Originally Posted by NormanF

There used to be a bewildering variety of tire sizes but they seem to have sorted themselves out into more or less five categories:

406 mm for folders, mini velo and bmx bikes, 559 mm for cruisers and standard mountain bikes, 584 mm for mid size mountain bikes and older French touring/city bikes, 622 mm for road bikes and 29er mountain bikes and 635 mm for path bikes and roadsters.