The Tyre Law

Tyre pressures

Tyre pressures should be maintained at or within a very close tolerance of the recommended pressures.

Tyre types

It is illegal to mix tyres of a different construction (cross-ply; bias belted or radial) on the same axle. Cross-ply and bias-belted tyres are seldom used on production cars, and are not widely available in the UK. Cross-ply and radial tyres should never be mixed on the same vehicle. Where a mix is necessary, radial tyres MUST only ever be used on the rear axle and cross-ply tyres on the front. This mix of tyres will produce 'understeer' whereas the opposite will produce 'oversteer'. (Oversteer refers to the car turning more tightly into a corner than it is steered; understeer indicates that the vehicle turns at less of an angle than it is steered). Of the two conditions, understeer is generally accepted to be easier to control.

Part-Worn Tyres

What are part-worn tyres?

'Part-worn' tyres are those which have been used previously - in other words they are 'second-hand'. Most part-worn tyres are imported, mainly coming from continental Europe.

What are the potential problems with part-worn tyres?

Part-worn tyres are usually sold with about 50 per cent or less of their original tread remaining (legal minimum is 2mm) and may have a few thousand miles more motoring in them. However, despite their remaining tread, it must be appreciated part-worn tyres are nevertheless USED TYRES. As such their purchase and use should be treated with a degree of healthy scepticism. In many cases, such tyres will be perfectly sound. However, it is possible that they have been bumped up and down kerbs and over other obstacles. They may have been run over or under-inflated, and may have sustained irreparable and invisible damage to their structure.

The cost of part-worn tyres reflects their second-hand state and this no doubt contributes to their attraction to motorists. The purchase and use of part-worn, instead of new, tyres may enable some owners to afford to keep their vehicles on the road. The tyre industry continues to express concern about the sale and use of part worn tyres. However, it is important to consider the issue objectively and make a reasoned judgement about the real risks of using such tyres.

RoSPA's advice, like that of Trading Standards Officers, is 'let the buyer beware'. Whether the purchase of part-worn tyres is a good economic proposition or not, there can be little argument that a tyre which is only half worn but is in all other aspects sound, is likely to be safer than a tyre worn to the legal limit.

Before purchasing part-worn tyres always ask to see them inflated before they are fitted to the vehicle and check for any lumps or bulges.

Retreaded Tyres

What is a retreaded tyre?

A retreaded tyre - also known as a remould - is made from a used tyre. Old tyres which are not sound should never be used as components for retread tyres. The essential building block for a retreaded tyre is a used tyre whose tread is worn-out but whose carcass (basic structure) is sound. Retreading involves stripping away both the remaining tread and sidewall of the used tyre. The final part of the process moulds new rubber to the old carcass.

What standards govern the production of retreaded tyres?

In the past, retread tyres have been manufactured in accordance with BS AU 44e. However, this standard did not specify a type approval test for retreaded tyres, which would guarantee a standard tyre quality.

On 1st January in 2004, ECE Regulations 108 and 109 came into effect, making it mandatory for retreaded tyres to be subject to a type approval test. This ensures that retread manufacturers must meet a specified basic standard in terms of the tyres' suitability for retreading prior to the process, and their performance after it. It is now illegal to sell retreaded tyres that that do not have the "e" mark.

Are there any problems with retreaded tyres?

In the majority of cases, retreaded tyres perform satisfactorily provided the manufacturer's guidance about maximum vehicle loadings and maximum speeds is followed. Like all tyres; overloading, sustained high speeds, and under or over-inflation all contribute to increased tyre wear and/or premature failure.

Never buy a retreaded tyre without the "e" mark.

Illegal tyres

Tread

It is illegal to have a tyre on the road if the grooves of the tread pattern of every tyre fitted to the wheel of the vehicle do not have a tread depth of at least 1.6mm throughout a continuous band comprising the central three quarters of the breadth of the tread and around the entire outer circumference of the tyre. (Breadth of tread means the width of that part of the tyre which is in contact with the road surface under normal conditions).

This applies to tyres on cars, light vans (not exceeding 3,500kg gross weight) and light trailers.

For goods vehicles over 3.5 tonnes the minimum tread depth requirement remains at 1mm (along with other requirements).

It is also illegal to have a tyre on the road if the tyre:

· Is not suitable for the chosen use of the vehicle or trailer

· The tyre is not suitable relative to the other types of tyre fitted

· Is not properly inflated

· Has a cut or break in the rubber in excess of 25mm or 10% of the section width in length which exposes the casing cords

· Has a lump or bulge caused by separation or partial failure of it's structure

It is illegal to drive if:

· Tyres of a different structure (i.e diagonal (cross)ply, radial or belted radius) are fitted on the same axle

· Radial tyres are fitted on the front axle with diagonal(cross) ply tyres on the rear axle

· A temporary spare is being used outside it's stated limitations

Failure to comply with the above:

· Could lead to prosecution, a heavy fine and a driving licence penalty

· Will lead to failure in a legal inspection

· Undermines the safety of all road users

Legal requirements - care and condition

It is a legal requirement to keep tyres in good condition.

The following regulations apply:

· All tyres must be suitable (i.e. the correct type and size) to the vehicle

· All tyres must be inflated to the vehicle or tyre manufacturers' recommended pressures

· 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

· 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% 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 a tyre's structure

· No portion of the ply or cord structure should be exposed

Run flat and temporary use spare tyres

Regulations permit the legal use of "run flat" tyres and what are described as temporary use spares (provided they are identified as such) in a partially inflated or flat condition.

The following conditions apply:

· The vehicle speed must not exceed 50mph

· The temporary use spare tyre or the wheel to which it is fitted must be a different colour to the other wheels on the vehicle

· A label must be attached giving clear instructions about the precautions to be observed when it is being used

If you do not comply with the above, the legal provision that allows their use ceases to apply.

Lightweight trailer tyres

From 1 April 1987, tyres fitted to lightweight trailers must be designed to support the maximum axle weight recommended by the manufacturer at its maximum permitted speed (i.e. currently 60mph).

To the best of our knowledge, the information contained here is correct, but the law is subject to change from time to time.

If you need specific legal advice you should consult a solicitor for a full appraisal of the relevant aspects of the law.