'16 Ram 2500 CTD first tow. Some thing is wrond

I have a 2010 Dodge 3500, pulling 1100-1200 lbs. I use tow haul in towns, but turn it off otherwise. I usually use cruise control on the road. As a hill becomes steeper, speed will drop 3-4 mph below set speed before a downshift. On downhill grades, as speed increases, the speed may go 4-5 mph over before a downshift. I consider it normal. Down long 6% grades with curves, I will usually adjust the cruise down several mph below my usual 59 mph set speed.