rideclassic2025 said:
for the speed rating on the tires i had a print out of what speed each rating could do and it said the ZR was rated for 150+ so what does that mean, i thought that was the highest rating, so hwat do cars do that go faster if thats the highest one, sorry if htat sounds stupid but its really late.
Speed Rating
In Europe, where selected 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 capability of the vehicles to which they are applied. Speed ratings are established in kilometers per hour and subsequently converted to miles per hour (which explains why speed ratings appear established at "unusual" mile per hour increments). Despite the tire manufacturer's ability to manufacturer tires capable of high speeds, none of them recommend the use of their products in excess of legal speed limits.
Speed ratings are based on laboratory tests where the tire is pressed against a large diameter metal drum to reflect its appropriate load, and run at ever increasing speeds (in 6.2 mph steps in 10 minute increments) until the tire's required speed has been met.
It is important to note that speed ratings only apply to tires that have not been damaged, altered, under-inflated or overloaded. Additionally, most tire manufacturers maintain that a tire that has been cut or punctured no longer retains the tire manufacturer's original speed rating, even after being repaired because the tire manufacturer can't control the quality of the repair.
Over the years, tire speed rating symbols have been marked on tires in any of three ways shown in the following examples:
225/50
SR16225/50
SR16 89
Sor 225/50R16 89
S Each of these was an acceptable method of identifying speed ratings.
Early tires had their speed rating symbol shown "within" the tire size, such as 225/50SR16. Tires using this type of branding were not to have been produced after 1991.
225/50SR16112 mph, 180 km/h225/50HR16130, 210 km/h225/50VR16in excess of 130 mph, 210 km/h 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:
M81 mph130 km/h
N87 mph140km/hTemporary Spare TiresP93 mph150 km/h
Q99 mph160 km/hStudless & Studdable Winter TiresR106 mph170 km/hH.D. Light Truck TiresS112 mph180 km/hFamily Sedans & VansT118 mph190 km/hFamily Sedans & VansU124 mph200 km/h
H130 mph210 km/hSport Sedans & CoupesV149 mph240 km/hSport 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.
W168 mph270 km/hExotic Sports CarsY186 mph300 km/hExotic 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.
225/50ZR16in excess of 149 mph, 240 km/h205/45ZR17 88W168 mph, 270 km/h285/35ZR19 99Y186 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 99Y186 mph, 300 km/h285/35ZR19 (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.