What do tyre sizes mean?

1st July 2019

We may already have a little knowledge about what tyres are best for which road conditions - but when it comes to replacing your tyres, what do tyre sizes mean? Numbers, letter, words and symbols show on the sidewall of your tyre - but what does the number on a tyre mean? Find out everything now.

Tyre markings explained

Tyre markings are set to indicate many factors when it comes to finding out information about your tyres, such as size, brand and range. Through these markings, you can learn about:

  • Tread pattern
  • Width
  • Speed rating
  • Sidewall height
  • Diameter
  • Load index

What do the numbers on tyres mean?

But, what does it all mean? The image below shows the tyre sidewall markings, broken down into separate sections:

  • 195 - width: This is measured in millimetres - and this shows the width of the tyre's cross section, also known as the section width.
  • 65 - aspect ratio: Looking at the tyre's width to height as a percentage, this marking can show if the tyre has a short sidewall compared to width. This could mean it may be noisier, but has better handling and a more stable ride.
  • R - internal construction of the tyre: Common in most tyres, this indicates if the tyre has radial-ply construction. An alternative to this would be bias-ply tyres, which are common in motorcycle tyres, or Crossply tyres - which are more rigid than radial tyres.
  • 15 - diameter: This is measured in inches - and shows the diameter of the wheel that the tyre is designed to fit.

As well as the tyre markings above, there can often also be other sequences of numbers, too. These numbers (for example: 92H) show:

  • Load index (92): This shows the maximum load each tyre can carry when it's inflated to its maximum safe pressure. This means that the index is 92 - not that the tyre can support 92kg. A tyre with a load index of 92 can support around 615kg of weight.
  • Speed rating (H): This indicates the maximum speed the tyre can carry the load safely. Speed ratings vary from A, being the lowest, to Y, highest, with the exception of H - which is classified between U and V. Each letter corresponds to an equivalent of mph e.g. H = 130 mph. Examples of speed symbols and their mileage per hour are:

Speed Symbol Miles/Hour
N 87mph
H 130mph
S 112mph
U 124mph
Y 186mph

Find out more information on tyre markings today from our detailed guide.

So now you?ve learnt what the numbers and letters on car tyres mean, why not choose your own? Find the perfect tyres to buy online today from The Tyre Group.

Buy tyres online with The Tyre Group for fitment at one of our branches in the Midlands, South West England, South Wales and Scotland Contact The Tyre Group incorporating Malvern Tyres, Discount Tyres, County Tyre, King David Tyres Ltd and AutoTyre & Battery Co. We have more than 50 branches located throughout the Midlands, South West England, South Wales and Scotland