2008 MERCEDES-BENZ G500 Owner's Manual

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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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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302 Operation
Tires 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.1 Treadwear
2 Traction
3 Temperature resistance Quality grades can be found, where
applicable, 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
example, 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 condit ions of their use,
however, and may depart significantly
from the norm due to variations in driving
habits, service practices and differences in
road characteristics and climate.
iFor illustration purposes only. Actual data
on tires are specific to each vehicle and may vary
from data shown in above illustration.
TreadwearTractionTemperature
200AAA
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303
Operation
Tires and wheels
Traction
The traction grades, from highest to
lowest, are AA, A, B, and C. Those grades
represent the tire’s ability to stop on wet
pavement as measured under controlled
conditions on specified government test
surfaces of asphalt and concrete. A tire
marked C may have poor traction perfor-
mance.
Temperature
The temperature grades are A (the high-
est), B, and C, representing the tire’s resis-
tance to the generation of heat and its
ability to dissipate heat when tested under
controlled conditions on a specified indoor
laboratory test wheel. Sustained high tem-
perature can cause the material of the tire
to degenerate and reduce tire life, and
excessive temperature can lead to sudden
tire failure. The grade C corresponds to a
level of performance which all passenger
car tires must meet under the Federal
Motor Vehicle Safety Standard No. 109.
Grades B and A represent higher levels of
performance on the laboratory test wheel
than the minimum required by law.
Warning!G
The traction grade assigned to this tire is
based on straight-ahe
ad braking traction
tests, and does not include acceleration,
cornering, hydroplaning, or peak traction
characteristics.
Warning!G
The temperature grade for this tire is
established for a tire that is properly inflated
and not overloaded. Excessive speed,
underinflation, or excessive loading, either
separately or in combination, can cause
excessive heat build-up and possible tire
failure.
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