Low hum between 45-60mph

2018 Tundra SR 4.6L 4x4 90K miles. At speed starting at 45mph there is a deep hum sound that seems to come from the rear of the truck. Nothing terrible sounding, sounds like elevated tire noise. I have had tires recently replaced and alignment done and the noise is still occurring. Suspecting a bad wheel bearing, I jacked up the truck and physically tried to wiggle each wheel to see if there was wheel bearing play. There is none. I asked a dealer to take a look and they said the rear drivers side wheel bearing needs to be replaced. I took to a local shop to have it replaced and they said the wheel bearing was fine. The shop recommended that I take it to a place in town that specializes in rear differentials to see if they can find anything. I haven't brought it there yet. Thought I would ask here if anyone has experienced rear-end humming noise or has any tips on what it might be. Thanks

 

I would suggest you look at the rear tire balance weight first. Some may have fallen off or incorrectly balanced. I put on new tires, got an alignment and had weird road noise at around 45+ mph. They initially gave me a sheet to show proof, but found that they had to rebalance the tire again. Hope this helps!

 

With the brakes assembled and the other end of the axle in the diff i doubt you're going to feel much by hand in the way of wiggle until it's to the point of sparks flying and air gaps. A lot of the time you can't even feel a bad front bearing either until just before it converts to a 3-wheeler.

Have a cheap infrared thermometer? Sometimes that can nail down the bad bearing.

 

Today I had the wheel bearing in question replaced. Truck rides like new. Noise is gone. Tech used a stethoscope to identify the bad bearing. You are correct, the bearing was bad but had no play in it with the wheel on when I physically tested it.

Thanks