With about 75,000+ hard driven miles and many spent in part time as well as full time 4x4, the front hub bearings are shot. I heard this annoying noise that I attributed to a more aggressive set of tires that were recently put on. Anyway, long story short is thank god I have the extended warranty.
So if you're driving around and you think that hum is nothing to be worried about, be sure to give the front hub bearing a once over.

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06 Liberty Sport
DIESEL
Skid Row Engine and Fuel Tank Skid Plates, straight pipe, modified air box, Tow Hooks, 245/70/16 Hankook ATM RF10s, Kennedy Lift Pump,Home Made Provent, Husky Liners throughout, Wet Okole seat covers, All J Products Rear Storage Shelf, Fumoto, Frozen Rotors-Cross Drilled and Slotted, and Bilsteins all around