Tire Speed Rating

Tire Speed Rating

In Germany some highways do not have speed limits and high-speed, driving is permitted. Speed ratings were established to match the speed capability of tires with the top speed ability of the cars to which they are used. Speed ratings are established in kilometers per hour and consequently transformed into miles per hour (which explains why speed scores appear developed at "unusual" mile per hour increments). Despite the tire manufacturer's ability to make tires capable of high speeds, none of them suggest the usage of their items more than legal speed limits. The maximum operating speed of a vehicle should be limited to the most affordable speed ranked tire on the automobile.

Speed ratings are based on lab tests where the tire is pushed versus a large diameter metal drum to show its proper load, and go for ever increasing speeds (in 6.2 mph actions in 10 minute increments) up until the tire's required speed has been satisfied.

It is very important to keep in mind that speed ratings just apply to tires that have not been damaged, changed, under-inflated or overloaded. Furthermore, the majority of tire producers maintain that a tire that has actually been cut or punctured not keeps the tire maker's initial speed rating, even after being fixed because the tire maker cannot manage the quality of the repair.

For many years, tire speed rating signs have actually been marked on tires in any of 3 methods shown in the following examples:

225/50SR16225/50SR16 89Sor 225/50R16 89S

Each of these was an acceptable method of identifying speed ratings.

Early tires had their speed rating sign shown "within" the tire size, such as 225/50SR16. Tires utilizing this type of branding were not to have been produced after 1991.

225/50SR16112 mph, 180 km/h
225/50HR16130, 210 km/h
225/50VR16in excess of 130 mph, 210 km/h

Beginning in 1991, the speed symbol representing a repaired maximum speed ability of new tires should 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 signs, optimum speeds and typical applications are shown listed below:

L75 mph120 km/hOff-Road & Light Truck Tires
M81 mph130 km/hTemporary Spare Tires
N87 mph140km/h
P93 mph150 km/h
Q99 mph160 km/hStudless & Studdable Winter Tires
R106 mph170 km/hH. D. Light Truck Tires
S112 mph180 km/hFamily Sedans & Vans
T118 mph190 km/hFamily Sedans & Vans
U124 mph200 km/h
H130 mph210 km/hSport Sedans & Coupes
V149 mph240 km/hSport Sedans, Coupes & Sports Cars

Different Tire Speed Ratings

When Z-speed rated tires were initially introduced, they were believed to show the highest tire speed rating that would ever be required, in excess of 240 km/h or 149 miles per hour. While Z-speed rated tires can speeds in excess of 149 mph, how far above 149 miles per hour was not identified. That ultimately triggered the vehicle market to add W- and Y-speed scores to identify the tires that satisfy the needs of new cars that have very high top-speed abilities.

W168 mph270 km/hExotic Sports Cars
Y186 mph300 km/hExotic Sports Cars

While a Z-speed rating still frequently appears in the tire size classification of these tires, such as 225/50ZR16 91W, the Z in the size signifies a maximum speed ability in excess of 149 miles per hour, 240 km/h; the W in the service description suggests the tire's 168 mph, 270 km/h maximum speed.

225/50ZR16in excess of 149 mph, 240 km/h
205/45ZR17 88W168 miles per hour, 270 km/h
285/35ZR19 99Y186 miles per hour, 300 km/h

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

285/35ZR19 99Y186 miles per hour, 300 km/h
285/35ZR19 (99Y)in excess of 186 mph, 300 km/h

As vehicles have actually increased their top speeds into Autobahn-only ranges, the tire speed scores have progressed to better identify the tire's capability, permitting motorists to match the speed of their tires with the leading speed of their vehicle.

Here is a video on Tire Speed Ratings and other tire measurements