All tires have speed ratings, which indicate the highest speed they can accommodate safely. Ratings are communicated using letters A through Z, ranging from 3 mph up to 186 mph. In general, you can find your tire's speed rating on the sidewall. Many people have questions about ZR and R ratings specifically, and it's important to understand what these symbols mean when shopping for a new set. 

The Difference Between ZR and R Rating on Tires

ZR Ratings

In the past, seeing ZR stamped on the sidewall meant the tire could be used up to speeds of 150 mph while still offering safe and reliable performance. Today, ZR still indicates a tire is capable of high speeds but is broken down into three separate speed ratings listed as V, W, or Y. Seeing a V listed means the top speed is 149 mph, a W refers to top speeds of 168 mph, and Y indicates the tire can safely reach 186 mph. 

In this case, the ZR will appear before the rim measurement, and V, W, or Y will be listed as the last character. As an example, the tire code P275/40ZR17 93W means the tire is 275 millimeters wide, has an aspect ratio of 40% (which indicates the tire's height as compared to its width), has a 17-inch rim, has a load index of 93, and is safe up to speeds of 168 mph. 

R Ratings

When you see an R within the code before the rim measurement, it simply indicates that the tire uses radial construction. Radials receive strength and durability thanks to interior steel cords, known as plies. Plies are coated with rubber, which helps limit movement and create stability. Less movement also prevents heat from generating while driving, which keeps the tire in good shape for longer periods.

Radial tires tend to be more flexible and often have greater traction than non-radial types, since more tread retains contact with the road when driving. Speed ratings for R tires are just the same as those for ZR tires, depending on the last letter appearing in the sidewall code.  

With so many different characteristics to consider, choosing the right set of tires for your vehicle is often confusing. The dependable team at Pono Tires can help you choose a safe and reliable set of tires. Since 1974, this tire shop has served customers all over Oahu, offering high-quality used tires that are rigorously tested for your satisfaction. Visit the website for testimonials and more information on their services. You can also call (808) 888-7666 for an estimate.