Well depending in which state you are in affects the speed limits .....
In Western Australia Speed Limits vary across the State; however the maximum limit is 110 kilometres per hour. It is an offence to travel above the speed limit.
Major metropolitan arterial roads are generally capped at 60 kilometres per hour while suburban streets are almost exclusively limited to 50 kilometres per hour.
School zones are clearly marked and restricted to 40 kilometres per hour for two, one hour periods at the beginning and end of the school day.
Freeways and highways vary from 80 kilometres to 110 kilometres per hour.
The Western Australia Police use radar and other speed monitoring devices, and fines are enforceable - even for visitors.
Cheers
Darren