I’ve had my 2002 Suzuki XL7 for 7 years and about 3 months ago, I noticed that as a go past 55mph, my car creates this vibration that almost makes me think that it is trying hard to run. Took it to the mechanic and they diagnosed after test driving and lifting it up that the wheels needed replacement. As it turns out when the car was running while lifted, the rear driver’s wheel wobbled. The tires werefairly new, about 3 years old. They suspected some cord separation inside. I went and had all four wheels replaced but the vibration was still there. I took it back and they think rear differential is the problem, either the bearings need to be replaced or the whole differential axle. The mechanic drained the differential fluid and showed me how it was almost metallic in color. The cost of replacing the bearings is $1100; to replace the whole differential with a used 88K miles, no warranty is $1400 and $1700 with warranty. What do you think is another possible diagnosis for it. I just did not want this to be another wheel incident where it didn’t solve the problem. I heard that since it’s a 4WD that it may be the drive train also. I appreciate anything you can advice me.
Let's start with terminology.
Wheel = the round metal thing that is bolted on.
Tyre = The round rubber thing.
Now having said that, I would suggest taking your car to a really good tyre shop or to a frame shop and have them check it out. They have more experience, training and equipment than most general auto shops. It likely will cost less in the long run.
I know this is old, but I hope you took Mr. Meehan’s advice. If not you have likely spent a lot of money and still have the same problem. High speed vibrations in a narrow speed range can usually be blamed on the front tires. I’d rotate the rear tires to front, and if that helps or not, get the front end inspected and if it checks out, the front wheels aligned.