49 C.F.R. § 230.99
Tender truck axles
The minimum diameters of axles for various axle loads shall be as follows:
| Axle load (in pounds) | Minimum diameter of journal (in inches) | Minimum diameter of wheel seat (in inches) | Minimum diameter of center (in inches) |
|---|---|---|---|
| 50000 | 51⁄2 | 73⁄8 | 67⁄16 |
| 38000 | 5 | 63⁄4 | 57⁄8 |
| 31000 | 41⁄2 | 61⁄4 | 55⁄16 |
| 22000 | 33⁄4 | 5 | 43⁄8 |
| 15000 | 31⁄4 | 45⁄8 | 37⁄8 |