Noise in rear end?

I recently put 4 new tires on my 2012 TRD Sport Dcab (40K miles) Toyo Open Country AT's. I have been driving for about 2 weeks now and have noticed a sound coming from the rear end (I'm pretty sure from the back...it seems louder if i jam my head backwards while driving) At first I thought it was the AT tire but it is way too loud for that and as I said, only seemed to be coming from the rear end. Its quiet until about 35mph and gets louder as i go faster. Like a low growl or rumble not a whine or squeal. It also gets quiet when i turn left sharply or go around a left curve. I know it sounds like a wheel bearing but was wondering about any other things to consider? I also have a slight vibration from the back that I always thought was an unbalanced wheel so I was thinking maybe carrier bearing but with only 40k miles?
Any thoughts and thanks....
FYI I had 5100's installed set at .85 (rest stock) and an alignment just before new tires. I doubt it has any bearing but coincidental.