stevebez

Guys ... thought for those wiith de-resticted cars would be interested in this info from Continental Tyres Germany... since the tyres ar ZR rated (ie.>240km.h) there theoretically is no top limit - and I was interested to know what I could do safely at a Vmax event I am considering entering.

The tyres that came stock on my car are :-

Front
245/40/18 ZR DOT CUUY P5HK 4205

Rear
265/35/18 ZR DOT CUJW N5HK 3005

If your DOT codes are the same (the first 8 letters) than this speed rating data will apply to you too, the last 4 digits of the DOT code will differ as they refer to the week (ww) and year (yy) the tyre was manufactured.

Thsi is their reply...

"Hello Steve,

This tyre sizes we have in different versions.

245/40 ZR 18 ContiSportContact 2:
max speed 300km/h at 1106 kg / axle
max speed 270km/h at 1300 kg / axle

265/35 ZR 18 XL ContiSportContact 2:
max speed 290km/h at 1240 kg / axle
max speed 260km/h at 1460 kg / axle

That means we can confirm max speed of 290 km/h [ed. 180mph] for your car by fitting the mentioned tyres."

Rgds Steve.

glennbaz

I think you should read this from Tire Rack

Beginning in 1991, the speed symbol denoting a fixed maximum speed capability of new tires must be shown only in the speed rating portion of the tire's service description, such as 225/50R16 89S. The most common tire speed rating symbols, maximum speeds and typical applications are shown below:

M 81 mph 130 km/h
N 87 mph 140km/h Temporary Spare Tires
P 93 mph 150 km/h
Q 99 mph 160 km/h Studless & Studdable Winter Tires
R 106 mph 170 km/h H.D. Light Truck Tires
S 112 mph 180 km/h Family Sedans & Vans
T 118 mph 190 km/h Family Sedans & Vans
U 124 mph 200 km/h
H 130 mph 210 km/h Sport Sedans & Coupes
V 149 mph 240 km/h Sport Sedans, Coupes & Sports Cars


When Z-speed rated tires were first introduced, they were thought to reflect the highest tire speed rating that would ever be required, in excess of 240 km/h or 149 mph. While Z-speed rated tires are capable of speeds in excess of 149 mph, how far above 149 mph was not identified. That ultimately caused the automotive industry to add W- and Y-speed ratings to identify the tires that meet the needs of new vehicles that have extremely high top-speed capabilities.

W 168 mph 270 km/h Exotic Sports Cars
Y 186 mph 300 km/h Exotic Sports Cars


While a Z-speed rating still often appears in the tire size designation of these tires, such as 225/50ZR16 91W, the Z in the size signifies a maximum speed capability in excess of 149 mph, 240 km/h; the W in the service description indicates the tire's 168 mph, 270 km/h maximum speed.

225/50ZR16 in excess of 149 mph, 240 km/h
205/45ZR17 88W 168 mph, 270 km/h
285/35ZR19 99Y 186 mph, 300 km/h


Most recently, when the Y-speed rating indicated in a service description is enclosed in parentheses, such as 285/35ZR19 (99Y), the top speed of the tire has been tested in excess of 186 mph, 300 km/h indicated by the service description as shown below:

285/35ZR19 99Y 186 mph, 300 km/h
285/35ZR19 (99Y) in excess of 186 mph, 300 km/h


As vehicles have increased their top speeds into Autobahn-only ranges, the tire speed ratings have evolved to better identify the tires capability, allowing drivers to match the speed of their tires with the top speed of their vehicle.





Related Links:
Calculating Tire Dimensions
Contact Patch
The Plus Concept
Tire Size Conversion Chart
Tire Size Information

stevebez

Yep - I looked into this in some depth ... the reason I was confused is that there was no W or Y rating noted on my tyre whatsoever... I am just about to have a delimit done (and also planning a weekend at the 'ring'), so I wanted to be 100% sure!

Rgds Steve.