REFERENCE 32-00 · RUNNING GEAR
Fastener Torque Spec Chart
Lug nuts, suspension U-bolts, and hanger/shackle bolts — the fasteners most responsible for a wheel or axle failure on the road. Covers travel trailers and fifth wheels through Class A motorhomes.
The wheel/axle manufacturer’s spec always governs. Torque values below vary by wheel maker (Lionshead, Dexter, Lippert, and others) and stud size — use these as a sanity-check range, not a final answer. Always check the spec plate or the manufacturer’s current manual before torquing.
Lug Nut Torque (Conical Seat)
| Wheel / Stud / Nut | Final Torque | Common On |
|---|---|---|
| 12″–13″ wheels, 1/2″-20 studs, 60° cone nut | 60–75 ft-lb | Small single-axle trailers |
| 14″–16.5″ wheels, 1/2″-20 studs, 60° cone nut | 100–120 ft-lb | Most travel trailers |
| 16″–16.5″ wheels (8-on-6.5″), 9/16″-18 studs, 60° cone nut | 140–170 ft-lb | Larger trailers and 5th wheels (7K–8K axles) |
| 16.5″ × 9.75″ stud-piloted, 5/8″-18 studs, 90° cone nut | 175–225 ft-lb | Heavy 5th wheels |
| 17.5″ hub-piloted, 5/8″-18, 90° cone nuts + clamp ring (greased threads) | 190–210 ft-lb | Heavy 5th wheels, toy haulers |
| 17.5″ hub-piloted, 5/8″-18 non-swivel flange nut | 275–325 ft-lb | Heavy 5th wheels, toy haulers |
| 17.5″ hub-piloted, 5/8″-18 swivel flange nut | 150–175 ft-lb | Some 17.5″ trailer setups |
| Medium/heavy-duty hub-piloted, M22×1.5 flange nuts | ~450–500 ft-lb, per the chassis maker | Class A diesel and heavy motorhome chassis: use the chassis manual |
5/8″-18 STUD TIGHTENING STAGES (FT-LB, DEXTER #409)
| Wheel / nut | 1st stage | 2nd stage | Final |
|---|---|---|---|
| 16.5″ × 9.75″ stud-piloted, 90° cone nut | 50–60 | 120–125 | 175–225 |
| 17.5″ hub-piloted, 90° cone nuts + clamp ring (greased) | 50–60 | 100–120 | 190–210 |
| 17.5″ hub-piloted, non-swivel flange nut | 50–60 | 90–200 | 275–325 |
| 17.5″ hub-piloted, swivel flange nut | 50–60 | 60–110 | 150–175 |
Re-torque rule: re-torque after the first 10, 25 and 50 miles on any newly mounted wheel (Dexter), then check regularly. Fasteners seat and settle under initial load. Snug every nut to about 10 ft-lb first, then tighten in stages in a star/cross pattern, never around the circle. Dexter’s stages: 12–13″ wheels 20–25, then 35–40, then 60–75 ft-lb. 14–16.5″ wheels with 1/2″ studs 20–25, then 50–60, then 100–120 ft-lb. 9/16″ studs 20–25, then 50–60, then 140–170 ft-lb. On 5/8″ studs the stages vary by nut type (cone nut, clamp ring, flange or swivel flange), so follow the row above. Values are from Dexter Product Bulletin #409; the wheel maker’s spec governs if it differs.
Suspension U-Bolt Torque
| Axle Rating | Bolt Size | Torque |
|---|---|---|
| 2,000 lb | 3/8″ hex nut | 30–50 ft-lb |
| 3,500 lb | 7/16″ nut (older) | 45–70 ft-lb |
| 3,500 lb | 7/16″ serrated flange nut (Dexter, Nov 2024+) | 70–90 ft-lb |
| 5,200–7,000 lb | 1/2″ hex nut | 45–70 ft-lb |
| 5,200–7,000 lb | 1/2″ flange nut | 70–80 ft-lb |
| 5,200–7,000 lb | 1/2″ serrated flange nut (Dexter, Nov 2024+) | 90–110 ft-lb |
| 8,000 lb | 9/16″ nut | 65–95 ft-lb |
| 8,000 lb | 9/16″ serrated flange nut (Dexter, Nov 2024+) | 100–120 ft-lb |
| 9,000–10,000 lb (D90, D100G) | 5/8″-11 hex nut | 110–150 ft-lb |
Match the row to the nut you actually have: serrated flange nuts take more torque than plain hex nuts on the same bolt. Values are dry threads per the Dexter service manual and Product Bulletin #505 (Nov 2024). Dexter calls for inspecting all suspension fasteners at least every 6,000 miles. Check torque with the trailer’s weight on its tires.
Hanger & Shackle Bolts
Per Dexter, standard (non-shoulder) shackle, spring-eye and equalizer bolts with 9/16″ threads are snug fit only. The parts must rotate freely, and locknuts or cotter pins hold the assembly together. Shoulder-type shackle bolts with 7/16″ threads torque to 30–50 ft-lb. These are pivot points, not rigid joints, so over-tightening binds the equalizer and wears it out early. Inspect for elongated holes or cracked hangers at every axle service.
OUR TOOL KIT
Torque wrenches and gear for running-gear work
EPAuto 1/2-inch Drive Click Torque Wrench (10–150 ft-lb) — Covers every lug nut and U-bolt spec on this chart. Re-torque lug nuts after the first 50 miles on new or re-mounted wheels.
LEXIVON 1/4-inch Drive Click Torque Wrench (20–200 in-lb) — For the small stuff: battery terminals, bus bars and appliance fasteners, where a big wrench over-tightens.
Lincoln 1134 pistol-grip grease gun with 18-inch whip hose — Greases trailer bearings, zerks, and slide gears; the whip hose reaches tight fittings. Once you go cordless you do not go back.
Teslong Dual-Lens Borescope — Snakes behind walls, into tanks, and under slides so you see the problem before you cut anything.
LevelMatePRO+ Wireless Leveling System — Tells you exactly how many inches to raise each side. Leveling without the yelling.
TOPDON TC002C Duo Thermal Camera — Turns your phone into heat vision. We use thermal to find a cooking lug or a failing breaker before it melts something.
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Related Reference Pages
Tires, TPMS & Brakes Guide
Chassis & Engine Maintenance Guide
Seasonal Maintenance Checklist
Full Field Guide
⚠ Safety note: This page is for informational purposes only and is not a substitute for the advice of a qualified professional. Under- or over-torqued wheel and suspension fasteners can cause wheel separation or axle failure while towing or driving. Always verify torque values against your specific wheel/axle manufacturer’s current spec plate or manual, and use a calibrated torque wrench. United Mobile RV LLC is not responsible for outcomes of DIY work performed using this reference. Rev. 2 — October 2026 (lug, U-bolt and shackle values updated to Dexter published specs).
Not sure what’s going on with your rig? We diagnose it properly, on-site.