Durometer reading.

[oldtrackchamp4x]

Would a tire with a 55 reading be much better on a dry slick track as compared to a tire with a 6o reading and with all other things being equal, or could you even tell the difference?

[powerslide]

Unless you are running more than 20 laps the 55 would be better. Unless you are running somewhere rubbered up or extremely abrasive, then the 60 MIGHT be better at the end.