5. How to Measure Wheel Gap?
The outside of the tire sidewall is usually the widest point of your wheel and tire (unless the tires are 'stretched' across the rim. With the tire/wheel on the car and the car on the ground at its desired ride height, place a straight edge or ruler between the outermost tire spot and the inside of the fender lip. The distance is your wheel gap and your spacer size. This is the max spacer size so it would be a good idea to choose a spacer one size lower to account for suspension travel.