tire pressure MERCEDES-BENZ S-Class 2008 W221 Comand Manual

596 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 Tire and Loading Informa-
tion placard on the driver’s door B-pillar
(page 585) or, if available, the sup-
plemental tire inflation pressure
information on the inside of the fuel fill-
er flap (
page 570), make sure the tire
inflation pressure of all four tires is cor-
rect.

Switch on the ignition (
page 370).

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 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 Tire and Loading Informa-
tion placard on the driver’s door B-pillar
(
page 585). Some vehicles may have supple-
mental tire inflation pressure information for
driving at high speeds (
page 591) 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 570).
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 289).

597 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.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.

598 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 604)
2DOT, Tire Identification Number (TIN)
(page 602)
3Maximum tire load (
page 603)
4Maximum tire inflation pressure
(
page 603)
5Manufacturer
6Tire ply material (
page 606)
7Tire size designation, load and speed
rating (
page 598)
8Load identification (
page 601)
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 754).
i
For illustration purposes only. Actual data
on tires are specific to each vehicle and may vary
from data shown in above illustration.

599 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 598) indicates
the nominal tire width in mm.
Aspect ratio
The aspect ratio2 (page 598) 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 598) 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 600).Rim diameter
The rim diameter4 (
page 598) 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 598) 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 603) where the maximum load as-
sociated with the load index is indicated in
kilograms and lbs.

602 OperationTires and wheelsIn addition to tire load rating, special load
identification1 may be molded into the
tire sidewall following the letter designat-
ing the tire speed rating6 (
page 598).
No specification given: absence of any text
(like in above example) indicates a
standard load (SL) tire.
XL (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 Identification 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”.
1DOT
2Manufacturer’s identification mark
3Tire size
4Tire type code (at the option of the tire
manufacturer)
5Date of manufactureDOT (D
epartment o
f T
ransportation)
A tire branding symbol1 (
page 602)
which denotes the tire meets require-
ments of the U.S. Department of Transpor-
tation.
Manufacturer’s identification mark
The manufacturer’s identification mark2
(
page 602) denotes the tire
manufacturer.
New tires have a mark with two symbols.
Retreaded tires have a mark with four sym-
bols. For more information on retreaded
tires (
page 582).
Tire size
The code3 (
page 602) indicates the
tire size.
Tire type code
The code4 (page 602) may, at the
option of the manufacturer, be used as a
descriptive code for identifying significant
characteristics of the tire.
i
For illustration purposes only. Actual data
on tires are specific to each vehicle and may vary
from data shown in above illustration.

603 Operation
Tires and wheels
Date of manufacture
The date of manufacture5 (
page 602)
identifies the week and year of manufac-
ture.
The first two figures identify the week,
starting with “01” to represent the first full
week of the calendar year. The second two
figures represent the year.
For example, “3202” represents the 32nd
week of 2002.
Maximum tire load
1Maximum tire load ratingThe maximum tire load is the maximum
weight the tires are designed to support.
For more information on tire load rating
(
page 599).
For information on calculating total and
cargo load capacities (
page 587).
Maximum tire inflation pressure
1Maximum permissible tire inflation
pressure
This is the maximum permissible tire
inflation pressure for the tire.
Always follow the recommended tire
inflation pressure (
page 590) for proper
tire inflation.
i
For illustration purposes only. Actual data
on tires are specific to each vehicle and may vary
from data shown in above illustration.Warning!
G
Do not overload the tires by exceeding the
specified load limit or total load limit as indi-
cated on the Tire and Loading Information
placard located on the driver’s door B-pillar
(page 585). Overloading the tires can
overheat them, possibly causing a blowout.
Overloading the tires can also result in han-
dling or steering problems, or brake failure.
i
For illustration purposes only. Actual data
on tires are specific to each vehicle and may vary
from data shown in above illustration.

604 OperationTires and wheels
Uniform Tire Quality Grading Standards (U.S. vehicles)
Tire manufacturers are required to grade
tires based on three performance
factors: treadwear, traction and
temperature resistance.
1Treadwear
2Traction
3Temperature resistanceQuality grades can be found, where appli-
cable, on the tire sidewall between tread
shoulder and maximum section width. For
example:
All passenger car tires must conform to
federal safety requirements in addition to
these grades.
Treadwear
The treadwear grade is a comparative rat-
ing based on the wear rate of the tire when
tested under controlled conditions on a
specified government test course. For ex-
ample, a tire graded 150 would wear one
and one-half (1
1/2) times as well on the
government course as a tire graded 100.
The relative performance of tires depends
upon the actual conditions of their use,
however, and may depart significantly
Warning!
G
Never exceed the max. tire inflation
pressure. Follow recommended tire inflation
pressures.
Do not underinflate tires. Underinflated tires
wear excessively and/or unevenly, adverse-
ly affect handling and fuel economy, and are
more likely to fail from being overheated.
Do not overinflate tires. Overinflated tires
can adversely affect handling and ride com-
fort, wear unevenly, increase stopping dis-
tance, and result in sudden deflation
(blowout) because they are more likely to
become punctured or damaged by road de-
bris, potholes etc.
i
For illustration purposes only. Actual data
on tires are specific to each vehicle and may vary
from data shown in above illustration.
Treadwear
Traction
Temperature
200
AA
A

606 OperationTires and wheelsTire ply material
1Plies in sidewall
2Plies 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 driv-
en no more than 1 mile (1.6 km).
Curb weight
The weight of a motor vehicle with stan-
dard equipment including the maximum
capacity of fuel, oil, and coolant, and, if so
equipped, air conditioning and additional
optional equipment, but without passen-
gers and cargo.
i
For illustration purposes only. Actual data
on tires are specific to each vehicle and may vary
from data shown in above illustration.

607 Operation
Tires and wheels
DOT (D
epartment o
f T
ransportation)
A tire branding symbol which denotes the
tire meets requirements of the
U.S. Department of Transportation.
GAWR (G
ross A
xle W
eight R
ating)
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.
GVW (G
ross V
ehicle W
eight)
The GVW comprises the weight of the
vehicle including fuel, tools, spare wheel,
installed accessories, passengers and
cargo and, if applicable, 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 V
ehicle W
eight R
ating)
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 certi-
fication label located on the driver’s door
B-pillar.
Kilopascal (kPa)
The metric unit for air pressure. There are
6.9 kilopascals (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.
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, roof rack, heavy duty
battery, and special trim.

608 OperationTires and wheelsPSI (P
ounds per s
quare i
nch)
A standard unit of measure for air pressure
-> bar, kilopascal (kPa).
Recommended tire inflation pressure
The recommended tire inflation pressure
for normal driving conditions is listed on
the Tire and Loading Information placard
located on the driver’s door B-pillar and
provides best handling, tread life and
riding comfort. If so equipped, supplemen-
tal information 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 (T
ire I
dentification N
umber)
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 identifica-
tion 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 rubber-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.
Traction
Force exerted by the vehicle on the road
via the tires. The amount of grip provided.
Tread
The portion of a tire that comes into
contact with the road.
Treadwear indicators
Narrow bands, sometimes called
“wear bars” that show across the tread of
a tire when only
1/16in (1.6 mm) of tread
remains.