The conversions come from the same library as our tire size converter, which follows the ISO 5775 standard (the ETRTO system) and the way Schwalbe converts inches to millimeters. An ETRTO size has two numbers: the tire width and the bead seat diameter (BSD), both in millimeters. If the second number doesn’t match your rim, the tire won’t fit; the width, on the other hand, has some leeway depending on the rim.
Road, gravel and touring (622 rim)
| Size | ETRTO (ISO) | Also called | Typical use |
|---|---|---|---|
| 700 × 23C | 23-622 | — | Road |
| 700 × 25C | 25-622 | 28 × 1 5/8 × 1 | Road |
| 700 × 28C | 28-622 | 28 × 1 5/8 × 1 1/8 | Road |
| 700 × 30C | 30-622 | — | Road |
| 700 × 32C | 32-622 | 28 × 1 5/8 × 1 1/4 | Wide road and gravel |
| 700 × 35C | 35-622 | — | Gravel and touring |
| 28 × 1 5/8 × 1 3/8 | 37-622 | 700 × 37C | Touring and hybrid |
| 700 × 38C | 38-622 | — | Gravel and touring |
| 700 × 40C | 40-622 | 28 × 1 5/8 × 1 1/2 | Gravel |
| 700 × 42C | 42-622 | — | Gravel and city |
| 700 × 45C | 45-622 | — | Gravel |
| 28 × 1.75 | 47-622 | 700 × 47C, 28 × 1 5/8 × 1 3/4 | Touring and e-bike |
| 700 × 50C | 50-622 | — | Mountain-style gravel |
The C in 700C has nothing to do with width: it’s the old French system’s letter for the 622 mm diameter. In the fractional system, the width is the last number: 28 × 1 5/8 × 1 3/8 is a 37 mm tire.
29” mountain bike (622 rim)
| Size | ETRTO (ISO) | Typical use |
|---|---|---|
| 29 × 2.1 | 54-622 | XC and marathon |
| 29 × 2.2 | 56-622 | XC and marathon |
| 29 × 2.25 | 57-622 | XC and marathon |
| 29 × 2.35 | 60-622 | Trail and enduro |
| 29 × 2.4 | 62-622 | Trail and enduro |
| 29 × 2.5 | 64-622 | Trail and enduro |
| 29 × 2.6 | 65-622 | Trail and enduro |
27.5” and 650B (584 rim)
| Size | ETRTO (ISO) | Also called | Typical use |
|---|---|---|---|
| 650B × 42 | 42-584 | 26 × 1 1/2 (British) | 650B gravel |
| 650B × 47 | 47-584 | — | 650B gravel |
| 27.5 × 2.25 | 57-584 | — | XC and trail |
| 27.5 × 2.4 | 62-584 | — | Trail and enduro |
| 27.5 × 2.6 | 65-584 | — | Trail and enduro |
| 27.5 × 2.8 | 70-584 | — | Plus (wide tire) |
27.5” and 650B are the same 584 mm rim. Mountain bikers say 27.5”; gravel riders and classic bikes say 650B.
26”, 650C, older and kids’ sizes
| Size | ETRTO (ISO) | Also called | Typical use |
|---|---|---|---|
| 650 × 23C | 23-571 | — | Triathlon and small road frames |
| 26 × 1.75 | 47-559 | — | Classic MTB and touring |
| 26 × 1.95 | 50-559 | — | Classic MTB |
| 26 × 2.1 | 54-559 | — | Classic MTB |
| 26 × 1 3/8 | 37-590 | 650 × 37A | Classic city bike |
| 27 × 1 1/4 | 32-630 | — | Older road bikes |
| 24 × 1.75 | 47-507 | — | Kids (ages 8-12) |
| 20 × 1.75 | 47-406 | — | Kids, BMX and folding bikes |
| 16 × 1.75 | 47-305 | — | Kids (ages 4-6) |
| 16 × 1 3/8 | 35-349 | — | Brompton-style folding bikes |
| 14 × 2.125 | 54-254 | — | Kids (ages 3-5) |
| 12 1/2 × 2 1/4 | 57-203 | — | Kids and balance bikes (ages 2-4) |
How to read the chart
- Decimal inches round their own way. Schwalbe and the standard convert 2.40” to 62 mm, even though 2.4 × 25.4 is 61, and 1.75” to 47 mm. If your tire has the ETRTO size molded on the sidewall, that number wins.
- “28 inch” is ambiguous. It can be a 622 (700C) or a 635 (28 × 1 1/2, the classic Dutch city bikes). The same goes for 26”: it can be 559 (mountain), 571 (650C) or 590 (26 × 1 3/8 city bikes).
- 24” and 20” vary too. The ones in the chart are the kids’ bike and BMX sizes, the best sellers, but there are 24” wheels with 520, 540 or 547 mm rims and 20” wheels with 451 mm rims. Check the four-digit number on the sidewall before you buy.
- Will it fit your rim? Tire width depends on the rim’s internal width. The converter tells you which widths the ETRTO standard allows for your rim.
If you change sizes, also update your bike computer with the wheel circumference chart and your pressure with the road, gravel or mountain bike tire pressure chart. For kids, the wheel size that fits them is in kids’ bike size by age. And if you need the size to buy a spare tube, our guide to fixing a flat tire explains what to carry in your saddle bag.
Frequently asked questions
What does 25-622 mean on a bike tire?
It's the ETRTO size (ISO 5775 standard): 25 mm wide with a 622 mm bead seat diameter on the rim. It's the same as 700 × 25C and 28 × 1 5/8 × 1.
Are 29" and 700C the same wheel size?
Yes: both use a 622 mm rim. Mountain bikers call it 29" after the outer diameter with a wide tire; road and gravel riders call it 700C. That's why a 700 × 50C and a 29 × 2.0 are the same size, 50-622.
Are 26 x 1.75 and 26 x 1 3/4 the same tire?
No. The first is a mountain bike size, 47-559, and the second fits a 571 rim, the same as 650C. Decimal and fractional inch sizes aren't interchangeable even when they look identical.