Marcos - thanks for the link. Interesting read. Now that the thread is 5 1/2 years old we have a bit more data to go on. Most of the arguements posed in that thread say that rubber tires do not (or should not) perform as well on pan cars as foam. While that is obviously true, I think that with the advent of the GT-R class and the performance achieved in F1, I wonder if those assumptions still hold to such a large degree?