Hope all are well during these uncertain times!!
I have an 06 Tradewinds 40F on a Freightliner chassis. I purchased it 3 years ago, and upon the initial test drive, I noticed a slight vibration in the steering wheel 58-62 mph or so. Above that, 65 or faster, it pretty much goes away as it does below that. The tires at that time were one year old, and had <1,000 miles on them. I have tried a number of tire shops in the quest to get them balanced, but mine are a larger center hole and no shops here (Sacramento and surrounding area) have the adapter for these. They do have balancing beads in them, and I have had the tires broken down, had the beads checked and recentered, no change. Since most of our trips have only been under 5 hours, I have just put up with it. Until now.
I tried again another tire shop in the area, they again broke the tires down, reinflated flat as supposed to be done with beads, and tired the Centramatic balancing rings. That made the problem worse! I returned again today, and since the tires were on the less expensive side, I opted to put on Michelins; no balancing beads but did install the Centramatic rings. The problem persists, although not as bad.
Front shocks are new in the past year, that made no change. Front end alignment has been done and all joints checked, all good. Coach has 46K miles on her and always maintained. No accidents to my knowledge.
The vibration is clearly in the steering wheel, not in seat, so I don't believe its a drivetrain issue. Next step will be to remove the Centramatic rings and just try it with nothing just to see. I hope one day to be able to figure this out, so reaching out here to others, maybe someone has had a similar issue! Thanks all for reading, glad to give further info if needed.