Rubber Grind
 

2002 V8 4.6
After driving about 15 miles, and when I drive slowly, under 5mph, there is a roaring in the back of the car that sounds like rubber sliding against rubber. It is very quiet outside the car. It doesn't affect the car's driving at all, but it is annoying and sound potentially bad.
The slower I go, the slower the sound is, if that makes sense.

It's not the brake pads, cause i just replaced them.