Colin is till in the land of Oz I think, so will be on here at strange times. 
  
I think it's 20mm for the rear and 25mm for the front to clear the calipers. 
The front is a minimum of 23mm. 
  
I bought a set of four 25mm, was not 100% happy so now running without spacers just got one and a socket in the boot should I need it. 
  
Not sure if I'll go back to running them or not.