I pull a tridem axle 14 foot bed trailer, with a 1000 gallon (imperial gallon) water tank with my 2004 5.4 4x4 ext cab. I only pull it once every two weeks a total distance of ten miles all on backroads/private roads. I have never gotten a total weight of the trailer fully loaded, but my guess is over 15,000 lbs. Truck handles it well up to 45 mph. After that speed it can get sketchy..... not enough weight on the tongue I believe, it will fish tail a bit. Just my thoughts...