218Checking and refilling levels
Tyre useful life
The useful life of tyres is dependent on tyre pressure, driving
style and fitting.
Fig. 142 Tyre tread wear
indicators
Fig. 143 Diagram for
changing wheels Wear indicators
The original tyres on your vehicle have 1.6 mm high “tread wear indicators”
⇒ Fig. 142, 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 217.
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. 143. 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.
