I get a rear 'wumpf, wumpf' noise every so often, mainly, but not only when driving at low speeds. It's quite unpredictable and almost sounds like a rubbing. I recently got new tyres, which is when it appeared, but I jacked the rear end up and could not find any rubbing at all. There was plenty of clearance. Any ideas? It seems to be getting slightly worse.

EDIT: I jacked up the back again and the rear right wheel makes a periodic chaffing every revolution. I'm thinking wheel bearing or warped rotors?

Well if you jack it up everything will be hanging down!

Look for signs of rubbing, wear.

I had a similar noise recently after buying my TE. Got my Mechanic to look at the rear brakes as i believed it was 1 side sticking. They completely overhauled the rear brakes and now no noise. But need a little bit more adjustment on the Handbrake.