MERCEDES-BENZ G55AMG 2008 W463 Owner's Manual

290 Operation
Tires and wheels
The 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 39).
Press buttonj ork until the
current inflation pressures for each tire
appear in the multifunction display.
Example illustration
iPossible 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.
iWhen the vehicle has been parked for longer
than 20 minutes, the message
Tire pressure
displayed only 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.
iWith 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
reflect the actual spare tire inflation pressure.
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291
Operation
Tires and wheels
Warning!G
The Advanced TPMS does not indicate a
warning for wrongly selected inflation pres-
sures. Always adjust ti
re 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.
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
Tire and Loading Information placard or the
tire inflation pressure label (if available). If
your vehicle has tires of a different size than
the size indicated on the Tire and Loading
Information placard or the tire inflation
pressure label (if av ailable), 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 yo ur tires is significant-
ly underinflated. Acco rdingly, when the low
tire pressure telltale illuminates, you should
stop and check your tires as soon as possi-
ble, and inflate them to the proper pressure.
Driving on a significantly underinflated tire
causes the tire to over heat and can lead to
tire failure.
Underinflation also reduces fuel efficiency
and tire tread life, and may affect 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 a Advanced TPMS malfunc-
tion indicator to indica te when the system is
not operating properly. The Advanced TPMS
malfunction indicator is combined with the
low tire pressure telltale. When the system
detects a malfunction, the telltale will flash
for approximately 1 minute and then remain
continuously illuminate d. This sequence will
continue upon subsequent vehicle start-ups
as long as the malfunction exists.

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292 Operation
Tires and wheels
Tire inflation pressure warnings
If the system detects a significant loss of
tire inflation pressure in one or more than
one tire, a message appears in the multi-
function display.
Example illustration
The respective tire is indicated by a red
rectangle. In addition, a warning signal
sounds.Restarting Advanced TPMS
The TPMS usually recognizes new refer-
ence values automatically, for example
when you have

adjusted the tire inflation pressure

changed wheels or tires

mounted new wheels or tires
USA only: When the malf
unction indicator is
illuminated, the system may not be able to
detect or signal low tire pressure as
intended.
USA only: Advanced 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 Advanced TPMS from functioning prop-
erly. Always check the Advanced TPMS mal-
function telltale after replacing one or more
tires or wheels on your vehicle to ensure
that the replacement or alternate tires and
wheels allow the Advanc ed TPMS to contin-
ue to function properly.
iOperating radio transmission equipment
(e.g. wireless headsets, two-way radios) in or
near the vehicle could cause the Advanced
TPMS to malfunction.
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.

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293
Operation
Tires and wheels
If you want to set new reference values
manually:
Using the Tire and Loading Information
placard on the driver’s door B-pillar
(
page 280) or, if available, the
supplemental tire inflation pressure
information on the inside of the fuel
filler flap (
page 264), make sure the
tire inflation pressure of all four tires is
correct.
Press button è orÿ on the mul-
tifunction steering wheel repeatedly
until the standard display menu
appears in the multifunction display.
Press button j ork repeatedly
until you see the current inflation
pressures for each tire appear in the
multifunction display or the following
message appears in the multifunction
display:
Tire pressure
displayed
only after
driving for
a few minutes
Press the reset button (page 130).
The following message will appear in
the multifunction display:
Restart
tire pressure
monitor?
Press the æ button.
The following message will appear in
the multifunction display:
Tire pressure
monitor
restarted
After driving a few minutes the system
verifies that the cu rrent tire inflation
pressures are within the system’s
specified range. Afte rwards the current
tire inflation pressures are accepted as
reference pressures and then moni-
tored.
If you wish to cancel activation:
Press the ç button.
iRestart the TPMS after adjusting the tire in-
flation pressure to the inflation pressure recom-
mended for the vehicle operating condition. Tire
pressure should only be adjusted on cold tires.
Observe the recommended tire inflation pres-
sure on the Tire and Loading Information placard
on the driver’s door B-pillar (
page 280). Some
vehicles may have supplemental tire inflation
pressure information for driving at high speeds
(
page 287) or for vehicle loads less than the
maximum loaded vehicle condition
(
page 287). If such information is provided, it
can be found on the inside of the fuel filler flap
(
page 264).
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294 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
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:
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.
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295
Operation
Tires and wheels
1
Uniform Quality Grading Standards
(
page 302)
2 DOT, Tire Identification Number (TIN)
(
page 299)
3 Maximum tire load (
page 300)
4 Maximum tire inflation pressure
(
page 301)
5 Manufacturer
6 Tire ply material (
page 304)
7 Tire size designation, load and speed
rating (
page 295)
8 Load identification (
page 298)
9 Tire name Tire size designation, load and speed
rating
1 Tire width
2 Aspect ratio in %
3 Radial tire code
4 Rim diameter
5 Tire load rating
6 Tire speed rating 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.
iFor 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 414).
iFor illustration purposes only. Actual data
on tires are specific to each vehicle and may vary
from data shown in above illustration.
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296 Operation
Tires and wheels
Tire width
The tire width1 (
page 295) indicates
the nominal tire width in mm.
Aspect ratio
The aspect ratio 2 (
page 295) 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 code 3 (
page 295) indicates
the tire construction type. The “R” stands
for radial tire type. Letter “D” means
diagonal 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 297). Rim diameter
The rim diameter
4 (
page 295) 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 rating 5 (
page 295) 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 300) where the maximum load
associated with the load index is indicated
in kilograms and lbs.
Warning!G
The tire load rating mu st always be at least
half of the GAWR (
page 305) 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.
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297
Operation
Tires and wheels
For additional information on tire load
rating, see “Load identification”
(
page 298).
Tire speed rating
The tire speed rating 6 (
page 295)
indicates the approv ed maximum speed
for the tire. Summer tires

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 rating
5
(
page 295) and the tire speed
rating 6 (
page 295).
If your tire includes “ZR” in the size
designation and no service
description 5 and 6 (
page 295) is
given, the tire manufacturer must be
consulted for the maximum speed
capability.
iTire load rating 5 (page 295) and tire
speed rating 6 (
page 295) 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.
iTire load rating 5 (page 295) and tire
speed rating 6 (
page 295) are also referred
to as “service description”.
IndexSpeed rating
Qup to 100 mph (160 km/h)
Rup to 106 mph (170 km/h)
Sup to 112 mph (180 km/h)
Tup to 118 mph (190 km/h)
Hup to 130 mph (210 km/h)
Vup to 149 mph (240 km/h)
Wup to 168 mph (270 km/h)
Yup to 186 mph (300 km/h)
(Y)above 186 mph (300 km/h)
ZRabove 149 mph (240 km/h)
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298 Operation
Tires and wheels
If a service description5 and 6
(
page 295) is given, the speed
capability 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
capability 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 ZR18 (99Y).
The “(Y)” speed rating in parenthesis
designates the maximum speed
capability 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
Load identification
1 Load identification
IndexSpeed rating
QM+S1
1or M+S .for winter tires
up to 100 mph (160 km/h)
TM+S1up to 118 mph (190 km/h)
HM+S1up to 130 mph (210 km/h)
VM+S1up to 149 mph (240 km/h)
iNot all M+S rated tires provide special
winter performance. Make sure the tires you use
show M+S and the mountain/snowflake
marking . on the tire sidewall. These tires
meet specific snow traction performance
requirements of the Rubber Manufacturers
Association (RMA) and the Rubber Association
of Canada (RAC) and have been designed
specifically for use in snow conditions.
iFor illustration purposes only. Actual data
on tires are specific to each vehicle and may vary
from data shown in above illustration.
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299
Operation
Tires and wheels
In addition to tire load rating, special load
identification
1 may be molded into the
tire sidewall following the letter designat-
ing the tire speed rating (
page 295).
No specification given: absence of any text
(like in above example) indicates a
standard load (SL) tire.
XL or Extra Load: designates an extra load
(or reinforced) tire.
Light Load: designates a light load tire.
C, D, E: designates load range associated
with the maximum load a tire can carry at
a specified pressure.
DOT, Tire Identifica tion Number (TIN)
U.S. tire regulations require each new tire
manufacturer or tire retreader to mold a
TIN into or onto a sidewall of each tire
produced.
The TIN is a unique identifier which facili-
tates efforts by tire manufactures to notify
purchasers in recall situations or other
safety matters concerning tires and gives
purchasers the means to easily identify
such tires.
The TIN is comprised of “Manufacturer’s
identification mark”, “Tire size”, “Tire type
code” and “Date of manufacture”. 1
DOT
2 Manufacturer’s identification mark
3 Tire size
4 Tire type code (at the option of the tire
manufacturer)
5 Date of manufacture
iFor illustration purposes only. Actual data
on tires are specific to each vehicle and may vary
from data shown in above illustration.
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