The following is an excerpt of an article that was posted on Jalopnik.com: "The speed ratings of tires are more than just about the maximum allowable speed that the rubber can carry a load before failing, exploding, and causing a massive accident. It's one of the many numbers written on a particular tire's sidewall, and it can give drivers an idea of how it could affect the ride quality. The tire speed rating is typically an alphabetic symbol next to the load index or load rating, which ranges from S to Y; with each letter corresponding to a speed rating. For instance, an S-rated tire can handle up to 112 mph, while a U-rated tire is good for 124 mph. Higher up the spectrum is V-rated rubber at 149 mph, while the Z, W, and Y can reach 149+ mph, 168 mph, and 186 mph, respectively. Tires with higher speed ratings offer superior grip, handling, and stopping power, making them ideal for aggressively tuned factory sports cars and exotic hypercars. Moreover, they provide better heat dissipation at higher speeds, but that's where the benefits end. Sporty tires with speed ratings that are higher up the alphabet benefit from stiffer casings and softer rubber compounds to reduce "flexing" of the rubber. Flexing or squirming produces more heat, so a stiff construction is better for maximum heat dissipation. However, the advanced materials and construction also bring downsides, such as a stiffer ride quality, faster wear, and mediocre performance in cold weather. You're fortunate to have a car that requires a V or higher speed rating, but lower speed ratings are more ideal if grand touring comfort is the goal." Read More: https://www.jalopnik.com/1964771/how-tire-speed-ratings-affect-ride-quality/
