I'm trying to debug a rumbling noise problem. The sound is similar to the noise you get on a smooth road when you bike with mountain bike tires, on a bike, except that it's much more "grave".
The sound continues to rumble when I'm in neutral, and so presumably my gearbox is fine. It is really loud when I'm between 50-70km/h — 35-50miles/h. Outside that range, the natural engine noise covers it up.
I have two questions to isolate whether the problem is due to a mechanical part (#1) or the tires (#2).
I know that because the car is a front-wheel drive, this accordeon rubber-coated part that you see in the picture (what is that called?) will fail sooner or later. Is it possible that the failure of this part would produce a rumbling noise? By shifting the steering ever so slightly right and left at the noisy speed range, I continue to hear the noise; would that mean that part is fine? Could it have failed even if the rubber still looks like it holds the lubricant inside? Am I already getting a warning and a subsequent failure would leave the car incapacitated on the road/highway?
I'm wondering if these (some lousy F-branded) tires are now much more noticeably rumbling because my windows are often down in the summer, but they could have conceivably been like that in the winter. Question: Do tires that have ridges perpendicular to the road, as you see in the picture, have a tendency to be noisy?
Most perplexing is that the noise appeared immediately after I went (to a certain major C-chain popular for tire changing) to rotate the tires. They merely lifted then took down the car, but, foolishly, I let them drive the car from the parking lot and back.