Faint Low Frequency Howl at 50mph+

[zibzer]

Hello, just bought a 2010 Sierra Z71. Nice truck and first time with 4wd. I noticed while driving a faint low frequency howl at 50mph+ very much similar to heavy treaded tires. However, my tires are not aggressive and don't have all that much tread left to be honest. I've never had this noise in any 2wd I've driven so maybe it is just normal for 4wd? It happens in 2wd/4wd/auto though. It's not really noticeable with the radio on, but quite noticeable with the radio off. I'm not too worried because I still have warranty for almost 25,000miles, But before I waste time getting it diagnosed at the dealer I figured I would ask here if it was simply a normal sound.

[gmtech4]

take it in to be sure

[jaredlucky16]

I would look into your tires since you said there isnt much tread sounds like they may be cupped

[zibzer]

Well, the tech said it was normal, though will check it out Thursday. Never had this sound on my gmt800 or previous gmt900. At least I've got some time for warranty repairs