2008 MERCEDES-BENZ CLK350 page 92

342 Operation
Tires and wheels
Run Flat Indicator (Canada only)
While the vehicle is being driven, the Run
Flat Indicator monitors the set tire inflation
pressures by evaluating each wheel’s rota-
tional speed. This allows the system to de-
tect a significant loss of pressure in a tire.
If a wheel’s rotational speed changes due
to falling tire inflation pressure, you will
see a corresponding warning message in
the multifunction display.
The Run Flat Indicator may function in a re-
stricted manner or with a delay

if snow chains are mounted to the
vehicle

in presence of ice and snow

if you are driving on a loose surface
(e.g. sand or gravel)

if you are driving in a very sporty man-
ner (involving rapid acceleration or high
speeds in curves)

if you are driving with the roof loaded
(CLK coupe) or very heavy cargo
Warning!G
When the multifunction display shows the
message
Tire Pressure Check Tires,
one or more of your tires is significantly un-
derinflated. You should stop and check your
tires as soon as possible, and inflate them to
the proper tire inflation pressure as indicat-
ed on the vehicle’s Tire and Loading
Information placard or, if available, on the
tire inflation pressure label. Driving on a sig-
nificantly under-inflated tire causes the tire
to overheat and can lead to tire failure. Un-
derinflation also reduces fuel efficiency and
tire tread life, and may affect the vehicle’s
handling and stopping ability. Each tire, in-
cluding the spare, should be checked
monthly when cold and set to the recom-
mended tire inflation pressure as specified
on the Tire and Loading Information placard
on the driver’s door B-pillar (
page 334) or,
if available, on the tire inflation pressure la-
bel located on the inside of the fuel filler flap
(
page 320).
Warning!G
The Run Flat Indicator does not provide a
warning for wrongly selected tire inflation
pressures. Always adjust tire inflation pres-
sure according to the Tire and Loading
Information placard on the driver’s door
B-pillar (
page 334) or, if available, on the
tire inflation pressure label located on the
inside of the fuel filler flap (
page 320).
The Run Flat Indicator does not replace
regular checks of the tire inflation pressures
since a gradual pressure loss in more than
one tire cannot be detected by the Run Flat
Indicator.
The Run Flat Indicator is not able to issue a
warning due to a sudden dramatic loss of
tire inflation pressure (e.g. tire blowout
caused by a foreign object). In this case
bring the vehicle to a halt by carefully apply-
ing the brakes and avoiding abrupt steering
maneuvers.

343 Operation
Tires and wheels
Restarting the Run Flat Indicator
The tire inflation pressure monitor must be
restarted in the following situations:

If you have changed the tire inflation
pressure

If you have replaced the wheels or tires

If you have installed new wheels or
tires
Using the Tire and Loading Information
placard on the driver’s door B-pillar or,
if available, the tire inflation pressure
label on the inside of the fuel filler flap,
make sure the tire inflation pressure of
all four tires is correct.
Switch on the ignition (page 38).
Make sure the standard display menu
appears in the multifunction display
(
page 147).
Press buttonk orj repeatedly
until the following message appears in
the multifunction display:
Press the reset button in the
instrument cluster (
page 138).
The following message will appear in
the multifunction display:
Restart
Run Flat Indicator?
Cancel
Yes
If you wish to confirm activation:
Press buttonæ.
The following message will appear in
the multifunction display:
Run Flat Indicator
Restarted
After a certain “learning phase”, the Run
Flat Indicator checks the set pressure val-
ues for all four tires.
If you wish to cancel activation:
Press buttonç.
or
Wait until the message
Restart
Run Flat Indicator?
Cancel
Yes
disappears.
Warning!G
The Run Flat Indicator can only warn you in
a reliable manner if you have set the correct
tire inflation pressures for each tire.
If an incorrect tire inflation pressure was
set, the system will monitor the pressure
according to the incorrect value.

344 Operation
Tires and wheels
Checking tire pressure electronically
with the Tire Pressure Monitoring
System (TPMS), (USA only)
The TPMS only functions on wheels that
are equipped with the proper electronic
sensors. It monitors the tire inflation pres-
sure, as selected by the driver, in all four
tires. A warning is issued to alert you to a
decrease in pressure in one or more of the
tires.
iThe Tire Pressure Monitoring System
(TPMS) is equipped with a combination low tire
pressure/TPMS malfunction telltale in the
instrument cluster (
page 29). Depending on
how the telltale illuminates, it indicates a low tire
pressure condition or a malfunction in the TPMS
system itself:

If the telltale illuminates continuously, one
or more of your tires is significantly underin-
flated. There is no malfunction in the TPMS.

If the telltale flashes for 60 seconds and
then stays illuminated, the TPMS system
itself is not operating properly.
iThis device complies with Part 15 of the
FCC Rules. Operation is subject to the following
two conditions:
(1) This device may not cause harmful interfer-
ence, and
(2) this device must accept any interference
received, including interference that may
cause undesired operation.
Any unauthorized modification to this device
could void the user’s authority to operate the
equipment.Warning!G
The TPMS does not indicate a warning for
wrongly selected inflation pressures. Always
adjust tire inflation pressure according to
the Tire and Loading Information placard on
the driver’s door B-pillar or, if available, the
supplemental tire pressure information on
the inside of the fuel filler flap.
The TPMS is not able to issue a warning due
to a sudden dramatic loss of pressure (e.g.
tire blowout caused by a foreign object). In
this case bring the vehicle to a halt by care-
fully applying the brakes and avoiding
abrupt steering maneuvers.

346 Operation
Tires and wheels
Tire inflation pressure warnings
If the system detects a significant loss of
tire inflation pressure in one or more than
one tire, a message appears in the multi-
function display.
Example illustration
In addition, a warning signal sounds.Restarting the TPMS
The TPMS must be restarted when you
have adjusted the tire inflation pressure to
a new level (e.g. because of different load
or driving conditions). The TPMS is then
recalibrated to the current tire inflation
pressures.
Using the Tire and Loading Information
placard on the driver’s door B-pillar
(
page 334) or, if available, the
supplemental tire inflation pressure
information on the inside of the fuel
filler flap (
page 320), make sure the
tire inflation pressure of all four tires is
correct.
Switch on the ignition (page 38).
Press buttonè orÿ on the
multifunction steering wheel repeat-
edly until the standard display menu
appears in the multifunction
display (
page 147).
Warning!G
It is the driver’s responsibility to calibrate
the TPMS on the recommended cold infla-
tion pressure. Underinflated tires affect the
ability to steer or brake the vehicle. You
might loose control over the vehicle.
iRestart the TPMS after adjusting the tire in-
flation pressure to the inflation pressure recom-
mended for the vehicle operating condition. Tire
pressure should only be adjusted on cold tires.
Observe the recommended tire inflation pres-
sure on the Tire and Loading Information placard
on the driver’s door B-pillar (
page 334). Some
vehicles may have supplemental tire inflation
pressure information for driving at high speeds
(
page 340) or for vehicle loads less than the
maximum loaded vehicle condition
(
page 335). If such information is provided, it
can be found on the inside of the fuel filler flap.

347 Operation
Tires and wheels
Press button j ork repeatedly
until the following message appears in
the multifunction display:
Tire Pressure
Monitor Active
Menu: R-Button
Press the reset button (page 138).
The following message will appear in
the multifunction display:
Restart tire
tire pressure
monitor?
Cancel
Yes
Press buttonk orj to
selected
Yes.
Press the æbutton.
The following message will appear in
the multifunction display:
Tire Pressure
Monitor
Restarted
After driving a few minutes the current
tire inflation pressure values are
accepted as reference pressures and
then monitored.
If you wish to cancel activation:
Press buttonk orj to
selected
Cancel.
Press the æbutton.Potential problems associated with
underinflated and overinflated tires
Underinflated tires
Underinflated tires can:

cause excessive and uneven tire wear

adversely affect fuel economy

lead to tire failure from being
overheated

adversely affect handling
characteristics
Warning!G
Follow recommended tire inflation
pressures.
Do not underinflate tires. Underinflated tires
wear excessively and / or unevenly,
adversely affect handling and fuel economy,
and are more likely to fail from being
overheated.

348 Operation
Tires and wheels
Overinflated tires
Overinflated tires can:

adversely affect handling
characteristics

cause uneven tire wear

be more prone to damage from road
hazards

adversely affect ride comfort

increase stopping distance
MOExtended system*
The MOExtended system allows you to
continue driving your vehicle even if there
is a total loss of pressure in one or more
tires.
You may only use the MOExtended system
in conjunction with the Run Flat Indicator
(
page 342).
For information on driving in the event of
pressure loss in one or more tires (emer-
gency mode), see the “Practical hints” sec-
tion (
page 463).
Tire labeling
Besides tire name (sales designation) and
manufacturer name, a number of markings
can be found on a tire.
Following are some explanations for the
markings on your vehicle’s tires:
Warning!G
Follow recommended tire inflation
pressures.
Do not overinflate tires. Overinflated tires
can adversely affect handling and ride
comfort, wear unevenly, increase stopping
distance, and result in sudden deflation
(blowout) because they are more likely to
become punctured or damaged by road
debris, potholes etc.

349 Operation
Tires and wheels
1Uniform Quality Grading Standards
(
page 356)
2DOT, Tire Identification Number (TIN)
(
page 353)
3Maximum tire load (
page 354)
4Maximum tire inflation pressure
(
page 355)
5Manufacturer
6Tire ply material (
page 357)
7Tire size designation, load and speed
rating (
page 349)
8Load identification (
page 352)
9Tire nameTire size designation, load and speed
rating
1Tire width
2Aspect ratio in %
3Radial tire code
4Rim diameter
5Tire load rating
6Tire speed ratingGeneral:
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.
iFor illustration purposes only. Actual data
on tires are specific to each vehicle and may vary
from data shown in above illustration.
For more information, see “Rims and tires”
(
page 482).
iFor illustration purposes only. Actual data
on tires are specific to each vehicle and may vary
from data shown in above illustration.

350 Operation
Tires and wheels
Tire width
The tire width1 (
page 349) indicates
the nominal tire width in mm.
Aspect ratio
The aspect ratio2 (
page 349) 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
The tire code3 (
page 349) indicates
the tire construction type. The “R” stands
for radial tire type. Letter “D” means diag-
onal 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” (
page 351).Rim diameter
The rim diameter4 (
page 349) is the
diameter of the bead seat, not the
diameter of the rim edge. Rim diameter is
indicated in inches (in).
Tire load rating
The tire load rating5 (
page 349) is a
numerical code associated with the
maximum load a tire can support.
For example, a load rating of 91 corre-
sponds to a maximum load of 1 356 lbs
(615 kg) the tire is designed to support.
See also “Maximum tire load”
(
page 354) where the maximum load
associated with the load index is indicated
in kilograms and lbs.
Warning!G
The tire load rating must always be at least
half of the GAWR (
page 358) of your
vehicle. Otherwise, tire failure may be the
result which may cause an accident and/or
serious personal injury to you or others.
Always replace rims and tires with the same
designation, manufacturer and type as
shown on the original part.
Warning!G
Do not overload the tires by exceeding the
specified load limit as indicated on the Tire
and Loading Information placard located 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.