Bicycle tyre and tube sizing is ridiculously confusing. Sheldon Brown has a comprehensive explanation and comparison on his site at Tire Sizing Systems.
Here’s a table of sizing from recent tyres and inner tubes I bought (Schwalbe AV17 and AV19 tubes, for my 29er mountain bike, so these are larger sizes):
| ISO | Fractional / Decimal | French |
|---|---|---|
| 28-622 | 28 x 15/8 x 11/8 | 700 x 28C |
| 30-622 | 28 x 1.20 | 700 x 30C |
| 32-622 | 28 x 15/8 x 11/4 | 700 x 32C |
| 37-622 | 28 x 15/8 x 13/8 | 700 x 35C |
| 40-622 | 28 x 1.50 | 700 x 38C |
| 42-622 | 28 x 1.60 | 700 x 40C |
| 47-622 | 28 x 1.75 | 700 x 45C |
| 50-622 | 28 x 2.00 | |
| 60-622 | 28 x 2.35 |
| ISO | Fractional / Decimal | French |
|---|---|---|
| 32-630 | 27 x 11/4 |
| ISO | Fractional / Decimal | French |
|---|---|---|
| 40-635 | 28 x 11/2 | 700 x 38B |
