As I am seriously considering ordering 15" Trigo wheels for my cobra, having looked at Roger Kraus racing Cobra tires , he appears to supply a good range of 15" tires! A lot of racers appear to be using 17" tires, probably for the extra room for bigger brakes and also the lower tire profiles. Do the Goodyear/ Hoosier 15" road and race tires provide comparable grip to a 17" equivalent tire?
http://rogerkrausracing.com/cobra.html