How To Measure Wheel Bolt Circle, Width and Rear Spacing
There are three important measurements to be considered before buying racing wheels. These measurements are to identify the wheel bolt circle (or bolt pattern), the wheel width and the wheel offset (or rear spacing). Follow these steps to ensure that you purchase the correct wheels for your application.
Measuring Wheel Bolt Circles:
- For 4-Lug Wheels measure center to center of the 2 holes that are diagonally across from each other
- For 5-Lug Wheels measure from the back of a hole to the center of the second hole, skipping the next hole
Measuring Wheel Width:
- Wheel width is determined be measuring the distance between the inner edges of the rim beads.
Measuring Wheel Rear Spacing (Back Spacing):
- To measure wheel rear spacing (or backspacing), place the wheel face down and lay a straight edge across the back of the wheel and measure down to the mounting pad of the wheel to determine back spacing.
- A lot of people refer to this measurement as offset but Offset is measured from the center of the rim. So a 8" wide rim with a 3" back spacing has 1" of Negative offset
Use this illustration to assist you in the proper wheel measurement before purchasing your racing wheels.