Well I'm a year later and still no further.
I wanted to change the roles of my vive wands to trackers for full body tracking. But in vrchat only my shoulder moves when I move my feet. First I couldn't change the role from shoulder to feet because they weren't recognized by steam vr even tough they were tracked and I could see them. 
But now I have switched to a new PC, used a new steam account, and now I CAN change the role of the tracker to my feet but still only my shoulder moves. I have asked this question before but got no further, I have asked people in vr chat with full body tracking and nothing. 
Please PLEASE somebody know something.