2018 MERCEDES-BENZ G-CLASS flat tire

All about wheels and tires
UniformTire Quality Grading Stand-
ards
Overview ofTire Quality Grading Stand-
ards
Uniform Tir eQuality Grading Standards are U.S.
governmen tspecifications. Their purpose is to
provid edriver swit hunifor mreliable information
on tire performance data. Tir emanufacturers
hav eto grad etires usin gthree performance fac -
tors: :tread wear grade, ;traction grad eand
= temperature grade. These regulation sdo no t
apply to Canada. Nevertheless, all tires sold in
North America are provided wit hth ecorre-
sponding qualit ygrading marking son th eside -
wall of th etire.
Quality grades can be found, wher eapplicable,
on th etire sidewall between tread shoulder and
maximum section width.
Example:
RTreadwear grade: 200
RTraction grade: AA
RTemperaturegrade: A
All passenger car tires mus tconform to th estat-
utory safet yrequirements in addition to these
grades.
iThe actual value sfor tires are vehicle-spe-
cific and may deviat efrom th evalue sin th e
illustration .
Treadwear
The treadwear grad eis acomparative rating
base don th ewear rat eof th etire when tested
under controlled condition son aspecifie dU.S.
governmen tcourse. Fo rexample, atire graded 15
0would wear on eand one-half times as well
on th egovernmen tcours eas atire graded 100.
The relative performance of tires depend supon
th eactual condition sof their use, however ,and
may depar tsignificantly from th enorm due to
variation sin drivin ghabits, servic epractice s
and difference sin road characteristics and cli -
mate.
Traction
GWARNIN G
The traction grad eassigned to this tire is
base don straight-ahead braking traction
tests, and does no tinclude acceleration ,cor-
nering, hydroplaning ,or peak traction char-
acteristics .
!Avoid wheelspin. This can lead to damag eto
th edrive train .
The traction grades –from highest to lowes t –
are AA ,A, Band C. Those grades represen tth e
tire' sabilit yto stop on wet pavemen tas meas -
ured under controlled condition son specifie d
governmen ttest surfaces of asphalt and con-
crete. Atire marke d Cmay hav epoor traction
performance .
The saf espee don awet ,snow covered or icy
road is always lower than on dry road surfaces.
You should pay special attention to road condi-
tion swhen temperatures are around freezing
point.
Mercedes-Benz recommends aminimum tread
dept hof ã in (4 mm) on all four winte rtires .
Observ eth elegally require dminimum tire tread
dept h (
Ypage 258). Winte rtires can reduce th e
braking distanc eon snow-covered surfaces in
comparison wit hsummer tires .The braking dis-
tance is still muc hfurther than on surfaces that
are no ticy or covered wit hsnow. Tak eappro-
priate car ewhen driving.
Further information on winte rtires (M+ Stires )
(
Ypage 259).
Temperature
GWARNIN G
The temperature grad efor this tire is estab-
lished for atire that is properly inflated and
no toverloaded. Excessive speed, underinfla-
tion ,or excessive loading ,either separately or
All about wheels and tires269
Wheels and tires
Z

PSI (pounds per square inch)
A standard unit of measure for tire pressure.
Aspect ratio
Relationship between tire height and tire width
in percent.
Tire pressure
This is pressure inside the tire applying an out-
ward force to each square inch of the tire's sur-
face. The tire pressure is specified in pounds per
square inch (psi), in kilopascals (kPa) or in bar.
The tire pressure should only be corrected when
the tires are cold.
Cold tire pressure
The tires are cold:
Rif the vehicle has been parked with the tires
out of direct sunlight for at least three hours
and
Rif the vehicle has not been driven further than
1 mile (1.6 km)
Tread
The part of the tire that comes into contact with
the road.
Bead
The tire bead ensures that the tire sits securely
on the wheel. There are several steel wires in the
bead to prevent the tire from coming loose fromthe wheel rim.
Sidewall
The part of the tire between the tread and the
bead.
Weight of optional extras
The combined weight of those optional extras
that weigh more than the replaced standard
parts and more than 2.3 kg (5 lbs). These
optional extras, such as high-performance
brakes, level control, a roof rack or a high-per-
formance battery, are not included in the curb
weight and the weight of the accessories.
TIN (Tire Identification Number)
This is a unique identifier which can be used by
a tire manufacturer to identify tires, for example
for a product recall, and thus identify the pur-
chasers. The TIN is made up of the manufactur-
er's identity code, tire size, tire type code and
the manufacturing date.
Load bearing index
The load bearing index (also load index) is a code
that contains the maximum load bearing capa-
city of a tire.
Traction
Traction is the result of friction between the tires
and the road surface.
TWR (Tongue Weight Rating)
The TWR specifies the maximum permissible
weight that the ball coupling of the trailer tow
hitch can support.
Treadwear indicators
Narrow bars (tread wear bars) that are distrib-
uted over the tire tread. If the tire tread is level
with the bars, the wear limit of áin (1.6 mm)
has been reached.
Occupant distribution
The distribution of occupants in a vehicle at their
designated seating positions.
Total load limit
Nominal load and luggage load plus 68 kg
(150 lbs) multiplied by the number of seats in
the vehicle.
Changing a wheel
Flat tire
You can find information on what to do in the
event of a flat tire in the "Breakdown assistance"
section (
Ypage 246).
Rotating the wheels
GWARNING
Interchanging the front and rear wheels may
severely impair the driving characteristics if
the wheels or tires have different dimensions. The wheel brakes or suspension components
may also be damaged. There is a risk of acci-
dent.
Rotate front and rear wheels only if the wheels and tires are of the same dimensions.
Changing a wheel275
Wheels and tires
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Observe the following when raising the vehi-
cle:
RTo raise the vehicle, only use the vehicle-spe-
cific jack that has been tested and approved
by Mercedes-Benz. If used incorrectly, the
jack could tip over with the vehicle raised.
RThe jack is designed only to raise and hold the
vehicle for a short time while a wheel is being
changed. It must not be used for performing
maintenance work under the vehicle.
RAvoid changing the wheel on uphill and down-
hill slopes.
RBefore raising the vehicle, secure it from roll-
ing away by applying the parking brake and
inserting wheel chocks. Do not disengage the
parking brake while the vehicle is raised.
RThe jack must be placed on a firm, flat and
non-slip surface. On a loose surface, a large,
flat, load-bearing underlay must be used. On a
slippery surface, a non-slip underlay must be
used, e.g. rubber mats.
RDo not use wooden blocks or similar objects
as a jack underlay. Otherwise, the jack will not
be able to achieve its load-bearing capacity
due to the restricted height.
RMake sure that the distance between the
underside of the tires and the ground does not
exceed 1.2 in (3 cm).
RDo not place your hands or feet under the
raised vehicle.
RDo not lie under the vehicle.
RDo not start the engine when the vehicle is
raised.
RDo not open or close a door when the vehicle is raised.
RMake sure that no persons are present in the
vehicle when the vehicle is raised.
XUsing lug wrench :, loosen the bolts on the
wheel you wish to change by about one full
turn. Do not unscrew the bolts completely.
XAssemble the pump lever for the jack from the vehicle tool kit.
XTurn lowering screw =on the jack clockwise
as far as it will go using notch ;on the pump
lever.
Pressure release screw =is closed.
iDo not turn pressure release screw =by
more than one to two revolutions. Otherwise,
hydraulic fluid could escape.
XPosition jack Avertically under the jacking
point of axle carrier tube ?.
Changing a wheel277
Wheels and tires
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