Working out a stud pattern, particularly for items like vehicle wheels, involves measuring the diameter of the circle on which the studs are arranged. This measurement is commonly known as the Pitch Circle Diameter (PCD).
What is a Stud Pattern (PCD)?
A stud pattern, or PCD, defines the diameter of the circle passing through the center of all the studs or bolt holes on a hub or wheel. It's a crucial specification for ensuring a wheel fits correctly onto a vehicle's hub. The pattern is typically expressed as a measurement in millimeters (mm) followed by the number of studs (e.g., 5x112mm means 5 studs on a 112mm diameter circle).
Measuring the Stud Pattern
The method for measuring the PCD depends on whether the pattern has an even or odd number of studs.
Measuring Even Stud Patterns
For patterns with an even number of studs (like 4 or 6), the process is straightforward.
- Method: Measure from the center of one stud to the center of the directly opposite stud.
- Reference: According to the provided information, "For an even stud pattern (4 or 6 studs) You can simply measure from the centre of one stud to the centre of the opposite stud."
- Example: If you have a 4-stud pattern, measure from the center of one hole to the center of the hole directly across from it. If this measurement is 100mm, your PCD is 4x100mm.
Measuring Odd Stud Patterns
For patterns with an odd number of studs (like 3 or 5), you cannot measure directly across. The measurement involves finding the largest distance between studs.
- Method: Measure from the center of one stud to the furthest edge of the opposite stud.
- Reference: Based on the provided information, "If you have an odd number of studs you must measure from the centre of one stud, to the furthest edge of the opposite stud".
- Example: For a 5-stud pattern, pick one stud. Measure from the center of that stud to the outer edge (the furthest point) of the stud directly opposite it across the center. This measurement gives you the PCD.
Summary of Measurement Methods
Here's a quick overview:
| Number of Studs | Measurement Method |
|---|---|
| Even (e.g., 4, 6) | Center of one stud to center of opposite stud |
| Odd (e.g., 3, 5) | Center of one stud to furthest edge of opposite stud |
Understanding how to accurately measure the stud pattern is essential for selecting compatible wheels for your vehicle. Always double-check your measurements and the vehicle's required specifications.
