We did exactly what you are asking about....(same truck) we ran the NITTOS and switched to 245/70/19.5,Michelin XDS2 everything stayed essential the same, lots of room in the wheel wells.
The offset of the Ricksons worked well..
I found the Nittos had to much flex, the sidewalls on the commercial 19.5's we run are like cement, no bulging, the Nittos seemed to be driving on the sidewalls they bulged so bad... I was expecting rock damage with them, now I don't even think of it...
If you have a rear sway bar, stable loads and 19.5 commercial tires you will have no sway...