To properly measure your wheel gap you will need a few simple tools:

• Measuring device with millimeter units
• Straight edge--Yard stick or similar

1. Place a straight edge flush with the face of the wheel and tire combination. Make sure the straight edge touches the tire in two spots to keep the straight edge even with the tire.
2. Use the measuring device to measure from the inside of the straight edge to the inner fender lip. (see diagram)
3. Make sure that the measurement is taken at the point where the wheel and tire is closest to the fender. For instance, on a car with a large amount of negative camber the tire and wheel may be closest at the front or rear edge of the fender.