I wrote an earlier post about a low humming sound which makes itself more noticeable over 30mph. When I put the car in neutral going at these speeds, the sound doesn't change, so I'm ruling out the exhaust, transmission, engine.
It was first diagnosed by a shop as wheel bearings, but upon closer inspection, it turns out that the bearings are fine. Then the shop said that they suspect its the tires. So I went to a tire shop, had the tires checked out, and they said the tires were completely fine. No cupping or uneven ear. While I was there, I had them do an alignment, and they said that the car weren't that much off spec. Driveability is fine. The noise is just annoying. Any ideas out there?

How did they determine that "upon closer inspection, it turns out that the bearings are fine."?

Your symptoms are classic hub problems, particularly if the car vibrates and the vibration changes with speed. I've replaced hubs that otherwise looked and felt fine and it fixed the problem.

...Lee

I agree, sounds like wheel bearings. They can make noise and still seem tight with no problems upon inspection.
--
1998 Volvo S70