How to Measure Wheel Backspace

Items required to measure wheel backspace:

  • Tape measure
  • Straight edge
  • Wheel w/o tire (preferred)

The easiest way to measure backspace is to lay the wheel face down onto the ground so the backside of the wheel is facing up.  Take a straight edge and lay it diagonally across the inboard flange of the wheel.  Take a tape measure and measure the distance from where the straight edge contacts the inboard flange to the hub mounting pad of the wheel.  This measurement is backspace.  The above photo shows three wheels with 2″,3″, & 4″ backspace.

Measuring Wheel Offset

To calculate offset you’ll need the following measurements:

  • Wheel backspace
  • Wheel Width
  • Wheel Center line (outboard flange to inboard flange measurement / 2)

Subtract:

  • Wheel center line from Wheel backspace to get offset.
  • If backspace is less than the wheel centerline the offset is negative
  • If backspace is greater than the wheel centerline the offset is positive

Tip:

  • To convert from inches to mm multiply by 25.4
  • To convert from mm to inches divide by 25.4

Backspace to Offset Conversion Chart

The table below is a quick reference for finding offset. Pick the rim width and follow the row over to the backspace of your wheel.

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