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DepotOps report: B-double and road train limits
Made 29 Sept 2026, 5:53 pm at depotops.com.au/combination-check. An estimate from the figures entered, not a weighbridge certificate, permit or legal advice.
Enter the weighbridge figure for each axle group of a B-double, road train or twinsteer and see every group and the gross checked against the HVNL, with the working shown.
Rules checked 30 Sept 2026 against NHVR general mass limits information sheet (1 Aug 2026), NHVR reduced mass amount and Mass, Dimension and Loading National Regulation (in force). Official pages are watched weekly for changes.
e.g. 11R22.5 ≈ 279, 295/80 = 295, 315/80 = 315, 385/65 = 385
| Axle group | Limit | Actual (kg) | Margin | Status |
|---|---|---|---|---|
| Steer | 6.0 t | — | ||
| Drive tandem | 17.0 t | — | ||
| Lead trailer tri-axle | 21.0 t | — | ||
| Rear trailer tri-axle | 21.0 t | — | ||
| Gross (9 axles) | 64.5 t | 0 kg | — |
Steer limit 6.0 t — Standard steer axle.
MDL Schedule 1 s2(1): the gross must not exceed the lowest of —
Gross limit 64.5 t (reduced mass amount)
Enter each group's first and last axle, measured from the steer axle. Defaults are typical dimensions — measure your vehicle.
Tightest spacing: Steer → Drive tandem (4.90 m) — limit 28.0 t.
| Spacing | Length | Table | Steer + | Allowance + | Limit | Mass | Status |
|---|---|---|---|---|---|---|---|
| Steer → Drive tandem | 4.90 m | 27.0 t | — | 1 | 28.0 t | — | |
| Steer → Lead trailer tri-axle | 12.90 m | 48.5 t | — | 1 | 49.5 t | — | |
| Steer → Rear trailer tri-axle | 22.10 m | 62.5 t | — | 2 | 64.5 t | — | |
| Drive tandem → Lead trailer tri-axle | 9.30 m | 40.5 t | — | 1 | 41.5 t | — | |
| Drive tandem → Rear trailer tri-axle | 18.50 m | 57.0 t | — | 2 | 59.0 t | — | |
| Lead trailer tri-axle → Rear trailer tri-axle | 11.70 m | 47.0 t | — | 1 | 48.0 t | — |
Each spacing's limit applies to the combined mass of its two end groups and every group between them. Allowance: +1 t when the reduced mass amount is 55 t or less, +2 t above (s5(5A)). Where the Euro VI drive transfer applies, spacings containing the drive but not the steer carry the same increase (Sch 5B s2).