How to Read & Find Tyre Size

By David Sholicar

Many tyres have a somewhat bewildering array of markings (letters and numbers) on them. This article will ensure you fully understand how to research and buy tyres for your vehicle. Alternatively, you can also use our Online Tyre Finder Tool and search the best tyres to fit your car. Click on Button below for more details on Online Tyre Finder Tool:

How to read and find Tyre Size

What do the numbers on tyres mean?

By the end of this article, you will fully understand what the numbers and letters on the side of your tyre mean, which parts relate to the tyre size, composition dimensions and capabilities. You can also book a FREE Tyre check at one of your local garages at the time that suits you and one of our trained technicians can help you with deciding best tyres for your car. Use the button below to book a FREE tyre check appointment with Protyre.

Each of these digits/letters represents something different and provides important information. When it comes to how to read tyre size, the first five digits of the code are the ones to concentrate on.

  • The first three digits belong together and indicate the width of the tyre (in millimetres). In the example above, the tyre is 195mm wide.

  • The two digits following the first slash are what is known as the aspect ratio. Essentially this is the height of the tyre as a percentage of the width. So, in the example, the tyre has an aspect ratio of 55, meaning the profile height is 55% of its total width (107.25mm).

Simply enter your car reg and choose from the best available options:

  • Search by Registration
  • Tyre Search by Size
  • GB
  • Pointer

What do tyre sizes mean?

It is important to know exactly what is meant by tyre size. The code that is found on the tyres gives more than just the basic size. The size elements are essentially the tyre’s height and width. Tyre sizes will also vary depending on the type of vehicle i.e. van and lorry tyres tend to be larger/chunkier than car tyres. Read What Size Tyre Fits My Car? for more information.

What do the remaining letters/numbers mean?

After the number that indicates the aspect ratio, there is a letter. In the example used, this is R. This stands for Radial and is a specific type of construction. It means that the steel belt inner construction is angled at 90 degrees to the direction of travel, resulting in extra strength. Almost all new car tyres are radials.

The next two digit number after the slash indicates the diameter of the wheel (in inches) - essentially how wide the wheel is across the centre. It is measured as the distance between the two bead seat areas. In the example, the number is 16 so will fit a 16-inch wheel rim. Calculate what tyre size you need
The next two digits belong together and represent the Load Index. This is the maximum load that the tyre is able to carry when inflated to the correct level. Each double digit number represents a different weight (in KGs). 91 is the number in the example and this corresponds to a weight of 615KG. Overloading any vehicle is dangerous and can increase fuel consumption, impact on handling, and can even occasionally cause catastrophic tyre failure. Read Can You Use a Tyre with a Higher Load Rating? for more information

The final letter represents the Speed Rating of the tyre. This is the maximum speed that the tyre can cope with under its maximum load. Each letter represents a corresponding speed. The example we are using has an H rating which equates to 130mph (210kmh).  Read Tyre Speed Rating for more information.

Buying new tyres or changing your tyres?

When it comes to replacing tyres, you can either stick with what you have (although perhaps a newer version), or you can try something different. This really depends on whether you are happy with the performance of your current tyres or you want something different (perhaps sportier).
You can use an online tyre size calculator to see whether the size that you are considering will fit your vehicle. But this is only a rough guide and it is key to stay within the sizing tolerances of your vehicle as per the manufacturer’s guideline. Tyres that are the wrong size can result in the steering wheel pulling, rubbing against the suspension, reduced clearance or a noisier ride than usual.
If you’re considering changing to different sized tyres, you should first establish whether they are the right fit for your vehicle in terms of suspension, gearing and bodywork.

Book a FREE Tyre Check to make it easy for yourself!

All Protyre garages are staffed by experienced and qualified fitters and stock a range of premium tyres from well-known manufacturers such as Pirelli, Bridgestone, Falken and Sumitomo, as well as some from budget tyre manufacturers such as Autogrip, Fullrun, and Runway.

If you feel that your tyres are underperforming or that they may need to be replaced, why not book a free tyre check at a Protyre garage near you? To find your nearest Protyre garage, all you need to do is enter your postcode using the button below!

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About the author

Article Author Photo
By David Sholicar
David is the National Retail Operations Manager for Protyre. One of David’s areas of responsibility and expertise is dealing with the DVSA and MOT’s for Protyre. As the Authorised Examiner Designate Manager ( AEDM ) David deals with applications for changes to the many Vehicle Testing Stations ( VTS’s) including managing the growth of the Number of MOT testing stations that Protyre operate, allocating MOT tester roles, and monitoring the MOT Test logs to ensure that Protyre MOT standards are maintained as the best in the industry.
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