My suspicion is that there is something loose (pebble, rock, or some other small, foreign object) behind the hub cap, but I hear a crackling or popping sound (almost like Pop Rocks or Rice Krispies) when my 2011 Kia Rio gently rolls forward or backward at a slow speed. It almost sounds "sandy," if that makes sense, like the noise a heavy car might make when rolling forward over a sandy or salted pavement. (I'm trying to be as descriptive as possible to help cue people in.) However, it seems to occur even on smooth pavement, and the Kia Rio is comparatively not a heavy car.

The sound either goes away or becomes inaudible (indistinguishable from background noise) when actually driving. It does not occur when immobile/idling. The sound is irregular, in the sense that it seems more like random crackling or popping. From the driver's seat, it seems like it's coming from beneath the car or near the wheels.

This is my first car in many years--I have lived in a city and been using public transit for a long time--so I am willing to admit that I am just not accustomed to the sounds that a car normally makes. Preliminary Internet research seems to have ruled out things like bad brakes or suspension, but I'm not sure. It would be great to learn that this is just one of those noises cars can make, and that it's innocuous.

2 Answers 2


If there are no noticeable rocks/debris as Steve states another possibility is it may be normal noise. Tires will deform slightly when rolling to form a flat contact patch with the road surface. When this happens the rubber treads stretch and compress and make "groaning" sounds. The quality and type of rubber, the tread pattern, and the age of the tire can greatly effect the noise the rubber makes in addition to the road surface.

As a tire comes up to normal driving speeds this deflection becomes normal background noise. Sometimes this effect can form a resonance with the air cavity of the tire and form a droning sound.

There also may be some mechanical issues with bearings or other rolling parts. Normally bearing issues will become louder the faster it turns, but in the early stages of failure this may not be the case.

If the noise changes while rolling over different road surfaces, asphalt vs concrete vs coated/painted, it's like just normal tire noises. If it remains the same trapped debris is more likely.

  • Thanks for responding. I'll try to test it on different surfaces. I do think that the tires are probably rather cheap. I listened to some examples of bearing issues on YouTube and elsewhere, and it sounds very different from those. Also, the noise is not at all related to turning/steering. But I'll keep that possibility in mind. Jul 8, 2015 at 18:18
  • After several months of driving, I think that I can conclude that it is normal noise due to relatively cheap tires. Thank you! Sep 22, 2015 at 2:44

Common causes from personal experience are general related to stones or pebbles jammed somewhere. Places to check are in the tyre treads themselves and also between the brake disc and the dust guard behind the disc (don't burn yourself though as the disc can become quite hot after recent operation).

  • Thanks for responding. When you say "also between the brake disc and the dust guard behind the disc," how might I go about doing that? Apologies for my extreme inexperience. Jul 8, 2015 at 16:02
  • If you take the wheel off, you'll see something like this. The thing on the left with the lip on it behind the brake disc (the metal circular surface) is the dust guard, and rocks tend to get caught in there. Also it's worth reiterating - these parts get hot, so be careful.
    – zhang
    Aug 7, 2015 at 19:23

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