Agree with alboy and GAmes. gcwr is a guide to know when you need to drive more conservatively. With my pacbrake, good tires, and constant monitoring of gauges (see sig) I and the truck are "comfortable" being 2Klbs over gcwr.

Ranger 391 hit the nail on the head wrt tire/axle ratings. I make sure I'm under all axle/tire ratings and drive conservatively, staying within the speed limits. Down shifting with the pacbrake, I've made shorter stops w/13.5Klbs than I could with my old 8Klb 5er. See #s below:

GVW: Rated: 9,900/Loaded 10,120 (over by 220lbs)
Ax Wt (front) Rated:4,750/Loaded 4,460 (under by 220lbs)
Ax Wt (rear): Rated 6,150/Actual 5,660 (under by 490lbs)
GCWR: 19,000/Actual 21,000 (over by 2,000lbs)
Trailer Axle Wt: 10,880lbs
Trailer Wt: 13,480lbs
Tongue Wt: 2,600lbs (19.3% of trailer wt)

 

Pulling the same load on the same road with 3:73's and later changing the rear to 4.10, the load shown on the Attitude was 74%. After the gear change
it was showing 53%. Big differance all the way around. Fuel mileage was up towing and I lost 1 mpg running lite. Boost with the 3.73's was 27psi flat ground and 17psi with the 4.10. EGT's were down over 100 degrees.

If I could have got 4.30's I would have installed them. 4.56's were to big for running lite.