Just accidentally found this on a forum which seems dedicated to tyres. One guy has written to Avon regarding Cobra Tyres & he has posted the reply, here it is & I hope he doesn't mind.
Dear Gary,
Thank you for contacting Avon Tyres. The Cobra features a single tread compound, but uses technology derived from our sport tires to give it amazing handling & grip across all areas of the tread. Our casing design helps to give you a very large contact patch while cornering, by using our system called Advanced Variable Belt Density. This system uses material wound around the tire at a zero degree angle. Each strand is wound farther away as they reach the shoulder of the tire, giving you a giant contact patch while leaning. The strands of material are wound closer together in the center of the tread for added stability and wear resistance. This system gives you the benefits of extra grip on corners and a more stable, wear resistant center patch all while being much more predictable than duel compounds.
Thank you for your interest in Avon Tyres and ride safely.
Jesse Priel
Avon Customer Service
c/o Hoppe & Assoc, Inc.
PO. Box 5112
Lynnwood, WA 98036 USA
Tel: 800-624-7470, Fax: 425-771-4246