Wheel Frontspacing Calculator
Find how far the wheel sticks out. Use the calculator below. Results update as you type.
How the Wheel Frontspacing Calculator Works
This calculator works by subtracting backspacing from the wheel's overall width. Frontspacing is the distance from the mounting face to the outer lip.
- Enter the rim width, for example 9.0 in.
- Enter the offset, for example −12 mm.
- Read the backspacing: 4.53 in.
- Read the frontspacing: 5.47 in (139 mm).
The Formula
The formula is Frontspacing = (Wheel Width + 1 in) − Backspacing.
Frontspacing = (Width + 1) − Backspacing Backspacing = (Width ÷ 2) + Offset (in) + 0.5The 1 in term is the 2 flange lips. Worked example: an 8.5 in wheel at ET35 has 6.13 in backspacing and 9.5 − 6.13 = 3.37 in frontspacing.
Conversion Table
The conversion table gives frontspacing in inches for 5 widths and 6 offsets. Values run from 2.23 in (7.0 in at ET+45) to 6.48 in (10.0 in at ET−25).
Frontspacing plus backspacing always equals the wheel's overall width.
| Width (in) | ET−25 | ET−12 | ET0 | ET+18 | ET+35 | ET+45 |
|---|---|---|---|---|---|---|
| 7.0 | 4.98 | 4.47 | 4.00 | 3.29 | 2.62 | 2.23 |
| 8.0 | 5.48 | 4.97 | 4.50 | 3.79 | 3.12 | 2.73 |
| 8.5 | 5.73 | 5.22 | 4.75 | 4.04 | 3.37 | 2.98 |
| 9.0 | 5.98 | 5.47 | 5.00 | 4.29 | 3.62 | 3.23 |
| 10.0 | 6.48 | 5.97 | 5.50 | 4.79 | 4.12 | 3.73 |
What Is the Wheel Frontspacing Calculator?
The Wheel Frontspacing Calculator is a tool that finds how far a wheel extends outward from the hub face. Frontspacing controls poke and the fender clearance of the wheel lip.
Builders use frontspacing to compare wheels for flush or outward stance, and to estimate how much a deep-dish lip shows.
Common Uses
This calculator has 4 uses: poke prediction, lip-depth estimates, fender checks and wheel comparison.
- Predict poke: See how far the wheel lip sits outward.
- Estimate lip depth: Judge the visible lip on deep-dish wheels.
- Check fenders: Compare with measured fender space.
- Compare wheels: Rank wheels by lip projection.