2018 MERCEDES-BENZ AMG GT ROADSTER ECU

Underinflated or overinflated tires
Underinflated tires
GWARNING
Tires with pressure that is too low can over-
heat and burst as a consequence. In addition, they also suffer from excessive and/or irreg-
ular wear, which can severely impair the brak-
ing properties and the driving characteristics.
There is a risk of an accident.
Avoid tire pressures that are too low in all the
tires, including the spare wheel.
Underinflated tires may:
Roverheat, leading to tire defects
Radversely affect handling
Rwear excessively and/or unevenly
Rhave an adverse effect on fuel consumption
Overinflated tires
GWARNING
Tires with excessively high pressure can burst
because they are damaged more easily by
road debris, potholes etc. In addition, they
also suffer from irregular wear, which can
severely impair the braking properties and the driving characteristics. There is a risk of an
accident.
Avoid tire pressures that are too high in all the
tires, including the spare wheel.
Overinflated tires may:
Rincrease the braking distance
Radversely affect handling
Rwear excessively and/or unevenly
Rhave an adverse effect on ride comfort
Rbe more susceptible to damage
Maximum tire pressures
:Example: maximum permissible tire pres-
sure
Never exceed the maximum permissible tire
inflation pressure. Always observe the recom-
mended tire pressure for your vehicle when
adjusting the tire pressure (
Ypage 264).
iThe actual values for tires are vehicle-spe-
cific and may deviate from the values in the
illustration.
Checking the tire pressures
Important safety notes
Observe the notes on tire pressure
(Ypage 264).
Information on air pressure for the tires on your
vehicle can be found:
Ron the vehicle's Tire and Loading Information
placard on the B-pillar
Rin the tire pressure table in the fuel filler flap
(Ypage 126)
Rin the "Tire pressure" section
Checking tire pressures manually
To determine and set the correct tire pressure,
proceed as follows:
XRemove the valve cap of the tire that is to be
checked.
XPress the tire pressure gage securely onto the
valve.
XRead the tire pressure and compare it to the
recommended value on the Tire and Loading
Information placard or the tire pressure table
(
Ypage 264).
266Tire pressure
Wheels and tires

The tire pressure must be corrected when the
opportunity arises.
RIf theCheck Tiresmessage appears in the
multifunction display, the tire pressure in at
least one tire has dropped significantly. The
tires must be checked.
RIf the WarningTireMalfunctionmessage
appears in the multifunction display, the tire
pressure in at least one tire has dropped sud-
denly. The tires must be checked.
Observe the instructions and safety notes in the
display messages in the "Tires" section
(
Ypage 191).
If the wheel positions on the vehicle are rotated,
the tire pressures may be displayed for the
wrong positions for a short time. This is rectified after a few minutes of driving, and the tire pres-
sures are displayed for the correct positions.
Restarting the tire pressure monitor
When you restart the tire pressure monitor, all
existing warning messages are deleted and the
warning lamps go out. The monitor uses the cur-
rently set tire pressures as the reference valuesfor monitoring. In most cases, the tire pressure
monitor will automatically detect the new refer-
ence values after you have changed the tire
pressure. However, you can also set reference
values manually as described here. The tire
pressure monitor then monitors the new tire
pressure values.
XSet the tire pressure to the value recommen-
ded for the corresponding driving situation on
the Tire and Loading Information placard on
the driver's side B-pillar (
Ypage 264).
You can find more tire pressure values for
various operating conditions in the tire pres-
sure table inside the fuel filler flap
(
Ypage 264).
XMake sure that the tire pressure is correct on
all four wheels.
XSwitch on the ignition (Ypage 111).
XPress òon the steering wheel to call up
the list of menus.
XPress 9or: on the steering wheel to
select the Servicemenu.
XPressa.
XPress9or: to select Tire Pres‐sure.
XPressa.
The current tire pressure for each wheel or
the Tire pressure will be displayed
after driving a few minutesmessage
will be displayed in the multifunction display.
XPress :.
The UseCurrentPressuresasNewRef‐erenceValuesmessage appears in the mul-
tifunction display.
If you wish to confirm the restart:
XPress a.
The TirePress.MonitorRestartedmes-
sage appears on the multifunction display.
After driving for a few minutes, the system
checks whether the current tire pressures are
within the specified range. The new tire pres-
sures are then accepted as reference values
and monitored.
If you wish to cancel the restart:
XPress %.
The tire pressure values stored at the last
restart will continue to be monitored.
Loading the vehicle
Instruction labels for tires and loads
GWARNING
Overloaded tires can overheat, causing a
blowout. Overloaded tires can also impair the steering and driving characteristics and lead
to brake failure. There is a risk of accident.
Observe the load rating of the tires. The load
rating must be at least half of the GAWR of
your vehicle. Never overload the tires by
exceeding the maximum load.
Two instruction labels on your vehicle show the maximum possible load.
(1) The Tire and Loading Information placard is on the B-pillar on the driver's side. The Tire
and Loading Information placard shows the
permissible number of vehicle occupants
and the maximum permissible load of the
vehicle. It also contains details of the tire
Loading the vehicle269
Wheels and tires
Z

Speed rating
The speed rating is part of the tire identification.It specifies the speed range for which the tire is
approved.
GVW (Gross Vehicle Weight)
The gross vehicle weight includes the weight of the vehicle with fuel, tools, the spare wheel,
accessories installed, vehicle occupants, lug-
gage and the drawbar noseweight if applicable.
The gross vehicle weight must not exceed the
gross vehicle weight rating GVWR as specified
on the vehicle identification plate on the B-pillar
on the driver's side.
GVWR (Gross Vehicle Weight Rating)
The GVWR is the maximum permitted gross
weight of the fully laden vehicle (weight of the
vehicle including all accessories, vehicle occu-
pants, fuel, luggage and the drawbar nose-
weight if applicable). The gross vehicle weight
rating is specified on the vehicle identification
plate on the B-pillar on the driver's side.
Maximum loaded vehicle weight
The maximum weight is the sum of:
Rthe curb weight of the vehicle
Rthe weight of the accessories
Rthe load limit
Rthe weight of the factory installed optional
equipment
Kilopascal (kPa)
Metric unit for tire pressure. 6.9 kPa corre-
sponds to 1 psi. Another unit for tire pressure is
bar. 100 kilopascals (kPa) are the equivalent of
1 bar.
Load index
In addition to the load-bearing index, the load
index may also be imprinted on the sidewall of
the tire. This specifies the load-bearing capacity
of the tire more precisely.
Curb weight
The weight of a vehicle with standard equipment
including the maximum capacity of fuel, oil and
coolant. It also includes the air-conditioning sys-
tem and optional equipment if these are instal-
led in the vehicle, but does not include passen-
gers or luggage.
Maximum load rating
The maximum tire load is the maximum permis-
sible weight in kilograms or lbs for which a tire is
approved.
Maximum permissible tire pressure
Maximum permissible tire pressure for one tire.
Maximum load on one tire
Maximum load on one tire. This is calculated by
dividing the maximum axle load of one axle by
two.
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 kilopascal (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 from
the wheel rim.
Sidewall
The part of the tire between the tread and the
bead.
278All about wheels and tires
Wheels and tires

An arrow on the sidewall of the tire indicates its
correct direction of rotation.
Storing wheels
Store wheels that are not being used in a cool,
dry and preferably dark place. Protect the tires
from oil, grease, gasoline and diesel.
Mounting a wheel
Preparing the vehicle
XStop the vehicle on solid, non-slippery and
level ground.
XApply the electric parking brake manually.
XBring the front wheels into the straight-ahead position.
XShift the transmission to position j.
XSwitch off the engine.
XWith KEYLESS-GO start function or vehi-
cles with KEYLESS-GO:open the driver's
door.
The vehicle electronics are now in key posi-
tion u. This is the same as the SmartKey
having been removed.
or
XRemove the SmartKey from the ignition lock.
XIf included in the vehicle equipment, remove
the tire-change tool kit from the vehicle.
XSafeguard the vehicle against rolling away.
Securing the vehicle to prevent it from
rolling away
If your vehicle is equipped with a wheel chock, it
can be found in the tire-change tool kit
(
Ypage 248). The folding wheel chock is an additional safety
measure to prevent the vehicle from rolling
away, for example when changing a wheel.
XFold both plates up
:.
XFold out lower plate ;.
XGuide the lugs on the lower plate fully into the
openings in base plate =.
XPlace chocks or other suitable items under
the front and rear of the wheel that is diago-
nally opposite the wheel you wish to change.
Raising the vehicle
GWARNING
If you do not position the jack correctly at the
appropriate jacking point of the vehicle, the
jack could tip over with the vehicle raised.
There is a risk of injury.
Only position the jack at the appropriate jack-
ing point of the vehicle. The base of the jack
must be positioned vertically, directly under
the jacking point of the vehicle.
!Only position the jack at the appropriate
jacking point of the vehicle. Otherwise, you
could damage the vehicle.
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.
280Changing a wheel
Wheels and tires

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 or the trunk lid
when the vehicle is raised.
RMake sure that no persons are present in the
vehicle when the vehicle is raised.
Vehicles with hub caps: the hub cap covers
the wheel bolts. Before you can unscrew the
wheel bolts, you must remove the hub cap.
XTo remove: take socket;and lug wrench
= from the vehicle tool kit (Ypage 248).
XPosition socket ;on hub cap :.
XPosition lug wrench =on socket ;.
XUsing lug wrench =, turn hub cap:coun-
ter-clockwise and remove it.
XTo install: before installing, check hub cap :
and the wheel area for soiling and clean if
necessary.
XPut hub cap :in position and turn until it is in
the right position.
XPosition socket ;on hub cap :.
XAttach lug wrench =to socket ;and
tighten hub cap :.
The tightening torque must be
18 lb-ft (25 Nm).
iNote that the hub cap should be tightened
to the specified torque of 18 lb-ft (25 Nm).
Mercedes-Benz recommends that you have
the hub cap installed at a qualified specialist
workshop.
XUsing lug wrench =, loosen the bolts on the
wheel you wish to change by about one full
turn. Do not unscrew the bolts completely.
The jacking point is centered between the front
and rear wheel arches (arrow).
Changing a wheel281
Wheels and tires
Z

XPosition jackAat jacking point ?.
XMake sure that the base of the jack is posi-
tioned directly under jacking point ?.
XTurn crankBclockwise until jack Asits
completely on jacking point ?and the base
of the jack lies evenly on the ground.
XTurn crank Buntil the tire is raised a maxi-
mum of 1.2 in (3 cm) off the ground.
Removing a wheel
!AMG ceramic high performance composite
brake system:
When detaching or attaching the wheel, the
wheel rim may hit against the ceramic brake
disc and damage it.
Proceed with caution and seek the assistance
of a second person.
!Do not place wheel bolts in sand or on a dirty
surface. The bolt and wheel hub threads could
otherwise be damaged when you screw them in.
When mounting/removing wheels, and for as
long as the wheels are removed, avoid applying
any external force on the brake disks. This could
impair the level of comfort when braking.
XUnscrew the uppermost wheel bolt com-
pletely.
XScrew alignment bolt :into the thread
instead of the wheel bolt.
XUnscrew the remaining wheel bolts fully.
XRemove the wheel.
Mounting a new wheel
GWARNING
Oiled or greased wheel bolts or damaged
wheel bolts/hub threads can cause the wheel bolts to come loose. As a result, you could
lose a wheel while driving. There is a risk of
accident.
Never oil or grease wheel bolts. In the event of
damage to the threads, contact a qualified
specialist workshop immediately. Have the
damaged wheel bolts or hub threads
replaced/renewed. Do not continue driving.
GWARNING
If you tighten the wheel bolts or wheel nuts
when the vehicle is raised, the jack could tip
over. There is a risk of injury.
Only tighten the wheel bolts or wheel nuts
when the vehicle is on the ground.
Always pay attention to the instructions and
safety notes in the "Changing a wheel" section
(
Ypage 279).
Only use wheel bolts that have been designed
for the wheel and the vehicle. For safety rea-
sons, Mercedes-Benz recommends that you
only use wheel bolts which have been approved for Mercedes-Benz vehicles and the respective
wheel.
!AMG ceramic high performance composite
brake system:
When detaching or attaching the wheel, the
wheel rim may hit against the ceramic brake
disc and damage it.
Proceed with caution and seek the assistance
of a second person.
!To prevent damage to the paintwork, hold
the wheel securely against the wheel hub
while screwing in the first wheel bolt.
282Changing a wheel
Wheels and tires