The amount of advanced technology that goes into today's premium branded car tyres is often not appreciated. Tyres, after all, are usually a distress purchase and to most consumers are simply "black and round".

Tyre technology, however is continuously evolving, driven to a high degree by the technical demands of the vehicle manufacturers but also, to a degree, by the requirements of an increasingly demanding aftermarket.

Tyre performance can be affected by three things - by changes to the tyre structure, by altering the tread pattern and by varying the rubber compounds used in the tyre, particularly in the tread. It is not surprising to see that the leading tyre manufacturers have a variety of proprietary technologies covering all these areas.

Take Bridgestone for example. Currently, the world's largest tyre manufacturer lists 14 key technologies covering, casing, tread pattern design and compounding. Some of these, such as the use of unidirectional tread patterns, silica compounds and rim guards to protect against kerbing damage are commonplace but some are unique to Bridgestone. Examples of the kind of technologies highlighted by Bridgestone are:

Diamond Bead - A new construction method for the bead coil, which increases the torsional stiffness of the bead coil to create a more uniform contact patch and therefore improved handling.

Flat Force Block - A new tread block design, which varies the angle of the block edges in accordance with their size. This provides a more uniform contact pressure and therefore a smoother ride.

Key Hole Sipes - These narrow slots in the tread increase in width as the tyre wears helping the tyre to maintain performance as it gets older.

Multicell Compound - An advanced and unique foam rubber based compound, the high porosity of which anables water absorption and an increased "edge-effect" to improve grip on ice.

Riblet - These are circumferential micro-grooves located on the surface of multicell compound tyres. These aborb a film of water on icy surfaces for improved grip when the tyres are new and before the multicell pores become visible.

If tyre manufacturers are continuing to evolve their tyre technology with a view to gaining a competitive advantage over their rivals, there are certain areas of technology, which are coming in for particular attention. One of these is undoubtedly the area of run-flat tyres and the associated area of tyre pressure monitoring systems.

The leading manufacturers differ to some degree in the tyre technology they are using for their run-flat systems.

Michelin's PAX system, for example incorporates a special wheel with an asymmetric profile, which allows a support ring to be inserted, which bears the vehicle's load and allows it to be steered at zero pressure.

However, their Michelin ZP system functions by means of more robust sidewalls, reinforced with a special rubber compound to carry the vehicle weight. An innovative bead area, delps the deflated tyre stay on the rim.

A further example of the use of compounding to obtain a stiffer sidewall is Goodyear's Run-On Flat system. This system incorporates reinforced sidewall inserts using Goodyear's own compounding technology in order to create higher sidewall striffness. In addition, rim guards and tensioning devices on the outside of the sidewall are used to help maintain tension in the case of a flat.

Continental, like Michelin has two systems. The ContiSupportRing is a metal ring on a flexible support directly mounted on the rim, whereas the company's SSR self-supporting run-flat tyre incorporates a special rubber reinforcement in the sidewall, which takes the vehicle weight after pressure has been lost.

Bridgestone has also taken the support ring route with its Bridgestone Support Ring system.

So where next for tyres? We wait with interest to see how the tyre manufacturers can further innovate their products and keep improving tyre technology.