I have a 1995 C220 with 76500 miles that has excessive road noise. I have Goodyear Assurance P205/60-15 tires that I first rotated, then replaced the front tires (which were really the rear tires before the rotation) because they were worn on the inside, then recently had the front bushings repaired and a computer alignment of all four wheels at the dealer, then replaced the rear tires because they were wearing excessively on the inside. After all this I still have a lot of road noise with louder harmonics at different speeds. At times, it's so loud you can't carry on a conversation in the car. It didn't use to be this bad. Any thoughts on what I need to look at next? Thanks.

 

I had this same problem with my last car, a BMW 3 series.
Turned out to be the tires. I never would have believed it myself, but it was.
The noise at some speeds was unbearable, especially lower speeds. It would do it in a parking lot!
I thought the transmission was about to fall out by the sound of it. Roaring jet-like noise. Awful.
Tires were Kuhmo, recommended as replacements for my Michelins. Bad choice. Wore down overnight
and caused this problem within 8,000 miles! I'm not saying for sure this is your problem, but.....could be.

 

It turned out to be the rear bearings. Got them replaced and it's back to peace and quiet again. BTW, this is a costly repair, it takes about 4.5 hours per side plus parts to repair. But, my service guy said that this is first time he has seen a Mercedes in for repair of bearings. They didn't even have the parts in stock.