How to Find/Measure a Tyre Size
Where to find your Tyre/Wheel Size
The size of the tyre is usually either printed or embossed on the side wall of the tyre itself or sometimes just inside the tread. You will usually see two different size measurements on the tyre and the first of these will read like this:
This is the Imperial measurement. The problem with this measurement is that there can be a number of different sizes within this measurement making it very difficult to determine exactly what size tyre you need.
The second measurement is the metric measurement and will read like this:
This set of numbers is much more precise and you can't go wrong with this one. The first two digits, so in the case above its 25, refers to the width of the tyre in millimetres, so 25 mm wide. This is a standard width on most every day wheelchair tyres.
The second part of this measurement is the 540 and this refers to the diameter of the inside of the tyre in millimetres. This does not equate to 24 inches as it is measured from the inside of the tyre, not to the outside so converting 540 mm to inches will give the wrong information as 540 mm equates to just over 22 inches.
Most Common Wheel Sizes
Within the wheelchair world there are certain sizes that are more common than others. The main four wheel sizes are:
|Tyre Size in Inches||Tyre Size in Millimetres|
How to Measure Your Wheel
To measure a wheelchair wheel, you will need a measuring tape or ruler. Here's a step-by-step guide to help you measure the diameter of a wheelchair wheel:
- If possible, remove the wheel from the chair.
- Find a flat surface where you can place the wheel and secure it to prevent it from moving during the measurement process.
- Locate the center of the wheel you want to measure. This is usually where the axle is positioned.
- Take your measuring tape or ruler and extend it across the wheel's center, from one side to the other NOT including the tyre, only measure to the outer part of the wheel rim.
- Read the measurement in millimetres. Subtract 10mm from the number to take into account the depth of the rim.
- Compare that final number to the chart above to determine your tyre size.