Tyre basics

Minimum tread depth
Tyres on cars must have a tread depth of at least 1.6mm. However, below 2mm of tread, wet weather performance drops considerably, so change your tyres sooner rather than later.

Run-flat and temporary use spare tyres
Regulations permit the legal use of ‘run-flat’ tyres (provided they are identified as such) in a partially inflated or flat condition, and what are described as ‘temporary use’ spare tyres. When a temporary use spare tyre is being used, the vehicle speed must not exceed 80kmh, and a special high-inflation pressure is normally used, otherwise the legal provision which permits their use ceases to apply. The temporary use spare must have a label of different colour attached to the wheel giving clear information about the precautions to be observed when it is being used.

Tyre care
The essential ingredient for keeping tyres in good condition, to provide optimum performance and give maximum life, is air. It is air that keeps tyres fit and safe and carries the weight of the vehicle and its load, not the rubber or the casing material.

Tyre care at home or in the garage
Tyres should be checked regularly either at home or when visiting a service station or tyre service centre. In particular, prior to any journey they should be examined for obvious signs of underinflation, wear, cuts in the tread or sidewalls, bulges in the sidewalls, and stones and foreign objects trapped in the tread grooves (which should be removed). It is useful to check for leakage at the valves (especially following inflation) and to replace missing valve caps. A small tool can be obtained to check remaining tread depth. If the tyres show any sign of uneven wear the vehicle should be checked to ensure correct alignment and balance of the wheels.

Tyre pressures should not be checked during or immediately after a journey while the tyres are still warm. This will result in an incorrect pressure reading. It is worth investing in a pocket tyre gauge so you can check pressures regularly.

Tyre maintenance check list
Tyres will provide greater life if they are properly maintained – it is an inexpensive task which takes only a few mwheninutes at regular intervals. The following checklist will be helpful in this task:

  1. Check the correct pressures against the manufacturer’s recommendations as given in the vehicle’s handbook.
  2. Adjust pressures as necessary.
  3. Clean dirt from valves and fit valve caps all round.
  4. Remove stones and other foreign objects from treads.
  5. Have the steering alignment corrected if front tyres show signs of excessive or uneven wear.
  6. Examine brakes if tyres show signs of wear through wheel locking.
  7. Have front wheels and tyres balanced if there are signs of vibration, wheel wobble or patchy tyre wear.


Tyre care on the road
The way in which a car is driven can contribute to excessive tyre wear and damage. For example, not adjusting the pressures when the car (or van) is fully laden or when driven at high speeds are major contributors. The following additional advice will help to protect your tyres:

  1. When undertaking long journeys, especially at speed on motorways, examine the tyres both before and during the journey (but do not check pressures while the tyres are warm).
  2. Avoid harsh braking, fierce acceleration and fast cornering (the steering wheel of cars with power steering should not be turned while the car is stationary).
  3. Avoid driving over or scrubbing against kerb edgings or other raised obstructions.
  4. If it is absolutely necessary to drive over rough, uneven, unmade ground or over ground littered with debris, check the tyres soon afterwards to ensure that no foreign objects have become trapped in the tread patterns and examine the sidewalls for cuts or bulges.
    Avoiding tyre troubles
    There are many individual causes of tyre troubles. However, the three abuses which will cause most problems, and the greatest costs, are underinflation, overloading and speeding.

    Underinflation
    Surveys show that at least 20% of all tyres are significantly underinflated. Neglect of inflation pressures is one of the principle causes of rapid shoulder wear, uneven tread wear and premature tyre failure, and it is an abuse which surveys show to be on the increase. NB. It should be stressed that overinflation may also result in inferior vehicle handling, excessive tyre wear and premature failure.

    Overloading
    Loading cars, light vans and lightweight trailers above what they are designed to carry is illegal. It is also likely to put excessive strain on the tyres, resulting in greater than normal deflection and overheating which, in turn, lead to more rapid wear, greater susceptibility to impact damage and the danger of premature failure. NB. The vehicle’s handbook will give increased inflation pressures for full load conditions.

    Speeding
    Travelling for long distances on motorways at sustained high speeds and generally exceeding statutory speed limits imposes strenuous demands on tyres, especially in terms of heat generation. Tyres in good condition and correctly inflated are designed to withstand the heat build-up at their maximum rated speeds. However, if inflation pressures are significantly below those recommended then excessive heat will be generated and, in consequence, wear will be accelerated and deflection will be greater with the risk of premature, and sometimes catastrophic, failure.