I've had this rhythmic humming since I bought my jeep and just thought it was the old tires. I have replaced the tires, a bad u-joint, and cat converter. Still have the noise.

It gets louder and faster with higher RPM/Speed. 55-60 is when you can really hear it and 70 it is almost a full drone as opposed to rhythm. But it seems to almost go away when I take my foot off of the gas. It is making driving on the highway at high speeds very loud and dangerous feeling which I think is more than just "a jeep thing". I also get very bad gas mileage (10-12 in city) on 29.5s.

I will have to take it in I suppose. What should I tell the techs to check?

Thanks in advance, Dan

 

I would have them check the front and rear pinions. I would also have the front hubs checked as well. Bad wheel bearings/hubs would be loud and give more drag and cause a decrease in MPG's.