Tor,
     
>I think that was the same type of tires the PO used for the road,but with 
>almost no tread left when we bought the car. I can't
>see the reason, they give no grip until they are warm,and according to 
>you they do not even get warm on the track :-/
Oops.  I just got your question.  Performance tires, and especially the 
ones with the softer compounds, have an optimum operating temporature, 
usually higher than ambient since competition motoring would put them at 
a higher temperature anyway.  Outside that range (up or down), they don't 
grip as well.
Rod 
     
     
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