Western Australian Consolidated Regulations Western Australian Consolidated Regulations (1) The distance
between the coupling pivot point on the drawbar of a dog trailer, and the
centre of the front axle group or of the front single axle of the trailer,
must —
(a) not
be over 5 m; and
(b) not
be under 3 m, if the trailer is used in a road train over 19 m long. 
Length of a drawbar on a dog trailer
(2) The distance
between the coupling pivot point on a drawbar, and the centre of the axle
group or single axle on a trailer with only one axle group or single axle
(except a semi-trailer) must not be over 8.5 m.