tyres

[azfiddle]

I think the refers to the width of the tire in cm (23 cm, 25 cm, 28 cm etc).

We buy CO2 cartridges in bulk from a sporting goods store. They are not exactly the right size but much cheaper and we can get them to work for us.

[pll]

I think the refers to the width of the tire in cm (23 cm, 25 cm, 28 cm etc).

We buy CO2 cartridges in bulk from a sporting goods store. They are not exactly the right size but much cheaper and we can get them to work for us.

23, 25 and 28 are the widths in millimeters. (23 cm would be more than 9 inches...). The "c" really should be next to the rim size (700c), as it refers to the French nomenclature for sizing tires. See Sheldon Brown: http://www.sheldonbrown.com/tire-sizing.html