Calculating the Pitch Circle Diameter (PCD)


The Pitch Circle Diameter (PCD) is the diameter of the circle which passes through the centre of all the studs, wheel bolts or wheel rim holes.

The easiest way calculate the PCD is as follows:

1) Identify the size of rim or tyre size. (This helps to narrow down the likely PCD sizes)
2) Measure the distance 'S' between two adjacent studs from the centre of each hole.
3) Using the calculator enter the number of studs/holes and  'S' and press 'calculate'.
3) Using the relevant diagram depending on the number of studs you have you should be
         able to identify the correct PCD.

Note: Imperial sizes are commonly used on UK trailers whereas European trailers use metric.

4 Stud 5 Stud 6 Stud
4 Stud Diagram 5 Stud Diagram 6 Stud Diagram

PCD Calculator
Select Number of Studs/Holes  
Enter measurement S in millimetres  
   
Pitch Circle Diameter (PCD) =   mm
     
     


 
 
Rim Size
Studs
    S
 
PCD
 
8" Rim
3
76.90mm
 
88.8mm
   
3
95.26mm
 
110mm
 
 
4
70.71mm
 
100mm
 
4
71.84mm
 
101.6mm (4")
 
4
81.32mm
 
115mm
 
4
91.92mm
 
130mm
     
 
10" Rim
4
70.71mm
 
100mm
   
4
71.84mm
 
101.6mm (4")
   
4
79.20mm
 
112mm
   
5
65.83mm
 
112mm
   
4
81.32mm
 
115mm
   
4
91.92mm
 
130mm
   
4
98.78mm
 
139.7mm (5½")
       
 
12" Rim
4
70.71mm
 
100mm
   
4
71.84mm
 
101.6mm (4")
   
5
65.83mm
 
112mm
   
4
91.92mm
 
130mm
   
4
98.78mm
 
139.7mm (5½")
   
5
82.29mm
 
140mm
   
5
97.04mm
 
165.1mm (6½")
       
 
13" Rim
4
70.71mm
 
100mm
   
4
79.20mm
 
112mm
   
5
65.83mm
 
112mm
   
4
91.92mm
 
130mm
   
4
98.78mm
 
139.7mm (5½")
   
5
82.29mm
 
140mm
   
5
97.04mm
 
165.1mm (6½")
       
 
14" Rim
4
70.71mm
 
100mm
   
5
65.83mm
 
112mm
   
5
82.29mm
 
140mm
   
5
89.58mm
 
152.4mm (6")
   
6
102.5mm
 
205mm
       
 
16" Rim
5
97.04mm
 
165.1mm (6½")
 




PCD Calculation Formula

4 Stud PCD = S  
0.7071
     
     
5 Stud PCD = S  
0.5878  
     
     
6 Stud PCD = S  
0.5