Our rig prior before buying the Phoenix Cruiser was a Roadtrek 210 P class B. Now, that is built on an extended Chevy van chassis and weighs over 8000 pounds before you start adding all your stuff like 30 gallons of water (250+ pounds), camping gear, etc. Remember, this much weight sets on only four wheels since it was a van conversion.
The RT came with Bridgestone tires. After five years, I replaced them. I got very confused listening to all the chatter about tires and so I called the factory up in Kitchener. Ontario. I asked what tires they recommended and they said they really don't recommend tires, but all they could say was they put the Bridgestones on all their RVs. I asked why and got a response that it had to do with the stiffness of the sidewalls. Wow! That was interesting.
Apparently, some E rated tires have different degrees of stiffness to respond, I assume, to torque stress from turning, etc. In any event, I bought four brand new Bridgestones just like came on the rig when I bought it new. All I know is that the vehicle rode as quietly and comfortably and was as stable as a car. I talked to my tire guy I have used a very long time and he told me he didn't sell them but would get them for me if that was what I wanted. They cost fifty bucks a tire more (not just from him but from other sources I checked) and I paid it. My tire guy said based on my conversation with the factory, he would probably have done the same thing. Heck, I had never heard of "sidewall stiffness". Seems there is a lot of science in tires. And to think I used to buy used Montgomery (aka Monkey) Ward tires and put 'em on my 65 Chevy!!

Paul