Tyres
should be inspected often, and the following list
highlights some of the faults to look out for. If
any of these conditions are present, consult a tyre
expert.
1.
One-sided wear. This takes various forms. A regular
smooth band of wear all around the tyre on the inside
or the outside of the tread is a sign of incorrect
camber. Too much toe-in causes irregular one-sided
wear.
2.
Tread-centre wear. Regular wear of this kind is normally
a sign of high tyre pressure. Driving fast for long
distances may cause this on low-profile tyres, because
traveling at 120 km/h wears a tyre out twice as fast
as travelling at 70 km/h.
3.
Inner- and outer-edge wear. If both inner and outer
edges are worn, it usually implies that the tyres
have been run at too low a pressure at normal speeds.
4.
Irregular bald spotting. Known as cupping, this is usually
caused by worn shock absorbers, worn suspension bushes,
or even loose wheel bearings.
The
importance of the correct pressure can not be over-emphasised.
If the pressure is too low it affects the tyre in
a number of ways.
As
speed rises, excessive contact patch deformation leads
to a wave being formed in the tread, which generates
excessive heat, causing structural damage or even
tyre failure. The extra flexibility will affect steering
behaviour, directional stability, durability and rolling
resistance. Even occasional low pressure driving,
or periodic vehicle overloading, may cause damage
that only shows up much later as a blowout.
Tyre
pressures, including the spare, should be checked
at least once a week, before the tyres have heated
up, ie before 10 km have been driven, using a good
pressure gauge.
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| This
tyre shows a dangerous cut in the centre of the
tread and uneven wear. Would you trust it at high
speed? |
Missing
valve caps should be replaced, since they are there
to prevent dirt from clogging the valves, which could
cause a loss of air pressure.
Tyre
rotation is a very contentious area, with some companies
recommending it, other companies saying nothing, and
BMW for one advising against it. Rotating the tyres
regularly evens out the wear, but eventually all the
tyres will have to be replaced at the same time, which
is expensive.
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