The following gallery is just a small portion of broken thread-in studs that have been shared with us. There are many more that most people don't bother documenting or sharing. Contrary to popular belief, these failures are not correlated to having wheel spacers. In fact, more than 50% of the failures shared with us occurred WITHOUT them. And, some of these failures were with brand new studs installed prior to the event. 


Also, notice how almost all these failures occur inside the threads of the wheel hub, or flush with the hub face. This area is where "bending" stress is at its highest and where the fundamental difference between a press-in style stud and thread-in lies. Press-in studs have much more material and strength at this point due to how it interfaces with the hub vs thread-in studs. Let the pictures and video do the talking.