MERCEDES-BENZ S550 2007 W221 Owner's Manual

510 OperationTires and wheelsPlacard (Example B)
1Vehicle Tire Information placard with
recommended cold tire inflation
pressures
Placard (Example B) lists the recommend-
ed cold tire inflation pressures for maxi-
mum loaded vehicle weight. The tire
inflation pressures listed apply to the tires
installed as original equipment.Important notes on tire inflation
pressure
Tire temperature and tire inflation pressure
are also increased while driving, depending
on the driving speed and the tire load.
If you will be driving your vehicle at high
speeds of 100 mph (160 km / h) or higher,
where it is legal and conditions allow,
consult the placard on the inside of the fuel
filler flap on how to adjust the cold tire in-
flation pressure. If you do not adjust the
tire inflation pressure, excessive heat can
build up and result in sudden tire failure.Be sure to readjust the tire inflation
pressure for normal driving speeds. You
should wait until the tires are cold before
adjusting the tire inflation pressure.
Some vehicles may have supplemental tire
inflation pressure information for vehicle
loads less than the maximum loaded vehi-
cle condition (
page 518). If such infor-
mation is provided, it can be found on the
placard located on the inside of the fuel fill-
er flap (
page 489).
Tire inflation pressure changes by approxi-
mately 1.5 psi (0.1 bar) per 18°F (10°C) of
air temperature change. Keep this in mind
when checking tire inflation pressure
where the temperature is different from
the outside temperature.
i
Placard (Example B) may list recommended
cold tire inflation pressures for different vehicle
loads.
Warning!
G
If the tire inflation pressure repeatedly
drops:

Check the tires for punctures from
foreign objects.


Check to see whether air is leaking from
the valves or from around the rim.

511 Operation
Tires and wheels
Checking tire inflation pressure
Regularly check your tire inflation pressure
at least once a month.
Check and adjust the tire inflation
pressure when the tires are cold. The tires
can be considered cold if the vehicle has
been parked for at least 3 hours or driven
less than 1 mile (1.6 km).
If you check the tire inflation pressure
when the tires are warm (the vehicle has
been driven for several miles or sitting less
than 3 hours), the reading will be
approximately 4 psi (0.3 bar) higher than
the cold reading. This is normal. Do not let
air out to match the specified cold tire in-
flation pressure. Otherwise, the tire will be
underinflated.Checking tire inflation pressure
manually
Follow the steps below to achieve correct
tire inflation pressure:

Remove the cap from the valve on one
tire.

Firmly press a tire gauge onto the
valve.

Read tire inflation pressure on tire
gauge and check against the recom-
mended tire inflation pressure on the
placard on the driver’s door B-pillar
(page 503). If necessary, add air to
achieve the recommended tire inflation
pressure.

Install the valve cap.

Repeat this procedure for each tire.Checking tire inflation pressure elec-
tronically with the Advanced Tire Pres-
sure Monitoring System (Advanced
TPMS)*, (standard on U.S. vehicles)
i
If you have overfilled the tire, release tire in-
flation pressure by pushing the metal stem of the
valve with e.g. a tip of a pen. Then recheck the
tire inflation pressure with the tire gauge.
i
The Advanced
Tire
Pressure
Monitoring
System (Advanced TPMS) is equipped with a
combination low tire pressure/TPMS malfunc-
tion telltale in the instrument cluster
(page 28). Depending on how the telltale illu-
minates, it indicates a low tire inflation pressure
condition or a malfunction in the TPMS system it-
self:


If the telltale illuminates continuously, one
or more of your tires is significantly under-in-
flated. There is no malfunction in the TPMS.


If the telltale flashes for 60 seconds and
then stays illuminated, the TPMS system it-
self is not operating properly.

512 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 inflation pressure inquiries are made
using the multifunction display. The
present inflation pressures are displayed
only after a few minutes of travel time.
Switch on the ignition (
page 315).

Press( or& to select the menu
“Service”.

Press$ or% to select “Tire
pressure”.

Press#.
i
Possible differences between the readings
of a tire inflation 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
The menu overview can be found on
(
page 243).
i
When the message “Tire pressures dis-
played after driving a few minutes” appears in
the display, the individual inflation pressure val-
ues are matched with the tires. The individual
values are displayed after a few minutes driving.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 without wheel sensor
mounted, the system may still indicate the tire
inflation pressure of the removed wheel for some
minutes. If this happens, keep in mind that the
indicated value where the spare wheel is mount-
ed does not reflect 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 placard on the driver’s door B-pillar or, if
available, the supplemental tire pressure in-
formation 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.

513 Operation
Tires and wheels
Warning!
G
Each tire, including the spare (if provided),
should be checked monthly when cold and
inflated to the inflation pressure recom-
mended by the vehicle manufacturer on the
vehicle placard or the tire inflation pressure
label. (If your vehicle has tires of a different
size than the size indicated on the vehicle
placard or the tire inflation pressure label,
you should determine the proper tire infla-
tion pressure for those tires).
As an added safety feature, your vehicle has
been equipped with a tire pressure monitor-
ing system (TPMS) that illuminates a low tire
pressure telltale when one or more of your
tires is significantly under-inflated. Accord-
ingly, when the low tire pressure telltale illu-
minates, you should stop and check your
tires as soon as possible, and inflate then to
the proper pressure. Driving on a significant-
ly under-inflated tire causes the tire to over-
heat and can lead to tire failure.
Under-inflation also reduces fuel efficiency
and tire tread life, and may effect the vehi-
cle’s handling and stopping ability. Please
note that the TPMS is not a substitute for
proper tire maintenance, and it is the driv-
er’s responsibility to maintain correct tire
pressure, even if under-inflation has not
reached the level to trigger illumination of
the TPMS low tire pressure telltale.
Your vehicle has also been equipped with a
TPMS malfunction indicator to indicate
when the system is not operating properly.
The TPMS malfunction indicator is com-
bined with the low tire pressure telltale.
When the system detects a malfunction, the
telltale will flash for approximately
one minute and then remain continuously il-
luminated. This sequence will continue upon
subsequent vehicle start-ups as long as the
malfunction exists. When the malfunction
indicator is illuminated, the system may not
be able to detect or signal low tire pressure
as intended.
TPMS malfunctions may occur for a variety
of reasons, including the installation of
replacement or alternate tires or wheels on
the vehicle that prevent the TPMS from
functioning properly. Always check the
TPMS malfunction telltale after replacing
one or more tires or wheels on your vehicle
to ensure that the replacement or alternate
tires and wheels allow the TPMS to continue
to function properly.i
If a condition causing the TPMS to malfunc-
tion develops, it may take up to 10 minutes for
the system to signal a malfunction using the
TPMS telltale flashing and illumination se-
quence.
The telltale extinguishes after a few minutes driv-
ing if the malfunction has been corrected.
i
Operating radio transmission equipment
(e.g. wireless headsets, two-way radios) in or
near the vehicle could cause the TPMS to mal-
function.

514 OperationTires and wheelsReactivating Advanced TPMS
The TPMS must be reactivated when you
have adjusted the tire inflation pressure to
a new level (e.g. because of different load
or driving conditions). The TPMS is then
recalibrated to the current tire inflation
pressures.
Using the tire placard on the driver’s
door B-pillar (
page 503) or, if avail-
able, the supplemental tire inflation
pressure information on the inside of
the fuel filler flap (page 489), make
sure the tire inflation pressure of all
four tires is correct.

Switch on the ignition (
page 315).

Press( or& to select the menu
“Service”.

Press$ or% to select “Tire
pressure”.

Press#.
You will see

the current inflation pressures for
each tire
or


the message
Tire pressures
displayed after driving
a few minutes
appear in the multifunction display.

Press%.
The message
Use current pressure
values as new
reference values
To confirm press “OK”
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
Reactivate the TPMS after adjusting the tire
inflation pressure to the inflation pressure rec-
ommended for the vehicle operating condition.
Tire inflation pressure should only be adjusted
on cold tires. Observe the recommended tire in-
flation pressure on the placard on the driver’s
door B-pillar (
page 503). Some vehicles may
have supplemental tire inflation pressure infor-
mation for driving at high speeds (
page 510)
or for vehicle loads less than the maximum load-
ed vehicle condition. If such information is pro-
vided, it can be found on the inside of the fuel
filler flap (
page 489).
i
After wheel rotation or sensor replacement,
the vehicle must be parked for 20 minutes be-
fore attempting to reactivate the TPMS.
i
The menu overview can be found on
(
page 243).

515 Operation
Tires and wheels

Press#.
The message
Tire pressure monitor
reactivated
appears in the multifunction display.
After a few minutes driving, the current
tire inflation pressure values are ac-
cepted as reference values and then
monitored.
If you wish to cancel activation:

PressL.
or

Press$ to exit menu screen.Run Flat Indicator (Canada only)
While the vehicle is being driven, the Run
Flat Indicator monitors the set tire inflation
pressures by evaluating each wheel’s rota-
tional speed. This allows the system to de-
tect a significant loss of pressure in a tire.
If a wheel’s rotational speed changes due
to falling tire inflation pressure, you will
see a corresponding warning message in
the multifunction display.
The Run Flat Indicator may function in a re-
stricted manner or with a delay if:


snow chains are mounted to the
vehicle


in presence of ice and snow


you are driving on a loose surface (e.g.
sand or gravel)


you are driving in a very sporty manner
(involving rapid acceleration or high
speeds in curves)
i
When the wheel positions are changed on
the vehicle, it is possible that the air pressure is
temporarily displayed for the wrong position.
This will be corrected after driving for several
minutes, and the air pressure will be shown for
the correct position.
Warning!
G
When the multifunction display shows the
message “Tire pressure Check tires”, one or
more of your tires is significantly under-in-
flated. You should stop and check your tires
as soon as possible, and inflate them to the
proper tire inflation pressure as indicated on
the vehicle’s tire information placard. Driv-
ing on a significantly underinflated tire caus-
es the tire to overheat and can lead to tire
failure. Under-inflation also reduces fuel ef-
ficiency and tire tread life, and may affect
the vehicle’s handling and stopping ability.
Each tire, including the spare, should be
checked monthly when cold and set to the
tire inflation pressure recommended by the
vehicle manufacturer on the vehicle placard
or the tire inflation pressure label.

516 OperationTires and wheels
Reactivating the Run Flat Indicator
The tire inflation pressure monitor must be
reactivated in the following situations:

If you have changed the tire inflation
pressure


If you have replaced the wheels or tires


If you have installed new wheels or
tires

Using the tire placard on the driver’s
door B-pillar (
page 503) or, if avail-
able, the inside of the fuel filler flap
(
page 489), make sure the tire infla-
tion pressure of all four tires is correct.

Switch on the ignition (
page 315).

Press( or& to select the menu
“Service”.

Press$ or% to select “Tire
pressure”.

Press#.
The message
Run Flat Indicator
active
Reactivation possible: OK
appears in the multifunction display.

Press#.
The message
Tire pressure
now OK?
appears in the multifunction display.
Warning!
G
The Run Flat Indicator does not provide a
warning for wrongly selected tire inflation
pressures. Always adjust tire inflation pres-
sure according to the placard on the driver’s
door B-pillar or fuel filler flap.
The Run Flat Indicator does not replace reg-
ular checks of the tire inflation pressures
since a gradual pressure loss in all four tires
cannot be detected by the Run Flat
Indicator.
The Run Flat Indicator is not able to issue a
warning due to a sudden dramatic loss of
tire inflation pressure (e.g. tire blowout
caused by a foreign object). In this case
bring the vehicle to a halt by carefully apply-
ing the brakes and avoiding abrupt steering
maneuvers.
Warning!
G
The Run Flat Indicator can only warn you in
a reliable manner if you have set the correct
tire inflation pressures for each tire.
If an incorrect tire inflation pressure was
set, the system will monitor the pressure ac-
cording to the incorrect value.
i
The menu overview can be found on
(
page 243).

517 Operation
Tires and wheels
If you wish to confirm activation:
Press$ or% to select “Yes”.

Press#.
The message
Run Flat Indicator
reactivated
appears in the multifunction display.
After a certain “learning phase”, the Run
Flat Indicator checks the set pressure val-
ues for all four tires.
If you wish to cancel activation:

PressL.
or
When the message
Tire pressure
now OK?
appears in the multifunction display:

Press$ or% to select “No”.

Press#.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
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.

518 OperationTires and wheelsTire labeling
Besides tire name (sales designation) and
manufacturer name, a number of markings
can be found on a tire.
Following are some explanations for the
markings on your vehicle’s tires:1Uniform Quality Grading Standards
(
page 524)
2DOT, Tire Identification Number (TIN)
(page 522)
3Maximum tire load (
page 523)
4Maximum tire inflation pressure
(
page 523)
5Manufacturer
6Tire ply material (
page 525)
7Tire size designation, load and speed
rating (
page 518)
8Load identification (
page 521)
9Tire nameTire size designation, load and speed
rating
1Tire width
2Aspect ratio in %
3Radial tire code
4Rim diameter
5Tire load rating
6Tire speed rating
i
For illustration purposes only. Actual data
on tires are specific to each vehicle and may vary
from data shown in above illustration.
For more information, see “Rims and tires”
(
page 655).
i
For illustration purposes only. Actual data
on tires are specific to each vehicle and may vary
from data shown in above illustration.

519 Operation
Tires and wheels
General:
Depending on the design standards used,
the tire size molded into the sidewall may
have no letter or a letter preceding the tire
size designation.
No letter preceding the size designation
(as illustrated above): Passenger car tire
based on European design standards.
Letter “P” preceding the size designation:
Passenger car tire based on U.S. design
standards.
Letter “LT” preceding the size designation:
Light Truck tire based on U.S. design
standards.
Letter “T” preceding the size designation:
Temporary spare tires which are high
pressure compact spares designed for
temporary emergency use only. Tire width
The tire width1 (
page 518) indicates
the nominal tire width in mm.
Aspect ratio
The aspect ratio2 (page 518) is the
dimensional relationship between tire
section height and section width and is
expressed in percentage. The aspect ratio
is arrived at by dividing section height by
section width.
Tire code
The tire code3 (
page 518) indicates
the tire construction type. The “R” stands
for radial tire type. Letter “D” means diag-
onal or bias ply construction; letter “B”
means belted-bias ply construction.
At the tire manufacturer’s option, any tire
with a speed capability above 149 mph
(240 km/h) can include a “ZR” in the size
designation (for example: 245/40 ZR 18).
For additional information, see “Tire speed
rating” (
page 520).Rim diameter
The rim diameter4 (
page 518) is the
diameter of the bead seat, not the
diameter of the rim edge. Rim diameter is
indicated in inches (in).
Tire load rating
The tire load rating5 (page 518) is a
numerical code associated with the
maximum load a tire can support.
For example, a load rating of 91 corre-
sponds to a maximum load of 1 356 lbs
(615 kg) the tire is designed to support.
See also “Maximum tire load”
(
page 523) where the maximum load as-
sociated with the load index is indicated in
kilograms and lbs.