Older Tire Sizes
Older Tire Sizes
This section, and the chart we link to below, is provided primarily for reference. We are trying to carry a broad selection of tires to fit many different bikes, but many of these tire sizes are no longer available as new. You may therefore need to find someone carrying old stock in order to find some of the more obscure tire sizes. If you have an older bike that you're trying to fit with new tires, perhaps this information will help you find what you're looking for.
Bicycles have been around for over a century so you can imagine the number of different tire sizes that have been produced. For many decades, each country that produced bicycles created their own tires sizes. Over the last twenty years, the industry has started to stabilize on the relatively few tire sizes mentioned above. Owners of older bicycles, though, have quite a challenge in finding the ride size tire to fit their steed.
Older tire widths are usually specified as either a decimal number (e.g., 1.5") or a fractional measurement (e.g., 1 1/2"). Generally, tires that are specified with decimal widths are not compatible with tires specified in fractional widths; this can be a hint that can help you find the correct size.
ISO (ERTRO) Tire Sizes
In order to try and reduce some of the confusion with tire sizes, the International Organization for Standardization (ISO) developed a universal tire sizing system, known as the ETRTO system (after the European Tyre and Rim Technical Organization). This tire sizing system also uses two numbers, although they're reversed from traditional measurements. The first number refers to the tire or rim width in millimeters and the second refers to the diameter of the bead seat of the rim, also in millimeters. For example, a 700C x 23 tire would be specified as 23-622. The bead seat diameter of a 700C rim is 622mm.
A complete list of ISO sizes can be found here.