Before we start with this article, you should know that in the last 20 years, all vehicle manufacturers have started to equip their models with “speed-rated” tires. This was both a response to the government’s push for tire safety and to the improved handling requirements of newer vehicles that drove changes in steering and suspension systems. And, now even the family sedans and economy cars are coming from the factory with high performance tires.
And you’ve probably noticed that all tires are getting bigger. Take this for example:a Chevy Cavalier from the late 1980s and early 1990s sported 13” tires (P185/80R13). Rebadged as Cobalt in 2006, the essentially similar vehicle was now shod with 15” tires in the base model, with upgrades to 16-, 17- and 18-inch tires in the high-end packages (215/45ZR18 93W for the Cobalt SS Supercharged version).
S, T, H, V, W, and Y…what do all those letters mean, and why is it necessary to understand this tire speed rating?
First, you should know that the speed-rating system we use today evolved from a rating system used in Europe to ensure safe performance from tires at specific speeds. So, when they perform a tire test, the tires were matched to the maximum speed the vehicle could attain.