How to Read Tire Size

Tire sizes might seem like a random string of numbers and letters to the uninitiated, but they hold essential information for car owners. Knowing how to read and understand tire sizes can prove incredibly beneficial, allowing you to select the right tire for your vehicle and ensure its performance and safety.

The tire size is usually printed on the side of the tire in a format that might look something like this: P215/65R15 95H. While it might appear complex at first glance, each segment of this code holds specific information.

How to Read Tire Size

Tire Type

The letter at the beginning of the tire size denotes the tire type. In this case, P stands for Passenger - a tire designed for passenger vehicles. Other letters you might come across include LT for Light Truck, T for Temporary (as in spare tires), and ST for Special Trailer.

Section Width

The first number represents the section width of the tire in millimeters. This is the measurement of the tire's width from one sidewall to the other. In our example, tread width is 215 millimeters.

Aspect Ratio

The number after the slash is the aspect ratio. This figure represents the height of the tire's cross-section as a percentage of its width. Here, the height is 65% of the tire's width.

Construction Type

The R in the sequence stands for Radial, indicating the tire's construction. Radial tires have layers of fabric with cords running radially, or at 90 degrees to the direction of travel, providing improved strength and durability. Other letters you may see include D and B for Diagonal or Bias Ply construction.

Rim Diameter

The number following the construction type represents the diameter of the wheel (or rim) in inches. This is the size of the wheel that the tire is intended to fit. In our example, tire fits on 15 inch wheels.

Load Index

The following number, 95 in our example, is the load index. This is a numerical code that corresponds to the maximum load that the tire can carry when properly inflated. Higher numbers indicate a greater load capacity.

Speed Rating

The final letter in our sequence, H, represents the speed rating. This indicates the maximum speed the tire can handle when it's correctly inflated and carrying its maximum load. H means the tire is rated for speeds up to 130 miles per hour.

Understanding how to read tire sizes can help ensure you select the right tire for your vehicle, driving conditions, and personal preferences. The tire's specifications influence various aspects of performance, including handling, traction, ride comfort, and load carrying capacity. As such, being familiar with these details is a significant step towards a safer and more comfortable driving experience.

While it is essential to understand tire sizes, it's also important to consult with tire professionals or refer to your vehicle's owner manual to ensure the tires you're considering are suitable for your vehicle and the driving conditions you encounter. Always prioritize safety and performance over cost when choosing tires. After all, they are the only parts of your vehicle that come into direct contact with the road, and understanding their size and characteristics can go a long way in ensuring an optimal driving experience.

All listed guides, data and/or calculations are for informational purposes only. does not warrant or make any representations regarding the accuracy of or the results of the use of this information.