Home » Help & Advice » How To Read Your Tyre Size

How To Read Your Tyre Size

Understanding the key markings on your vehicle’s tyres will help to identify their exact size and specifications should you require a replacement. This quick and simple tool explains the meanings behind the numbers, letters and codes so you can find the right tyre for your vehicle.

  • Tyre Size
  • Wheel Size
  • Load Index
  • Speed Rating
  • Date of Manufacture
  • Run Flat
  • Reinforced

Section width (225)

This number shows the width of the tyre measured in millimetres. This tyre is 225 mm wide.

Aspect Ratio (55)

This number signifies the percentage of the tyre’s width. The aspect ratio for this tyre is 55% of the 225 width (which equates to 123.75mm).

Construction (R)

This letter shows how the tyre was constructed. The R on this tyre stands for radial which is the most common type for new cars manufactured today.

Rim/Wheel Diameter

This number represents the size of the tyre’s inner rim diameter measured in inches. The number marked on this tyre shows that it fits on a 16 inch wheel rim.

Load Index (91)

This code indicates the maximum weight the tyre can carry - the weight corresponds with the relevant code number. The 91 code on this tyre means it can carry up to 615kg - this can vary from tyre to tyre.

Speed Rating (V)

This symbol represents the maximum speed a tyre can carry its load. The speed symbol ‘V’ on this tyre equates to 149mph. It’s worth noting that choosing a lower speed rating than one which is suitable for your car may invalidate your insurance.


This stands for ‘Reinforced’ to show that the tyres have been specially reinforced to withstand extra weight. Depending on the manufacturer, other symbols used to show this include XL, EXL, RF, REINF and RFD.


This stands for ‘Run Flat’ tyres which have been specially manufactured to withstand the weight of the vehicle in the event of a puncture, and still be able to transport the vehicle to the required stop. Depending on the manufacturer, other symbols used to show this include ROF, EMY, ZP, SSR and DSST.

Date of Manufacture


This means that the tyre meets the Department of Transport safety standards.


These 8 letters are a serial number to show the type of tyre and the facility it was made in.


This number represents the age of the tyre. The first 2 digits signify the week of the year that the tyre was produced in. The last 2 digits represent the year it was produced in. This tyre is marked 2118, meaning it was manufactured in the 21st week of 2018.

It’s worth noting that if the date on your tyres exceeds six years, you should have them inspected to test whether they are still roadworthy.

This website uses cookies to enhance your browsing experience... moregot it


COVID-19 update

The wearing of masks is now as a personal choice.

We are open for business. Read More