I've been chasing the noise caused by cupped MTRs on my 06 Rubicon. It was a very metallic sound and only happened at slow speeds (1-5mph) and was independent of braking. I searched the forums and others have had this noise and new tires or rotating has "cured" it for them. I knew the cupping of my tires was causing it but wanted to know what the noise was. I drove down the road and hung out the door with my phone shooting video and what I found kind of surprised me. The rattling metallic sound is my front springs oscillating on their lower perch. I have the video but couldn't upload it here. You can see the spring start to vibrate and then as I get to about 2mph, the speed of the vibration in the spring speeds up and the noise becomes apparent. Here's my theory...under heavy braking it doesn't occur because the springs are being weighted very heavily. But, with a light slowing action, possibly one spring has more weight than the other maybe due to road camber and the oscillation is strong enough to let it shake the base of the spring against the axle perch. Wish I could upload the video because it's really obvious, but, I will "cure" the noise tomorrow with a rotation now that I found it. And before somebody says it, everything on the front end is tight and good. I hope this helps anyone else going through this because it was driving me insane! Happy wheeling!!!