2018 MERCEDES-BENZ CLA COUPE light

If the tire pressures have been set to the lower
values for lighter loadsand/or lowerroad
speeds, the pressures shoul dbereset to the
higher values:
Rif you want to drive with an increased load
and/or
Rif you want to drive at higher speeds
iThe tire pressures for increased loadsa nd/
or higher road speeds, shown in the tire pres-
sure table, may have anegative effect on driv-
ing comfort.
If the tire pressure is not set correctly, this can
leadtoane xcessive build up of heat and asud-
den loss of pressure.
For more information, contact aqualifieds pe-
cialist workshop.
Important notes on tire pressure
GWARNING
If the tire pressure drops repeatedly,t he
wheel,v alve or tire may be damaged. Tire
pressure that is too low may resultinatire
blow-out. There is arisk of an accident.
RCheck the tire for foreign objects.
RCheck whether the wheel is losing air or the
valve is leaking.
If you are unabl etorectify the damage, con-
tact aqualifieds pecialist workshop.
GWARNING
If you fit unsuitable accessorieso nto tire
valves ,the tire valves may be overloaded and
malfunction, which can cause tire pressure
loss. Due to their design, retrofitted tire pres- sure monitors keep the tire valve open. This
can also resultint ire pressure loss. There is a
risk of an accident.
Only screw the standard valve cap or other
valve caps approved by Mercedes-Benz for
you rvehicle onto the tire valve.
Use asuitable pressure gauge to check the tire
pressure. The outer appearance of atire does
not permit any reliable conclusion aboutt he tire
pressure. On vehiclese quipped with the elec-
tronic tire pressure monitor, the tire pressure
can be checked in the on-board computer. The tire temperature and pressure increase
when the vehicle is in motion. This is dependent
on the driving speed and the load.
Therefore, you shoul
donly correct tire pres-
sures when the tires are cold.
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 been driven less than 1mile
(1.6 km)
The tire temperature changes depending on the
outsidet emperature ,the vehicle speed and the
tire load.Ift he tire temperature changes by
18 ‡(10 †), the tire pressure changes by
approximately 10 kPa (0.1 bar/1.5 psi).T ake
this into account when checking the pressure of
warm tires. Only correct the tire pressure if it is
too low for the current operating conditions. If
you check the tire pressure when the tires are
warm, the resulting valuew illbehigherthan if
the tires were cold. This is normal. Do not
reduce the tire pressure to the values pecified
for cold tires. The tire pressure would otherwise
be too low.
Observe the recommended tire pressures for
cold tires:
Ron the Tire and Loading Information placard
on the B-pillaront he driver's side
Rin the tire pressure table in the fuel fillerf lap
(Ypage 139)
Underinflated or overinflated tires
Underinflated tires
GWARNING
Tires with pressure that is too low can over-
heat and burst as aconsequence. In addition,
they also suffer from excessive and/or irreg-
ularw ear, which can severelyi mpair the brak-
ing propertiesa nd the driving characteristics.
There is arisk 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
292Tire pressure
Wheelsa nd tires

shown in theServ.menu of the multifunction
display, see illustration (example).
For information on the message display, refer to
the "Checking the tire pressure electronically"
section (
Ypage 296).
Important safety notes
GWARNING
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 adifferent size than
the size indicated on the Tire and Loading
Information placard or, if available, the tire
pressure label,y ou should determine the
proper tire pressure for those tires.
As an added safety feature, your vehicle has
been equipped with atire pressure monitoring
system (TPMS) that illuminates alow 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,a nd inflate them to the proper
pressure. Driving on asignificantly 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 asubstitute 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 amalfunction, the warning lamp
will flash for approximately aminute 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 avariety of
reasons, including the installation of incom-
patible replacement or alternate tires or
wheels on the vehicle that prevent the TPMS
from functioningp roperly. Always check the
TPMS malfunction telltale after replacing one
or more tires or wheels on your vehicle to
ensure that the replacement or alternate Tires
and wheels allow the TPMS to continue to
function properly.
It is the driver's responsibility to set the tire
pressure to that recommended for cold tires
which is suitable for the operating situation
(
Ypage 290). Note that the correct tire pressure
for the current operating situation must first be
taught-in to the tire pressure monitor. If asub-
stantial loss of pressure occurs, the warning
threshold for the warning message is aligned to
the taught-in reference values. Restart the tire
pressure monitor after adjusting the pressure of
the cold tires (
Ypage 297). The current pres-
sures are saved as new reference values. As a
result, awarning message will appearift he tire
pressure drops significantly.
The tire pressure monitor does not warn you of
an incorrectly set tire pressure. Observe the
notes on the recommended tire pressure
(
Ypage 290).
The tire pressure monitor is not able to warn you
of as udden loss of pressure, e.g. if the tire is
penetrated by aforeign object. In the event of a
sudden loss of pressure, bring the vehicle to a
halt by braking carefully.A void abrupt steering
movements.
Tire pressure295
Wheels and tires
Z

The tire pressure monitor hasayellow warning
lamp in the instrument cluster for indicating
pressure loss or amalfunction. Whether the
warning lamp flashes or lights up indicates
whether atire pressure is too low or the tire
pressure monitor is malfunctioning:
Rif the warning lamp is lit continuously, the tire
pressure on one or more tires is significantly
too low. The tire pressure monitor is not mal- functioning.
Rif the warning lamp flashes for around a
minute and then remains lit constantly, the
tire pressure monitor is malfunctioning.
In addition to the warning lamp, amessage
appears in the multifunction display.O bserve
the information on display messages
(
Ypage 211).
It may take up to ten minutes for amalfunction
of the tire pressure monitor to be indicated. A
malfunction will be indicated by the tire pres-
sure warning lamp flashing for approximately
one minute and then remaining lit. When the
malfunction has been rectified, the tire pressure
warning lamp goes out after afew minutes of
driving.
The tire pressure values indicated by the on-
board computer may differ from those meas-
ured at agas station with apressure gauge. The
tire pressures shown by the on-board computer
refer to those measured at sea level. At high
altitudes, the tire pressure values indicated by a
pressure gauge are higher than those shown by the on-board computer. In this case, do not
reduce the tire pressures.
The operation of the tire pressure monitor can
be affected by interferenc efrom radio transmit-
ting equipment (e.g. radio headphones, two-way
radios) that may be being operated in or near the vehicle.
Checking the tire pressur eelectroni-
cally
XMake sure that the SmartKey is in position 2
in the ignition lock (Ypage 122).
XPress =or; on the steerin gwheel to
select the Serv.menu.
XPress the9or: button to select
Tire Pressure.
XPress the abutton.
The current tire pressure of each tire is shown
in the multifunction display. If the vehicle was parked for longer than
20 minutes, the
Tire pressure will be
displayed after driving afew minutesmessage is shown.
After ateach-in process, the tire pressure mon-
itor automatically detect snew wheels or new
sensors. As long as aclear allocation of the tire
pressure value to the individual wheels is not
possible, the Tire
PressureMonitorActivemessage is shown instead of the tire pressure
display.The tire pressures are already being
monitored.
If an emergencys pare wheel is mounted, the
system may continue to show the tire pressure
of the wheel that has been removed for afew
minutes. If this occurs, notet hat the value dis-
played for the position where the spare wheel is
mounted is not the same as the current tire
pressure of the emergencys pare wheel.
Tire pressuremonitor warning mes-
sages
If the tire pressure monitor detect sapressure
loss in one or more tires, awarning message is
shown in the multifunction display.T he yellow
tire pressure warning lamp then lights up.
RIf the Please Correct Tire Pressuremessage appears in the multifunction display,
the tire pressure in at least one tire is too low.
The tire pressure must be corrected when the
opportunit yarises.
RIf the Check Tire Pressuremessage
appears in the multifunction display,t he tire
pressure in one or more tires has dropped
significantly. The tires must be checked.
RIf the TirePressureWarningTireFail‐uremessage appears, the tire pressure in one
or more tires has dropped suddenly. The tires
must be checked.
Observe the instructions and safety notes in the
display messages in the "Tires" section
(
Ypage 211).
If the wheel positions on the vehicle are rotated,
the tire pressures may be displayed for the
wrong positions for ashort time. This is rectified
after afew minutes of driving, and the tire pres-
sures are displayed for the correctp ositions.
296Tirepressure
Wheels and tires

tire load rating and speedrating required for
your vehicle.
:Tire width
;Nomina laspec tratio in %
=Tire code
?Rimd iame ter
ALoadb earing index
BSpeed rating
General: depending on the manufacturer's
standards ,the size imprinted in the tire wall may
not contain any letters or mayc ontain one letter
thatp recedes the size description.
If there is no letter preceding the size descrip-
tio n(as shown above): these ar epassenger
vehicl etiresa ccording to Europea nmanufac-
turing standards.
If "P "precedes the size description: these are
passenge rvehicl etiresa ccording to U.S. man-
ufacturin gstandards.
If "LT" precedes the size description: these are
light truck tire saccording to U.S. manufacturing
standards.
If "T "precedes the size description: compact
emergency wheels with high tire pressure that
ar eo nlyd esig nedf or temporary us einanemer-
gency.
Tire width: tire width:shows the nominal tire
width in millimeters.
Aspec tratio: aspect ratio ;is the size ratio
between the tire height and tire width and is
shown in percent. The aspect ratio is calculated
by dividing the tire width by the tire height.
Tire code: tire code=specifie sthe tire type.
"R "r epresents radial tires; "D" represents diag-
ona ltire s; "
B" represents diagona
lradial tires.
Optionally ,tire sw itham aximum spee dofover
149 mph (240 km/h )mayhave "ZR" in the size description, depending on the manufacturer
(e.g. 245/40Z
R18).
Rim diameter: rim diameter?is the diameter
of the bead seat, not the diamete rofthe rim
flange .The ri mdiame teriss pecifie din
inches (in).
Load-bearin gind ex: load-bearing index Ais a
numerical cod ethats pecifie sthe maximum
load-bearing capacity of atire.
Do not overload the tire sbyexceeding the
specifie dloa dlimit .The maximu mpermissible
load can be found on the vehicle's Tire and
Loading Informatio nplacard on the B-pillar on
the driver's side (
Ypage 298).
Example:
Load-bearin gindex 91 indicates amaximum
load of 1,356 lb (61 5kg)thatt he tire scan bear.
For furtheri nformation on the maximum tire
load in kilograms and lbs, see(
Ypage 304).
For furtheri nformation on the load bearing
index, see" Loadindex" (
Ypage 304).
Speed rating: speedrating Bspecifie sthe
approved maximum spee dofthe tire.
iTire data is vehicle-specific and mayd eviate
fromt he data in the example.
Regardles softhe spee drating ,alway sobser ve
th

e spee dlimit s. Drive carefull yand adap tyou r
drivin gstyle to the trafficc onditions.
Summert ires
IndexSpeed rating
Qup to 100 mph (16 0km/h)
Rup to 106 mph (17 0km/h)
Sup to 112 mph (18 0km/h)
Tup to 118 mph (19 0km/h)
Hup to 130 mph (21 0km/h)
Vup to 149 mph (24 0km/h)
Wup to 168 mph (27 0km/h)
Yup to 186 mph (30 0km/h)
ZR...Yup to 186 mph (30 0km/h)
ZR...(..Y)ove r186 mph (300 km/h)
ZRove r149 mph (240 km/h)
ROptionally ,tire sw itham aximum spee dof
ove r149 mph (24 0km/h )mayhave "ZR" in
Alla bout wheels an dtires303
Wheel sand tires
Z

the size description, depending on the man-
ufacturer (e.g. 245/40ZR18).
The service specification is made up of load-
bearing index Aand spee drating B.
RIf the size description of your tire includes
"ZR" and there ar enoservice specifications,
as kt he tire manufacturer in order to fin dout
the maximum speed.
If as ervice specification is available, the max-
imum spee dislimited according to the speed
rating in the service specification. Example:
245/40Z R1897Y.Int his example," 97 Y" is
the service specification. The letter "Y" rep-
resents the speed rating. The maximum
speed of the tire is limited to 186 mph
(300 km/h).
RThe size descriptionf or all tires with maxi-
mum speedsofo ver 186 mph (300 km/h)
must include "ZR" andthe service specifica-
tion must be given in parentheses.E xample:
275/40 ZR 18 (99 Y) .Speed rating "(Y)" indi-
cates that the maximum speed of the tire is
over 186 mph (300 km/h). Ask the tire man-
ufacturer aboutt he maximum speed.
All-weather tires and winter tires
IndexSpeed rating
QM +S1up to 100 mph (160 km/h)
TM+S1up to 118 mph (190 km/h)
HM +S1up to 130 mph (210 km/h)
VM+S1up to 149 mph (240 km/h)
iNot 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 isnowflake symbo lonthe 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 you rvehi-
cle from exceeding aspeed of 130 mph
(210 km/h).
The speed rating of tires mounted at the factory
may be higher than the maximum speed that the
electronic speed limiter permits. Make sure that you
rtires have the required
speed rating, e.g. when buying new tires. The
required speed rating for you rvehicle can be
found in the "Tires" section (
Ypage 312).
Further information aboutr eading tire data can
be obtained from any qualifieds pecialist work-
shop.
Load index
In addition to the load-bearing index, load
index :may be imprinted after the letters that
identify speed rating on the sidewall of the tire.
Speed rating (
Ypage 302).
RIf no specification is given: no text (as in the
example above), represents astandard load
(SL) tire
RXL or ExtraL oad: represents areinforced tire
RLight Load: represents alightl oad tire
RC, D, E: represents aload range that depends
on the maximum load that the tire can carry at
ac ertain pressure
iTire data is vehicle-specific and may deviate
from the data in the example.
Maximum load rating
1Or M+S ifor winter tires.
304Allabout wheels and tires
Wheelsa nd tires

PSI (pounds per squareinch)
Astandard 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
1m ile (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.
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, aroof rack or ahigh-per-
formanceb attery, are not included in the curb
weight and the weight of the accessories.
TIN (Tire Identification Number)
This is aunique identifier which can be used by
at ire manufacturer to identify tires, for example
for aproduct 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 acode
that contains the maximum load bearing capa-
city of atire.
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 áin (1.6 mm)
has been reached.
Occupant distribution
The distribution of occupants in avehicle at their
designated seating positions.
Total load limit
Nominal load and luggage load plus 68 kg
(15 0lbs)m ultiplied by the number of seats in
the vehicle.
Changing awheel
Flat tire
The "Breakdown assistance" section
(Ypage 271) contains information and notes on
how to deal with aflat tire. Information on driv-
ing with MOExtended tires in the event of aflat
tire can be found under "MOExtended tires (tires
with run-flat characteristics" (
Ypage 271).
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 arisk of acci-
dent.
Rotate front and rear wheels only if the wheels and tires are of the same dimensions.
!On vehicles equippedw ithatire pressure
monitor ,electronic components are located
in the wheel.
Changing awheel307
Wheels and tires
Z