Don't forget 16". You can get Hoosier slicks in 16, I use 25x12x16's and 25x13x16's on my Cobra. They barely fit though. There are racing tires available in 15" sizes, Goodyear has several sizes and compounds. There are alot of radial racing tires in 17 including R compound DOT tires.
Here's some ideas:
http://www.rogerkraustires.com/gyCobra.html