Humming Noise coming from rear.

Hi, I have recently had a problem with my durango and it seems to be humming which sounds to be coming from the rear.It starts to hum at about 25/30 mph and continues until I let off the gas. If I just even tap the gas going anything faster than 30 it will start to hum but once I let off the gas it immediately goes away. Also when I come to stop it sounds like a sort of rubbing/humming noise going from 20 mph to a stop. This problem just started yesterday actually and seems to have gotten worse over the course of 1 day. I do not think it is the bearings because I checked the tire for shakes or movement and it does not shake side to side at all. Also I did recently get a flat tire and had to have a rear tire repaired so I'm thinking it could just be that tire making the noise but im not sure since it did not start making the noise until about 2 weeks after the tire repair. It does make the noise on gravel/pavement and dirt roads so I think that rules out the tire. BTW its a 2000 durango 5.9L 4x4

Any help would be greatly appreciated, thanks.