Quote Originally Posted by 2COR517 View Post
What's an internal shank?

And explain to us all how the un-threaded, and therefore un-stretched, portion of the stud increases strength? In layman's terms...
Since you seem to have some confusion about the make-up of a standard fastener, or in this case a lugnut, an internal shank on a lugnut is defined as the threaded portion of the lugnut that passes through the flange portion of the wheel rim, this type lugnut is normally used on thicker aluminium wheels where a normal lugnut would not have a high enough thread count and a higher thread count is desired for safety.

And again since you are confused as to where the weakest point of a fastener is it's in the threads, the threads are more likely to strip and have a lessor strength than any other portion of a fastener be it the stud or the lugnut.

For more information on this subject I recommend you try searching the internet further. Manufacturers of fasteners and bolts would be a good place to start.