Tyre Technical

Tyres are highly-engineered, complex components that suffer a tough life and have extreme demands placed upon them.
In general, a tyre has four main functions:

  • To contain a volume of pressurised air
  • To transmit traction and braking forces to the road surface
  • To provide directional stability
  • To supplement the vehicle’s main suspension system
    It’s also important to remember that it’s only the four contact patches of your tyres, each about the size of your hand, which are responsible for your car’s acceleration, steering and braking. So, it’s important that you select your tyres correctly and look after them when they are fitted.


Tyre design is something of a compromise. Many functions the tyre has to perform contradict each other such as grip vs long service life, or rapid steering response vs comfortable ride.
When choosing tyres think carefully of what is most important to you to get the right balance of performance criteria – eg fuel economy or wet grip. Ask your tyre dealer to recommend a tyre which is most suited to your vehicle and these requirements.

Tyre markings

The markings on your tyre sidewalls contain a vast amount of information which is extremely detailed.
For most, the important markings relate to the size, load and speed index as these are often needed seeking a replacement. Don’t just rely on the sidewall markings for the size when replacing tyres as the current tyre may have been incorrectly selected and fitted to the car. It’s always best to check your vehicle handbook or with the vehicle manufacturer for the correct size. Also, the pressure settings printed on the sidewall are not the recommended levels. (See Tyre Basics)
For those curious about what all of the markings mean, TyreSafe has unscrambled the mystery

Winter tyres

Until recently demand for winter tyres in the UK was extremely low. However, many drivers are now waking up to the added safety benefits of winter tyres.
Winter tyres are not to be confused with ‘snow’ or ‘studded tyres’. Winter tyres have a tread pattern with more sipes (or fine tread grooves) and more importantly, contain more natural rubber. This means they do not harden in cold temperatures and can therefore grip the road more effectively than standard ‘summer’ tyres.
Winter tyres perform more effectively (i.e. shorter stopping distances and higher levels of grip) at temperatures below seven degrees Celsius. It’s therefore recommended that drivers in the UK switch to winter tyres in October when it becomes cold and damp and then back to summer tyres in April when temperatures rise.
While performance in the snow and ice is dramatically improved with winter tyres, they also offer much improved safety in cold, wet conditions and are therefore appropriate for the entire winter period.

Runflat tyres

Runflat tyres are nothing new although their use has increased significantly in recent years.
Runflats have reinforced sidewalls which can support the weight of the vehicle in the event of loss of air. They allow drivers to travel for 50 miles at 50mph without any air in the tyres.
Runflat tyres which have been damaged or driven while ‘flat’ cannot be repaired as significant damage may have occurred to the internal structure of the tyre.
It’s essential that runflat tyres are only fitted to cars equipped with a tyre pressure monitoring system (TPMS) as drivers will be unaware that their tyres have lost pressure.


Tyre pressure monitoring systems (TPMS) have become increasingly popular, including aftermarket systems and in line with EU legislation, all new cars built from 2012 onwards must include a TPMS.
The systems monitor loss of pressure inside the tyre and alert the driver to this problem. Not only will this help drivers improve their fuel efficiency (as it will ensure correct inflation levels are maintained), it is also expected to reduce a number of tyre related accidents as blowouts often occur as a result of under-inflated tyres.
Drivers of vehicles with TPMS fitted should ensure their systems are regularly serviced in line with the vehicle manufacturer’s specifications to ensure their ongoing reliability and accuracy.

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