What is my tyre size?

Author Name – Louise Helsby

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It is important that you know how to read your tyre size. In this article, we aim to increase your understanding of tyre sizes with a simple and easy to read tyre size guide.

You will need to know your tyre size for a variety of reasons. You may be due a tyre change and you want to browse for some new tyres online, or you may have had a blow out and need to inform a recovery service of the tyre size.

Whatever the reason, it is important that you know where to locate the tyre size and how to read the tyre sidewall to ensure you find out the correct tyre size for your vehicle.

Related: When should I replace my car tyres?

How do I find out my tyre size?

The easiest way to find your tyre size is by simply looking on the sidewall of the tyre. Tyre manufacturers always feature the tyre size on the sidewall of the tyre.

Some premium vehicles such as Mercedes however, have different size tyres on the front and back, so you need to ensure that you get the correct tyre size of the specific tyre that you are looking to change.

If you cannot find the tyre size on the sidewall of the tyre, you will find it in the vehicle handbook.

If you do not have a vehicle handbook or the tyre size isn’t displayed on the tyre sidewall, you can retrieve your tyre size by imputing your vehicle registration into our ‘search by reg’ tyre size look up.

How to read my tyre size?

Your tyre size will look consists of a series of letters and numbers so it is important to distinguish what these mean.

what is my tyre size


The first set of numbers indicates the width of the tyre from the tyre tread to the sidewall in mm.

Example - 205 = 205mm


The profile of the tyre is the next two numbers. This is the height of the tyre as a percentage of the tyre width.

Example – 55 = The height of the tyre is 55% the width of the tyre.

tyre size help

Wheel size

The wheel size consists of two factors.

R = The tyre construction

The R represents the construction of the tyre. In this case the R says that the tyre is a radial ply construction. It is very uncommon that you will come across a tyre designed for a car that isn’t a radial ply construction.

16 = Rim diameter

The 16 suggests that the rim is 16 inches in diameter.

Tyre speed rating

The speed rating also consists of two factors.

96 = Load index

The load index is a number that indicates what the maximum load capacity for that tyre. Many different tyres have varying load indexes as they purpose a wide variety of vehicles that vary in weight. 

W = Speed symbol

The speed symbol indicates what speed the tyre is able to withstand. If you had a tyre with a low speed symbol and put it on an extremely fast car, this can be dangerous as the tyre will not be able to operate at that kind of speed.

What are the risks of dangerous tyres?

Every year, dangerous tyres lead to around 5,000 convictions, 900 casualties, and 160 deaths or serious injuries. Not only that, but illegal tyres can actually end up costing you more than the price of a new set: you could face fines of up to £2500 and 3 points on your licence per illegal tyre, not to mention that if you're found to have illegal tyres in an accident, it can invalidate your insurance.

A free tyre check from National can make sure your four wheels are ready for the road. Book in now to stay safe on your journeys.

Book a Free Tyre Check

Want to know more about looking after your tyres? Check out our online tyre safety hub.

Where can I get my tyres changed?

After you have found your tyre size and now you know what it means, you may have begun the process of browsing for new tyres for your car. At National Tyres and Autocare, we stock major tyre brands such as Continental, Bridgestone, Pirelli, Michelin, Goodyear and Dunlop.

On our website, you can search for a tyre by tyre size, or by entering your vehicle registration number. If you decide to search by reg, it is important that you manually check whether the tyre size is correct to ensure the tyres can be fitted.

Once you have chosen your desired tyre, simply add it to your basket, choose a fitting date at one of our 250 nationwide garages and make the purchase. It has also never been easier to afford the tyres you want with our National payment assist, spreading the cost over 4 payments.

Related: Click here to find your nearest branch

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