Wanna know whats best for a car? check autox nationals results under Street Touring. different tires work best for different weight/power cars, as well as different wheel sizes. (direzzas suck in 14/15" sizes for example, but rule in 18's)
http://www.scca.org/documents/result...ook%20file.pdf
ST/STS - R1R/RS3
STR - RS3
STX - RS3
STU - Direzza/AD08