Mercedes-Benz R-Class 2006 Owners Manual User Manual
Page 378
377
Operation
Tires and wheels
Aspect ratio
The aspect ratio
2 (
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 code
3 (
page 376) 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” (
Rim diameter
The rim diameter
4 (
page 376) 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 rating
5 (
page 376) 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 1356 lbs
(615 kg) the tire is designed to support.
See also “Maximum tire load”
(
page 382) where the maximum load as-
sociated 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 386) of your vehi-
cle. Otherwise, tire failure may be the result
which may cause an accident and/or seri-
ous 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 plac-
ard 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.