2019 MERCEDES-BENZ AMG GT ROADSTER wheel size

R
Local regulations may restrict the use of snow
chains. Observe the appropriate regulations if you wish to mount snow chains.
R do not exceed the maximum permissible
speed of 31 mph (50 km/h).
You may wish to deactivate ESP ®
(Y page 63)
when pulling away with snow chains mounted.
You can thereby allow the wheels to spin in a
controlled manner, achieving an increased driv-
ing force (cutting action). Tire pressure
Tire pressure specifications
Important safety notes G
WARNING
Underinflated or overinflated tires pose the
following risks:
R the tires may burst, especially as the load
and vehicle speed increase.
R the tires may wear excessively and/or
unevenly, which may greatly impair tire
traction.
R the driving characteristics, as well as steer-
ing and braking, may be greatly impaired.
There is a risk of an accident.
Follow recommended tire inflation pressures
and check the pressure of all the tires includ-
ing the spare wheel:
R monthly, at least
R if the load changes
R before beginning a long journey
R under different operating conditions, e.g.
off-road driving
If necessary, correct the tire pressure.
The data on the Tire and Loading Information
placard and tire pressure table shown here are
examples. Tire pressure specifications are vehi- cle-specific and may deviate from the data
shown here. The tire pressure specifications
that are valid for your vehicle can be found on
the Tire and Loading Information placard and
tire pressure table on the vehicle. General notes The recommended tire pressures for the tires
mounted at the factory can be found on the
labels described here.
Further information on tire pressures can be
obtained at a qualified specialist workshop.
Tire and Loading Information placard 0043
Recommended tire pressures
The Tire and Loading Information placard is on
the B-pillar on the driver's side (Y page 271).
The Tire and Loading Information placard con-
tains the recommended tire pressures for cold
tires. The recommended tire pressures are valid for the maximum permissible load and up to the
maximum permissible vehicle speed.
Tire pressure table The tire pressure table is on the inside of the fuel
filler flap. It shows the tire pressure for all tires
permitted at the factory for this vehicle; see
illustration (example).
If a tire size precedes a tire pressure, the tire
pressure information following is only valid for
that tire size. 266
Tire pressureWheels and tires

X
If the tire pressure is too low, increase the tire
pressure to the recommended value.
X If the tire pressure is too high, release air. To
do so, press down the metal pin in the valve,
using the tip of a pen for example. Then check the tire pressure again using the tire pressure
checker.
X Screw the valve cap onto the valve.
X Repeat these steps for the other tires. Tire pressure monitor
General notes If a tire pressure monitor is installed, the vehi-
cle's wheels have sensors that monitor the tire
pressures in all four tires. The tire pressure mon-
itor warns you if the pressure drops in one or
more of the tires. The tire pressure monitor only functions if the corresponding sensors are
installed in all wheels.
Information on tire pressures is displayed in the
multifunction display. After a few minutes of
driving, the current tire pressure of each tire is
shown in the Service
Service menu of the multifunction
display; see illustration (example). For information on the message display, refer to
the "Checking the tire pressure electronically"
section (Y page 270).
Important safety notes G
WARNING
Each tire, including the spare (if provided),
should be checked at least once every two
weeks when cold and inflated to the pressure recommended by the vehicle manufacturer
on the Tire and Loading Information placard on the driver's door B-pillar or the tire pres-
sure 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, if available, the tire
pressure label, you should determine the
proper tire pressure for those tires.
As an added safety feature, your vehicle has
been equipped with a tire pressure monitoring system (TPMS) that illuminates a low tire pres-
sure telltale when one or more of your tires
are significantly underinflated. Accordingly,
when the low tire pressure telltale lights up,
you should stop and check your tires as soon
as possible, and inflate them to the proper
pressure. Driving on a significantly underin-
flated 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 vehicle's handling and stopping ability. Please note that
the TPMS is not a substitute for proper tire
maintenance, and it is the driver's responsi-
bility to maintain correct tire pressure, even if underinflation has not reached the level to
trigger illumination of the TPMS low tire pres-
sure telltale.
Your vehicle has also been equipped with a
TPMS malfunction indicator to indicate when
the system is not operating properly. The
TPMS malfunction indicator is combined with
the low tire pressure telltale. When the sys-
tem detects a malfunction, the warning lamp
will flash for approximately a minute and then remain continuously illuminated. This
sequence will be repeated every time the vehi-
cle is started as long as the malfunction
exists. When the malfunction indicator is illu- minated, the system may not be able to detect
or signal low tire pressure as intended.
TPMS malfunctions may occur for a variety of reasons, including the installation of incom-
patible replacement or alternate tires or
wheels on the vehicle that prevent the TPMS
from functioning properly. Always check the
TPMS malfunction telltale after replacing one
or more tires or wheels on your vehicle to Tire pressure
269Wheels and tires
Z

sizes and corresponding pressures for tires
mounted at the factory.
(2) The vehicle identification plate is on the B- pillar on the driver's side. The vehicle iden-
tification plate informs you of the gross
vehicle weight rating. It is made up of the
vehicle weight, all vehicle occupants, the
fuel and the cargo. You can also find infor-
mation about the maximum gross axle
weight rating on the front and rear axle.
The maximum gross axle weight rating is
the maximum weight that can be carried by one axle (front or rear axle). Do not exceed
the maximum gross vehicle weight or the
maximum gross axle weight rating for the
front or rear axle. 0043
B-pillar, driver's side Maximum permissible mass.
X
Maximum permissible gross vehicle
weight 0043is listed on the Tire and Loading
Information placard: "The combined weight of occupants and cargo should never exceed
XXX kilograms or XXX lbs."
The gross weight of all vehicle occupants, load
and luggage must not exceed the specified
value. i
The specifications shown on the Tire and
Loading Information placard in the illustration
are examples. The maximum permissible load is vehicle-specific and may deviate from the
data shown here. The maximum permissible
load that applies for your vehicle can be foundon your vehicle's Tire and Loading Informa-
tion placard. Number of seats
Maximum number of seats
0043indicates the
maximum number of occupants allowed to
travel in the vehicle. This information can be
found on the Tire and Loading Information plac-
ard.
i The specifications shown on the Tire and
Loading Information placard in the illustration
are examples. The number of seats is vehicle- specific and can differ from the details shown.
The number of seats in your vehicle can be
found on the Tire and Loading Information
placard. Determining the correct load limit
Step-by-step instructions The following steps have been developed as
required of all manufacturers under Title 49,
Code of U.S. Federal Regulations, Part 575 pur-
suant to the "National Traffic and Motor Vehicle
Safety Act of 1966".
X Step 1: Locate the statement "The combined
weight of occupants and cargo should never 272
Loading the vehicleWheels and tires

Tire labeling
Overview 0043
Uniform Tire Quality Grading Standard
(Y page 279)
0044 DOT, Tire Identification Number
(Ypage 278)
0087 Maximum tire load (Y page 278)
0085 Maximum tire pressure (Y page 268)
0083 Manufacturer
0084 Tire material (Y page 279)
006B Tire size designation, load-bearing capacity
and speed rating (Y page 276)
006C Load index (Y page 278)
006D Tire name
The markings described above are on the tire in
addition to the tire name (sales designation) and the manufacturer's name.
i Tire data is vehicle-specific and may deviate
from the data in the example.
Tire size designation, load-bearing
capacity and speed rating G
WARNING
Exceeding the stated tire load-bearing capa-
city and the approved maximum speed could
lead to tire damage or the tire bursting. There is a risk of accident.
Therefore, only use tire types and sizes
approved for your vehicle model. Observe the tire load rating and speed rating required for
your vehicle. 0043
Tire width
0044 Nominal aspect ratio in %
0087 Tire code
0085 Rim diameter
0083 Load bearing index
0084 Speed rating
General: depending on the manufacturer's
standards, the size imprinted in the tire wall may not contain any letters or may contain one letterthat precedes the size description.
If there is no letter preceding the size descrip-
tion (as shown above): these are passenger
vehicle tires according to European manufac-
turing standards.
If "P" precedes the size description: these are
passenger vehicle tires according to U.S. man-
ufacturing standards.
If "LT" precedes the size description: these are
light truck tires according to U.S. manufacturing standards.
If "T" precedes the size description: compact
emergency wheels with high tire pressure that
are only designed for temporary use in an emer-
gency.
Tire width: tire width0043shows the nominal tire
width in millimeters.
Height-width ratio: aspect ratio0044is the size
ratio between the tire height and tire width and is shown in percent. The aspect ratio is calcula-ted by dividing the tire width by the tire height.
Tire code: tire code0087specifies the tire type.
"R" represents radial tires; "D" represents diag-
onal tires; "B" represents diagonal radial tires.
Optionally, tires with a maximum design speed
of over 149 mph (240 km/h) may have "ZR" in 276
All about
wheels and tiresWheels and tires

the size description, depending on the manu-
facturer (e.g. 245/40 ZR 18).
Rim diameter: rim diameter0085is the diameter
of the bead seat, not the diameter of the rim
flange. The rim diameter is specified in
inches (in).
Load-bearing index: load-bearing index0083is a
numerical code that specifies the maximum
load-bearing capacity of a tire.
Do not overload the tires by exceeding the
specified load limit. The maximum permissible
load can be found on the vehicle's Tire and
Loading Information placard on the B-pillar on
the driver's side (Y page 271).
Example:
Load-bearing index 91 indicates a maximum
load of 1,356 lb (615 kg) that the tires can bear.
For further information on the maximum tire
load in kilograms and lbs, see (Y page 278).
For further information on the load bearing
index, see "Load index" (Y page 278).
Speed rating: speed rating0084specifies the
approved maximum speed of the tire.
i Tire data is vehicle-specific and may deviate
from the data in the example.
Regardless of the speed rating, always observe
the speed limits. Drive carefully and adapt your
driving style to the traffic conditions.
Summer tires Index Speed rating
Q up to 100 mph (160 km/h)
R up to 106 mph (170 km/h)
S up to 112 mph (180 km/h)
T up to 118 mph (190 km/h)
H up to 130 mph (210 km/h)
V up to 149 mph (240 km/h)
W up to 168 mph (270 km/h)
Y up to 186 mph (300 km/h)
ZR...Y up to 186 mph (300 km/h)
ZR...(..Y) over 186 mph (300 km/h)
ZR over 149 mph (240 km/h) R
Optionally, tires with a maximum design
speed of over 149 mph (240 km/h) may have "ZR" in the size description, depending on the
manufacturer (e.g. 245/40 ZR18).
The service specification is made up of load-
bearing index 0083and speed rating 0084.
R If the size description of your tire includes
"ZR" and there are no service specifications,
ask the tire manufacturer in order to find out
the maximum design speed.
If a service specification is available, the max-
imum speed is limited according to the speed rating in the service specification. Example:
245/40 ZR18 97 Y.In this example, "97 Y" is
the service specification. The letter "Y" rep-
resents the speed rating. The maximum
design speed of the tire is limited to 186 mph (300 km/h).
R The size description for all tires with maxi-
mum design speeds of over 186 mph
(300 km/h) must include "ZR", andthe ser-
vice specification must be given in brackets.
Example: 275/40 ZR 18 (99 Y). Speed rating
"(Y)" indicates that the maximum design
speed of the tire is over 186 mph (300 km/h). To find out the maximum design speed, ask
the tire manufacturer.
All-weather tires and winter tires Index Speed rating
Q M+S
1 up to 100 mph (160 km/h)
T M+S
1 up to 118 mph (190 km/h)
H M+S
1 up to 130 mph (210 km/h)
V M+S
1 up to 149 mph (240 km/h)
i
Not all tires with the M+S marking provide
the driving characteristics of winter tires. In
addition to the M+S marking, winter tires also
have the 004Dsnowflake symbol on the tire
wall. Tires with this marking fulfill the require- ments of the Rubber Manufacturers Associa-
tion (RMA) and the Rubber Association of
Canada (RAC) regarding the tire traction on
snow. They have been especially developed
for driving on snow.
An electronic speed limiter prevents your vehi-
cle from exceeding a speed of 130 mph
(210 km/h).
1 Or M+S 004Dfor winter tires. All about wheels and tires
277Wheels and tires Z

The speed rating of tires mounted at the factory
may be higher than the maximum design speed permitted by the electronic speed limiter.
Make sure that your tires have the required
speed rating, e.g. when buying new tires. The
required speed rating for your vehicle can be
found in the "Tires" section (Y page 285).
Further information about reading tire data can
be obtained from any qualified specialist work-
shop.
Load index In addition to the load-bearing index, load
index
0043may also be imprinted on the sidewall
of the tire. You will find this after the letter that identifies the speed rating (Y page 276).
R If no specification is given: no text (as in the
example above), represents a standard load
(SL) tire
R XL or Extra Load: represents a reinforced tire
R Light Load: represents a light load tire
R C, D, E: represents a load range that depends
on the maximum load that the tire can carry at a certain pressure
i Tire data is vehicle-specific and may deviate
from the data in the example. Maximum load rating Maximum tire load
0043is the maximum permis-
sible weight for which the tire is approved.
Do not overload the tires by exceeding the
specified load limit. The maximum permissible
load can be found on the vehicle's Tire and
Loading Information placard on the B-pillar on
the driver's side (Y page 271).
i The actual values for tires are vehicle-spe-
cific and may deviate from the values in the
illustration.
DOT, Tire Identification Number (TIN) US tire regulations stipulate that every tire man-
ufacturer or retreader must imprint a TIN in or on the sidewall of each tire produced. The TIN is a unique identification number. The
TIN enables the tire manufacturers or retreaders to inform purchasers of recalls and other safety-
relevant matters. It makes it possible for the
purchaser to easily identify the affected tires.
The TIN is made up of manufacturer identifica-
tion code 0044, tire size 0087, tire type code 0085and
manufacturing date 0083.
DOT (Department of Transportation): tire
symbol 0043marks that the tire complies with the 278
All about wheels and tiresWheels and tires

requirements of the U.S. Department of Trans-
portation.
Manufacturer identification code: manufac-
turer identification code 0044provides details on
the tire manufacturer. New tires have a code
with two symbols. Retreaded tires have a code
with four symbols.
For further information about retreaded tires,
see (Y page 285).
Tire size: identifier0087describes the tire size.
Tire type code: tire type code0085can be used by
the manufacturer as a code to describe specific
characteristics of the tire.
Date of manufacture: date of manufacture0083
provides information about the age of a tire. The
first and second positions represent the week of manufacture, starting with "01" for the first cal-
endar week. Positions three and four represent
the year of manufacture. For example, a tire that
is marked "3214" was manufactured in week 32 in 2014.
i Tire data is vehicle-specific and may deviate
from the data in the example.
Tire characteristics This information describes the type of tire cord
and the number of layers in sidewall 0043and
under tire tread 0044.
i Tire data is vehicle-specific and may deviate
from the data in the example.
Definition of terms for tires and loading Tire ply composition and material used
Describes the number of plies or the number of
layers of rubber-coated fabric in the tire tread
and sidewall. These are made of steel, nylon,
polyester and other materials. Bar
Metric unit for tire pressure. 14.5038 pounds
per square inch (psi) and 100 kilopascals (kPa)
are the equivalent of 1 bar.
DOT (Department of Transportation)
DOT-marked tires fulfill the requirements of the U S Department of Transportation.
Normal occupant weight
The number of occupants for which the vehicle
is designed multiplied by 68 kilograms (150 lbs).
Uniform Tire Quality Grading Standards
A uniform standard to grade the quality of tires
with regards to tread quality, tire traction and
temperature characteristics. The quality grad-
ing assessment is made by the manufacturer
following specifications from the U.S. govern-
ment. The ratings are molded into the sidewall of the tire.
Recommended tire pressures The recommended tire pressure applies to the
tires mounted at the factory.
The Tire and Loading Information placard con-
tains the recommended tire pressures for cold
tires on a fully loaded vehicle and for the maxi-
mum permissible vehicle speed.
The tire pressure table contains the recommen-
ded pressures for cold tires for various operat-
ing conditions, i.e. differing load and speed con-
ditions.
Increased vehicle weight due to optional
equipment The combined weight of all standard and
optional equipment available for the vehicle,
regardless of whether it is actually installed on
the vehicle or not.
Rim
This is the part of the wheel on which the tire is
mounted.
GAWR (Gross Axle Weight Rating)The GAWR is the maximum gross axle weight
rating. The actual load on an axle must never
exceed the gross axle weight rating. The gross
axle weight rating can be found on the vehicle
identification plate on the B-pillar on the driver's
side. All about wheels and tires
279Wheels and tires Z

Weight of optional extras
The combined weight of those optional extras
that weigh more than the replaced standard
parts and more than 5 lbs (2.3 kg). These
optional extras, such as high-performance
brakes, level control, a roof rack or a high-volt-
age 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.
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 00CDin (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
The "Breakdown assistance" section
(Y page 250) contains information and notes on
how to deal with a flat tire. Rotating the wheels
G
WARNING
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.
! On vehicles equipped with a tire pressure
monitor, electronic components are located
in the wheel.
Tire-mounting tools should not be used near
the valve. This could damage the electronic
components.
Only have tires changed at a qualified spe-
cialist workshop.
Always observe the instructions and safety
notes in the "Mounting a wheel" section
(Y page 282).
The wear patterns on the front and rear tires
differ, depending on the operating conditions.
Rotate the wheels before a clear wear pattern
has formed on the tires. Front tires typically
wear more on the shoulders and the rear tires in
the center.
On vehicles that have the same size front and
rear wheels, you can rotate the wheels accord-
ing to the intervals in the tire manufacturer's
warranty book in your vehicle documents. If no
warranty book is available, the tires should be
rotated every 3,000 to 6,000 miles (5,000 to
10,000 km). Depending on tire wear, this may
be required earlier. Do not change the direction
of wheel rotation.
Clean the contact surfaces of the wheel and the
brake disc thoroughly every time a wheel is rota- ted. Check the tire pressure and reactivate the
tire pressure monitor if necessary. Direction of rotation
Tires with a specified direction of rotation have
additional benefits, e.g. if there is a risk of hydro- planing. These advantages can only be gained if
the tires are installed corresponding to the
direction of rotation. Changing a wheel
281Wheels and tires Z