Materials, eco tyres and progress

摘要

Over the last few weeks I've been canvassing views on the development of eco-friendly tyres. It's been quite a fascinating journey, and generated some results I was not expecting. It's now over 20 years since Michelin first launched a silica tread compound onto the market. Since then, we've discovered a lot about rolling resistance. One of the first things we learned was that rolling resistance and wet grip are inextricably linked. That is based on the hysteresis function: the more energy a compound absorbs as it distorts, the more grip it offers on a wet road. Unfortunatley, however, that same equation leads to poor fuel efficiency. There is one small difference between these two measurements, however, and that is the timescale of the response. Where the distortion due to rolling is concerned, the timescale is measured in a few milliseconds.