What does tyre size mean?

To the untrained eye, the side wall of a tyre can look like a meaningless set of numbers, letters and symbols. Hidden amongst these is the tyre size. But what does it look like and, more importantly, what does it mean?

How the tyre size might appear.

Dissecting the code

The tyre size might read like this: P195/55 R16 87 V. Hardly user friendly but, when you know what it all means, you’ll realise it tells you useful information about the tyre’s construction, size and type.

1 Cross section width

The first three numbers, in this case 195, refer to the section width of the tyre. This is the measurement, in millimetres, from the tyre’s inner sidewall to its outer sidewall.

2 Aspect ratio

The aspect ratio, or profile, refers to the height of the sidewall as a % of the section width. In our example, 55 means the height is equal to 55% of the 195mm width. The bigger the aspect ratio, the bigger the sidewall will be.

3 Construction type

The letter R means the tyre is a radial construction. Almost all new car tyres are radials.

4 Rim

The number to the right of the construction type is the rim diameter, measured in inches. In this case, it’s a 16” wheel.

5 Load index 

The final number is the load index i.e. the maximum load (in kg) that the tyre can carry. See chart below


6 Speed symbol

The final character (in this case V) relates to the maximum speed of use. Again, the following table will clarify what your tyre’s symbol means.

Where can I find my car’s tyre size?

You’ll find you car’s tyre size on the tyres’ sidewall, in your car’s vehicle manual as well as on a sticker inside the driver’s door. If you’re still unsure, visit your nearest Uniroyal dealership for advice.