[Perfectlap]

How smooth is your typical autocross venue? Here in NJ we had one that was awful and another (stadium) that is the total opposite. If the surface sucks (think hard oatmeal) you will shred an expensive set of tires quickly. I made this mistake the first time I mounted r-comps.

Also consider the effect of doing double duty (street/track) on the same tires in your weather region. Here we get couple months of warm and lots of cold. The street use wears out the tire and on coldish track days you'll then have to notch it down some... if you have a lead foot tendency, a lot some. Some times you think the bite will be there.... and then it's not.