The ZR you find after the load rating of your tire on the sidewall is an older and outdated indication of speed rating for tires! This meant that the tire was built to handle speeds of over 150 mph (241 kph) and was generally utilized on performance vehicles.

A new system of single-character ratings has replaced the older rating system and the ZR indicator. Currently, the letter “V” is the closest, as it indicates that the tire can handle over 149 mph (240 kph), while the following letter, “W,” is for tires that can take over 168 mph (270 kph) of speed. 

The slowest-rated tire is “P,” which can’t be used for over 98 mph (158 kph), and “Vmax” is the highest rating, explicitly built for Bugatti, and can handle over 249 mph (401 kph).

So what does “R” mean on a tire now?

You will now find the letter “R” on a tire in two different places. First, the letter R can mean radial tire, which is located in the tire size indicator of the sidewall. Finally, the letter “R” is a speed indicator, meaning the tire can handle over 106 miles per hour.

Where is a speed rating found on a tire?

The speed rating of a tire is found after the sizing information. You are likely used to the tire size information, which generally looks like “245/65 R17”. 

However, some tires will show the speed rating and the load rating. This will look like this “245/65R17 85ZR”. The 85 shows the load rating, and the ZR indicates a performance tire that can handle over 150mph.

Conclusion

While the ZR rating on tires has been retired, the indicator V has been replaced, meaning that a tire is rated for driving over 149 miles per hour. The Letter “R” is also an indicator of speed, meaning that a tire can handle over 106 miles per hour. If you want a great example of a V rated tire, this one right here should do it! (Paid Link)