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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.

underside of car near tire

I have two questions to isolate whether the problem is due to a mechanical part (#1) or the tires (#2).

  1. 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?

  2. 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.

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    Try rotating your tires again see if the sound moves. Cheap tires tend to be somewhat noisy FWIW. – Ben Jul 21 '17 at 0:24
  • Agree with Ben. Bought a set of tires for my car. They were uber quiet ... for the first 100-150 miles. When the new wore off, they became NOISY to say the least. Also, what is the year/make/model of the vehicle? Type of tires (brand/model)? – Pᴀᴜʟsᴛᴇʀ2 Jul 21 '17 at 0:40
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Ok.. So firstly the rubber things you need the name of are called CV boots.. The boots cover and protect the CV (constant velocity) joints, whist also allowing them to flex as the vehicle steers. CV joints don't normally rumble when they fail, they will usually start knocking first especially at low speeds when cornering and accelerating at the same time.

Your tyres are obviously the first thing to check here as you mention that this noise only started following having the tyres rotated.

A tyre with block type treads usually makes a sort of hum type noise on the road. A bearing is normally a heavier drone type sound.

Also possibilities here are wheel bearings, and less likely but still possible are gearbox differential bearings. You mention that the sound continues when in neutral...this also could still be a wheel bearing or differential bearings, as both are always rotating whether in neutral or not.

If this is just an ordinary two wheel drive vehicle (manual or auto) and you're not averse to doing your own work.. Then you can do a basic check on the wheel bearings.. Secure the vehicle by making sure that it's on level ground and that the handbrake is securely ON.

Then jack up one front wheel at a time, preferably with a good trolley jack, so that its off the ground by a couple of inches (use an axle stand too) but don't place it too close to any rotating parts.

Whilst each wheel is off the ground.. Grab the tyre at opposite points and pull/push on the tyres alternately with both hands to see if there is any 'play' in the wheel bearings.. You may be able to feel this 'play' if the bearings are particularly bad. There should be no play at all here. Then try and spin each wheel by hand to see if you can hear any noises (this is harder with the driving wheels. ) So what many mechanics will do, and you can do too if you're confident about the vehicles safety and security on the jack is..

Warning.. DO NOT ROCK THE VEHICLE whilst on the jack.

Start the engine, and whilst each wheel is off the ground separately.. Put the car in 2nd gear if its a manual, and let the clutch out SLOWLY, so that the wheel that's off the ground can rotate. It can help if someone can assist you here by effectively operating the vehicle as described, whist you listen near each wheel for any bearing noise.

It's the same procedure as above with an automatic vehicle but instead you'll just let your foot off the brake slowly so that the wheel starts to rotate, you may need a LITTLE throttle. Then listen for the drone of bearing noise.

ALWAYS.. be ready to hit the brake should the vehicle move or slip on the jack. This won't happen though if the car is on level ground and jacked up SAFELY & SECURELY.

  • If the bearing isn't loose and you have both wheels off the ground assuming fwd, put your hand on the spring and rotate the wheel by hand. – Ben Jul 21 '17 at 16:03
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Just as an addition to the answer of @Orb: You should check your tires for sawtooth wear that often has an identical noise as a failing bearing

About the CV joints: The CV joins can fail, but there is no guarantee that they will fail. It happens regularly that CV joins live longer than the rest of the car. Also they are not only used on FWD designs, but on most car designs. A failure of the CV joint is often difficult to tell from a failing bearing.

About the wheel bearings The bearings where most certainly not damaged by lifting the car or driving from the parking lot. Think of them as consumables that most of the time die from old age or other factors (especially water leakage)

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