To measure a wheel bolt pattern, you need to determine two things: the number of lug holes and the diameter of the circle that passes through the center of these holes (called the Pitch Circle Diameter or PCD). Here's how to measure it depending on the number of lug holes:
For Wheels with an Even Number of Lug Holes (e.g., 4, 6, 8 lugs)
- Measure the distance from the center of one lug hole directly across the wheel to the center of the opposite lug hole. This distance is the diameter of the bolt circle (PCD).
- The bolt pattern is expressed as the number of lug holes by the diameter of this circle, e.g., 4x100 mm or 6x139.7 mm
For Wheels with an Odd Number of Lug Holes (commonly 5 lugs)
- Measuring is a bit trickier because there is no directly opposite hole.
- One method is to measure from the center of one lug hole to the center of the second lug hole, skipping one lug hole in between.
- Then add a quarter of an inch (about 6.35 mm) to this measurement to estimate the bolt circle diameter.
- Alternatively, measure from the back of one bolt hole to the center of the second bolt hole or from the center of one hole to the center of the third hole and multiply by 1.05 to get the PCD.
- For example, if you measure 4.25 inches between holes on a 5-lug wheel, adding 0.25 inches gives you a 4.5-inch bolt circle diameter, so the pattern is 5x4.5 inches (or 5x114.3 mm)
Summary
- Count the number of lug holes.
- For even lug counts: measure center-to-center across the circle.
- For 5-lug wheels: measure center-to-center skipping one lug hole and add 0.25 inches, or use the multiplier method.
- Express the bolt pattern as "number of lugs x diameter of bolt circle" (e.g., 5x114.3 mm or 5x4.5 inches)
Using a bolt pattern gauge tool can give more precise measurements, but the above methods are effective for most purposes. Always verify with a bolt pattern guide or vehicle specifications to ensure correct fitment
