Took a long road trip in our '05 LS430 base. Everything worked fine. But I noticed that the drive line was noisier than normal. The outside temp was about 70 degrees and so the HVAC system was basically making no noise and I was listening to the car more than usual. I noticed this low rumbling that doesn't quite sound like the tires. It's really quite loud. Hard to describe. Could that be one or more wheel bearings starting to go? I can't localize the sound at all; no idea. Any heads-ups much appreciated.

 

My only wheel bearing years ago was a sound around 30-40mph and more like a steady, fairly faint whining/whirring tone. For once, dealer guessed right, in that changing the bearing fixed it. Around 100k miles if I recall. Grinding noise out of engine for me that made me think my engine was ripping apart (clearly not from wheels) lasted just around 20 seconds and went undiagnosed but preceded a dead alternator a couple of weeks later at around 150k miles. Doubt this is your sound but just letting you know weird sounds. If an odd thumping could also be heat shied loose/bad or a strut mount... Get it checked that nothing is loose / about to fall off and you might not find exact cause unless someone really cares to diagnose it.

 

Get someone else in the car who can move around and localise the sound while you drive,... or vice versa. :-)
Could be wheel bearings, could be prop-shaft, could be tyres.

 

I had my tires rotated and noticed a noise like a rubbing grinding. I think when they rotated my tires, the tech might have bent something in the brakes like a shield or something similar. Did u get ur tires rotated recently?