At 5,180 dry, you should be fine once loaded. What tires do you have on the Tundra? I had P rated tires (should have never bought them, but a long story) and replaced them with 10 ply E rated tires. On our last trip, I felt just a little flexing or movement of the truck while towing...not any sway, but I wasn't happy with what I felt. Did some more homework when I got home and it became obvious that the tires had to be replaced. Just the tire change eliminated an inch or two of sag at the hitch which I suspect is due to less flexing of the sidewall. I've towed my trailer for a few miles locally, but I need to take it out on the highway and make sure the current setup will be ok.
Now I know why there have been so many posts about LT tires on 1/2 ton trucks as they really make a difference.
