Any tyre fitted to the axle of a goods vehicle must be designed and manufactured to be strong enough to support the maximum permitted axle weight. Legislation sets out various rules for mixing tyre types and requirements for maintenance.
Aside from the safety risks that incorrect tyres can pose, it is worth noting that the penalties for illegal tyres on a goods vehicle are up to £5,000 fine and three penalty points, and possible disqualification from driving.
The responsibility is wide-ranging as not only is it an offence to use on the road a vehicle which does not comply with the following requirements, it is also an offence to cause or permit a vehicle to be so used, therefore covering drivers and management alike.
Most goods vehicles will have pneumatic tyres, however they are produced with different structure types.
Here is a quick guide on how to tell your bias-belted from your diagonal ply:
- the ply cords are laid at alternate angles of substantially less than 90 degrees to the peripheral line of the tread
- the ply cords are constrained by a circumferential belt of two or more layers of substantially inextensible cord material laid at alternate angles smaller than those of the ply cord structure.
- the ply cords are laid at alternate angles of substantially less than 90 degrees to the peripheral line of the tread, but not a bias-belted tyre.
- the ply cords are laid at an angle of substantially 90 degrees to the peripheral line of the tread
- the ply cords are stabilised by a substantially inextensible circumferential belt.
With a variety of types of tyre structure available, it is illegal to mix different types of tyres in certain circumstances:
- Different types of structure should not be fitted to the same axle
- A vehicle with only two axles, each equipped with one or two single wheels should not be fitted with:
- a diagonal-ply tyre or a bias-belted tyre on its rear axle if a radial-ply tyre is fitted on its front axle
- a diagonal-ply tyre on its rear axle if a bias-belted tyre is fitted on the front axle.
- Tyres fitted to the steerable axles, or the driven axles, should be of the same type of structure.
Conditions and maintenance
Tyres of the right type and combinations are no use if they have been poorly maintained and in such a condition as to create a risk when used on the road.
It is illegal to fit a tyre on HGVs, if:
- It is unsuitable for the use of the vehicle, such as using a tyre at a higher speed or heavier load than the service description specifies
- It is unsuitable in terms of the types of tyre fitted to the other wheels (see above)
- It is not suitably inflated, for example in terms of the vehicle manufacturers’ guidance;
- It is not maintained in such condition as to be fit for the use of the vehicle.
- It has a defect which might in any way cause damage to the surface of the road or damage to persons on or in the vehicle or to other persons using the road
- It has a cut in excess of 25mm or 10% of the section width of the tyre (whichever is greater), and is deep enough to reach the ply or the cord
- It has a lump or bulge or tear caused by separation or partial failure of its structure
- It has any of its ply or cord exposed, no matter how small the cut is.
- The base of any groove which was in the original tread pattern is not clearly visible
- the grooves of the tread pattern do not have a depth of at least 1 mm throughout a continuous band measuring at least three-quarters of the breadth of the tread and round the entire outer circumference of the tyre, or
- if the grooves of the original tread pattern did not extend beyond three-quarters of the breadth of the tread, any groove which showed in the original tread pattern does not have a depth of at least 1 mm.
A re-cut pneumatic tyre should not be fitted if either its ply or cord has been cut or exposed by the re-cutting process; or it has been wholly or partially recut in a pattern other than the manufacturer’s recut tread pattern.