Actually Z rated tires are 149+ MPH. Supposedly you can go as fast you want with them.
Ya, that'* true for some the older design ZR which are supposed to be rated at 149+ but some of the newer high performance tires are rated using a different convention, for instance the new 2004 Crossfire has 255/35 ZR 19 96Y.
My Bird'* Pirelli'* are P255/60 R 15 102V and Bonne'* RSA'* are P235/55 17 98H.
Some cars sold with straight ZR rated tires, like the new 2003 Dodge SRT-4 and Subaru WRX STI for instance, are limited to 148 mph.
Mazda RX-8 is shod with 225/45R 18 91W but limited to 148 mph.???
Dodge Viper P345 30ZR 19 98Y....top speed 190 mph.
Maybe it'* a Europeon designation.???
The Audi RS 6 has 255/40 ZR 18 99Y but limited to 155....but then most Europeon cars are limited to 155 for road safety not tire liability reasons.
Do you or anyone elso have a better explanation of the tire rating designations.