I've bought a toad set and an RV set from Discount Tire. They're America's Tire in some states. I felt that the price was good, the shop was professional, and that I was treated very well overall. Toad got BFG, RV is Bridgestone Duravis R250. They called the warehouse and verified that the RV tires were fresh manufacture. Didn't worry about toad; we'll wear those out.
Some of the Big Boxes won't work tires on a vehicle they can't get on their lift, over their pit, into their building, whatever. Find one that'll go outside with a jack. Discount will.
Do you have a Spare? If so, make sure its DOT Code is fairly young, even if it's never been on the ground. You don't want to have a flat, 100 miles from getting to wherever, and a spare that blows in 50 miles because it was 15 years old.
And, have the new tires mounted with
Dually Valves. CW has them now, and all you need is a Rear Wheel set. For Front and Spare, be sure the tire shop installs metal valves. All but the shortest will reach through the front hub caps/wheel simulators.