Hub Nut Torque Guide for Trucks & Trailers
Correct hub nut torque is critical for commercial vehicle safety. Under-torqued hub nuts loosen during operation and cause wheel-off incidents; over-torqued nuts stretch studs, damage bearings, and crack drums. This guide gives you the torque specs and procedures used by OEM and aftermarket service shops worldwide.
Why hub nut torque matters
Wheel bearings rely on a precisely controlled clamping force to stay in place while the wheel rotates at highway speed. The hub nut sets that force. Every commercial vehicle OEM publishes a torque value designed to hold the bearing cone firmly without exceeding the elastic limit of the stud or the brinelling threshold of the bearing race.
If the hub nut is too loose, the cone creeps back and forth under load, generating heat, fretting wear, and ultimately a catastrophic wheel detachment. If it's too tight, the stud stretches plastically (no longer recoverable), the bearing is pre-loaded beyond design, and grease starvation follows. Both failure modes are common, both are expensive, and both are 100% preventable with a torque wrench.
Standard hub nut torque specs (commercial)
| Vehicle / Axle | Stud size | Torque (Nm) | Torque (ft-lb) |
|---|---|---|---|
| BPW trailer axle (light) | M18 × 1.5 | 270 ± 20 | 200 ± 15 |
| BPW trailer axle (heavy, H series) | M20 × 1.5 | 380 ± 30 | 280 ± 22 |
| SAF trailer axle (SK / SK-R series) | M22 × 1.5 | 510 ± 40 | 375 ± 30 |
| KAMAZ 65115 / 6520 (front) | M20 × 1.5 | 380–420 | 280–310 |
| KAMAZ 65115 / 6520 (rear) | M22 × 1.5 | 510–560 | 375–413 |
| Mercedes-Benz Actros / Atego | M22 × 1.5 | 510 ± 40 | 375 ± 30 |
| Volvo FH / FM | M22 × 1.5 | 540 ± 40 | 398 ± 30 |
| Scania R / G series | M22 × 1.5 | 520 ± 40 | 383 ± 30 |
| MAN TGX / TGS | M22 × 1.5 | 540 ± 40 | 398 ± 30 |
Note: Values above are typical OEM recommendations. Always cross-check with the axle maker's service manual for your exact hub variant. KAMAZ hubs in particular have different torque specs depending on drum type (cast vs. steel) and bearing series (2007124 vs. 7517).
The correct tightening sequence
Hub nuts on multi-stud wheels must be tightened in a star (criss-cross) pattern, never in a sequential circle around the hub. The star pattern keeps the drum face from distorting and ensures even clamping load on every stud.
- Hand-tighten all nuts in star pattern until they seat against the washer.
- First pass: torque to 50% of final value, in star pattern.
- Second pass: torque to 100% of final value, in star pattern.
- Mark nut and stud with a paint pen so loosening is visible during pre-trip inspection.
Common mistakes
- Using an impact wrench to "final torque" — impact tools give no torque feedback and almost always over-torque.
- Re-using one-time-use nuts — many BPW / SAF hub nuts are single-use; reusing them risks stripping or cracking.
- Skipping the second pass — single-pass torquing leaves uneven preload; the second pass equalizes it.
- Not re-torquing after first 50–100 km — new studs and bearings settle; a re-torque is mandatory in most OEM warranty terms.
Stud and nut grade pairing
Hub studs on commercial axles are typically grade 10.9 or grade 12.9. Pair them with hub nuts of the same or higher grade. Mixing grade 8 nuts on grade 10.9 studs is a common cost-cutting mistake that fails under thermal cycling.
When to replace hub studs
- Visible necking (diameter reduction between threads and shank).
- Rust streaking from the thread root.
- Thread deformation under the nut.
- After any wheel-off or severe over-torque event.
Need hub nuts or studs?
HOJON supplies OEM-grade hub nuts and wheel studs for BPW, SAF, KAMAZ, Mercedes-Benz, Volvo, Scania, and MAN axles. Custom thread pitches and grades on request. Request a quote with your axle model and stud spec — we ship from Ningbo within 5–7 days.