Recently I have noticed a howling, kind of roaring, noise while driving on the highway. It sounds like the noise is coming from the front right side, (but may not be) and greatly increases on a left hand curve. I just noticed this earlier this week. Could it be tires? alignment? worn front end parts? There is no shake, shimmy or wobble felt through the steering wheel or truck. It really sounds like I'm running mud grips on the truck, but I'm not. And it's pretty loud, inside the truck anyway. It's a 1996 4.9L auto.

And if it matters, the right (passenger) side is approx. one inch lower than the left.

Thanks, John

 

Wheel bearings

 

yep. because its increases with load, its the wheel bearings.