
Tire size designation, load and speed
rating:Tire width;Aspect ratio in %=Radial tire code?Rim diameterALoad index BSpeed symbol
iFor illustration purposes only. Actual data
on tires are specific to each vehicle and
may vary from data shown in above
illustration.
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
Tire width : indicates the nominal tire width
in millimeters.
Aspect ratio
Aspect ratio ; 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
Tire code = 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” (Y page 237).
Rim diameter
Rim diameter ? is the diameter of the bead
seat, not the diameter of the rim edge. The
rim diameter is indicated in inches (in).
Load index
GWarning!
The tire load rating must always be at least
half of the GAWR of your vehicle. Otherwise,
tire failure may be the result which may cause
an accident and/or serious injury to you or
others.
Always replace rims and tires with the same
designation, manufacturer and type as shown
on the original part.
GWarning!
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.
Load index A is a numerical code associated
with the maximum load a tire can support.
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For example, a load rating of 91 corresponds
to a maximum load of 1356 lb (615 kg) the
tire is designed to support. See also
“Maximum tire load” (Y page 231) where the
maximum load associated with the load index
is indicated in kilograms and lbs.
For additional information on the load index,
see “Load identification” ( Y page 238).
Speed symbol GWarning!
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 serious
personal injury and possible death, for you
and for others.
Regardless of the tire speed rating, local
speed limits should be obeyed. Use prudent
driving speeds appropriate to prevailing
conditions.
Speed symbol B indicates the approved
maximum speed (tire speed rating) for the
tire.
Summer tires
IndexSpeed ratingQup 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)ZR...Yup to 186 mph (300 km/h)IndexSpeed ratingZR...(..Y)above 186 mph (300 km/h)ZRabove 149 mph (240 km/h)
R 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 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
load index A and speed symbol B.
If your tire includes “ZR” in the size
designation and no service description is
given, the tire manufacturer must be
consulted for the maximum speed
capability.
If a service description 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).
R 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 ZR 18 (99Y). The “(Y)”
speed symbol 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
IndexSpeed ratingQ M+S 20up to 100 mph (160 km/h)T M+S20up to 118 mph (190 km/h)20
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IndexSpeed ratingH M+S20up to 130 mph (210 km/h)V M+S20up 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/
snowflakeimarking 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.
An electronic speed limiter prevents your
vehicle from exceeding a speed of:
RAll models except ML 63 AMG:
130 mph (210 km/h)
RML 63 AMG:
155 mph (250 km/h)
RML 63 AMG with increased top speed:
171 mph (275 km/h)
The factory equipped tires on your vehicle
may have a tire speed rating above the
maximum speed permitted by the electronic
speed limiter.
Make sure your tires have the required tire
speed rating as specified for your vehicle in
the “Technical data” section (Y page 352),
for example when purchasing new tires.
If you are uncertain about the correct reading
of the information given on a tire’s sidewall,
any authorized Mercedes-Benz Center will be
glad to assist you.
Load identification
iFor illustration purposes only. Actual data
on tires are specific to each vehicle and
may vary from data shown in above
illustration.
In addition to the load index, special load
identification : may be molded into the tire
sidewall following the letter designating the
speed symbol B (Y page 236).
RNo specification given: absence of any text
(like in above example) indicates a
standard load (SL) tire.
RXL or Extra Load: designates an extra load
(or reinforced) tire.
RLight Load: designates a light load tire.
RC, 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.
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