49 C.F.R. § 230.99
Tender truck axles.
Cite as 49 C.F.R. § 230.99 (2026)
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
5
1
⁄
2
7
3
⁄
8
6
7
⁄
16
38000
5
6
3
⁄
4
5
7
⁄
8
31000
4
1
⁄
2
6
1
⁄
4
5
5
⁄
16
22000
3
3
⁄
4
5
4
3
⁄
8
15000
3
1
⁄
4
4
5
⁄
8
3
7
⁄
8