How fast can you drive while towing

How fast can you drive on a motorway while towing a rib or Optimist trailer?

No, not 120 km/hr, as a number of IODAI parents discovered this year, the speed limit while towing is 80km/hr. Not mentioning any names but 3 of our parents now have 2 penalty points each and we are only half way through the season !! Take care while travelling to the nationals.