Thanks everyone for the input. After listening to the noise carefully and going through all the relevant bolts I’ve concluded the noise must be coming from the underside of the mudguard. The three “arms” that hold it in place seem to be welded to the underside with 1-2”x3-4” tabs, and it sounds like the middle one has either loosened up or bent a bit and is making odd contact with the mudguard itself. I don’t have a jack to take the wheel off and can’t get easy access to remove the bolts to loosen up the mudguard myself. Might be a job for the dealer as I’m not much of a mechanic.
Does this sound plausible?
