I observed this wear on the original Continental tires on our 2009 Navion (Sprinter 3500 170"WB). Even after diligent rotations, I found it necessary to replace them at 40,000 miles while on the road during the winter. The Michelin LTX M/S2 tires exhibited no uneven wear. Both sets of tires free of any vibration and steered straight. The Michelin tires improved ride quality and traction.
The 2018 Navion (same Sprinter chassis and Continental tires) has had a shimmy since day one. Loading has no effect. Handling is normal and steers straight. Various tire pressures have no effect. First tire shop balanced the tires and made an improvement, let's say about 50%. Up to about 60 MPH, it feels OK. Above that speed it actually hurts my hands. The second tire shop 1,400 miles into my trip, placed wheel weights not only on the inside diameter, but outside as well. That made another incremental improvement to where it was tolerable for the next 2,000 miles.
I was out in the driveway jacking up the Navion with the intention of rotating the front wheel with the outside rear wheel one side at a time to prove that the problem is either a bad tire or wheel. I got as far as testing the front wheels for anything out of round. Micrometer perfect. Then I caught myself and said, "Why in the world should I be doing this? The RV dealer sold me a new RV and this should never have left the factory." Or, at least the driver who drove the almost 2,000 miles from Iowa to Oregon should have said something about how bad it shook. The dealer would not have a reason to take it out on the open road miles away from their location, so it is not their fault. I am going to wait for some official direction from the dealer and/or Winnebago on this issue before I take any action of my own.
The essential difference between the 2009 and the 2018 Navion is that the OEM tires (front and rear outside) were re-fitted onto alloy wheels. It looks like Winnebago is using the Alcoa alloy wheels on many of their products, so I would assume that the wheel has been properly vetted for being a direct replacement for the stock steel wheels. Bad tire from the factory or damage from refitting?
There are about 6,500 miles on the odometer right now; 4,500 uncomfortable miles of my own. if I knew that the tires were at fault, I would put 6 (or 7) new Michelin tires on now. Why not? I do like the way they ride and why not enjoy them from now on since I intend to put some miles on the RV. I remember when we were in Albuquerque and I stopped in at Discount tires and had new Michelins put on all around. By the time we reached Flagstaff, Arizona, I was saying, "Daddy's got new shoes!" Maybe it is not so dramatic and everything is subjective, but I noticed the improvement. And, after enough miles on the clock I noticed the absence of scrubbing on the tread. Another aspect that I just remembered was that the Michelins did not have the same tendency as the Continentals for wandering side to side from irregularities in the pavement such as rutting from studded tires. (They blame that on big trucks. If that was true, why do the ruts match the track of cars?) All that being said, I should not have to buy new tires for a new RV because I have to, only if I want to.
