254 Wheels and tyres
Wheel balance
The wheels on new vehicles are balanced. However, various factors encoun-
tered in normal driving can cause them to become unbalanced, which re-
sults in steering vibration.
Unbalanced wheels should be rebalanced, as they otherwise cause exces-
sive wear on steering, suspension and tyres. A wheel must also be reba-
lanced when a new tyre is fitted.
Incorrect wheel alignment
Incorrect wheel alignment causes excessive tyre wear, impairing the safety
of the vehicle. If tyres show excessive wear, you should have the wheel
alignment checked by a Technical Service.
WARNING
There is a serious danger of accidents if a tyre bursts during driving!
●The tyres must be replaced at the latest when the tread wear indica-
tors are worn ⇒ page 253. Failure to do so could result in an accident.
Worn tyres do not grip well at high speeds on wet roads. There is also a
greater risk of aquaplaning.
●At continuously high speeds, a tyre with insufficient pressure flexes
more. This causes it to overheat. This can cause tread separation and tyre
blow-out. Risk of accident. Always observe the recommended tyre pres-
sures.
●If tyres show excessive wear, you should have the running gear
checked by a Technical Service.
●Keep chemicals such as oil, fuel and brake fluid away from tyres.
●Damaged wheels and tyres must be replaced immediately!
For the sake of the environment
Under-inflated tyres will increase fuel consumption.
Run-flat tyres*
Run-flat tyres allow you to continue driving even with a
punctured tyre, in the majority of cases.
In vehicles that are factory-fitted with run-flat tyres1) the loss of tyre
pressure is indicated on the instrument panel.
Driving with run-flat tyres (emergency running)
–Leave the ESC/ASR on (Electronic Stability Control), or switch it
on ⇒ page 71.
–Continue driving carefully and slowly (80 km/h maximum).
–Avoid sudden manoeuvres and sharp turns.
–Avoid driving over obstacles (for example kerbs) or potholes.
–Pay attention if the ESC/ASR activates often, if smoke comes
from the tyres or there is a smell of rubber, if the vehicle vi-
brates or there are clattering noises. If any of these occur, stop
the vehicle.
The run-flat tyres have a tag on the side of the tyre, with the description:
“DSST”, “Eufonia”, “RFT”, “ROF”, “RSC”, “SSR” or “ZP”.
The sides of this type of tyre are reinforced. When the tyres lose air they are
supported on the sides (emergency driving).
The loss of pressure in the tyre is shown on the instrument panel. You can
then drive a maximum of 80 km and if the circumstances are favourable (for
example, low load), even more.
1) Depending upon version and country.
