2008 MERCEDES-BENZ G500 fuel pressure

288 Operation
Tires and wheels
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.
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
inflation pressure. Otherwise, the tire will
be underinflated.
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 over-
heated.
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.
Do not overload the tires by exceeding the
specified load limit as indicated on the Tire
and Loading Information placard 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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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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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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301
Operation
Tires and wheels
For more information on tire load rating
(
page 296).
For information on calculating total and
cargo load capacities (
page 282).
Maximum tire inflation pressure
1 Maximum permissible tire inflation
pressure
This is the maximum permissible tire
inflation pressure for the tire. Always follow the recommended tire
inflation pressure (
page 286) for proper
tire inflation.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.
iFor illustration purposes only. Actual data
on tires are specific to each vehicle and may vary
from data shown in above illustration.
Warning!G
Never exceed the max. tire inflation
pressure. Follow recommended tire inflation
pressures.
Do not underinflate tire s. Underinflated tires
wear excessively and/or unevenly,
adversely affect handling and fuel economy,
and are more likely to fail from being over-
heated.
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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304 Operation
Tires and wheels
Tire ply material1 Plies in sidewall
2 Plies 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 3 hours or
driven no more than 1 mile (1.6 km).
Curb weight
The weight of a motor vehicle with stan-
dard equipment incl uding the maximum
capacity of fuel, oil, and coolant, and, if so
equipped, air conditioning and additional
optional equipment, but without passen-
gers and cargo.
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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305
Operation
Tires and wheels
DOT (Department of Transportation)
A tire branding symbol which denotes the
tire meets requirements of the
U.S. Department of Transportation.
GAWR (G
ross Axle Weight Rating)
The GAWR is the maximum permissible
axle weight. The gross vehicle weight on
each axle must never exceed the GAWR for
the front and rear axle indicated on the
certification label located on the driver’s
door B-pillar.
GTW (G
ross Trailer Weight)
The GTW is the weight of the trailer plus
the weight of all ca rgo, equipment, luggage
etc. loaded on the trailer. GVW (G
ross Vehicle Weight)
The GVW comprises the weight of the
vehicle including fuel, tools, spare wheel,
installed accessories, passengers and
cargo and, if applic able, trailer tongue
load. The GVW must never exceed the
GVWR indicated on the certification label
located on the driver’s door B-pillar.
GVWR (G
ross Vehicle Weight Rating)
This is the maximum permissible vehicle
weight of the fully loaded vehicle (weight of
the vehicle including all options, passen-
gers, fuel, and cargo and, if applicable,
trailer tongue load). It is indicated on
certification label located on the driver’s
door B-pillar.
Kilopascal (kPa)
The metric unit for air pressure. There are
6.9 kPa to 1 psi; another metric unit for air
pressure is bars. There are 100 kilopascals
(kPa) to 1 bar. Maximum load rating
The maximum load in kilograms and
pounds that can be carried by the tire.
Maximum loaded vehicle weight
The sum of curb weight, accessory weight,
total load limit, and production options
weight.
Maximum tire inflation pressure
This number is the greatest amount of air
pressure that should ever be put in the tire
under normal driving conditions.
Normal occupant weight
The number of occupants the vehicle is
designed to seat, multiplied by
68 kilograms (150 lbs).
Occupant distribution
The distribution of occupants in a vehicle
at their designated seating positions.
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306 Operation
Tires and wheels
Production options weight
The combined weight of those installed
regular production options weighing over
5 lbs (2.3 kilograms) in excess of those
standard items which they replace, not
previously considered in curb weight or
accessory weight, including heavy duty
brakes, ride levelers, heavy duty battery,
and special trim.
PSI (P
ounds per square inch)
A standard unit of measure for air pressure
-> bar, kilopascal (kPa).
Recommended tire inflation pressure
Recommended tire inflation pressure for
normal driving conditions is listed on the
Tire and Loading Information placard locat-
ed on the driver’s door B-pillar. Provides
best handling, tread life and riding com-
fort. If so equipped, supplemental informa-
tion pertaining to special driving situations
can be found on the tire inflation pressure
label on the inside of the fuel filler flap. Rim
A metal support for a tire or a tire and tube
assembly upon which the tire beads are
seated.
Sidewall
The portion of a tire between the tread and
the bead.
TIN (Tire Identification Number)
Unique identifier which facilitates efforts
by tire manufacturers to notify purchasers
in recall situations or other safety matters
concerning tires and gives purchases the
means to easily identify such tires. The TIN
is comprised of “Manufacturer’s identifi-
cation mark”, “Tire size”, “Tire type code”
and “Date of manufacture”.
Tire load rating
Numerical code associated with the
maximum load a tire can support. Tire ply composition and material used
This indicates the number of plies or the
number of layers of ru
bber-coated fabric in
the tire tread and sidewall. Tire manufac-
turers also must indicate the ply materials
in the tire and sidewall, which include
steel, nylon, polyester, and others.
Tire speed rating
Part of tire designation; indicates the
speed range for which a tire is approved.
Total load limit
Rated cargo and luggage load plus
68 kilograms (150 lbs) times the vehicle’s
designated seating capacity.
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