Link: How to Measure Wheel Holes

You can measure wheel holes by using the bolt pattern, which is the diameter of an imaginary circle formed by the centers of wheel lugs. It is also known as the bolt circle or pitch-circle diameter (PCD). Common bolt patterns are 4-, 5-, 6- or 8-lug holes. A bolt circle of 5x100 would indicate a 5-lug pattern on a circle with a diameter of 100mm. There are different methods of measuring PCD depending on how many lugs there are.

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