Mercedes-Benz 2009 GL320 BlueTEC Operator's Manual page 290

Operation
Tires and wheels
Tire load rating
G Warning!
The tire load rating must always be at least
half of the GAWR of your vehicle.
Otherwise, tire failure may be the result
which may cause an accident and/or
serious injury to you or others.
Always replace rims and tires with the same
designation, manufacturer and type as
shown on the original part.
G Warning!
Do not overload the tires by exceeding the
specified load limit as indicated on the Tire
and Loading Information placard 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.
Tire load rating is a numerical code
5
associated with the maximum load a tire can
support.
For example, a load rating of 91 corresponds
to a maximum load of 1356 lb (615 kg) the
tire is designed to support. See also
"Maximum tire load" ( Y page 291) where the
288
maximum load associated with the load index
is indicated in kilograms and lbs.
For additional information on tire load rating,
see "Load identification" ( Y page 289).
Tire speed rating
G Warning!
Even when permitted by law, never operate
a vehicle at speeds greater than the
maximum speed rating of the tires.
Exceeding the maximum speed for which
tires are rated can lead to sudden tire
failure, causing loss of vehicle control and
possibly resulting in an accident and/or
serious personal injury and possible death,
for you and for others.
Regardless of the tire speed rating, local
speed limits should be obeyed. Use prudent
driving speeds appropriate to prevailing
conditions.
Tire speed rating indicates the approved
6
maximum speed for the tire.
Summer tires
Index Speed rating
Q up to 100 mph (160 km/h)
R up to 106 mph (170 km/h)
S up to 112 mph (180 km/h)
T up to 118 mph (190 km/h)
H up to 130 mph (210 km/h)
V up to 149 mph (240 km/h)
W up to 168 mph (270 km/h)
Y up to 186 mph (300 km/h)
ZR...Y up to 186 mph (300 km/h)
ZR...(..Y) above 186 mph (300 km/h)
ZR above 149 mph (240 km/h)
At the tire manufacturer's option, any tire
R
with a speed capability above 149 mph
(240 km/h) can include a "ZR" in the size
designation (for example: 245/40 ZR18).
To determine the maximum speed