Outer Wheel Position Calculator
See how the outer rim edge moves. Use the calculator below. Results update as you type.
How the Outer Wheel Position Calculator Works
This calculator works by subtracting the offset from the wheel half-width to find the distance from the hub face to the outer bead seat.
- Enter the rim width, for example 9.0 in (228.6 mm).
- Enter the offset, for example ET30.
- Read the outer position: 84.3 mm (3.32 in) from the hub face.
- Compare with the current wheel to see the outward change.
The Formula
The formula is Outer Position = (Width × 25.4 ÷ 2) − Offset.
Outer Position (mm) = Width (in) × 12.7 − ET (mm) Outer Change (mm) = Outer_new − Outer_oldWorked example: an 8.0 in ET45 wheel sits at 56.6 mm. A 9.0 in ET35 wheel sits at 79.3 mm, a change of +22.7 mm outward.
Conversion Table
The conversion table gives the outer bead seat distance for 7 widths and 5 offsets. Distances run from 43.9 mm (7.0 in at ET45) to 107.0 mm (10.0 in at ET20).
Higher offsets lower the outer position, pulling the wheel face inward.
| Width (in) | ET20 | ET30 | ET35 | ET40 | ET45 |
|---|---|---|---|---|---|
| 7.0 | 68.9 | 58.9 | 53.9 | 48.9 | 43.9 |
| 7.5 | 75.2 | 65.2 | 60.2 | 55.2 | 50.2 |
| 8.0 | 81.6 | 71.6 | 66.6 | 61.6 | 56.6 |
| 8.5 | 87.9 | 77.9 | 72.9 | 67.9 | 62.9 |
| 9.0 | 94.3 | 84.3 | 79.3 | 74.3 | 69.3 |
| 9.5 | 100.6 | 90.6 | 85.6 | 80.6 | 75.6 |
| 10.0 | 107.0 | 97.0 | 92.0 | 87.0 | 82.0 |
What Is the Outer Wheel Position Calculator?
The Outer Wheel Position Calculator is a tool that finds where the outer edge of a wheel sits relative to the hub mounting face. Outer position controls how flush the wheel sits with the fender.
The figure lets you compare wheels of different widths and offsets on one scale.
Common Uses
This calculator has 4 uses: flush fitment, fender clearance, legal checks and wheel comparison.
- Set flush fitment: Match the outer face to the fender line.
- Check fender clearance: Compare with measured outer space.
- Check legal limits: Keep wheels inside fender rules.
- Compare wheels: Rank wheels by outward reach.