Vibration/rattling noise above 30km/h

[NoAcars]

When driving in pure EV mode (but also in serial or parallel hybrid) a rattling noise emerges from the front of the car at speeds above around 20 - 30 km/h. The frequency increases with speed increase. You can feel the vibration minimally in the steering wheel. The vibration is a kind of loud when driving at lower speeds in pure EV mode compared to the silence without the rattling/vibration at low speeds.
I had it checked at my dealer a few months ago, but they could not find anything. They made a remark about a slight thud when it was standing still and engaging R or D. Finally they blamed the sound on slightly cupped rear tyres.
I didn't trust it then and after switching to my winter tyre set, I could tell first of all that the tyres were not cupped and secondly the rattling noise remained. Now when switching back again to new summer tyres, I know for sure that the tyres are not causing it, while the noise remains.
What I noticed is that when I steer a few degrees (maybe 5 degrees on the steering wheel) to the left the noise worsens and when steering to the right the sound silences.

As a preventive measure I will exchange the rear e-motor front mount, even though I don't really notice this well known thud when the rubber bushing is bust (as can be seen in an other topic).

Any ideas what could be causing this?

Wheel bearings were checked by the dealer, but I don't know whether I can trust them. How can I check it myself? What other rotational parts can cause these vibrations? I am thinking about replacing all 3 front motor mounts, but I doubt if this will help.
Is there a pump somewhere which is speeddependent?
Any ideas what to check?

 

[BruceHF]

Just a thought! Have you had your wheels aligned at all. When last did you have them done?

 

[AndyInOz]

I'd like to second the idea of getting your wheel alignment checked.

Take it to a specialist tyre place and tell them your concerns. A good tyre company will check all your steering components (and the wheel balancing) before attempting a wheel alignment.

It's awkward to check wheel bearings if you don't have access to a lift, but...

If you jack up a wheel, you can grab the outsides of the tyre and try to rock it back and forth (left to right and top to bottom). You should feel no movement or sensation when you're doing this.

Also try to manually rotate the tyre while the wheel is in the air, the rotation should be free and smooth, any clicks, or bumps in the rotation should be regarded with suspicion. If you do hear noises, it could guide you to the problem location.

Be very careful if you try to do these checks, it's very easy to make a car fall off a jack or jack stand, hence me recommending that you take it to a specialist tyre place.