Most states require towing vehicles to observe the same speed limits as any other road vehicle. However, some jurisdictions may vary from this. For example, Western Australia currently restricts any vehicle towing a caravan/trailer to a maximum speed limit of 100km/h or the posted speed limit, whichever is the lesser value.
It is recommended that you become familiar with the requirements for each state that you plan to visit.
Some tow vehicle manufacturers and recreational vehicle manufacturers may also stipulate a reduced speed limit for their vehicle (or trailer) when towing.
The respective owner’s handbook will contain the details of any such restrictions.