2008 MERCEDES-BENZ G55AMG tire size

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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300 Operation
Tires and wheels
DOT (Department of Transportation)
A tire branding symbol 1 (
page 299)
which denotes the tire meets require-
ments of the U.S. Department of
Transportation.
Manufacturer’s id entification mark
The manufacturer’s identification mark2
(
page 299) 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 277).
Tire size
The code 3 (
page 299) indicates the
tire size. Tire type code
The code
4 (
page 299) may, at the
option of the manufacturer, be used as a
descriptive code for identifying significant
characteristics of the tire.
Date of manufacture
The date of manufacture 5 (
page 299)
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
1 Maximum tire load rating
The maximum tire load is the maximum
weight the tires are designed to support.
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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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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307
Operation
Tires and wheels
Traction
Force exerted by the vehicle on the road
via the tires. The amou
nt 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.
TWR (T
ongue Weight Rating)
Maximum permissible weight on trailer
tongue. Uniform Tire Quality Grading Standards
A tire information system that provides
consumers with ratings for a tire’s traction,
temperature and treadwear. Ratings are
determined by tire manufacturers using
government testing procedures. The
ratings are molded into the sidewall of the
tire.
Vehicle maximum load on the tire
Load on an individual tire that is
determined by distributing to each axle its
share of the maximum loaded vehicle
weight and dividing it by two.
Rotating tires
Tire rotation can be performed on vehicles
with tires of the same dimension all
around. If your vehicle is equipped with
tires of the same dimension all around,
tires can be rotated, observing a
front-to-rear rotation pattern that will
maintain the intended rotation (spinning)
direction of the tire (
page 280).
In some cases, such as when your vehicle
is equipped with mixed-size tires (different
tire dimension front vs. rear), tire rotation
is not possible.
Warning!G
Rotate front and rear wheels only if the tires
are of the same dimension.
If your vehicle is eq uipped with mixed-size
tires (different tire dimensions front vs.
rear), tire rotation is not possible.
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334 Practical hints
What to do if …
Warning!G
Each tire, including the spare (if provided),
should be checked monthly when cold and
inflated to the infl ation 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 inside of 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 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 a Advanced Tire Pres-
sure Monitoring System (Advanced TPMS)
that illuminates a low tire pressure telltale
when one or more of your tires is signifi-
cantly underinflated. Accordingly, when the
low tire pressure telltale illuminates, you
should stop and check your tires as soon as
possible, and inflate them to the proper
pressure.
Driving on a significan tly underinflated tire
causes the tire to overheat 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 responsibi lity 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 indicate 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.When the malfunction indicator is
illuminated, the system may not be able to
detect or signal 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 af ter 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.
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