The "why" of the reason I decided to run spacers isn't so relevant as compared to "why" it (they, collectively) failed... I too stand by cheap studs being the root cause. I checked the torque on the studs just a few days prior...all were "normal" torque for Ford lugs, but apparently not for cheap chinese shit pot metal studs. I'd think that something like grade 5 strength isn't enough for 100+ pounds of torque on a stud. For sure, not these. Even the spacer body is aluminum. I'm about to start a return on these (if it's not been too long since purchase). I'll keep this updated with regards to my results. And the window for a return is past. Jesus, I'm irritated with this shit.