Strange droning noise - no one can find it’s cause

[Avensis2022uk]

2011 Avensis average miles private car. Otherwise excellent, at low speed I get this annoying droning / vibrating noise from the passenger rear side. 2 garages have checked on ramp can’t find anything at all

always at low speed 5-30mph, on all roads and more obvious when turning sharp right 

please help 

[Roy124]

Have you asked your wife? 

😅

[paul9]

Something jammed in the brake dust cover or the cover touching something it shouldn't?

[DerekHa]

Hi there,

The previous post could be the explanation, have had noises caused in the past by either a piece of gravel caught inside that gap or even a piece of thick crusty rust wegded in the same place.

Did the garages remove the offending wheel to get a proper look?

Another possible cause could be early indications the rear wheel bearing is worn and needs replacement. Modern bearings will usually continue to function well enough for relatively long periods without needing urgent attention, usually cornering will accentuate the noise as extra forces are put on the bearing when turning.

Best to jack up the car SAFELY and cheek for any play in bearing leaving the wheel on the vehicle. Have had occasions where there isn't any apparent play but no other explaination for the noise, replacing the bearing which has cured the problem.

[Ollyc90]

If I can't find anything wrong with the bearings I usually swap the wheels round to the opposite corner and see if the drone moves. If it does then replace the tyre.

[Parts-King]

Check the age and condition of the tyres, some older tyres that have deep cracks or delamination can cause droning, swop front to rear to see if you can get the droning to move 

[TonyHSD]

With the wheel in question in the air spin it carefully and hold the suspension spring with your other hand, if you feel vibrations it is likely a bad bearing. You can do the other side for reference. The suggestions for brake disc dust covers and worn out tyres are valuable. 

[Konrad C]

jack up car and spin each wheel with ear on body panel, to pin point the source. If no noise with the car jacked up, suspect the tyres. The reason are as follows, including wrong diagnosis:

I have dealt with wheel bearings and only recently did my brothers Micra. In that case I was not sure which wheel was making the noise, and suggested that we jack the car and spin each wheel with an ear on the body work. My brother thought that was too much work and just got a wheel bearing for the front wheel. I went to do the work, but forgot a tool. I checked the front wheel and it was fairly silent. The I jacked up and checked the rear, there was noise on the rear left. Confirmed by checking the rear right that was silent (no droning/rumble). All done by spinning wheel by hand with ear to body panel.
Another source of noise similar to failing wheel bearing is a tyre failing internally. Had this problem 12 years ago on my previous Avensis. Pump the tyre to a higher pressure and the noise reduces. A change of wheel/tyre sorts that out, but not after changing a wheel bearing made no difference! 
I once replaced a front wheel bearing for the second time, because the first replacement failed after 5 years. To make it worse I thought it was the other wheel, not expecting a newer bearing to fail so quick. Yes both bearings replace at the same time. 
I have done different types of wheel bearings, including hub bearings. This type of bearing should be easy to change, but can suffer from galvanic corrosion, where the bearing and hub carrier are of different metal, so stick together. I did a Prius front wheel bearings and brute force was needed!   
There is some of my experience of dealing with wheel bearings. 

[avetoy]

Many years ago my previous T25 had howling noise during driving at road speed... I knew it´s the wheel bearing but I was not sure which wheel. So I borrowed a stethoscope from a friend and with that it was easy to find out.

Another way would be to use some wooden stick: put the other end to wheel hub bearing housing and press your ear gently to the other end . Ask a friend to spin the wheel.

These methods are almost the same than Mr. Konrad suggested...