1997 GMC Suburban 4x4. Vortec V8. Question: Loud road noise at 55-65 mph (almost makes the truck feel like it is vibrating) but still feel full control of the vehicle. CV joints replaced, no change.

Tires wearing poorly (cupping) all replaced. Noise lessened/gone for about 100 miles, then returned.

Answer: The way you describe it, it does sound like a tire noise. Since they are fairly new, and unless they are totally worn already, I would not rule them out. You could have a few different things that make noise like that while driving. A bad wheel bearing / hub will sound like a loud growling/roar noise as you drive the vehicle and will increase and decrease with speed. Worn hub bearing could cause the tires to wear. Sounds like the tires are starting to wear again after noise gone for 100 miles, then returned. Have the front end alignment checked. Also, a possible bad bearing or gear in the rear end with make a sound like that too.

Same goes for the front differential too, a bad bearing or gear can be noisy. Less likely, but not out of the question would be a transmission noise, or even a transfer case problem. The fluid can be checked in the front/rear differentials, the transfer case, etc to see if there any discoloring or metal in the fluid, that would help locate the problem. As for the wheel bearings, they can be checked for excessive play and looseness if you can get the truck in the air. I'd re-check the tires first, make sure there is no uneven wear and the pressures are set correctly.