I have 3 superduties, they all pull 18,000 lbs regurlarly. The one I use the most has 279,000 miles on it and 70 % of the mileage has had atleast 12,000 lbs behind it and most of the time 18,000 lbs. I pull my tractor around farming, on a 32 ft, float. Combined is about 18,250. 2 of mine are single wheels and the other is a dually. They all do fine. If it shortens the life of the truck, I wonder how long mine would go that has 279,000 miles on it. Anyway, you will be fine, I just wouldnt try to drive 80. It will do it, but you cant really stop it real well, if need be.