When referring to the width of a tyre most people will assume that it is simply the measurement from one side of the tyre to the other. There are however four different width measurements which can be applied to a tyre:
- Overall width
- Section width
- Tread width
- Loaded width
Overall width of a tyre is the measurement from side to side including any additional sidewall items such as kerbing ribs, raised letters etc. This is important, particularly when upgrading tyre size, as different manufacturers tyres may have different overall widths even though the tyre size is the same.
Section width is the measurement of the tyre from side to side excluding any additional sidewall items such as kerbing ribs, raised letters etc.
Tread width is the portion of the tyre’s width that is covered by a tread pattern.
Loaded width is the same measurement as the overall width but taken when the tyre has the relevant load applied to it.
The diagram below puts these four widths into perspective: