74 Safety and SecurityOccupant safety
Emergency tensioning device (ETD),
seat belt force limiter
The seat belts are equipped with
emergency tensioning devices (ETDs) and
seat belt force limiters.
The ETD is designed to activate in the fol-
lowing cases:
in frontal or rear-end impacts exceed-
ing a preset severity level.
if the restraint systems are operational
and functioning correctly, see
1indicator lamp (
page 64).In an impact emergency tensioning
devices remove slack from the belts in
such a way that the seat belts fit more
snugly against the body. Belt force limiters
reduce the force exerted by the seat belts
on occupants during a crash.
Belts should not be worn twisted. In a
crash, you wouldn’t have the full width
of the belt to manage impact forces. The
twisted belt against your body could
cause injuries.
Pregnant women should also use a
lap-shoulder belt. The lap belt portion
should be positioned as low as possible
on the hips to avoid any possible pres-
sure on the abdomen.
Never place your feet on the instrument
panel, dashboard or on the seat. Always
keep both feet on the floor in front of the
seat.
iThe ETDs for the seats will only activate
if the respective seat belt is fastened
(latch plate properly inserted into
buckle).
Warning!
G
An emergency tensioning device (ETD) that
was activated must be replaced.
When scrapping the emergency tensioning
device, our safety instructions must be fol-
lowed. These are available at your autho-
rized Mercedes-Benz Center.
334 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 341)
2DOT, Tire Identification Number (TIN)
(page 339)
3Maximum tire load (
page 340)
4Maximum tire inflation pressure
(
page 341)
5Manufacturer
6Tire ply material (
page 343)
7Tire size designation, load and speed
rating (
page 334)
8Load identification (
page 338)
9Tire nameTire size designation, load and speed
rating
1Tire width
2Aspect ratio in %
3Radial tire code
4Rim diameter
5Tire load rating
6Tire speed rating
iFor illustration purposes only. Actual
data on tires are specific to each vehi-
cle and may vary from data shown in
above illustration.
For more information, see “Rims and
tires” (
page 439).
iFor illustration purposes only. Actual
data on tires are specific to each vehi-
cle and may vary from data shown in
above illustration.
335 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 334) indicates
the nominal tire width in mm.
Aspect ratio
The aspect ratio2 (page 334) 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 334) 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 336).Rim diameter
The rim diameter4 (
page 334) 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 334) 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 340) where the maximum load as-
sociated with the load index is indicated in
kilograms and lbs.
342 OperationTires and wheelsQuality grades can be found, where appli-
cable, on the tire sidewall between tread
shoulder and maximum section width. For
example:
All passenger car tires must conform to
federal safety requirements in addition to
these grades.Treadwear
The treadwear grade is a comparative rat-
ing based on the wear rate of the tire when
tested under controlled conditions on a
specified government test course. For ex-
ample, a tire graded 150 would wear one
and one-half (1
1/2) times as well on the
government course as a tire graded 100.
The relative performance of tires depends
upon the actual conditions of their use,
however, and may depart significantly
from the norm due to variations in driving
habits, service practices and differences in
road characteristics and climate.Traction
The traction grades, from highest to low-
est, are AA, A, B, and C. Those grades rep-
resent the tire’s ability to stop on wet
pavement as measured under controlled
conditions on specified government test
surfaces of asphalt and concrete. A tire
marked C may have poor traction perfor-
mance.
Treadwear
Traction
Temperature
200
AA
A
Warning!
G
The traction grade assigned to this tire is
based on straight-ahead braking traction
tests, and does not include acceleration,
cornering, hydroplaning, or peak traction
characteristics.
344 OperationTires and wheelsTire 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 stan-
dard equipment including the maximum
capacity of fuel, oil, and coolant, and, if so
equipped, air conditioning and additional
optional equipment, but without passen-
gers 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.
GVW (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.
356 OperationVehicle careAutomatic car wash
You can have your car washed in an auto-
matic car wash from the start. Automatic
car washes without brushes are prefera-
ble.
If the vehicle is very dirty, prewash it be-
fore running it through the automatic car
wash.Ornamental moldings
For regular cleaning and care of very dirty
chrome-plated parts, use a chrome clean-
er.
!Due to the width of the vehicle, fold in
exterior rear view mirrors prior to run-
ning the vehicle through an automatic
car wash to prevent damage to the
mirrors.
Make sure that the windshield wiper
switch is set to0 (
page 56). Other-
wise, the rain sensor could activate and
cause the wipers to move unintention-
ally. This may lead to vehicle damage.
iAfter running the vehicle through an au-
tomatic car wash, wipe any wax off of
the windshield (
page 357). This will
prevent smears and reduce wiping
noise which can be caused by residual
wax on the windshield.
When leaving the car wash, make sure
that the mirrors are folded out. Other-
wise they may vibrate.
447 Technical data
Main Dimensions
Main Dimensions
Model
SLK 280
SLK 350
SLK 55 AMG
Overall vehicle length
160.7 in (4 082 mm)
160.7 in (4 082 mm)
160.9 in (4 087 mm)
Overall vehicle width
70.4 in (1 788 mm)
70.4 in (1 788 mm)
70.6 in (1 794 mm)
Overall vehicle height
51.0 in (1 296 mm)
51.1 in (1 298 mm)
50.0 in (1 271 mm)
Wheelbase
95.7 in (2 430 mm)
95.7 in (2 430 mm)
95.7 in (2 430 mm)
Track, front
60.2 in (1530 mm)
60.1 in (1526 mm)
60.0 in (1 524 mm)
Track, rear
61.0 in (1549 mm)
61.0 in (1549 mm)
61.0 in (1 549 mm)