Wheel bearings

My 2002 Tundra Limited 2WD , 168,000 miles recently began what sounds like a wheel bearing hum, beginning at about 40 mph, gets real noisy at 60 and at 70 goes silent. I had it to a reputable garage today and they racked it and ran it and can not determine where the noise is coming from. They put it on the hwy and made the same observation I did. Tires are Firestone Destination LE3 with 16,000 miles on them, rotated every 5,000 miles. Any ideas folks?

 

Is it like a wub-wub drone?

And you don't have aftermarket exhaust in any way, that could be maybe confusing drone with wheel bearing?

 

No certainly not wub-wub, just a steady drone noise. Truck has the factory applied exhaust system in great condition, Georgia truck, no rust.

 

No change in acceleration vs cruising? Sometimes you can get a noisy bearing in front to change tone and/or quiet itself with side loading it (lateral - medial force) Got any mellow sweepers at the 40+ MPH range that you could test on? Whichever side goes quiet should turn you on to that sides front.

Bearings can me a PIA to diagnose sometimes, up to the point that you don't know until it is removed/disassembled.

 

My next question was going to be whether the drone subsides when he let off the gas. Great minds think alike

But yeah, curious, any change in the sound if you let off the gas totally in the middle of that range, stomp on the gas in that speed range, or joggle the wheel, safely?