Wheels on trackdays...

Exactly!
Sometimes its fun to overdrive them and squeeeel some rubber away. I wouldn't want to do that with my new F1's.

With the low cost of 2nd hand OEM wheels (everyone seems to upgrade!)it's not an expensive option.

I also have, in the past, run non road-legal rubber on the track (fine in the dry) to get more value from tyres...

After Castle Combe my front F1's were scrubbed to hell. Since then I have had to replace one when I kerbed the car at speed and took a chunk out of the tyre. I now have two gooduns on the front and at the back one is a little scrubbed. Gonna live with it and change all 4 at once - the prices I've seen quoted on this site are great.

But for my next trackday I have the old Avus 17" wheels with Bridgestone SO3's - only slightly worn so I'm thinking about using these. If it's wet they also handle better than the GSD-02's which I have aanyhow.