Today＇s challenge for the tyre designer is his ability to quickly define the better tyre meeting the very stringent and diversified specifications of tyre users and car makers. The design tools at his disposition include both experimental (analytical trye measurements or vehicle trials) and simulation. The latter has the advantage of allowing tyres to be optimised before they are made. Its performance depends on its ability to predict the physical data needed to analyse tyre performance and its reliability and response time.