Interpretation of words describing noises can differ from one person to the next , so are we talking about a " thump " which to me has always meant a more muffled sound like a rubber mallet hitting something solid and with very little or no resonance following, or are we talking about a " clunk " or a " clank " which implies more of a metallic sound , like banging pots and pans ? Wheel spacers or loose brake components would produce the latter, various bushings typically cause more of a thump , as will ( unfortunately ) numerous other things Given that it's a tiptronic I was thinking a flex plate starting to wear out but that noise would come more from the front / middle of the car not the rear ..unless there's something else in the transmission or differential causing the thump .. but I'd definitely focus on mounts, axle , sway bars bushings , etc. Whether 17 vs 16 wheels make a difference to any space tolerances getting closer and causing something to touch when going over bumps or dips , I don't know but sure sounds ( no pun intended ) to be something of that nature . Just conveying my experiences with the car, as I've had about every click, clank, clunk, thump, whine , whirr, buzz , rattle, rumble , ranging from loud metallic to more muffled sounds ...
p.s. to Jay and any / all of the three Bobs I know ; no I'm not talking about the " whine " that's occasionally heard stemming from the passenger seat , nor the " buzz " the driver might experience after a few too many liquid nutrients :-)
