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What do the markings on the side of my tyres mean?

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Have you ever wondered what all of the numbers and letters on the side wall of your tyres actually mean? Well, if so, here is Ecotyre Service’s jargon free guide to tyre markings!

Tyre Width:

This number is the width of the tyre across the face, in millimetres. In the image it would be 245mm.

Aspect Ratio:

The aspect ratio is the size of the tyre’s wide wall as a percentage of the width. In the image the tyre side wall is 45% of the width.


Tyre Construction

The letter relates to the tyre construction, in this case R for Radial. Radial is the most popular and usually the most appropriate type of tyre for road use. There are still some cases where a fitter might recommend a Cross Ply tyre instead, but this is relatively rare and our tyre technicians will be able to advise.

Tyre Diameter

The tyre diameter is the diameter of the inside of your tyre, measured in inches. In the image the tyre will fit onto a 17 inch wheel rim.

Load Index

The load index outlines the maximum working load of the tyre. The number corresponds to a weight as set out on a chart. In the image the number 99 relates to a maximum load weight of 775kg.

Speed Index

The speed index outlines the safe working speed of the tyre. For some reason the different letters you might see for your tyre’s speed rating aren’t quite in a logical order so ask our technician if you’d like to know more. The letter V in the example has a safe speed of 149mph.


Now that you understand your tyre markings, feel free to contact the experts today to order your new tyres or to book your mobile tyre fitting service.

We supply tyres for all major brands

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Ecotyre Services
Unit 2 Casting House
Birds Hill
Letchworth Garden City

Monday 8:00 – 18:00
Tuesday 8:00 – 18:00
Wednesday 8:00 – 18:00
Thursday 8:00 – 18:00
Friday 8:00 – 18:00
Saturday 8:30 – 13:00
Sunday Closed

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We can fit our extensive range of premium, mid-range and budget tyres at your premises for a great price.

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