Why are my tyres tearing after 10 laps?

Q. I was recently at the Motorland circuit in Spain. This track is very fast and has a strong left-hand bias and is tough on tyres.

The Dunlop Sportmax slick fitted to my 2004 Yamaha R1 wore really badly on the left side after 10 full speed laps.

What causes a tyre to wear like this and what can I do to prevent it?
Darren Starsmore, email
 
A. What you’ve got there is “cold tearing” which can have a number of causes, like the tyre compound chosen, suspension set-up, weather conditions, track surface and riding style.

Any of these parameters can affect, or be linked, to grip generated – which in turn generates heat, and this can amplify the surrounding issues.

According to Mark Sears, Chief Design and Development Engineer on bikes at Dunlop Motorsport: “This problem is part of a vicious circle – use a strong durable compound and little heat is generated, resulting in poor grip and often tearing.

“Use a softer compound to generate grip and tearing occurs again through lack of compound strength.

“Historically, cold tear occurs when the compound selected is not generating enough heat, hence it is ‘cold tearing’ and the polymers within the compound are breaking down.

“The tyre will have an operating temperature range of between 80-120°C and anything outside of this window could have adverse affects: too hot and the tyre squirms, too low gives inferior grip and abnormal wear pattern (such as cold tear).

“Likewise a poorly set up machine can extenuate the abrasion level, as can over enthusiastic throttle control. Pressure is less critical but will affect it: too low will give a larger contact patch to spread the load, create more deflection and thus heat.”