How To Read the Size of a Tire?

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How To Read a Tire Size?

Tire size is hard to read, especially when you have never done that.

Asking an expert to help you get out of this trouble will cost you time and money, plus it is difficult for a self-sufficient person who doesn’t like to rely on the help of others.

But, you don’t need to worry about that because this article will guide you on how to read the size of a tire.  

After reading this guide, inspecting the tire size will never be difficult for you, and you will be able to do it in a few seconds.

So, stick with it, and we will see you through the end until you get the best results.

How can I read the size of my tire?

If you have a tire, you might see a piece of information labeled on its sidewall in alphabetic and numeric characters.

This particular data is the tire size that tells you the comprehensive details about the tire. 

We will guide you on how to get detailed info on the tire using that specific information.

We will take P225/70R16 as an example of tire size to guide how to read it.

Type of Tire:

The high chances are that the first letter you will probably see on a tire size is P. It indicates which type of tire you’re using.

The P means you have a P-metric tire, referring to tires made to specific standards within the United States, intended for passenger vehicles. 

If you see a tire size beginning with no letter, such as 225/70R16 91S, it is a Euro metric tire. Both P-metric and Euro-metric tires have different load capacities.

On the other hand, If you point at the letter LT, the beginning or the end of the tire size means that the tire is intended for light trucks.

These tires require high inflation pressure compared to passenger tires. 


The three-digit numbers you see after the first letter indicate the tire’s width in tire size.

For instance, in a tire size P225/70R16 91S, the tire’s width is 225.

These three digits designate the tire’s width from sidewall to sidewall and are calculated in millimeters. 

Aspect Ratio:

The next comes of the tire size is the aspect ratio.

It is defined as the ratio of the height of the tire cross-section to its width.

The two-digit number that comes after the slash mark indicates the tire’s aspect ratio. 

For instance, in a tire size P225/70R16 91S, the aspect ratio is 70, meaning the tire’s height equals 70% of its width. The bigger the aspect ratio, the greater the tire’s sidewall.


The alphabetic letter comes after the aspect ratio tells you the tire’s construction.

If the letter is labeled as R, your tire is radial which means layers move radially across the tire.

Most contemporary tires are radial tires. 

Wheel or Rim Diameter:

The next part of the tire size describes its wheel diameter.

The two-digit number after the letter R is the wheel diameter of the tire.

For example, a tire with the P225/70R16 91S size would fit a wheel or rim with a 16-inch diameter.

Load Index:

The load index tells us how much your tire can lift load in pounds when it is properly inflated.

The load index of the tire will be found in the sequence after rim size.

There are two types of load index for passenger tires Standard Load and Extra Load.

If there is a mark indicating XL on the tire, it is an Extra load tire; otherwise, it will be a standard load tire.

Most tires come with standard load compatibility, and you will rarely have extra load tires.

This is because they’re only designed to work with heavy-weight vehicles.

Standard Load Euro-Metric: 225/70R16 91S

Extra Load Euro-Metric: 225/17R16 91S XL

Speed Rating:

The speed rating is the last viewpoint in the sequence of tire size, which is indicated by the alphabetic letter S.

It shows how much your tire is capable of reaching a speed limit. For example, a tire with an S speed rating can reach a maximum speed limit of 112 mph.

Moreover, the speed rating will be 106, 130, and 140 mph for R, H, and V tires.

Read More: 7 Best Tires For Subaru Forester

What are the other Markings on tires?

Besides the tire size, it is also good to know the purpose of other tire markings.

They are as follows:

Dot Symbol:  

The letter DOT symbol on the tire’s sidewall indicates that the tire meets the Federal Motor Vehicle Safety Standards.

Tire Identification Number:

The Tire ID Number is a series of 12 numbers and alphabets followed by the DOT symbol.

It tells you when and where the tire was manufactured. 

Air pressure number:

The number on the tire sidewall shows how much pressure your tire can handle.

Read More: Best Tires for Gravel Roads


Reading a tire size is not difficult as it seems all you need is profound knowledge about them.

We have described every detail about inspecting the tire size and other marking symbols.

We hope this article helps you increase your knowledge about understanding tire size and other vital things.

If yes, then also check out other interesting posts on our blog.  

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