The modern tyre is an intricately woven mixture of steel belts, advanced fabrics and rubber compounds. A far cry from the solid piece of rubber of early days. Radial tyres have become the industry standard, displaying many advantages over cross-ply tyres, in terms of wear, heat resistance and rigidity.
Any car less than 20 years old, should be fitted with radial tyres. Never mix radial and non-radial tyres. It could lead to poor handling and loss of vehicle control.
Standard car tyres usually have a symmetrical pattern running across the entire tread. Some high performance cars however are fitted with tyres with special tread patterns. These asymmetric and directional tyres must be fitted the right way round on the wheel. Incorrect fitting of both is a reason for MOT failure.
Asymmetric tyres have differing tread patterns on the inner and outer edges of the tread to improve performance.
On the outside edge, large stiff tread blocks help with cornering. On the inside edge, smaller tread blocks are designed to shift water and improve wet grip. The middle of the tread often has a continuous rib to help straight line stability.
The words ‘inside’ and ‘outside’ on the tyre sidewall indicate which way round the tyre should be fitted.
Directional tyres are designed to rotate in one direction only which is indicated by an arrow on the tyre sidewall.
These tyres are better at dispersing water which builds up in front of the tyre. They also reduce road noise and improve directional stability.
An alternative to winter tyres are All Season Tyres. These have a high silica content for low temperature flexibility and a tread pattern somewhere between a normal summer tyre and a winter tyre.
They are rarely as good as a specialist tyre but do perform better than a summer tyre on wintry roads and do avoid the hassle and cost of swapping wheels and tyres twice a year.
When replacing tyres, the safest option is obviously to choose new tyres. Part worn tyres can be fitted but various criteria have to be met. The Motor Vehicle Tyres (Safety) Regulations 1994 set out minimum safety standards for the supply of part-worn tyres.
Under the Regulations, part-worn tyres (except retreads) should have an EC approval mark and a speed and load capacity index moulded into the sidewall at the time of manufacture. In addition, all types of part-worn tyres must be marked ‘PART-WORN’ in upper case letters at least 4mm high.
It is illegal to have unsafe tyres in possession for sale.
Many vehicle manufacturers today supply their new cars with a non-standard spare wheel and tyre. This is lighter and slimmer than normal to save weight and space. For that reason, there is a maximum speed limit when using it – usually 50mph.
A space-saver wheel is intended for emergency purposes and should only be used as a temporary measure. Motorists should be advised to get the original car tyre repaired or replaced as soon as possible.
