I just got a snowtire/wheel package from Tirerack for my '18 GT, AWD Stinger. They supplied 13/16" lugnuts. I believe stock lugnuts are 21mm (?). The 13/16" socket adapter supplied tightly fit 19 stock lugnuts, had to use 21mm socket for the one lugnut (?). You should check the "web" or dealer for KIA's specifications.Does anybody have the specs for safety lug nuts for GT 19" wheels?