My personal works truck i have used are as follows:
1996 chevy 1500 4x4
1997 ford f350 4x4 drw single cab
2004 ford f350 4x4 drw extended cab
2006 ford f250 4x4 srw extended cab
1999 ford f550 4x4 drw single cab
2002 ford f550 4x4 drw crew cab
1970 ford f600 drw single cab
1997 ford fseries (f700). Single cab
Etc
I currently have a 10k, 14k, 10 ton, and 20 ton tag among others.
I move buildings and heavy machinery very often. I have broken pintle hooks and several trailer tongues. I have almost been wrecked several times by loads. Here are my thoughts. Load placement runs hand in hand with braking power. I recently towed a building package on a 14 k trailer to Va.using a f550 i could not drive faster than 60 due to improper tongue weight. Almost all factory work trucks especially ford come with inferior draw bars and hitches. I have meet several people that have beat the hitch straight off the frame on long distance hauls pulling campers.
Staying under a class 5 truck for hauling the f550 is king of the road. Good gearing , braking and strong frame it has.
I have pulled 20,000lbs + with an f250 sw it will
Do it. I only do it in emergency breaks downs or such. The manufacture ratings are a scam and a bunch of lyes, They are for marketing and general guides. Some times they are way too much to be safe. The only effective and safe way to move weight is with a tow vehicle that has more weight than the load and/or the load is putting weight on the tow vehicle by tongue weight or it is balanced over several axle points. The heaver the truck the safer it is. The more weight you can put on the rear axles the safer you are. Of course. Your tow rig and setup is only truly tested in failures. Lossing tires, axles, and trailer brakes have happened to me. Wet roads hard stopping and too much speed will wreck you.
It is very easy to get used to pulling to much then failure occurs. If it happens to you at the wrong time you will die. Single rear wheel trucks losing a tire pulling a load at speed will kill you. 14k trailer have axles that sit above the ubolts. Over load the axles and the bolts break and the axle will come loose
Emergency procedures will kill you in an overloaded rig. Do not play. If you can cruise along at slow speeds you are fine. 40 mph or more and the risk goes up quick.
If you want to see how tuff your truck is try driving it with out the trailer brakes, see how well it does not stop. Then think of what will happen under hard braking and they go out.
My f250 got 13k on the last set of brakes front and rear.
I have moved into tandem axle haulers and bigger trucks but it seems the bigger the truck the more you put on it and big is never big enough. My tandem dump
Has scaled at out 86k, way over weight and it will break something.
To me an f550 pulling ten tons is good. i would go more if it was a short slow trip. It feels safe and seems to handle failures ok. Having the proper weight on the rear axle is important. The older f550 to me are better than the new. Also Ford ran a lot of scams with their f450s recently putting on smaller wheels and taking away the beef. Then the next year putting back on better parts due to customer concerns.
They have also done that with the f550s here and there to. The trucks with the dana 135 rears running 4.88s are brutes. The auto trans are all crap and the 110 rear axles are not as good as the 135s. The new weight ratings are beyond me. It seems that in the old days they were more worried about keeping the number under the cdl regs even tho the trucks will do more. You can put 10 k on the bed of a f550.
Personally i think f550s should have air brakes standard and front and rear locking diffs, heavy push bumpers, manuel zf-7 trans and 7.3 motors beefed with more bigger forged parts with 100 extra ponies. Zf 7 is my new trans patent basically a zf 6 with another higher gear for highway speeds.
Problem is the average guy is not ready for that kind of hauler. And ford does not want a work truck that will last more than 200k. They need repeat business. Thats why the zf-6 is being phased out. It is heavy duty and almost impossible to break.