Wheel Offset Calculator
Measure your current wheel, enter the numbers below, and this will tell you the approximate wheel size and offset you should order.
This is just for the final “17x10 +25mm” style display.
Measure where the tire sits, lip-to-lip on the inside.
From hub pad to straightedge across the back lip.
1) Measure Wheel Width
- Lay the wheel face-down (back of wheel facing upward).
- Measure total width from outer lip to outer lip.
- Measure inside width where the tire actually seats (lip-to-lip).
- Inside width is usually about 1" less than total width.
2) Measure Backspace
- Keep the wheel face-down.
- Lay a straight board or straightedge across the back lip.
- Measure from the hub mounting pad (flat pad where the wheel bolts on) up to the bottom of the board.
- That measurement = Backspace.
3) Find Offset (What the Calculator is Doing)
- Take the inside width and divide by 2 → this gives the wheel centerline.
- Offset (inches) = Backspace – Centerline.
- Convert to mm: Offset (mm) = Offset (inches) × 25.4.
- Positive result → positive offset. Negative result → negative offset.
Quick Example
Inside width: 8"
Centerline: 4"
Backspace: 5.5"
Offset = 5.5 – 4 = +1.5" (≈ +38mm)
You would order something like: 17x8 wheel, +38mm offset.