he could have a hub issue, but there's usually some "feel" thing going on with it too. He's suggesting a knobby tire noise at speed.
Okay, my Wrangler (solid axle unlike yours) would make a tire noise after a few miles. It was toe'd in or out too much. With your new tires, I wouldn't normally suspect this.
..but getting an alignment surely wouldn't be unwise. If there are any suspension issues, they'll find them.