Hopefully i can help..
I note you dont mention any checks been done upto this point..so givin that - the first ideal checks id from here going by your description would be wheel bearings ..often these can sport the same syptoms as you describe becoming louder/grinding as such depending on the extent of the wear..it certainly would be the best place to start inc a routine check as far as the braking/discs..I do hope this helps
I've booked it into my local garage, I was getting bad tyre wear on the outside edges and they said it was my tracking (2 months ago), this noise has started since then. Ineed to change the tyres but don't want to waste money on tyres before getting this noise seen to, as I understand it a worn bearing can affect tyre wear too. The noise doesn't change in any way depending on speed, same tone fast or slow. I'm hoping bearings and nothing more sinister.
Yes normally tyre wear on the edges is down to tracking..but! they should never track a cars steering if it has issues with suspension/steering track end wear or even wheel bearing wear.as tracking would be pointless in a sense..as they try to compensate wear which shouldnt be there..but as starting point id say get the wheel bearings carefully checked out..before even considering getting new tyres at the moment...I do hope this helps