Hey out there from Nashville, my 1999 ML430, have it one year, 140k, nice shape. This happened 4 times in the past 10 months. 3 in TN on same road. 1 in WashDC.

Cruizing 60 to 80 mph, hit a very rough stretch of interstate, of course ML starts rumbling etc. It starts to rumble more, first time I was sure it was a flat tire (I am 70 years young, grew up in my Dad's gas station, still do my own work). Pulled over, no tire problem. Drove on without the problem.

So the next three times I put up with it but two of the times I had to stop for a while and then continue. Yesterday I checked all 4 wheels, they were all warm/hot but seemed about right.

Any suggestions other than avoid construction zones and bad highways?

Note in between these occurances I have replaced the front calipers and discs (just time for it) and put new Michelines on (great improvement, rides like a Rolls now), old tires were cracking.

I've seen various cars that:

Had a bad drive shaft center bearing / mount that usually spun OK but sometimes bounced around. ( Think of a electric motor with a bad bushing )

Inner tri pod style CV joints no longer hold the center shaft concentric with the housing.

If your drive shaft has rubber drive discs, have a look there.

My 97 C280 suddenly developed a ZZZZZZ sound after driving on a road where someone drove a track machine rippling the pavement. The noise when away after stopping but came back / went away ~ 15 miles later. I knew it was transmission planetary related as I have head this before. Pulled trans , rebuilt , replaced worn K2 bushing ( between front and rear trans shafts ) no noise for the next 8 K miles. 99 should have an uprated K2 needle bearing to solve this problem.

The transfer case might be making noise, I've had a planetary noise before. The transfer case should be Borg Warner and similar to Ford.