2005 MERCEDES-BENZ C CLASS COUPE fuel pressure

312 OperationTires and wheels
Install the valve cap.

Repeat this procedure for each tire.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
characteristics
iIf you have overfilled the tire, release
tire inflation pressure by pushing the
metal stem of the valve with e.g. a tip of
a pen. Then recheck the tire inflation
pressure with the tire gauge.
Warning!
G
Follow recommended tire inflation pres-
sures.
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 over-
heated.
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.
Do not overload the tires by exceeding the
specified load limit or vehicle capacity
weight as indicated on the placard on the
driver’s door B-pillar. Overloading the tires
can overheat them, possibly causing a
blowout.
Warning!
G
Follow recommended tire inflation pres-
sures.
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.


320 OperationTires and wheelsMaximum tire inflation pressure1 Maximum permissible tire inflation
pressure
This is the maximum permissible tire
inflation pressure for the tire. Always follow the recommended tire
inflation pressure (
page 309) for proper
tire inflation. Uniform Tire Quality Grading Standards
(U.S. vehicles)
Tire manufacturers are required to grade
tires based on three performance
factors: treadwear, traction and
temperature resistance.
1 Treadwear
2 Traction
3 Temperature resistance
iFor illustration purposes only. Actual
data on tires is specific to each vehicle
and may vary from data shown in above
illustration.
Warning!
G
Never exceed the max. tire inflation
pressure. Follow recommended tire inflation
pressures.
Do not underinflate tires. Underinflated tires
wear excessively and / or unevenly, adverse-
ly affect handling and fuel economy, and are
more likely to fail from being overheated.
Do not overinflate tires. Overinflated tires
can adversely affect handling and ride com-
fort, wear unevenly, increase stopping dis-
tance, and result in sudden deflation
(blowout) because they are more likely to
become punctured or damaged by road de-
bris, potholes etc.
iFor illustration purposes only. Actual
data on tires is specific to each vehicle
and may vary from data shown in above
illustration.

323
Operation
Tires and wheels
Tire and loading terminology
Accessory weight
The combined weight (in excess of those
standard items which may be replaced) of
automatic transmission, power steering,
power brakes, power windows, power
seats, radio, and heater, to the extent that
these items are available as
factory-installed equipment (whether
installed or not).
Air pressure
The amount of air inside the tire pressing
outward on each square inch of the tire.
Air pressure is expressed in pounds per
square inch (psi), or kilopascal (kPa) or
bars.
Aspect ratio
Dimensional relationship between tire
section height and section width
expressed in percentage.
Bar
Another metric unit for air pressure. There
are 14.5038 pounds per square inch (psi)
to 1 bar; there are 100 kilopascals (kPa)
to 1 bar.
Bead
The tire bead contains steel wires wrapped
by steel cords that hold the tire onto the
rim.
Cold tire inflation pressure
Tire inflation pressure when your vehicle
has been sitting for at least three hours or
driven no more than one mile (1.6 km). Curb weight
The weight of a motor vehicle with
standard equipment including the maxi-
mum capacity of fuel, oil, and coolant, and,
if so equipped, air conditioning and
additional optional equi
pment, but without
passengers and cargo.
DOT (D
epartment o
f T
ransportation)
A tire branding symbol which denotes the
tire meets requirements of the
U.S. Department of Transportation.
GAWR (G
ross A
xle W
eight R
ating)
The GAWR is the maximum permissible
axle weight. The gross vehicle weight on
each axle must never exceed the GAWR for
the front and rear axle indicated on the
Certification label located on the driver's
door B-pillar.

324 OperationTires and wheelsGVW (G
ross V
ehicle W
eight)
The GVW comprises the weight of the
vehicle including fuel, tools, spare wheel,
installed accessories, passengers and
cargo and, if applicable, trailer tongue
load. The GWV must never exceed the
GWVR indicated on the Certification label
located on the driver's door B-pillar.
GVWR (G
ross V
ehicle W
eight R
ating)
This is the maximum permissible vehicle
weight of the fully loaded vehicle (weight of
the vehicle including all options, passen-
gers, fuel, and cargo and, if applicable,
trailer tongue load). It is indicated on
Certification label located on the driver’s
door B-pillar. Kilopascal (kPa)
The metric unit for air pressure. There are
6.9 kPa to one psi; another metric unit for
air pressure is bars. There are
100 kilopascals (kPa) to one bar.
Maximum load rating
The maximum load in kilograms and
pounds that can be carried by the tire.
Maximum loaded vehicle weight
The sum of curb weight, accessory weight,
vehicle capacity weight and production
options weight.
Maximum tire inflation pressure
This number is the greatest amount of air
pressure that should ever be put in the tire
under normal driving conditions.Normal occupant weight
The number of occupants the vehicle is
designed to seat, multiplied by
68 kilograms (150 lbs).
Occupant distribution
The distribution of occupants in a vehicle
at their designated seating positions.
Production options weight
The combined weight of those installed
regular production options weighing over
5 lbs (2.3 kilograms) in excess of those
standard items which they replace, not
previously considered in curb weight or
accessory weight, including heavy duty
brakes, ride levelers, roof rack, heavy duty
battery, and special trim.

342 Practical hintsWhat to do if …Problem
Possible cause
Suggested solution
ú
(USA only)
±
(Canada only)
The yellow engine
malfunction indicator
lamp comes on while
driving.
There is a malfunction in:

The fuel management system


The ignition system


The emission control system


Systems which affect emissions
Such malfunctions may result in ex-
cessive emissions values and may
switch the engine to its limp-home
(emergency operation) mode.

Have the vehicle checked as soon as possi-
ble by an authorized Mercedes-Benz Center.
An on-board diagnostic connector is used
by the service station to link the vehicle to
the shop diagnostics system. It allows the
accurate identification of system
malfunctions through the readout of
diagnostic trouble codes. It is located in the
front left area of the footwell next to the
parking brake pedal.
A loss of pressure has been detect-
ed in the fuel system. The fuel cap
may not be closed properly or the
fuel system may be leaky.

Check the fuel cap (
page 288).
If it is not closed properly:

Close the fuel cap.
If it is closed properly:

Have the fuel system checked by an
authorized Mercedes-Benz Center.
Your fuel tank is empty.

After refuelling start, turn off and restart the
engine three or four times in succession.
The limp-home mode is canceled. You do not
need to have your vehicle checked.

365
Practical hints
What to do if …
Display symbol
Display message
Possible cause
Possible solution
4
Check gas cap.
See Operator’s Manual
A loss of pressure has been detected in
the fuel system. The fuel cap may not be
closed properly or the fuel system may be
leaky.

Check the fuel cap (
page 288).
If it is not closed properly:

Close the fuel cap.
If it is closed properly:

Have the fuel system checked by an
authorized Mercedes-Benz Center.
Y
Hood open
You are driving with the hood open.

Close the hood (
page 292).
I
Remove key.
You have forgotten to remove the
SmartKey.

Remove the SmartKey from the starter
switch.
Replace key
Drive to workshop
No additional code available for SmartKey.

Change the SmartKey.

399
Practical hints
Flat tire

Open flap
1 on electric air pump.

Pull out electrical plug 3 and air hose
with pressure gauge 4.

Remove the valve cap from valve.

Screw air hose 4 onto the tire valve.

Insert electrical plug 3 into vehicle
cigarette lighter socket.

Turn the SmartKey in the starter switch
to position 1.

Press I on electric air pump switch 2.
The electric air pump should now
switch on and inflate the spare tire.

Inflate the spare tire to approximately
36 psi (2.5 bar).
This takes about five minutes for the
spare tire. Air hose 4 and union
nut 5 can become hot during infla-
tion. Exercise proper caution to avoid
burning yourself when using the equip-
ment.

Press 0on electric air pump switch 2.

Turn the SmartKey in the starter switch
to position 0.

If the tire pressure is above 36 psi
(2.5 bar), release excess tire pressure
using the vent screw.

Detach the electric air pump.

Store the electrical plug and the air
hose behind the flap and place the air
pump back in the trunk.
!Do not operate the electric air pump
longer than six minutes without
interruption. Otherwise it may over-
heat.
You may operate the electric air pump
again after it has cooled off.
Warning!
G
Follow recommended inflation pressures.
Do not overinflate tires. Overinflated tires
can result in sudden deflation (blowout) be-
cause they are more likely to become punc-
tured or damaged by road debris, potholes,
etc.
Do not underinflate tires. Underinflated tires
wear unevenly, adversely affect handling
and fuel economy, and are more likely to fail
from being overheated.

419
Technical data
Rims and Tires
 Rims and Tires
Use only tires and rims which have been
specifically developed for your vehicle and
tested and approved by Mercedes-Benz.
Other tires and rims can have detrimental
effects, such as

poor handling characteristics


increased noise


increased fuel consumption
!Moreover, tires and rims not approved
by Mercedes-Benz may, under load, ex-
hibit dimensional variations and differ-
ent tire deformation characteristics
that could cause them to come into
contact with the vehicle body or axle
parts. This may result in damage to the
tires or the vehicle.
iFurther information on tires and rims is
available at any authorized
Mercedes-Benz Center. A placard with
the recommended tire inflation
pressures is located on the driver’s
door B-pillar. Some vehicles may have
supplemental tire inflation pressure
information for driving at high speeds
(page 310) or for vehicle loads less
than the maximum loaded vehicle con-
dition. If such information is provided,
it can be found on the placard located
on the inside of the fuel filler flap. The
tire inflation pressure should be
checked regularly and should only be
adjusted on cold tires. Follow tire
manufacturer’s maintenance recom-
mendation included with vehicle.