I may be in the minority, but I sometimes get wrapped around the axle trying to figure out what size tire I can put on my wheelchair rim (note: I’m not entirely alone because I know people that have had to return tires that didn’t fit their rims). One of my favorite websites includes the warning: “Please note: A 25” wheelchair wheel takes a (559) tire. Although some state they are a 26” x 1” (559), it is still considered a 25” (559) tire for a 25” wheelchair wheel. A 26” wheelchair wheel takes a 26” x 1” (590) tire.”
In the US we generally refer to the size of our wheels using the English or Imperial notation such as 26 x 1. In this case we might say we have 26″ wheels when in fact the rims themselves are somewhat smaller, since we are referring to the dimensions of the tire and not the rim (the diameter of the outer side of the tire is 26″ and the width of the tire is 1″).
Wheelchair tires typically use the European Tire and Rim Technical Organization (ETRTO) nomencature such as 25-590 where the rim diameter is 590mm (approximately 23″) and the tire width is 25mm (approximately 1″).
The simplest thing to do whan replacing your tires is to use the same size as the raised letters showing on the sidewall of your old tires. If you would like to swap for a different width or use a standard bicyle tire consider the discussion on the post here.
