Hey, man, I recorded a video of the noise. It has nothing to do with the wet lot (it made the same noise in bone dry conditions when I got it home). This is at about 80% rear braking. Is this the sound that may be normal? I hope it's normal, but I kind of hope it's not, because it isn't pleasant to the ears. Sounds like my grandma's old Mercury. Eckhhh...
https://youtu.be/NS1q9V3sRtI