| Bead seat (mm) | Sold as | Typical bikes |
|---|---|---|
| 203 | 12 1/2" | Kids’ bikes, some folding bikes |
| 254 | 14" | Kids’ bikes |
| 305 | 16" | Kids’ bikes, some folding bikes |
| 349 | 16 x 1 3/8" | Brompton and similar folding bikes |
| 355 | 18" | Some folding and kids’ bikes |
| 406 | 20" (decimal, e.g. 20 x 1.75) | BMX, kids’ bikes, most folding bikes, cargo bikes |
| 451 | 20 x 1 1/8", 20 x 1 3/8" | Older road-style kids’ bikes, some fast folding bikes |
| 507 | 24" (decimal, e.g. 24 x 1.95) | Kids’ mountain bikes |
| 520 | 24 x 1" | Small road bikes, wheelchairs |
| 540 | 24 x 1 3/8" | Wheelchairs, older kids’ bikes |
| 559 | 26" (decimal, e.g. 26 x 2.1) | Classic mountain bikes, many cruisers and touring bikes |
| 571 | 650C, 26 x 1 3/4" | Small triathlon and road bikes |
| 584 | 650B, 27.5" | Modern mountain bikes, gravel and randonneur bikes |
| 590 | 650A, 26 x 1 3/8" | Older English three-speeds and roadsters |
| 597 | 26 x 1 1/4", Schwinn 26 x 1 3/8" | Old club bikes, older Schwinn lightweights |
| 622 | 700C, 29", 28" | Road, gravel, hybrid, city and 29er mountain bikes |
| 630 | 27", 27 x 1 1/4" | Older road bikes (1970s–80s ten-speeds) |
| 635 | 28 x 1 1/2" | Traditional Dutch and Indian roadsters |
Reading the chart
Rows next to each other differ by only a few millimetres – 584 vs 590 vs 597, or 622 vs 630. A tire for a rim even 6 mm bigger won’t seat; one for a smaller rim won’t go on at all. When an old tire and a new one share a name but not a bead seat number, trust the number.
Not sure what you have? Type the size from your sidewall into the size decoder.