What Is PCD in Mags and How to Measure It Accurately

PCD is short for Pitch Circle Diameter, which is a term meaning the diameter of an imaginary circle that runs through the centres of all of the wheel bolt holes. PCD is an important specification to consider when fitting wheels to a vehicle. Incorrect PCD fitting may end with the wheel not fitting the hub in a secure manner, and incorrectly fitting the wheel may cause the vehicle to not be aligned correctly & can cause undue stress on the stud or bolt. 

PCD is normally stated or noted in a preference such as 5×114.3, where the first numeral (5) is the number of studs or bolts and the second numeral (114.3) is the diameter of the bolt circle in millimeters.

Table of Contents

Common PCD Patterns in Passenger Vehicles

Examples of Common PCDs:

How to Determine Your Vehicle’s PCD

1. Check the Wheel or Owner’s Manual

2. Count the Bolt Holes

3. Measure the Diameter Based on Bolt Count

Measuring PCD: Step-by-Step Instructions

For Even-Numbered Bolt Patterns (e.g., 4 or 6)

Example:

For Odd-Numbered Bolt Patterns (e.g., 3 or 5)

Important Notes on PCD Compatibility

PCD and Wheel Fitment

Conclusion

Common PCD Patterns in Passenger Vehicles

Most passenger vehicles use PCD configurations with 4, 5, or 6 bolts. Unusual cases include:

• 3-stud wheels, seen on models like Smart cars.
• 8-stud wheels, common on larger U.S. pickup trucks, especially as they enter markets like Australia.

Examples of Common PCDs:

• 4×100 – Compact vehicles
• 5×114.3 – Widely used across Japanese, Korean, and American cars
• 6×139.7 – Common in 4WD and utility vehicles
• 8×165.1 – Heavy-duty pickup trucks

How to Determine Your Vehicle’s PCD

1. Check the Wheel or Owner’s Manual

Many OEM wheels have PCD information stamped on the inside. Alternatively, the owner’s manual or manufacturer specifications online will list the PCD when you search by year, make, and model.

2. Count the Bolt Holes

Remove the wheel cover if needed. Count the number of bolts or studs to get the first number in the PCD value.

3. Measure the Diameter Based on Bolt Count

The method for measuring PCD depends on whether the number of bolts is even or odd.

Measuring PCD: Step-by-Step Instructions

For Even-Numbered Bolt Patterns (e.g., 4 or 6)

Use a ruler or caliper to measure from the center of one bolt to the center of the bolt directly opposite.

Example:

• 4 bolts, opposite bolts measure 100mm apart
  → PCD = 4×100

For Odd-Numbered Bolt Patterns (e.g., 3 or 5)

Measure from the center of one bolt to the center of an adjacent bolt. Then apply a specific multiplication factor:

Important Notes on PCD Compatibility

• PCD must match exactly between the wheel and the hub.
• Even a slight variation (e.g., using 5×112 wheels on a 5×114.3 hub) can cause vibration or unsafe driving conditions.
• Many aftermarket wheels list PCD clearly on the back or in the specifications sheet.

PCD and Wheel Fitment

While PCD is one factor in determining if a wheel fits, other important measurements include:

• Center Bore: Diameter of the hole at the center of the wheel.
• Offset (ET): Distance from the wheel’s hub mounting surface to the centerline.
• Bolt Thread Size: The Thread pitch and diameter of the wheel bolts or nuts.

Conclusion

To safely install or replace wheels, knowing the correct PCD is essential. Always verify the bolt count and use accurate measurement methods. Misaligned wheels due to incorrect PCD can compromise performance, safety, and wear on suspension components. Proper tools and exact figures eliminate guesswork and ensure secure, balanced wheel mounting.