i just put new tires on our f450 today, came with 19. 5's the last set we had on there were coopers, i dont remember the model, my estimate was the lasted 7 years and over 100k miles not to mention they where put on when i was 16 and i started running deliveries, i also drove like a bat out of hell. the truck is loaded pretty heavy about 50% of the time too, its our delivery truck. we dont get snow around here so i cant comment about snow, but the truck weighs 9k lbs, and is 2wd, before we put the cooper traction tires on it would get stuck on wet grass. after the coopers, it rarely got stuck at all that is untill we ground them down to look like drag slicks. they got replaced today because while picking up feed i found the left inside driver flat, and it was just getting to be time. never had any problems with them in those 7 years, should have heard the tire guys cussing and swearing about getting the rusted hub centric rims off.
i would also like to mention, since your looking at options, toyo also has what appears to be a good traction tire. m208 i think is what they are, i can look tomorrow and double check. the tire shop i went to has always treated me very well and has always given me good advice and info. that being said he was trying to sell me a set of tires, the shop said that the these paticular toyo tires are one of the best for 19. 5 rims and one of three good tires made by toyo, he said the open countries, these traction tires, and one other lt tire were some of the best tires ever built. its personal opinion so take it for what it is worth. so far i like them, i dont remember the weight rating, but its a 14 ply load range g tire.
talking to the guy today, they last tire to consider is the continential(sp?) tire. what i was told is they are going on the new fords now, and the company cant make them fast enough, they are a year behind in their orders. again supposed to be one of the best tires on the market if you can get them.
as for the squirm, the do float pretty bad in the beggining. both sets of 19. 5's i have driven would make the rear end wiggle behind you untill they broke in, thats with 4 tires on the rear. its not too bad and goes away in about 2k miles i think. as for a harsh ride i cant really say, the truck has stiff springs and bad shocks, plus it weighs a lot more than a pickup. on a 2500 i would think its a bit light and will probably always ride stiff, and squirm a little longer.