Tire Sizing: Learn How to Use the Tire Height Calculation

The correct tire size is vital for your car to perform well and to keep you safe. In choosing a tire, you should know your driving condition and inclination.

To determine the size of your tires, read on to know tire sizing: learn how to use the tire height calculation.

Finding the Tire Size

Regardless of the model and type of vehicle you have, the tire size appropriate for your car can be found easily.

You can either get a hold of your car’s manual, or check the guide for tire fit in the door of the glove compartment at the jamb of the driver’s side door and at the hatch of your car’s gas tank.

You can also find it on the side of your installed tires if you are sure that it is the right size.

After finding it, you will have to figure out what each letter and number represents.

Deciphering the Tire Size

You are probably perplexed with the size. You will find out what the numbers and letters arranged in a particular order stand for. We will use the size P215/60R16 94S for easier explanation.

P or LT

In the sequence of the size, you will see either the letter P or LT. P stands for P-metric. This is a character designated by the Tire and Rim Association for passenger vehicles.

These include sedans, sports utility vehicles, minivans, and small pickup trucks.

LT, on the other hand, means LT-metric. Designated by the same association, this represents light trucks which are used for transporting heavy freight or hauling trailers.

used tire

For other letters, T means temporary which can be seen on your extra tire. ST means special trailer.


The first 3 numbers that come after P or LT is the width which is in millimeters. In our sample, the width is 215 millimeters. For the tire width, it measured sidewall to sidewall.

Aspect Ratio

The next 2 numbers you see after the slash is your vehicle’s aspect ratio. Aspect ratio gives you information about the height of the cross section of your tire to the width.

This is in percentage, so the aspect ratio in our sample is 60%.

This means the height is 60% of the tire’s width. 60 aspect ratio gives you better handling performance compared with 75 aspect ratio.


The letter that comes after the aspect ratio is the kind of construction your tire has internally.

This is important for the maintenance of the stability of your tire. You will see either R or D. R means radial, and D means diagonal or bias ply.

The construction has layers of internal cords that are aligned radially.

Diameter of the Wheel 

The next numbers are the size of the wheel in inches. This indicates the measurement of the wheel from two ends.

In our sample tire size, it is intended for a wheel with 16 inches in diameter.

Load Index

The numbers separated from the sequence is the weight your properly inflated tires can hold. This figure is in pounds.

However, it does not accurately signify the exact weight the tires can support. An index is used to determine it.

Rate of Speed

The last letter in the sequence is the maximum speed capability of your tires. This is the ability of your tires to move fast based on test done.

S can move up to 112 mph and R can move until 106 mph. This does not mean that you should always drive at the mentioned speeds.

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How to Use a Tire Height Calculator

Now, you are familiar with the tire size code. This will come in handy when time comes that you need to use a tire size calculator.

hand holding a calculator

This tool can calculate the sidewall, diameter, revolutions per mile, width, and circumference of your tire.

Calculating for tires with inch measurement not complicated, but a metric tire is a different case.

If you have a metric tire, you can calculate the height by using this formula: (width in millimeters x aspect ratio / 2540 x 2) + (wheel diameter)

Using the same sample tire size, P215/60R16 94S, the computation is  (215 x 60 / 2540 x 2) + (16). This tire’s height is 26.1 inches.

Most tire calculators have features that help you decide which tire to purchase for a particular tire size.

This is advantageous since it can be overwhelming to look for one. You just need to fill in your tires’ size and you will see different tire suggestions.

There are more recommendations for metric tires so a tire calculator will come in handy. 

Some tire calculators you see online have an image to guide you through if you easily get confused with the numbers indicated on your tires.

Other calculators you can use are tire size comparison calculators, tire diameter calculators, and speedometer correction calculators.

Also read: Chilton vs Haynes manuals

Inquire to your Dealer

Although you are confident with your tires’ size and height computation, it will be helpful to ask your car dealer. You can be more sure that the information you interpreted is done correctly.

When choosing a car dealer, make sure that this person has ample experience.

Aside from the tire size and height interpretation, you will gain more insights about the proper maintenance of your car.

The right size for tires is highly vital. Therefore, it is better to take time to seek advice from professionals when you are in doubt.


Finally, getting the right tire size and height is not difficult when you know tire sizing: learn how to use the right tire height calculation.

You need to understand the important aspects of tire size and height so that your vehicle can perform at its best.

Although the size of tires is a code, it is not hard to understand. Moreover, using a tire height calculator is easy when you follow the formula given. If you are in doubt, do not hesitate to seek a car dealer’s help.