2007 MERCEDES-BENZ SL550 page 47

294 OperationTires and wheels
Reactivating the Run Flat Indicator
The tire inflation pressure monitor must be
reactivated 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 placard on the driver’s
door B-pillar or, if available, the inside
of the fuel filler flap, make sure the tire
inflation pressure of all four tires is cor-
rect.
Warning!
G
When the multifunction display shows the
message
Tire pressure Check tires
,
one or more of your tires is significantly un-
der-inflated. You should stop and check
your tires as soon as possible, and inflate
them to the proper tire inflation pressure as
indicated on the vehicle’s tire information
placard. Driving on a significantly under-in-
flated tire causes the tire to overheat and
can lead to tire failure. Under-inflation also
reduces fuel efficiency and tire tread life,
and may affect the vehicle’s handling and
stopping ability. Each tire, including the
spare, should be checked monthly when
cold and set to the recommended tire infla-
tion pressure as specified on the Tire And
Loading Information placard (
page 287)
or on the tire inflation pressure label
(
page 291).
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 placard on the driver’s
door B-pillar or fuel filler flap.
The Run Flat Indicator does not replace reg-
ular checks of the tire inflation pressures
since a gradual pressure loss in all four tires
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.
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 ac-
cording to the incorrect value.

295 Operation
Tires and wheels

Switch on the ignition (
page 39).
Make sure the standard display menu
appears in the multifunction display
(
page 145).

Press buttonk orj repeatedly
until the following message appears in
the multifunction display:Run Flat Indicator
active
Menu: R-Button

Press the reset button (
page 27).
The following message will appear in
the multifunction display:
Restart
Run Flat Indicator?
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.Checking tire pressure electronically
with the Tire Pressure Monitoring
System (TPMS), (USA only)
i
The T
ire P
ressure M
onitoring S
ystem
(TPMS) is equipped with a combination low tire
pressure/TPMS malfunction telltale in the in-
strument 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 under-in-
flated. There is no malfunction in the TPMS.


If the telltale flashes for 60 seconds and
then stays illuminated, the TPMS system it-
self is not operating properly.

297 Operation
Tires and wheels
Reactivating the TPMS
The TPMS must be reactivated 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 placard on the driver’s
door B-pillar (
page 286) or, if avail-
able, the supplemental tire pressure
information on the inside of the fuel fill-
er flap (
page 271), make sure the tire
inflation pressure of all four tires is cor-
rect.

Press buttonè orÿ on the mul-
tifunction steering wheel repeatedly
until the standard display menu ap-
pears in the multifunction display
(page 145).

Press thej or kbutton repeat-
edly until you see the following mes-
sage:Tire pressure monitor
active
Menu: R-button
TPMS malfunctions may occur for a variety
of reasons, including the installation of in-
compatible 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 ensure that the replacement or alternate
tires and wheels allow the TPMS to continue
to function properly.i
If a condition causing the TPMS to malfunc-
tion develops, it may take up to 10 minutes for
the system to signal a malfunction using the
TPMS telltale flashing and illumination se-
quence.
The telltale extinguishes after a few minutes driv-
ing if the malfunction has been corrected.
i
Operating radio transmission equipment
(e.g. wireless headsets, two-way radios) in or
near the vehicle could cause the TPMS to mal-
function.
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.
i
Reactivate the TPMS after adjusting the tire
inflation pressure to the inflation pressure rec-
ommended for the vehicle operating condition.
Tire pressure should only be adjusted on cold
tires. Observe the recommended tire inflation
pressure on the placard on the driver’s door
B-pillar (
page 286). Some vehicles may have
supplemental tire pressure information for driv-
ing at high speeds (
page 292) or for vehicle
loads less than the maximum loaded vehicle con-
dition (
page 292). If such information is pro-
vided, it can be found on the inside of the fuel
filler flap.


298 OperationTires and wheels
Press the reset button (
page 27).
The following message will appear in
the multifunction display:
Restart tire
pressure monitor?

Press the æbutton.
The following message will appear in
the multifunction display:Tire pressure monitor restartedAfter driving a few minutes the system
verifies that the current tire inflation
pressures are within the system’s
specified range. Afterwards the current
tire inflation pressures are accepted as
reference pressures and then moni-
tored.
If you wish to cancel activation:

Press the çbutton.Checking tire pressure electronically
with the Advanced Tire Pressure Moni-
toring System (Advanced TPMS)*,
(Canada 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.
Tire pressure inquiries are made using the
multifunction display. The present inflation
pressures are displayed only after a few
minutes’ travel time.

Switch on the ignition (
page 39).

Press thej or kbutton until
the current inflation pressures for each
tire appear in the multifunction display.
i
Possible differences between the readings
of a tire pressure gauge of an air hose, e.g. gas
station equipment, and the vehicle’s control
system can occur. Usually the readings issued by
the control system are more precise.
i
When the message
Tire pressure
displayed after driving for a few
minutes
appears in the multifunction display,
the individual inflation pressure values are
matched with the tires. The individual values are
displayed after a few minutes driving.
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 lose control over the vehicle.


300 OperationTires and wheelsReactivating Advanced TPMS*
The TPMS must be reactivated 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 placard on the driver’s
door B-pillar (
page 286) or, if avail-
able, the supplemental tire pressure
information on the inside of the fuel
filler flap (
page 292), make sure the
tire inflation pressure of all four tires is
correct.

Press buttonè orÿ on the mul-
tifunction steering wheel repeatedly
until the standard display menu
appears in the multifunction display
(page 139).

Press thej or kbutton repeat-
edly until you see the current inflation
pressures for each tire appear in the
display or the following message ap-
pears in the displayTire pressure
displayed after
driving for
a few minutes

Press the reset button (
page 27).
The following message will appear in
the multifunction display:
Restart tire
pressure monitor?

Press the æbutton.
The following message will appear in
the multifunction display:Tire pressure monitor restartedAfter a few minutes driving, the current
tire inflation pressure values are ac-
cepted as reference values and then
monitored.
If you wish to cancel activation:

Press the çbutton.
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 lose control over the vehicle.
i
Reactivate the TPMS after adjusting the tire
inflation pressure to the inflation pressure rec-
ommended for the vehicle operating condition.
Tire pressure should only be adjusted on cold
tires. Observe the recommended tire inflation
pressure on the placard on the driver’s door
B-pillar (
page 286). Some vehicles may have
supplemental tire pressure information for driv-
ing at high speeds (
page 292) or for vehicle
loads less than the maximum loaded vehicle con-
dition (
page 292). If such information is pro-
vided, it can be found on the inside of the fuel
filler flap.

301 Operation
Tires and wheels
Potential problems associated with
underinflated and overinflated tires
Underinflated tire inflation pressure
Underinflated tires can:

cause excessive and uneven tire wear


adversely affect fuel economy


lead to tire failure from being
overheated


adversely affect handling
characteristicsOverinflated tire inflation pressure
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*
(Canada vehicles) (
page 293) or TPMS
(U.S. vehicles) (
page 295).
For information on driving in case of pres-
sure loss in one or more tires (emergency
mode), see the “Operation” section
(
page 413).
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.
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.

302 OperationTires and wheelsTire 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:1Uniform Quality Grading Standards
(
page 309)
2DOT, Tire Identification Number (TIN)
(page 307)
3Maximum tire load (
page 308)
4Maximum tire inflation pressure
(
page 309)
5Manufacturer
6Tire ply material (
page 311)
7Tire size designation, load and speed
rating (
page 302)
8Load identification (
page 306)
9Tire nameTire size designation, load and speed
rating
1Tire width
2Aspect ratio in %
3Radial tire code
4Rim diameter
5Tire load rating
6Tire speed rating
i
For 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 435).
i
For illustration purposes only. Actual data
on tires are specific to each vehicle and may vary
from data shown in above illustration.

303 Operation
Tires and wheels
General:
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. Tire width
The tire width1 (
page 302) indicates
the nominal tire width in mm.
Aspect ratio
The aspect ratio2 (page 302) 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 302) 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 304).Rim diameter
The rim diameter4 (
page 302) 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 302) 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 308) where the maximum load as-
sociated with the load index is indicated in
kilograms and lbs.