How to calculate what tyre size you need

By David Sholicar

Most drivers know that not all tyres are the same and that the likelihood of a random tyre fitting your vehicle is fairly low. Tyres are manufactured with characteristics to suit driving in different conditions – from wet and icy, to Formula 1.   Use our Online Tyre Finder Tool and search the best tyres to fit your car. Click on the Button below for more details on our Online Tyre Finder Tool.

Tyre Size

Tyre condition and checks

The type of tyres on your car will have a direct effect on its safety, how it handles in the wet, cornering, general handling and – of course – braking. Tyres can also have a major effect on the comfort of driving your car; however, before you get to any of those factors, the tyres need to be the correct size. You could have the best tyres in the world, but they are worthless if they are too big or too small for the wheels of your vehicle.
At Protyre, we don’t just offer tyres but also the expertise of our trained technicians. Book a Free Tyre Check today and one of our experienced technicians will be able to help you at a time and day that suits you in your local garage. Simply use the button below to book a free check.

Book A Free Tyre Check

Even the most careful driver needs to replace their tyres from time to time. The state of your tyres will be assessed during your car’s annual MOT and if there are bald patches or shallow tread you will need new tyres. Protyre offers various discounts and offers on leading brands. Simply enter your car reg at the link below to find best tyre brands available for your car.

Buy Tyres

Protyre also offers MOTs that deliver terrific value. In addition, as tyre specialists, our knowledgeable staff can help you immediately with replacement tyres to get you back on the road.

Book an MOT

Find out your tyre size

You can also upgrade your tyres for greater comfort and safety. Before you can shop for tyres, you will need to know what size is suitable. In our experience, many people are unsure how to answer the question, "What is tyre size?" but should have the tools to find out close to hand. The first point of reference should be your owner's manual. This should have information on the tyres you already have, which will be labelled with measurements regarding the diameter of the wheel’s rim and the maximum load recommended. If the manual is lost, you can bring the car to a Protyre garage and our friendly staff will advise you on the tyre measurement your car will require in order to be driven safely.

How to measure tyre size

The diameter is a critical factor. This is related to how far the tyre will travel during a revolution, which affects gearing, torque, traction and the speedometer. If you're asking, “How are tyres measured?” first you’ll need to be aware that a tyre is sized by its inside diameter. The outside diameter is used to measure the aspect height or tyre profile, which is dictated by the sidewall. It gives the width of the tyre against its height as a percentage.
In general, a tyre that has a low profile, or short sidewalls relative to the width, will give a firm ride and good handling; however, these tyres can cost more and be noisier than tyres with higher aspect ratios. Change one of these measurements in a tyre and it will have an impact on the others. The diameter should remain constant.

The local garage you can trust

All Protyre garages have staff with many years’ experience who can help you with all the decisions regarding tyres. Enjoy easy selection here on the Protyre website, where you will find a vast range of tyres from all the major manufacturers in a variety of sizes, prices and features. We also have plenty of great deals, and our prices include tyre fitting – with same day fitting available across much of our range. If you are not sure what kind of tyres suit your car, just call us and book a free assessment.
Protyre operates more than 100 garages in our extensive network, so there is sure to be a Protyre garage near your home or your place of work. Protyre carry a wide range of tyres from manufacturers including Pirelli and Bridgestone. If you're unsure about the condition of your tyres, you can contact your local Protyre garage to arrange a free tyre safety check, where our tyre professionals can also advise you on your next steps. To find your local Protyre garage, click the button below.

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About the author

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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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