What are tyre sizes?

  • What do I need to know about tyre sizes
  • Why those numbers on the sidewalls are so important
  • Parkers explains the jargon

Tyre sizes concern the width and height of the rubber your car wears, as well as the maximum speed you're allowed to travel in them. Although the numbers are on the sidewall, very few people know how to decipher them.

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What do I need to know about tyre sizes?

In simple terms, the format of the tyre size will almost always follow this pattern on any modern car:

195/55 R16 87V

The numbers always break down in the following way:

195 The width of the tyre in mm. Typically, the higher the number, the more grip you get. But not always!

55 The profile of the tyre. By that, we mean the height of the sidewall expressed as a percentage of the width. So this one would be 97.5mm high.

R Means it's a radial tyre.

16 Is the diameter of the road wheel, expressed in inches.

87 This is the tyre's load rating. The higher the number, the more weight each tyre is able to carry. In this instance, 87 would equal 615kg. Multiply that figure by four, and you get an idea of the total load your car can carry. 

V The speed rating. Again, the higher the letter, the faster speed your car is capable of travelling safely. In this case, the tyre is guaranteed up to 149mph. There is a table of speed ratings below.

Why it's important to get the right tyres

Sometimes it might be tempting to buy a lower speed rated tyre (in the same size) for your car in order to cut the cost of your tyres. In speed-restricted UK you might wonder why you need 150mph+ rated tyres - but they are rated so highly for a reason.

In terms of longevity, heat resistance, and wear, you must stick to the recommended rating in order to remain safe. But you will also invalidate your insurance if you fit incorrectly-specified tyres - if in doubt, ask directly.

Tyre speed rating guide

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

Looking for more jargon-busting motoring meanings? Head over to our Parkers Car Glossary page and take a look at our other definitions.

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