Tyre Sizes and Markings Explained

The tyre market is filled with size, style and brand options – and knowing which choices can work for your vehicle may be confusing. When it comes to choosing the right tyre sizes, there may be several options that fit within your vehicle’s parameters.

Each tyre sidewall is etched with a series of numbers and reading these tyre markings can tell you important information about a tyre’s size and construction. In this article, we’ll explain how to read your tyre size and other information with total clarity.

What do tyre size numbers mean?

These tyre size numbers tell you many important pieces of information: tyre width, aspect ratio, construction, inside diameter of the tyre, load capacity, and speed rating.

Tyre markings – Let’s take a look at an example

Imagine that your tyre’s sequence of numbers says: 205/55 R16 91 V

  • 220 corresponds to your tyre width in mm.
  • 53 is the aspect ratio of the tyre, and simply put, this is the height of the sidewall as a percentage of the tread width e.g. in this case, the sidewall is 53% of the tread width.
  • R tells you the tyre is of radial construction, which is the expected construction for all modern tyres.
  • 19 is the diameter of the wheel rim, in inches.
  • 89 is the load index, i.e it details the load-carrying capacity of a tyre. The higher the number, the greater its load-carrying capacity.
  • V is the speed rating, which describes the maximum speed the tyre can reach when at full load. They are described in letter form, and each letter’s corresponding speed in mph can be found below.

Tyre Speed Ratings

N: 87mph, P: 93mph, Q: 99mph, R: 106mph S: 112mph, T: 118mph, U: 124mph, H: 130mph, V: 149mph, Z: 150+mph, W: 168mph, Y: 186mph

Generally speaking, you should aim to find a tyre that either matches or exceeds your car’s top speed – failing to do so can invalidate your insurance.

Should you change tyre size?mechanic giving advice on tyres

Some motorists wish to change their tyre size because they believe it will enhance the performance, speed and fuel consumption of their car. Careful research should be carried out before making this decision, as it could affect your insurance payouts and the general safety of your vehicle. Always check your car manufacturer’s recommendations, and if you’re still in doubt, check with your local mechanic for some further advice on tyre sizes and other considerations.

Watling Tyres have been operating since 1962, establishing ourselves as a trusted tyre dealer across Kent, Surrey and Sussex. We have a vast range of brands and sizes available, suitable for a diversity of vehicle makes – simply ask our team for some expert advice.


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