Kjeld, I‘m also invested in this tire combination. The Avons are track tires, but still street legal. They have about 5mm of useful tread depth and are made with a soft compound, meaning relatively rapid wear with outstanding traction, but will also pick-up small stones and shoot them to rear of the car. Avons are used by the Cobra colleagues and you will find plenty of interesting threads in their forums. Alternatives are Pirelli P12 in 255/60/VR15 and Pirelli P6000 in 205/60/VR15.