I recently bought some used rockstar 1s off a buddy , installed new tires, balanced , put tapered lug nuts on and I'm still getting a slight vibration above 40mph. Does anyone know if I need hub centric rings? XD says no, I think I do. Any help would be appreciated.

 

Btw it's a 2015 f250 XL single rear wheel regular cab

 

You should never "need" the rings. They are not structural. They simply make it easy to get the wheels perfectly centered. I would make sure your shop has someone that really knows what they are doing with checking to make sure the rims are true and are offsetting the heavy spots in the wheel and tire.