253
Wheels and tyres
Wear indicators
The original tyres on your vehicle have 1.6 mm high “tread wear indicators”
⇒ Fig. 171, running across the tread. Depending on the make, there will be
6 to 8 of them evenly spaced around the tyre. Markings on the tyre sidewall
(for instance the letters “TWI” or other symbols) indicate the positions of
the tread wear indicators. The minimum tread depth required by law is
1.6 mm (measured in the tread grooves next to the tread wear indicators).
Worn tyres must be replaced. Different figures may apply in export countries
⇒
.
Tyre pressure
Incorrect tyre pressure causes premature wear and could cause tyre blow-
out. For this reason, the tyre pressure should be checked at least once per
month ⇒ page 250.
Driving style
Fast cornering, heavy acceleration and hard braking all increase tyre wear.
Changing wheels around
If the front tyres are worn considerably more than the rear ones it is advisa-
ble to change them around as shown ⇒ Fig. 172. The useful life of all the
tyres will then be about the same time.
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.
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