Re: Track Days
On an old LJ Torana that I used to sprint. I used the 70 series road tyres and had to pump the up to buggery. The grip wasn't good, but neither was the braking, acceleration or handling.
On the next car (Honda CRX) that I used to sprint I used to have a spare set of wheels and swap the wheels over when my tyres (Bridgestone G-grids at the time) got too bald for the road. It was cheap, I got extra life out of the tyres but the road tyres weren't very good on the track.
On the car that I have now (Honda Integra) I have another 2 spare set of wheels and I use Bridgestone RE540s on them. The R rated tyres from Yokohama, Dunlop and Bridgestone are better on a track than almost all road tyres. Life, noise and wet weather performance aren't as good as road tyres. R rated tyres lopped 2.5-3.0 seconds off my lap times at Winton.
Road tyres will also cop a real pounding on the track, feathered edges, flat spots if no ABS, etc.