Wheel huming below 0°C

[komichal]

Hi All,
When driving below 0 °C (32 °F) faster than 70 km/h (44 mph) I hear a deep humming from the right tyre (not sure if front or rear). It started last winter. I thought that my winter tires were noisy because they were already dead so I bought 4 new ones for this winter (Kléber), however it did not help a single bit.

I also changed pads and rotors this summer - again no change between the two winters.

Naturally I suspected also the wheel bearing, however I have no clue why it would be noisy only in low temperatures. Moreover - front wheel bearings were both changed 3 years ago (some 30,000 km/18,500 miles) for a quality brand (SNR) which I expect should last a lot longer. Visual inspection of rear bearing did not reveal any suspicious behavior but surely under load things can change.

Before taking a blind shot and replacing the rear wheel bearing (100 USD for a a quality one here) I would like to ask you for additional opinions. The sound is really very similar to the one that a dead bearing does and is not anyhow linked to engine RPM, only to car speed. The car has driven total 180,000 km (112,000 miles).

Thank you.