A droning hum that rises with speed and changes when you weave the car is a wheel bearing — one of the more common GTI noises.
Diagnose:
- The hum loads up in a corner — turning right loads the left bearing, so the way the noise changes with cornering tells you the side.
- Jack it up, rock the wheel at 12-and-6, and spin it feeling for roughness.
The fix:
- Depending on generation the front is a bolt-on hub/bearing unit or a pressed bearing; rears similar. Replace the failed one — no need to do both sides unless both are noisy.
- Torque the axle/hub nut to spec (it's high) and use a new nut where specified.
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