What Do Tire Numbers Mean and How To Read Tire Size?

By David Barlow
Last updated: Nov 25, 2022
Tire Numbers mean

When checking the sidewall of a tire, you can see a series of numbers, for example, “P215/65R15 95H”. Manufacturers print such combinations of characters there to provide information regarding the tire, but what do the tire numbers mean? Let’s scroll down to find out more about this feature of your purchase!

What Do Tire Numbers Mean? 

The letters and tire numbers printed on the tire represent the model, width, aspect ratio, construction, wheel diameter, load index, and speed rating. For a better understanding, let’s take the series “P215/65R15 95H” as a reference.



Letters that stand at the beginning of the series are to inform the tire type. P means the P-Metric one manufactured under the United States standards mainly for passenger vehicles.

In case of an additional T following L (LT), the pairing indicates that the tire is suitable for light trucks. And the tires without letters at the beginning of the series are Euro-Metric ones.

See more: What Does LT Mean On A Tire? Differences Between LT & P-Metric



The next three-digit series – in this case is 215 – is to show how wide the tire is in millimeters. The tire’s width, in turn, determines the vehicle size it is suitable for.

Aspect Ratio

Aspect Ratio

The “65” beside the slash refers to the aspect ratio between the tire height and width. To simplify, the height of the tire is 65% of its width. The higher the ratio is, the bigger sidewall the tire will get. Based on the calculation, the sidewall is 139.75 millimeters (215 * 65%).

Tire Construction

Tire Construction

There is another letter that follows the aspect ratio showing the tire construction. There are three common initials for car tires: R, D and F

Letter R 

It means that the construction of the tire has layers running radially across the tire. 

The radial-construction tires offer an excellent road grip along with lower rolling resistance than others currently on the market. Thus, you can experience a comfortable ride and long drive, as these tires tend to last very long.

Letter D

D stands for diagonal. The tire with D construction (or bias-constructed tires) often features diagonal pliers. It is quite popular for motorcycles and trailers. 

Letter F

If the series has an F, it is a run-flat-tire. Thanks to its internal construction, the tire can support the car even in cases of deflation – hence the term “run-flat”.

Tire Wheel Diameter

Rim Diameter

Next up are symbols that represent the tire wheel diameter asides from its construction. Our example is the number “15” for this position. Undoubtedly, the tire wheel measures 15 inches in diameter

Load Index

Load Index

The next two or three digits are the indications of the load index representing the tire weight capacity. A tire with a higher index can support weight better, therefore are more suitable for heavy-duty vehicles.

According to the standards of the car manufacturing industry, the index of 95 in our example means that the tire can load up to 1,521 lbs with optimal inflation conditions.

See more: Tire Load Index And Using Instruction

Speed Rating

speed rating

As for the last letter – H (50-60 mph), drivers can tell the top speed that the tire can handle and provide enough control for a safe journey. The speed ratings usually start from A1, A2, … to Y, and (Y) corresponding up to above 186 mph

Choosing random tires for your car without learning about them first is never a good idea. A wrong choice can result in disadvantages and discomfort.

See more: Tire Speed Rating – All You Need For Driving Better

Hopefully, our explanation can help you make a decision on what to buy for your vehicle. For further information, feel free to drop us any inquiries.

View more: How To Read Tire Codes Date? DOT Tire Codes Complete Guilde

David Barlow

Automotive Experts at World Tire Review

Hi everyone, I’m David (Tireguy). I believe that finding tires can lead to a lot of confusion and frustration for almost every driver. That’s why I would like to bring my experiences and knowledges to develop World Tire Review blog, it will give people a deeper understanding of what choosing the right tire is really like!