Wheel spacer calculator
A spacer does one thing: it moves the wheel outward by its own thickness. That makes it arithmetically identical to reducing wheel offset by the same number of millimetres.
| Thickness | Effective offset | Track width | Inner clearance | Hardware needed |
|---|---|---|---|---|
| 3 mm | ET45 → ET42 | +6 mm | +3 mm | Usually original bolts |
| 5 mm | ET45 → ET40 | +10 mm | +5 mm | Usually original bolts |
| 10 mm | ET45 → ET35 | +20 mm | +10 mm | Longer bolts or extended studs |
| 12 mm | ET45 → ET33 | +24 mm | +12 mm | Longer bolts or extended studs |
| 15 mm | ET45 → ET30 | +30 mm | +15 mm | Longer bolts or extended studs |
| 20 mm | ET45 → ET25 | +40 mm | +20 mm | Bolt-on adapter |
| 25 mm | ET45 → ET20 | +50 mm | +25 mm | Bolt-on adapter |
| 30 mm | ET45 → ET15 | +60 mm | +30 mm | Bolt-on adapter |
Why people fit them
The honest reasons split into two. The first is clearance: a wider wheel or tyre fouling the strut can sometimes be cured by pushing the whole assembly out a few millimetres. The second is stance, filling the arch. Both are legitimate; they just have different tolerances for how far you can go.
What a spacer cannot do
It cannot gain arch clearance — it spends it. If your tyre is already close to the arch lip, a spacer moves it closer. It also cannot correct a wrong bolt pattern; an adapter that changes PCD is a different component with different engineering considerations.
Model your own change
Enter your current wheel and the same wheel with offset reduced by the spacer thickness in the fitment calculator to see the effect alongside a tyre change. Or compare offsets directly in the offset comparison.
Spacers alter scrub radius and load wheel bearings differently, and thread engagement is a safety-critical detail. Treat thickness selection as a mechanical decision, not a styling one.
How are these fitment figures calculated?
Fitment North calculates declared wheel and tyre geometry from the dimensions shown on the page, using the same tested method as the wheel-offset and tyre-size calculator. Tyre diameter uses rim diameter plus two calculated sidewalls; offset comparisons split width changes across inner and outer edges before applying the offset difference. Results are measurement aids, not vehicle approval. Confirm ratings, clearances and manufacturer guidance before fitting parts.