Hi folks - just joined the group after buying my first diesel. Quite a learning curve. This string has quite a history and very good info but I thought of a a couple of things to add.
LT vs ST tires: there is a difference in the way they are made and tires on trailers tend to carry a higher percentage of the rated weight. As others have noted, pressure should be checked often and pressurized to trailer recommendation. I found an interesting article at http://www.tirerack.com/tires/tirete...jsp?techid=219
WD hitches: I measured the unloaded distance from the top of the tires to the top of the wheel wells on my tow vehicle, then loaded the trailer and pulled it a few feet and remeasured. The drop should be even front and rear. My previous tow vehicle was a Honda Ridgeline. I tried less less spring tension (unloaded the front) and then got into a spring monsoon with a horrendous headwind and standing water. It was a handful, wandering all over the road. I stopped and added the tension back in and the problem was solved (gas mileage still sucked tho). You'd think a light trailer wouldn't affect a HD truck but it's a long distance from the rear tires to the hitch point which will act as a lever to lift the front of the truck.
Last thing from experience - weigh your trailer. Cool things you buy from camping world (like those pink flamingos) all add weight.
Several people mentioned checklists, I found a customizable trailer checklist app for my i-phone. Even with the checklist, I got distracted and saw the trailer door flapping open as I pulled out of the RV park.