The chevy Bolt circle is 8 on 6.5 inches, centerbore is 116mm a little over 4.5 inch. Ford was 170mm. 06 they went to 200mm is 7.875 inch. And centerbore of wheel is 160mm 6.300 inches. MMs divided by 25.4 gives inches. Centerbore or hub is only to center wheel not to carry the load. There is about .010 clearence. If the lug nuts were not holding it the wheel would move that much under a load. If it was it would be a press fit. Not confusing. Its just a bigger stronger truck period. Sorry if that upsets you chevy guys.

I guess that .010 of clearance is a lot... because I always need to hammer off wheels on chevys and fords if they wern't anti-seized.

Ok, your talking about hub center section. Thats fine if you show the chevy's is smaller, I will agree. The reason is that there are no locking parts in the hubs like on a ford. The ford need the large center section to fit the locking hubs, just like pre-IFS chevys.

Ok, so I agree the chevy is smaller. But then you say that hub centric isn't for loading, and that the lugs are. So you then change it back to only being 5mm smaller than fords.

Eitherway, I think your center bore measurements are off, if the lug pattern is 8x170, and the center bore is 160, that leaves 5 mm clearance between the bore and lug bolt center. Something doesn't add up.

In late 05 ford changed again to 8 0n 200mm. Which is 7.875 inch. The center bore is 160mm 6.300 inches.
8 0n 170 has 125mm bore. I make 1000s of wheel adapters and spacers for cars and trucks. My job to know bolt pattern. The 450s 550s have 10 on 225mm. Stop by a ford dealer an take a look.

who cares?

Awesome! I always have questions on bolt pattern/vehicles and wheels, backspacing too. Good to know someone to go to who will have the answer!

great info, thanks..Jeff