Influences on Car Tyre Design

What are the key technology developments that are influencing tyre design?

There are two main areas of technical development which are currently exerting the greatest influence over tyre design - rolling resistance and noise generation.

The reduction of a tyre's rolling resistance has the effect of reducing a vehicle's fuel consumption. This has been achieved through the effective use of silica in the tyre's tread compound. The impetus for developments in this field initially came from the tyre industry. However, these developments are now also being driven by the vehicle manufacturers. For more information on silica technology click here.

Michelin has been a pioneer in the trend towards lower rolling resistance with the introduction of their Energy range of tyres

The demand for lower noise, meanwhile, has resulted in a substantial change in tread pattern design in recent years. 8-10 years ago, for example, low profile tyres were characterised by open block patterns to assure swift water dispersal. This type of pattern, however, is not only noisier, it wears quicker too.

Now, largely due to increased legislation and improvements in compound technology, we are seeing a move to quieter rib type patterns broken up by narrow cross grooves with the blocks close together. With more rubber on the ground, this means not only better dry grip but improved mileage performance, no loss in wet grip and, of course, lower noise.

Meanwhile, the advent of computerised tyre modelling by tyre engineers has allowed tyre designers to calculate the optimum pitch sequence of the tread blocks in order to calculate the best possible tread design in terms of noise reduction.

The future importance of rolling resistance and noise generation in tyre design depends to a degree on the prevailing legislation. It is likely that future developments in terms of tyre noise reduction will focus on the tyre's ability to direct noise into the wheel arch where the noise can be dampened. Meanwhile the future development of electric vehicles will be a major factor in determining the future importance of rolling resistance in tyre design.

How do Design Influences Differ Between the OE and Aftermarket?

The original equipment manufacturers tend to be interested in three principal performance related areas when specifying new tyres for their vehicles. General handling, noise and comfort requirements are the main influences placed on the tyre manufacturer by the OE market although fuel consumption is a fourth area which is increasing in importance.

Goodyear's Infinitred tyre, designed for the US market, has been created with mileage performance as the overriding performance characteristic

Traditionally, tyre technology has been OE driven with technical advances being pulled along in line with technical advances in vehicle design. In the aftermarket, however, the main influencing factors are price and mileage performance which tend to be optimised to the detriment of other performance areas.

This, of course, brings us to the key question. Is the replacement tyre you buy from a tyre dealer exactly the same as the same brand and model of tyre that was fitted to your new vehicle? The answer is probably not. Tyres have to go through more than 50 different tests in order to get an OE approval and include minor design amendments that are often specific to the vehicle they fit. Aftermarket tyres, however, for economy of scale reasons and to avoid stocking problems at tyre dealer level, tend to be the best the best possible compromise between design criteria. Having said this, any minor design variations will be so minute that even the most discerning driver could not tell the difference.