Depends on the speed limit for towing in your state. The ticket writers, depending, usually write for 15 over. But there are areas that will tag you for less.
Tires do factor, the faster you go the hotter they get.
The faster you go, the longer it takes to stop. Imagine having to jump on the brakes at 75mph. Or a tire blows.
The faster you go, the more fuel you burn.
2006 Montana 3650RK with Improvements.
2014 Ford 6.7L PSD 4WD CC LB Dually & Hadley's.