Tyre Tips & Safety
The three most common causes of tyre problems, are under-inflation, overloading and speeding.
Under-inflation
Surveys by tyre service engineers show that at least 25 per cent of all tyres examined are under-inflated by more than 10 per cent. Neglect of inflation pressures is one of the principle causes of rapid shoulder wear, uneven tread wear and premature tyre failure.
Overloading
Loading cars, above what they are designed to carry is likely to put excessive strain on the tyres resulting in greater than normal deflection and overheating which, in turn, leads to more rapid wear, greater susceptibility to impact damage and the danger of premature failure.
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.
What the law requires
- Tyres must be suitable (ie of the correct type and size) for the use to which the vehicle is being put and must be inflated to the vehicle or tyre manufacturers' recommended pressures.
- Tyres of different types must not be fitted to opposite wheels of the vehicle (for example, radial-ply tyres must not be fitted to a wheel on the same axle as wheels already fitted with cross-ply tyres and vice versa, and a two-axle vehicle with single rear wheels must not have radial ply tyres on the front axle if cross ply tyres are fitted to the rear axle).
- No tyre must have a break in its fabric or a cut deep enough to reach the body cords. No cut must be more than 25mm or 10 per cent of the tyre's section width in length, whichever is the greater.
- There must be no lump, bulge or tear caused by separation or partial fracture of its structure, neither must any portion of the ply or cord structure be exposed.
Minimum tread depth
Tyres on cars, light vans (not exceeding 3,500kg gross weight) and light trailers must have a tread depth of at least 1.6mm* across the central three-quarters of the breadth of tread+ and in a continuous band around the entire circumference of the tyre. * For goods vehicles over 3.5 tonnes the minimum tread depth requirement remains at 1mm (along with other requirements). + Breadth of tread means the width of that part of the tyre which is in contact with the road surface under normal conditions.
Checking tread depth Lifesaver in your pocket
Checking the tread depth of your tyres may be a lot easier than you think. Inserting a 20p coin into the main tread grooves of your tyres gives you a good indication of whether your tyres have sufficient tread depth. If the outer band of the 20p coin is visible when inserted into the tread, your tyres may be illegal and you should have them checked by a qualified tyre specialist. If the outer band is not visible on the coin, then your tyres have a tread depth well above the legal limit.
The Law
The current law states that tyres must have a minimum of 1.6mm of tread across the central three quarters of the tyre, around its whole circumference. Drivers with tyres that fail to meet these standards face a fine of up to £2,500 and three penalty points per illegal tyre.
The dangers
Vehicles fitted with tyres that do not have the legal amount of tread pose a danger to the driver of that vehicle and to other road users. Stopping distances are increased, cornering ability is reduced and the likelihood of aquaplaning is increased, all as a result of illegal tread depth.
Tyre maintenance check list
Tyres will provide greater life if they are properly maintained - it is an inexpensive task which takes only a few minutes at regular intervals. The following Check List will be helpful in this task:
- Check the correct pressures against the manufacturer's recommendations as given in the vehicle Handbook.
- Adjust pressures as necessary.
- Clean dirt from valves and fit valve caps all round.
- Remove stones and other foreign objects from treads.
- Have the steering alignment checked if front tyres show signs of excessive or uneven wear.
- Examine brakes if tyres show signs of wear through wheel locking.
- Have front wheels and tyres balanced if there are signs of vibration, wheel wobble or patchy tyre wear.
TyreSafe, the non-profit tyre safety organisation has issued a warning to motorists in light of a recent increase in the number of premature tyre removals as a result of either kerbing damage or uneven tread wear due to wheel or axle misalignment.
Motorists mounting or hitting a kerb usually occurs during a parking manoeuvre. As most modern cars are now equipped with power steering, drivers consider that the presence of a kerb is not an obstacle to manoeuvring a car into a tight spot, which may lead to a tyre’s sidewall being pinched between the kerb and the wheel, or the steering system becoming misaligned.
Drivers are often unaware of any problem associated with such a manoeuvre until either the tread pattern shows rapid and irregular wear or a bulge appears on the tyre sidewall which increases the likelihood of an accident. The level of grip of an unevenly worn tyre is unpredictable in the wet, whilst a sidewall bulge, the result of a fracture in the carcass of the tyre, can cause a tyre to either lose pressure or in a worst case scenario a tyre blow-out.
Whilst it should be common practice for motorists, TyreSafe recommends that tyres should be maintained at the levels of pressure recommended by the vehicle manufacturer. The association also points out that drivers who are aware of having impacted a kerb with some force should have the tyre(s) inspected for any damage and the vehicle alignment checked by a tyre dealer. Tyre sidewall damage cannot be repaired and may lead to possible failure because of the leaking of air from the tyre.
http://www.rospa.com/roadsafety/advice/motorvehicles/tyres.htm#Law
http://www.theaa.com/motoring_advice/safety/car-tyres.html
http://www.rospa.org.uk/roadsafety/advice/motorvehicles/index.htm