Wheel Frontspacing Calculator
Calculate wheel frontspacing, the distance from the hub face to the outer rim edge. Shows how far a wheel pokes out, in mm and inches.
Calculate outward wheel projection.
Wheel Frontspacing Calculator: Tire Size Inputs
Compare two tire sizes here. Use the formulas and reference tables below for this tool's specific calculation.
How Wheel Frontspacing Calculator Works?
The Wheel Frontspacing Calculator works by subtracting backspacing from the overall wheel width, or subtracting the offset from half of the overall width. The tool uses 3 steps.
Enter wheel width
Type the nominal width, for example 10.0 in.
Enter offset or backspacing
Type ET−25 or 4.5 in of backspacing.
Read frontspacing
The calculator returns 164.7 mm (6.48 in) of frontspacing, the distance the outer flange sits from the hub face.
Wheel Frontspacing Calculator Formula
The Wheel Frontspacing Calculator formula is FS = (W_nom + 1) × 12.7 − ET, or FS = Overall width − BS.
FS = (W_nom + 1) × 12.7 − ETFS = (W_nom + 1) × 25.4 − BS- FS
- Frontspacing, hub face to outer flange (mm)
- BS
- Backspacing (mm)
- ET
- Offset (mm)
Worked example
A 9.0 in wheel at ET+18 has an overall width of 254 mm. Frontspacing is 127 − 18 = 109 mm (4.29 in), and backspacing is 145 mm (5.71 in).
Wheel Frontspacing Calculator Conversion Table
The Wheel Frontspacing Calculator conversion table lists frontspacing and backspacing for 7 wheel specs.
| Width | Offset | Backspacing | Frontspacing (mm) | Frontspacing (in) |
|---|---|---|---|---|
| 7.5" | ET+45 | 152.9 mm | 62.9 mm | 2.48 in |
| 8.0" | ET+35 | 149.3 mm | 79.3 mm | 3.12 in |
| 8.5" | ET+30 | 150.6 mm | 90.6 mm | 3.57 in |
| 9.0" | ET+18 | 145.0 mm | 109.0 mm | 4.29 in |
| 9.0" | ET+0 | 127.0 mm | 127.0 mm | 5.00 in |
| 10.0" | ET-25 | 114.7 mm | 164.7 mm | 6.48 in |
| 12.0" | ET-44 | 121.1 mm | 209.1 mm | 8.23 in |
What is Wheel Frontspacing Calculator?
A Wheel Frontspacing Calculator is a tool that measures how far a wheel's outer edge extends beyond the hub mounting face. Frontspacing decides wheel poke, the amount the wheel sticks out past the fender.
Frontspacing plus backspacing equals overall wheel width. A wider wheel with the same backspacing gains all of the extra width as frontspacing.
Owners of lifted trucks and widebody cars use frontspacing to plan fender flares.
What are the uses of Wheel Frontspacing Calculator?
There are 4 main uses of the Wheel Frontspacing Calculator, including poke planning and flare sizing.
Poke planning
Set how far the wheel sticks out past the body.
Flare sizing
Pick fender flares wide enough to cover the wheel.
Tire coverage rules
Check outward reach against local coverage rules.
Width upgrades
See where the extra width of a wider wheel goes.
Related Wheel Geometry & Fitment Tools
View All 134 Subtools →Calculate wheel mounting offset.
Compare old and new offsets.
Calculate backspacing using specified wheel dimensions.
Convert mounting measurements.
Account for spacer thickness.
Calculate inward and outward clearance changes.