Intermittent Humming at Highway Speed

[MNiceguy]

Just picked up a Laramie Night Edition (less than 500mi on the odo) and I need some guidance on something I noticed a couple nights back.

In 2WD, once I get to 70mph I can start to hear a very low-pitch humming or resonating sound. It's very subtle though. I only first heard it when listening to talk radio (through the pauses between dialogue). This is my third Hemi so I am very familiar with the sound and feel of MDS but this is not that. Along with the sound is a very slight buzzing/resonating feeling in the steering wheel.

Here's what I've done so far:

• Tire Pressure (I have 22" wheels) = Ran 36psi as per the door jam tag and then tried 40psi. No difference. Quick search on the Pirelli Scorpion A/T show that if anything, this is a really quiet tire; especially new
• The sound persists in Neutral (at highway speed)
• 100% repeatable
• Happens on any rigid road surface (grooved concrete, asphalt, etc..)
• It seems worse when the steering wheel is 'slack' or there is very little to no pressure being applied to the wheel in either direction
• Alignment and balance feel good. The truck holds its line and there are no shakes

I'm going to call up my dealer but I'd like to have information in my back pocket beforehand if at all possible. Any theories here?

 

[Loudram]

Try jacking the front up and spinning the tires by hand. See what that tells you. Also check for any play side to side and top to bottom. You shouldn't have any play with a truck that new.