We just purchase an '06 Pacifica Touring, and I've noticed that between 60 and 65 mph (about 2200rpm), there is a slight humming or resonance. It doesn't start until then, and disappears if I'm going faster. It's rhythmic, and almost sounds like the engine is alternately surging and coasting, although you don't feel any acceleration. I feel it in the floor of the car, and it feels similar to going over grooved pavement, only it's very slight.
Before I take it in, I wonder if anyone else has experienced this, and what it might be. Thanks!

 

I did with my factory tires (I think they were Bridgestones); but when I replaced them, it went away.

 

I have same issue..Been to dealer many times, but no one can find problem. Michelin came stock, but dealer put on Hankook when we purchased..I do not believe tires are the problem here.

Let me know what you find