this may sound nuts, but i had been carrying 60 lbs front and rear in my 99 3500 stock with camper and towing pkg. had the tires balanced and rotated and increased to 80 psi... . believe it or not it actually helped smooth out my ride. . weird i know but true. . i carry a 14000# fifth wheel sometimes and when i hook it up, the rear end on the truck only drops about 1 3/4 inches. this is with a 1900# tongue weight... i guess this is normal...