Wobble Bolts Explained: Safe PCD Variation & Fitment Guide
Summary: What Are Wobble Bolts?
Variable PCD bolts (commonly known as wobble bolts) feature an engineered floating conical collar that allows alloy wheels with up to a 2mm difference in PCD (pitch circle diameter) to be safely bolted onto your vehicle's hub. The most popular UK application is fitting BMW 5x120 alloy wheels onto Vauxhall Vivaro / Renault Trafic vans (5x118).
1. How Wobble Bolts Work Mechanically
Standard wheel bolts have a fixed 60° conical head machined directly into the bolt shank. If you attempt to force a standard bolt into a wheel hole that is offset by even 1mm, the bolt enters at an angle, bending the shank and placing catastrophic fatigue stress on the threads.
A wobble bolt solves this with a floating collar:
- The central threaded bolt threads straight and square into the vehicle's hub.
- The floating collar slides radially by up to ±1mm (giving 2mm total PCD tolerance across opposite studs) to seat flush inside the alloy wheel cavity.
- Full clamping force is transmitted squarely between the wheel and hub without lateral bending force on the bolt.
2. Safe PCD Variations (Max 2mm Rule)
Wobble bolts are engineered strictly for a maximum 2mm PCD difference. Never exceed this limit!
| Hub PCD | Wheel PCD | Difference | Common Example |
|---|---|---|---|
| 5x118 | 5x120 | 2.0mm (Safe) | BMW wheels on Vauxhall Vivaro A / Renault Trafic II / Fiat Ducato |
| 5x110 | 5x112 | 2.0mm (Safe) | Audi / VW / Mercedes wheels on Vauxhall Astra / Alfa Romeo / Saab |
| 5x112 | 5x114.3 | 2.3mm (Marginal) | Japanese wheels on VW / Audi / Mercedes |
| 5x114.3 | 5x120 | 5.7mm (DANGEROUS) | Vivaro B / Trafic Mk3 (2014+) CANNOT fit BMW wheels via wobble bolts! |
3. Why Spigot Rings Are Strictly Mandatory
When fitting BMW wheels (72.6mm center bore) onto Vivaro / Trafic hubs (71.1mm diameter), there is a 1.5mm gap. If you bolt the wheel on without spigot rings, the wheel will sit eccentric, shaking violently at 50-70mph and fatiguing the hub bolts. You must always install 72.6mm → 71.1mm hub centric spigot rings.
4. Commercial Van Load Ratings & MOT Legality
- TÜV Approved & MOT Legal: Our Bimecc wobble bolts are Class 10.9 high tensile steel, fully certified for highway and commercial use, and 100% compliant with UK MOT test standards.
- Check Wheel Load Ratings: Commercial vans like the Vivaro/Trafic carry substantial rear axle weights. Ensure any BMW wheels used have a load rating meeting or exceeding your van's Gross Axle Weight Rating (GAWR). Wheels from heavier vehicles like the BMW X5 (E53/E70) or 7-Series are commonly chosen for their robust weight capacity.
- Torque Spec: Tighten to 140 Nm (103 lb-ft). Always re-torque after 50 miles.
Looking for a Complete Wobble Bolt & Spigot Ring Kit?
Lucidity Motorsport provides complete 20-bolt sets including the required 72.6mm → 71.1mm spigot rings for Vauxhall Vivaro / Renault Trafic conversions.
View 20x M14x1.5 Wobble Bolt Kit
