I live in Michigan and the max speed for trucks or and vehicle pulling any trailer regardless of size other than "oversized vehicle/units" is 60 mph on 70 mph max on all Interstates. 70 is the max for any vehicle other than emergency vehicles in route in the state. The min on Interstates is 45 mph in our state. Max of 55 mph for trucks and/or vehicles with trailers if the posted speed limit is less than 70 on any Interstate in the state. You WILL be ticketed for over 60 mph while pulling a trailer and there are lots of radar equipped MDOT vehicles in hard to see places until it's too late on the Interstates and other main highways. Some of our friends are retired Michigan State Police and my younger brother was a Sheriff for years and they know the facts.
Most other states also have similar type truck/trailer speed restrictions.
Our 58-60 mph RV travel and 55 mph on non-Interstates (limited access) is right where it belongs as it's 13-15 mph over the min and at and only 10-12 below the max allowed on the state's Interstates.
If you don't like being behind us as we are in the right lane always, just move over and pass and shut up! You aren"t allowed to go any faster than us on the other streets so lump it!