Strange hum

[22crew]

01 Ext cab 7.3 short bed, 8 in lift, 38X15.50X20's, 100,020 miles. Just got new wheels and tires about 3 wks ago. I have started to notice when i am above 55 mph and take my foot off the gas it seems like there is slack in the driveline somewhere......seems to be coming from the front end. I can hear a type of moaning and feel it slightly in the floorboard. I really don't think it is from the new wheels and tires. I went from 16.5's to 20's but i don't think that would cause any issues. At slow speeds i do not hear or feel anything. I know the ball joints are good. Checked those when i put the new wheels on. Everything was nice and tight. I really have no idea. Has anyone experienced anything like this?

[NCHornet]

Wheel bearing going South. Is your carrier bearing shimmed correctly for the 8 inch lift? Hard to diagnose noises without being there. Awheel that big is going to hum with everything being perfect, if it is slightly out of balance it will really make some racket. I would have them speed balanced on the truck, not easy to find a place to do it, but once you have it done you will never go back to the tire shop/walmart method.

[22crew]

I've had the truck for 8 yrs and since day one i have had 38's and never heard this before. It drives like a dream. I don't believe i have a carrier bearing seeing that it's an ext cab. It only makes the hum when i let off the gas at high speed and there isn't a "load" on anything. Very hard to explain. I just changed out the right front hub about 3 months ago....maybe the left front is on it's way out now haha.....at least they're not that hard to change.