How to Measure the Wheel Backset

The backset on a wheel determines its location in the wheel well.

The backset of a wheel is the amount of space from the backside of the wheel hub to the outside of the rear flange. When ordering new wheels, the backset of the new wheels must match the backset of the original factory wheels. If the backset does not match, the new wheel will hit the inside of the wheel well or the body work. Either way, this will cause damage to your vehicle and the newly installed wheels.

Things You'll Need

• Tireless wheel
• Straight edge
• Tape measure

Instructions

1. Set the tireless wheel face down on a firm, flat surface. The section of the hub that bolts to the brakes should be face up.

2. Place a straight edge on top of the tireless wheel.

3. Set the end of the tape measure on the face of the hub. Read the number of the tape measure aligned with the bottom edge of the straight edge.

4. Move the straight edge 90 degrees. Take a second measurement to ensure the accuracy of the first dimension. If the dimensions are different, measure a second tireless wheel to determine if the first wheel is not straight.

5. Measure the backset of the new wheels to ensure they fit properly.

Tips & Warnings

• Set the wheel on the rear edge with the outer wheel face facing up and measure from the surface to the rear side of the hub if you don't have a straight edge.

References

• R and S Racing: Wheel Technical Information
• High-Impact Beadlock Wheels: How to Measure Backspacing
• MGA Guru: MGA With An Attitude: Wheel Offset Clarified