As a 19.5 guy...the extra cost is offset see my post above, you actually gain over the life of the tires...unless you are one who trades in a truck beofre you ware them out...My truck will be into the 200K mark when my 19.5 need changing.
Ride quality empty is a bit rough, but I'll trade that any day for the ride characteristics loaded up.
No need for a spare: 1. the OEM wheel and tire diameter will be very close to the 19.5. 2. Besides if you are running a dually you got 6 on the ground. 3. What is the flat rate for these commercial tires being used on a pick-up, very low! And if you do get a puncture or air loss situation call your towing folks to change the tire around until you can get to a place...POINT being your statements don't really hold much water...other than the initail outlay of funds. If you can do it you will gain the milage advantage and benefit from control and stability. Plus they look good...makes the truck and TC look like you mean business. But that was an added bennie in my case it was the terrible tire OEM size tire ware out senario that sold me.