Wheelchair tyres come in various sizes to fit different diameter wheels. So, when you are going to purchase a replacement, or a spare tyre, or inner tube, it is important to make sure that you purchase the correct size. All tyres and inner tubes have identification markings, however, these numbers can be confusing unless you know what they stand for.
24 inch = 540
25 inch = 559
26 inch = 590
The three digits are the metric (mm) size number which indicate the wheel diameter. A tyre or inner tube for a 24-inch wheel will bear the numbers 540, for a 25-inch wheel-559, and for a 26-inch wheel-590. Almost all wheelchairs have wheels of one of these three diameters.
The other two digits – such as 25-540 – indicates the tyre width. Most wheelchairs use one-inch wide tyres for normal use on standard wheels and 1 inch equals 25mm.
Wider tyres are sometimes used to get an improved grip on the road surface or to provide a softer, more comfortable ride. There are many different treads and technological advances now available in wheelchair tyres so be sure to investigate which is the most suitable for your needs and your budget.
Most inner tubes for wheelchair tyres have a Schrader valve. This is commonly called a “car valve” as they are the same kind of valve found on automobiles. They are a robust valve with an easily removable core, and the spring closure makes them easy to inflate. They have the advantage that you can get pumped up easily at your local petrol station.
A Presta valve is sometimes used for sports wheelchairs. This type of valve is rather more complicated to inflate and deflate as they need to be unscrewed and require a special pump or an adaptor. They are thinner and longer than the Schrader valves and can maintain a higher air pressure for increased mobility and performance.