Kevin, the Caterham 620r as "street" tyres, the real car uses Avon ZZR, that are road legal... and the ZZS tyres in the 620s have almost the same levels of grip, from a pistonheads thread, they say the zzs tyre pattern builds heat quickly for street use, but will overheat in track comparing with the zzr. What I would really like is the h-pattern gearbox that comes in the 620s !