The buffing around on two lane roads is something that just happens with gasoline motor homes because they are a lot lighter then diesel coaches. Same goes for the handling of the coach with strong cross winds. Gasoline motor homes usually have long over hangs on the rear. With cross winds you are going to get the wag the tail situation which will effect your control on the steering wheel. All this posts that say your camber is off and this and that are wasting your time and money.
Diesels do not have that problem because the diesel engine is on the rear, do not have the long over hang and usually weight around 10K lbs more then a gasoline coach of the same length.
Tires are applied by the manufacturer according to weight. The more weight, the bigger the tire to handle that weight.
Sorry, but that is the way it is, and that is why I only put 5K miles on a brand new gasoline coach and I got rid of it. Best move I could have ever made, even though I did lose some money, but I am happy for making such a move.