gait
Explorer
I find it odd that the lugs were tightening rather than loosening. ...
I've also thought that right hand thread on right side and left hand thread on left side would loosen. But I have no real way of checking and figure the designers knew what they were doing.
Examination of my failed lug/stud suggested the first one was loose enough for the wheel to move and flex the lug/stud until it broke. Different to it getting tighter, stretching and breaking. Previous stretch during fitting can create a place for crack initiation. Just a bit of work hardening can be sufficient.