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Calculate your tyre size

Having a set of high-quality and correctly inflated tyres is important to keeping you safe on the roads. A key part of this is knowing what size your tyres are and understanding how to read them.

The size of a tyre can be found on the sidewall. It appears as a combination of numbers and letters.

Tyre size info

While it might look confusing at first, it can be easily worked out. Follow the breakdowns in the table below to properly calculate the size of your tyres.

Sidewall markings images

Get to know your Tyres

Now you know what each value stands for, it’s time to work out what it all means.

Load Rating

The tyre load rating is usually found between the diameter reading and the speed rating on the sidewall marking.

This rating shows how much a tyre should be able to carry when inflated to its limit.It shouldn’t be mistaken for the weight of the tyre itself. You can calculate the load limit of your tyres using the table in the below PDF.

Load Rating PDF

An overloaded tyre has a higher risk of low pressure or blowing out, so it is especially important to refer to this if you are planning to add extra weight to your vehicle.

Your car insurance policy may become void if you have tyres with an incorrect load capacity. It is vital that you check that tyres with correct load ratings are fitted to your car.

Speed Rating

The final letter indicates what speed the tyre can safely reach when fitted to a vehicle. We have broken it down further in this table.

Speed rating info

The speed rating is decided from tests carried out by engineers, which involve running the tyre at 6.2mph in 10 minute increments until the required speed has been met.

If the tyres fitted to your car have a lower speed rating than they should, your car insurance policy could be invalidated. So, it is important to check this speed rating before buying new tyres.

Now that you know how to calculate the size of your tyres, you can use the search to find your perfect tyres.

*Same day garage fitting is only available on specific tyres in certain locations. Please enter your postcode on the select tyre page to see if tyres are available for same day fitting.

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