What I learned when I was choosing my tow was that the maximum safe limit is 80% of the rated tow capacity. If you have a 3500# tow capacity and the trailer weighed 3200#, you'd be at 91.4%. That sounds dangerous to me -- consider braking capacity in an emergency
I have no problem with people adding whatever safety margin makes them feel comfortable, but I do not see a need to add any. If 100% of the rated limits were unsafe, the limits would not be set there.
Please remember that the trailer weight
is not the only thing to consider - cargo and passenger load counts, too. I stay within all
of the load limits (GCWR, GVWR, GAWR, GTWR...), so I'm not concerned if I am right up to one of them. If people are selecting towing capacity without considering the rest of the load, then maybe it is a good idea to leave more margin.
The braking of any significant trailer is done primarily by the trailer brakes
. It would indeed be scary to have a couple tons of trailer being stopped by the brakes
on the truck... but I believe that the solution is to properly equip the rig with trailer brakes
and a suitable controller. The remaining braking work done by the truck is one of the factors which leads to the factory rating, and thus one of the reasons to not violate it.