What Causes the Humming Noise in a BMW 3 Series at Low Speeds?
2 Answers
The reasons for the humming noise in a BMW 3 Series at low speeds are: 1. Influence of body resonance; 2. Abnormal wear of the wheel hub bearing. Taking the 2021 BMW 3 Series as an example, it belongs to the mid-size car category with the following dimensions: length 4719mm, width 1827mm, height 1459mm, wheelbase 2851mm, front track 1543mm, rear track 1583mm, fuel tank capacity 59l, and curb weight 1555kg. The 2021 BMW 3 Series is equipped with a 2.0t turbocharged engine, featuring direct fuel injection, with a maximum horsepower of 156ps, maximum power of 115kw, maximum torque of 250nm, paired with an 8-speed automatic transmission.
My old BMW 3 Series also had that low-speed humming noise before, sounding like a piece of paper stuck in the tire when driving. After struggling for a while, I found out it was caused by the run-flat tires—the sidewalls of the BMW factory-fitted run-flat tires were too stiff, causing resonance even with slight road imperfections. Later, I tried three methods: reducing the tire pressure to 2.3 bar helped a lot; swapping the front and rear tires revealed that front tire wear and peeling could also cause noise; the most extreme was spraying the brake discs with a hose—if it was really the brake pads dragging, the noise would disappear instantly. However, if the humming gets louder when turning, it’s probably a bearing failure and needs immediate replacement. My friend’s car kept going until the bearing disintegrated, and even the half-shaft ended up damaged.
