapsible tire
(vehicles with 19" spare wheel only)”
(
page 402).
iThe tensioning straps are shown in red for
illustration purposes. The tensioning straps on
the spare wheel of your vehicle are black.

418 Practical hints
Flat tire
Preparing the vehicle
Prepare the vehicle as described
(
page 417).
Turn spare wheel bracket counter-
clockwise to loosen.
Take the spare wheel out of the trunk
(
page 401).
Removing tensioning straps
(vehicles with 19" spare wheel only)
A 19" spare wheel has two tensioning
straps on it that must both be removed be-
fore mounting the spare wheel.1Buckle
2Clip
Press on both clips 2 simultaneously
to release buckle 1.Lifting the vehicle
Prevent the vehicle from rolling away
by blocking wheels with wheel chocks
(not included) or other sizeable
objects.
When changing wheel on a level
surface:
Place one wheel chock or other
sizeable object in front of and
another wheel chock or sizeable
object behind the wheel that is
diagonally opposite to the wheel
being changed.
Always try lifting the vehicle using the
jack on a level surface. However,
should circumstances require you to do
so on a hill, place a wheel chock or
other sizeable object and the other
wheel chock or sizeable object as
follows:
Place wheel chocks or other size-
able objects on the downhill side
blocking both wheels of the axle not
being worked on.
iThe tensioning straps are shown in red for
illustration purposes. The tensioning straps on
the spare wheel of your vehicle are black.iKeep the tensioning straps in a safe place.
You will need them to store the spare wheel in
the trunk after use (
page 402).

419 Practical hints
Flat tire
Take the vehicle tool kit and the jack
out of the storage compartment under
the trunk floor (
page 400).
On wheel to be changed, loosen but do
not yet remove the wheel bolts
(approximately one full turn with
wrench).
The jack support tubes are located behind
the front wheel housings and in front of the
rear wheel housings.
Warning!G
The jack is designed exclusively for jacking
up the vehicle at the jack tubes built into
both sides of the vehicle. To help avoid
personal injury, use the jack only to lift the
vehicle during a wheel change. Never get
beneath the vehicle while it is supported by
the jack. Keep hands and feet away from the
area under the lifted vehicle. Always firmly
set parking brake and block wheels before
raising vehicle with jack.
Do not disengage parking brake while the
vehicle is raised. Be certain that the jack is
always vertical (plumb line) when in use,
especially on hills. Always try to use the jack
on level surface. Be sure that the jack arm is
fully inserted in the jack tube. Always lower
the vehicle onto sufficient capacity jack-
stands before working under the vehicle.
Warning!G
When turning the wheel wrench to loosen
the wheel bolts, make sure you position
hands on the wrench in such a way that you
avoid injury to yourself, such as scraping
your hands against the wheel. Make sure
turning the wheel wrench will not scratch or
damage the wheel rim.


422 Practical hints
Flat tire
Unscrew the alignment bolt, install last
wheel bolt and tighten slightly.
Inflating the spare tire (collapsible tire)
Take the electric air pump out of the
trunk (
page 400).1Flap
2Air pump switch
3Electrical plug
4Air hose with pressure gauge and vent
screw
5Union nut
Open flap 1 on air pump.
Pull out electrical plug 3 and air hose
with the pressure gauge 4.
Remove the valve cap from the tire
valve.
Screw union nut 5 onto the tire valve.
Warning!G
Always replace wheel bolts that are dam-
aged or rusted.
Never apply oil or grease to wheel bolts.
Damaged wheel hub threads should be
repaired immediately. Do not continue to
drive under these circumstances! Contact
an authorized Mercedes-Benz Center or call
Roadside Assistance.
Incorrect wheel bolts or improperly tight-
ened wheel bolts can cause the wheel to
come off. This could cause an accident. Be
sure to use the correct wheel bolts.
Warning!G
Only use genuine Mercedes-Benz wheel
bolts. They are identified by the Mercedes
star. Other wheel bolts may come loose.
Do not tighten the wheel bolts when the ve-
hicle is raised. Otherwise the vehicle could
fall off the jack.
!Do not lower the vehicle before inflating the
spare wheel tire. Otherwise the rim may be dam-
aged.
Warning!G
Observe instructions on air pump label.

423 Practical hints
Flat tire
Insert electrical plug 3 into vehicle
cigarette lighter socket (
page 244)
or the power outlet in the trunk
(
page 246).
Turn the SmartKey in the starter switch
to position1.
or
Press the KEYLESS-GO* start/stop
button on the gear selector lever once
without depressing the brake pedal.
PressI on the electric air pump
switch2.
The electric air pump should now
switch on and inflate the tire.
Inflate the spare tire:

SL 550 to 36 psi (2.5 bar)

SL 600, SL 55 AMG, SL 55 AMG
(Performance Package*), and
SL 65 AMG to 51 psi (3.5 bar)
This takes about 5 minutes.
Air hose4 and union nut5 can be-
come hot during inflation. Exercise
proper caution to avoid burning your-
self when using the equipment.
Press0 on the electric air pump
switch2.
Turn the SmartKey in the starter switch
to position0.
or
Press KEYLESS-GO* start/stop button
on the gear selector lever twice without
depressing the brake pedal.
The electric air pump should now be
switched off.
If the spare tire inflation pressure is
above the recommended tire inflation
pressure for the respective collapsible
tire (
page 453), release excess spare
tire inflation pressure using the vent
screw.
!Compare the recommended tire inflation
pressure for your vehicle with the tire inflation
pressure on the yellow label located on the spare
wheel rim.
If the tire inflation pressure on the yellow label
on the spare wheel rim differs from the values
given in this Operator’s Manual, inflate the tire to
the recommended tire inflation pressure given
on the yellow label on the spare wheel rim.
!Do not operate the electric air pump longer
than 8 minutes without interruption. Otherwise it
may overheat.
You may operate the air pump again after it has
cooled off.