ecu MERCEDES-BENZ SLK-Class 2015 R172 Repair Manual

when adjusting the tire pressure
(Y
page 314).
i The actual values for tires are vehicle-
specific and may deviate from the values in
the illustration. Checking the tire pressures
Important safety notes Observe the notes on tire pressure
(Y
page 314).
Information on air pressure for the tires on
your vehicle can be found:
R on the vehicle's Tire and Loading Informa-
tion placard on the B-pillar
R on the tire pressure label on the fuel filler
flap
R in the "Tire pressure" section
Checking tire pressures manually To determine and set the correct tire pres-
sure, proceed as follows:
X Remove the valve cap of the tire that is to
be checked.
X Press the tire pressure gauge securely onto
the valve.
X Read the tire pressure and compare it with
the recommended value on the Tire and
Loading Information placard (Y page 314).
X If the tire pressure is too low, increase it to
the recommended value.
X If the tire pressure is too high, release air by
pressing down the metal pin in the valve.
Use the tip of a pen, for example. Then,
check the tire pressure again using the tire
pressure gauge.
X Screw the valve cap onto the valve.
X Repeat these steps for the other tires. Tire pressure loss warning system
(Canada only)
General notes While the vehicle is in motion, the tire pres-
sure loss warning system monitors the set
tire pressure using the rotational speed of the wheels. This enables the system to detect
significant pressure loss in a tire. If the speed
of rotation of a wheel changes as a result of a loss of pressure, a corresponding warning
message will appear in the multifunction dis- play.
You can recognize the tire pressure loss warn-
ing by the Run Flat Indicator Active Run Flat Indicator Active
Press 'OK' to Restart
Press 'OK' to Restart message which
appears in the Service
Servicemenu of the multi-
function display. Information on the message
display can be found in the "Restarting the tire
pressure loss warning system" section
(Y page 318).
Important safety notes The tire pressure warning system does not
warn you of an incorrectly set tire pressure.
Observe the notes on the recommended tire
pressure (Y page 314).
The tire pressure loss warning does not
replace the need to regularly check the tire
pressure. An even loss of pressure on several tires at the same time cannot be detected by
the tire pressure loss warning system.
The tire pressure monitor is not able to warn
you of a sudden loss of pressure, e.g. if the
tire is penetrated by a foreign object. In the
event of a sudden loss of pressure, bring the
vehicle to a halt by braking carefully. Avoid
abrupt steering maneuvers.
The function of the tire pressure loss warning system is limited or delayed if:
R snow chains are mounted on your vehicle's
tires.
R road conditions are wintry.
R you are driving on sand or gravel. Tire pressure
317Wheels and tires Z

Load index
In addition to the load-bearing index, the load
index may also be imprinted on the sidewall ofthe tire. This specifies the load-bearing capa-
city more precisely.
Curb weight
The weight of a vehicle with standard equip-
ment including the maximum capacity of fuel, oil and coolant. It also includes the air-condi- tioning system and optional equipment if
these are installed in the vehicle, but does not
include passengers or luggage.
Maximum load rating
The maximum tire load is the maximum per-
missible 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
outward force to each square inch of the tire's
surface. 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:
R if the vehicle has been parked without
direct sunlight on the tires for at least three
hours and
R if the vehicle has been driven for less than
1 mile (1.6 km).
Tread
The part of the tire th at 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.
Weight of optional extras
The combined weight of those optional extras that weigh more than the replaced standard
parts and more than 2.3 kilograms (5 lbs).
These optional extras, such as high-perform-
ance brakes, level control, a roof rack or a
high-performance battery, are not included in
the curb weight and the weight of the acces-
sories.
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 purchasers. The TIN is made up of the
manufacturer'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 capacity of a tire. All about wheels and tires
331Wheels and tires Z

Cleaning the wheels
G
WARNING
The water jet from a circular jet nozzle (dirt
blasters) can cause invisible exterior damage to the tires or chassis components. Compo-
nents damaged in this way may fail unexpect-edly. There is a risk of an accident.
Do not use power washers with circular jet
nozzles to clean the vehicle. Have damaged
tires or chassis components replaced imme-
diately. Mounting a wheel
Preparing the vehicle X
Stop the vehicle on solid, non-slippery and
level ground.
X Apply the electric parking brake manually.
X Bring the front wheels into the straight-
ahead position.
X Vehicles with manual transmission:
fully depress the clutch pedal and engage
first or reverse gear.
X Vehicles with automatic transmission:
move the selector lever to P.
X Switch off the engine.
X Vehicles without KEYLESS-GO: remove
the SmartKey from the ignition lock.
X Vehicles with KEYLESS-GO: open the
driver's door.
The on-board electronics now have status
0. This is the same as the SmartKey having
been removed.
X Vehicles with KEYLESS-GO: remove the
Start/Stop button from the ignition lock
(Y page 140).
X If included in the vehicle equipment,
remove the tire-change tool kit from the
vehicle.
X Secure the vehicle to prevent it from rolling
away. i
Due to differences in vehicle equipment,
not all vehicles are equipped with a tire-
change tool kit. For information on which
tools are required to perform a wheel
change on your vehicle, consult an author- ized Mercedes-Benz Center.
Necessary wheel-changing tools can
include, for example:
R Jack
R Wheel chock
R Lug wrench
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
(Y page 292).
The folding wheel chock is an additional
securing measure to prevent the vehicle from
rolling away, for example when changing a
wheel.
X Fold both plates upwards 0043.
X Fold out lower plate 0044.
X Guide the lugs on the lower plate fully into
the openings in base plate 0087. Changing a wheel
333Wheels and tires Z

Securing the vehicle on level ground
X On level ground: place chocks or other
suitable items under the front and rear of
the wheel that is diagonally opposite the
wheel you wish to change. Securing the vehicle on slight downhill gradients
X On light downhill gradients: place
chocks or other suitable items in front of
the wheels of the front and rear axle.
Raising the vehicle G
WARNING
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.
! The jack is designed exclusively for jack-
ing up the vehicle at the jacking points.
Otherwise, your vehicle could be damaged. The following must be observed when raising
the vehicle:
R to raise the vehicle, only use the vehicle-
specific jack that has been tested and
approved by Mercedes-Benz. If used incor-
rectly, the jack could tip over with the vehi-
cle raised.
R the jack is designed only to raise and hold
the vehicle for a short time while a wheel
is being changed. It is not suited for per-
forming maintenance work under the vehi- cle.
R avoid changing the wheel on uphill and
downhill slopes.
R before raising the vehicle, secure it from
rolling away by applying the parking brake
and inserting wheel chocks. Never disen-
gage the parking brake while the vehicle is raised.
R the 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.
R do 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.
R make sure that the distance between the
underside of the tires and the ground does
not exceed 1.2 in (3 cm).
R never place your hands and feet under the
raised vehicle.
R do not lie under the vehicle.
R do not start the engine when the vehicle is
raised.
R do not open or close a door or the trunk lid
when the vehicle is raised.
R make sure that no persons are present in
the vehicle when the vehicle is raised. 334
Changing a wheelWheels and tires

X
Unscrew the uppermost wheel bolt com-
pletely.
X Screw alignment bolt 0043into the thread
instead of the wheel bolt.
X Unscrew the remaining wheel bolts fully.
X Remove the wheel.
Mounting a new wheel G
WARNING
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 ofdamage to the threads, contact a qualified
specialist workshop immediately. Have the
damaged wheel bolts or hub threads
replaced/renewed. Do not continue driving. G
WARNING
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" sec-
tion (Y page 332).
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.
! To prevent damage to the paintwork, hold
the wheel securely against the wheel hub
while screwing in the first wheel bolt. X
Clean the wheel and wheel hub contact
surfaces.
X Slide the wheel to be mounted onto the
alignment bolt and push it on.
X Tighten the wheel bolts until they are fin-
ger-tight.
X Unscrew the alignment bolt.
X Tighten the last wheel bolt until it is finger-
tight.
X Vehicles with a collapsible spare wheel:
inflate the collapsible spare wheel
(Y page 342). Only then lower the vehicle.
Lowering the vehicle G
WARNING
The wheels could work loose if the wheel nuts and bolts are not tightened to the specified
tightening torque. There is a risk of accident.
Have the tightening torque immediately
checked at a qualified specialist workshop
after a wheel is changed. 336
Changing a wheelWheels and tires