2008 MERCEDES-BENZ CL550 wheel

573 Operation
Tires and wheels

Switch on the ignition (
page 365).

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

Press$ or% to select “Tire
Pressure”.

Press#.
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 Advanced TPMS on the recommended
cold inflation pressure. Underinflated tires
affect the ability to steer or brake the vehi-
cle. 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 Advanced TPMS does not indicate a
warning for wrongly selected inflation pres-
sures. Always adjust tire inflation pressure
according to the Tire and Loading Informa-
tion placard on the driver’s door B-pillar or,
if available, the supplemental tire inflation
pressure information on the inside of the
fuel filler flap.
The Advanced TPMS is not able to issue a
warning due to a sudden dramatic loss of
pressure (e.g. tire blowout caused by a for-
eign object). In this case bring the vehicle to
a halt by carefully applying the brakes and
avoiding abrupt steering maneuvers.

574 OperationTires and wheelsWarning!
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
Tire and Loading Information placard on the
driver’s door B-pillar or, if available, the tire
inflation pressure label on the fuel filler flap.
If your vehicle has tires of a different size
than the size indicated on the Tire and
Loading Information placard or, if available,
the tire inflation pressure label, you should
determine the proper tire inflation pressure
for those tires.
As an added safety feature, your vehicle has
been equipped with an advanced tire pres-
sure monitoring system (Advanced TPMS)
that illuminates a low tire pressure telltale
when one or more of your tires is significant-
ly underinflated. Accordingly, when the low
tire pressure telltale illuminates, you should
stop and check your tires as soon as possi-
ble, and inflate then to the proper pressure.
Driving on a significantly underinflated tire
causes the tire to overheat and can lead to
tire failure.
Underinflation also reduces fuel efficiency
and tire tread life, and may effect the vehi-
cle’s handling and stopping ability. Please
note that the Advanced TPMS is not a sub-
stitute for proper tire maintenance, and it is
the driver’s responsibility to maintain cor-
rect tire pressure, even if underinflation has
not reached the level to trigger illumination
of the Advanced TPMS low tire pressure tell-
tale.
USA only:
Your vehicle has also been equipped with an
Advanced TPMS malfunction indicator to in-
dicate when the system is not operating
properly. The Advanced TPMS malfunction
indicator is combined with the low tire pres-
sure telltale. When the system detects a
malfunction, the telltale will flash for approx-
imately one minute and then remain contin-
uously illuminated. 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 sig-
nal low tire pressure as intended.
Advanced TPMS malfunctions may occur for
a variety of reasons, including the installa-
tion of replacement or alternate tires or
wheels on the vehicle that prevent the Ad-
vanced TPMS from functioning properly. Al-
ways check the Advanced TPMS
malfunction telltale after replacing one or
more tires or wheels on your vehicle to en-
sure that the replacement or alternate tires
and wheels allow the Advanced TPMS to
continue to function properly.i
If a condition causing the Advanced TPMS to
malfunction develops, it may take up to
10 minutes for the system to signal a malfunc-
tion using the Advanced TPMS telltale flashing
and illumination sequence.
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 Advanced TPMS
to malfunction.

575 Operation
Tires and wheels
Reactivating Advanced TPMS
The Advanced TPMS must be reactivated
when you have adjusted the tire inflation
pressure to a new level (e.g. because of dif-
ferent load or driving conditions). The Ad-
vanced TPMS is then recalibrated to the
current tire inflation pressures.
Using the Tire and Loading Information
placard on the driver’s door B-pillar
(page 564) or, if available, the sup-
plemental tire inflation pressure
information on the inside of the fuel fill-
er flap (
page 550), make sure the tire
inflation pressure of all four tires is
correct.

Switch on the ignition (
page 365).

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
Pressures As New
Reference Values
Press "OK" to Confirm
Tire Press.”
appears in the multifunction display.
Warning!
G
It is the driver’s responsibility to calibrate
the Advanced TPMS on the recommended
cold inflation pressure. Underinflated tires
affect the ability to steer or brake the vehi-
cle. You might lose control over the vehicle.
i
Reactivate the Advanced TPMS after adjust-
ing the tire inflation pressure to the inflation
pressure recommended for the vehicle operating
condition. Tire inflation pressure should only be
adjusted on cold tires. Observe the recommend-
ed tire inflation pressure on the Tire and Loading
Information placard on the driver’s door B-pillar
(
page 564). Some vehicles may have supple-
mental tire inflation pressure information for
driving at high speeds (
page 570) or for vehi-
cle loads less than the maximum loaded vehicle
condition. If such information is provided, it can
be found on the inside of the fuel filler flap
(
page 550).
i
After wheel rotation or sensor replacement,
the vehicle must be parked for 20 minutes be-
fore attempting to reactivate the Advanced
TPMS.
i
The menu overview can be found on
(
page 284).


576 OperationTires 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.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
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
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.


577 Operation
Tires and wheels
Tire 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 583)
2DOT, Tire Identification Number (TIN)
(page 581)
3Maximum tire load (
page 582)
4Maximum tire inflation pressure
(
page 583)
5Manufacturer
6Tire ply material (
page 585)
7Tire size designation, load and speed
rating (
page 577)
8Load identification (
page 581)
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 727).
i
For illustration purposes only. Actual data
on tires are specific to each vehicle and may vary
from data shown in above illustration.

578 OperationTires and wheelsGeneral:
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 577) indicates
the nominal tire width in mm.
Aspect ratio
The aspect ratio2 (page 577) 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 577) 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 579).Rim diameter
The rim diameter4 (
page 577) 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 577) 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 582) where the maximum load as-
sociated with the load index is indicated in
kilograms and lbs.

579 Operation
Tires and wheels
For additional information on tire load
rating, see “Load identification”
(page 581).
Tire speed rating
The tire speed rating6 (
page 577)
indicates the approved maximum speed
for the tire.Summer tires
Warning!
G
The tire load rating must always be at least
half of the GAWR (
page 586) of your
vehicle. Otherwise, tire failure may be the
result which may cause an accident and/or
serious personal injury to you or others.
Always replace rims and tires with the same
designation, manufacturer and type as
shown on the original part.
Warning!
G
Do not overload the tires by exceeding the
specified load limit as indicated on the Tire
and Loading Information placard located on
the driver’s door B-pillar. Overloading the
tires can overheat them, possibly causing a
blowout. Overloading the tires can also
result in handling or steering problems, or
brake failure.
i
Tire load rating5 (
page 577) and tire
speed rating6 (
page 577) are also referred
to as “service description”.
Warning!
G
Even when permitted by law, never operate
a vehicle at speeds greater than the
maximum speed rating of the tires.
Exceeding the maximum speed for which
tires are rated can lead to sudden tire
failure, causing loss of vehicle control and
possibly resulting in an accident and/or
personal injury and possible death, for you
and for others.
i
Tire load rating5 (
page 577) and tire
speed rating6 (
page 577) are also referred
to as “service description”.
Index
Speed rating
Q
up to 100 mph (160 km/h)
R
up to 106 mph (170 km/h)
S
up to 112 mph (180 km/h)
T
up to 118 mph (190 km/h)
H
up to 130 mph (210 km/h)
V
up to 149 mph (240 km/h)
W
up to 168 mph (270 km/h)
Y
up to 186 mph (300 km/h)
(Y)
above 186 mph (300 km/h)
ZR
above 149 mph (240 km/h)

580 OperationTires and wheels

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 exam-
ple: 245/40 ZR18). To determine the
maximum speed capability of the tire,
the service description for the tire must
be referred to. The service description
is comprised of the tire load rating5
(page 577) and the tire speed
rating6 (
page 577).
If your tire includes “ZR” in the size
designation and no service
description5 and6 (
page 577) is
given, the tire manufacturer must be
consulted for the maximum speed ca-
pability.
If a service description5 and6
(
page 577) is given, the speed capa-
bility is limited by the speed symbol in
the service description.
Example: 245/40 ZR18 97Y.
In this example, “97Y” is the service
description. The letter “Y” designates the speed rating and the speed capabil-
ity of the tire is limited to 186 mph
(300 km/h).


Any tire with a speed capability above
186 mph (300 km/h) must include a
“ZR” in the size designation AND the
service description must be placed in
parenthesis.
Example: 275/40 ZR 18 (99Y).
The “(Y)” speed rating in parenthesis
designates the maximum speed capa-
bility of the tire as being above
186 mph (300 km/h). Consult the tire
manufacturer for the actual maximum
permissible speed of the tire.All-season and winter tires
Index
Speed rating
QM+S
1
1or M+S.for winter tires
up to 100 mph (160 km/h)
TM+S
1
up to 118 mph (190 km/h)
HM+S
1
up to 130 mph (210 km/h)
VM+S
1
up to 149 mph (240 km/h)
i
Not all M+S rated tires provide special win-
ter performance. Make sure the tires you use
show M+S and the mountain/snow-
flake.
marking on the tire sidewall. These
tires meet specific snow traction performance
requirements of the Rubber Manufacturers As-
sociation (RMA) and the Rubber Association of
Canada (RAC) and have been designed specifi-
cally for use in snow conditions.