Tyres Whitwick with KCR Service and MOT Centre

Tread Depth & Safety

Tread Depth

A new car tyre begins life with approximately 8 mm of tread. The minimum legal tread depth is 1.6 mm, although the majority motoring organisations recommend replacing your tyres at 2 mm, and the majority of tyre manufacturers recommend changing at 3 mm.

As the tread depth reduces, the tyres ability to remove water from the road surface also reduces, increasing the risk of aquaplaning and because the tyre is unable to transmit traction and braking forces to the road as effectively the vehicles stopping distances increase.

You can check how close you are to the legal limit on all tyres by looking for the tread wear indicators:

These indicators are small raised areas at the bottom of the grooves. If the surface of the tread rubber is level with these raised areas the tyre tread depth is most likely very close to the legal limit of 1.6 mm, or could even be below it! The tyre should be checked and if necessary changed, because you may no longer be driving in sufficient safety and you could be breaking the law.

You can also carry out the simple 20p Test

Tyre Pressures

The correct tyre pressure is important for two reasons:

Safety and Economy-

• Safety can be reduced because of the higher risk of over/understeer, an increase in braking distances and a higher risk of aquaplaning
• Economy:- tyres with incorrect pressure will have a reduced life span and can increase fuel consumption

Checking tyre pressure

Tyres and their pressures should be checked regularly, at least once a month and before long trips, as they are susceptible to drops in pressure which can be caused by:

• natural leakage of air through the walls of the tyre
• drops in ambient temperature
• slow puncture

If your tyres are under inflated then your braking distance in the wet can be increased by up to 11m; that's more than the width of 2 pedestrian crossings or 2.5 car lengths

Prolonged running on under inflated tyres causes excess heat in the tyre, and in exceptional cases, can cause the tyre to fail and cause a rapid deflation.

If a tyre is 20% down on the correct pressure it will have a reduction in life of just over 20% (depending on use). This could mean replacing the tyres up to 5,000 miles sooner than normal.

Over-inflation will also increase abnormal wear which will be particularly accentuated in the middle of the tyre.

Under-inflated tyres will cause the engine to work harder and will increase your fuel consumption. A set of tyres that are under-inflated by 10psi will have the same effect as increasing the cost of fuel by 3p per litre (based on £1 per litre).