rim widths for each: Older markings Note how in the below sorted table the "inches" measure is inconsistent with the mm measures, if height varies: Some 28" tires then have less mm than a 27" tire. 584 mm tires are also marketed as 27.5" (outer diam.) tires. Older markings of wired-edge tires can be converted to ISO 5775 designations with the help of the following table: Such older markings can be appended to the ISO 5775 designation in parentheses. Beaded-edge tires Beaded-edge tires are mounted on hooked-bead rims. They are marked with an overall diameter code and a nominal section-width code, separated by a cross (×). An example for such a marking is 20×1.375 Rims ISO 5775-2 defines designations for bicycle rims. It distinguishes between Straight-side (SS) rims Crochet-type (C) rims Hooked-bead (HB) rims Both crochet (C) and hooked-bead (HB) rims have inner profiles that curve inwards near the outside diameter of the rim to provide a hook that helps retain the tire bead under high pressure. On modern bikes crochet rims are most common and hooked bead rims are rare. The distinction is primarily that hooked-bead rims lack the defined bead seat of straight side and hooked bead rims. The tire is held in position radially by the hook without a bead seat playing a role. Without a bead seat, the primary designation of the diameter in terms of the bead seat is not applicable, and the governing diameter is the OD. Rims are designated by their nominal rim diameter and their nominal width, separated by a cross (×). Both are measured in millimeters. The rim type codes SS or HB precede the rim designation, whereas code C is appended to the nominal width. Examples: SS 400×20, HB 422×25, 620×13C The nominal width of a rim is the inner width between the straight sides or beads as one can easily measure it with a caliper (see the standard for drawings and exact measurement procedures). The standard widths of straight-side rims are: 18, 20, 22, 24, 27, 30.5 The standard widths of crochet-type rims are: 13C, 15C, 16C, 17C, 19C, 21C, 23C, 25C The standard widths of hooked-bead rims are: 20, 25, 27 The diameters of straight-side and crochet-type rims are measured as the bead seat diameter (BSD). Standard values are: 194, 203, 222, 239, 248, 251, 279, 288, 298, 305, 317, 330, 337, 340, 349, 355, 357, 369, 381,