I want to order an adapter for my GM spare tire kit #19179359. I don't want to end up with the lug centric problems others have complained about. The adapter company told me they could add a hub centric ring to the adapter for a $15 up-charge but they need the center hole on the rim's exact measurement. Since I don't have the rim yet, I can't measure it. I need this kit done in short order as I have a road trip coming up so I wanted to get the adapter ordered ASAP. Can someone who has the GM wheel kit please measure the center hole and give me the exact measurement? I'd really appreciate it!!!