Shortest wheel nuts

[Bipotey]

I am building some hub adapters. They are going to be the type that bolt to the hub and then the wheel bolts to them.
Just a quick question, what do you guys think is the shortest amount of thread i can use? Im thinking 15mm but if i can go shorter I will because want these adapters to be as thin as they can.
Thanks for your time.

 

[NorthloopCup]

1.5x the diameter is the recommended minimum. So for example, 12mm bolt should have 18mm of thread as a minimum.

 

[Bipotey]

Thats great thanks. Might go for 20 just to be sure.