🛠 How to Measure Hub PCD (Pitch Circle Diameter)
Application: Use this guide to accurately measure the PCD (Pitch Circle Diameter) of 4, 5, and 6 stud trailer hubs.
Purpose: Correct PCD measurement ensures wheel and hub compatibility when replacing rims or hubs.
🔧 What is PCD?
PCD (Pitch Circle Diameter) refers to the diameter of an imaginary circle that passes through the center of all the wheel studs. It's typically measured in millimetres and expressed as the number of studs followed by the PCD (e.g., 5x114.3).
📐 How to Measure PCD by Stud Count
4-Stud Hubs
-
Method: Measure from the center of one stud directly across to the center of the opposite stud.
-
Example: A common 4-stud trailer hub has a PCD of 4x100mm or 4x114.3mm.
5-Stud Hubs
-
Method: Measure from the center of one stud to the outside edge of the furthest (non-adjacent) stud.
-
This indirect method is used because there is no directly opposite stud.
-
Example: Common sizes include 5x114.3mm, 5x120mm, or 5x112mm.
6-Stud Hubs
-
Method: Measure from the center of one stud directly across to the center of the opposite stud.
-
Example: A typical size is 6x139.7mm.
🔩 Common Wheel Stud Patterns for Trailers
This chart helps identify common PCD (Pitch Circle Diameter) measurements based on the number of studs. It's useful when matching trailer hubs and wheels.
| No. of Studs | PCD (Inches) | PCD (mm) | Stud-to-Stud (mm)* | Common Fitment |
|---|---|---|---|---|
| 4 Studs | 4" | 101.6 mm | 71.84 mm | Mini |
| 4 Studs | 4¼" | 108 mm | 76.33 mm | Escort / Cortina |
| 4 Studs | 4½" | 114.3 mm | 80.82 mm | Most Japanese |
| 4 Studs | 4¾" | 120.65 mm | 85.31 mm | — |
| 5 Studs | 4¼" | 108 mm | 63.45 mm | HT Holden |
| 5 Studs | 4½" | 114.3 mm | 67.18 mm | Falcon / Toyota |
| 5 Studs | 4¾" | 120.65 mm | 70.92 mm | Holden HQ |
| 5 Studs | 5" | 127 mm | 74.65 mm | Delta Alloy |
| 5 Studs | — | 140 mm | 82.29 mm | Agricultural |
| 6 Studs | 5½" | 139.7 mm | 68.85 mm | Land Cruiser |
📏 Pro Tip: Use a Vernier Caliper or Ruler
-
For best accuracy, use a vernier caliper for center-to-center measurements.
-
You can also use a PCD measuring template or printable PCD guide for more convenience.
⚠️ Important Notes
-
Always measure in millimetres (mm).
-
Ensure you're measuring from the correct points — especially on 5-stud hubs.
-
Confirm your trailer hub specs before purchasing wheels or replacement hubs.
📦 Tools You May Need
-
Ruler or measuring tape
-
Vernier caliper
-
PCD template (printable or plastic tool)