The family car has come across a problem. There is a persistent grinding sound coming from the rear of the car. The right rear wheel seems to be the origin of the noise. We've speculated it could be either wheel bearing or (hopefully not) trans-axle. We don't know what it could be and would like some help on the matter.

 

I have the exact same issue, especially while turning left, even when changing lanes. Speculated the same as you but have yet to find definitive answers.
Hopefully someone who has had this issue will chime in.

 

Have you checked the brake pads? If the pads are worn down in the rear, you may not really notice a change in braking performance since the rears only do a small percentage of the work, but you may have pads worn down to (or through) the backer. Can you give more info on the noise? Is it something that is speed-dependent in pitch? Does it always happen? Do you have a rumble that gets louder as road speed increases? Is it RPM-dependent? Any of those traits can narrow down the parts that can (or can't) cause the noise.

For the record, the three biggest causes of noise like that in the rear of the car are bad brake pads, stuck calipers, or bad wheel bearings.