What is the centre hub size for machining GM wheels

I am having the centre section of a set of GM Silverado rims (like the ones in the pic) machined for my Mazda. Does anyone know what diameter the hub needs to be cut to? I'm looking for the magic number to tell the shop. I searched the forums but couldn't find anyone who has stated the actual hub size for the B's
Are all years the same size, what about reg and extended cab?

Measure your hub?

Im a firm believer that grinding tabs is better than machining a wheel.

If you do find the measurement on line, don't trust it. All sites, I've seen list our center bore as the same as Mitsubishi, which is wrong.

Do you even read what you typed here! The tabs are concentric with the I.D. of the bearing that the hub is spinning in! Machining the rims is the way to go. Measure the I.D. of the brake hub alignment bore (that hole in the brake hub that fit over and slides down the outside diameter of the axle outer diameter and rests against the surface of the axle which the lug studs protrude through). The drum slides on the alignment mounting surface, the rim will. Maybe add .002 to the bore measurement. Let the machinist do the measuring (carry a brake drum with you and the rims, no tires), you notice, he does this for a living?
I have made things to the specs of someone else before. If not right they paid for the wrong dimension, and the corrected dimension too!

Yes i know what i read. With the right lugnuts you dont need to worry.

Bassackwards. Won't fit on the TOO BIG HUB OF TRUCK. Hence the conversation about boring out the too small alignment i.d. of the rims to fit over the TOO LARGE DIAMETER ALIGNMENT O.D's of HUBS of the truck.
But, yes were this a conversation about too large i.d. of the rim, but bolt pattern is right, we used to do that everyday in the '60s-on (I am sure this was done long before I started doing it), and just depend on the lugs centering and keeping centered, the rim.
That said, I never would have replaced the snowflake rims on my '77 Bandit with rims that did not have the right i.d.
Would not want life dependant on just the lug's strength doing a 180 at fifty miles per hour, without touching the brake, ending up in oncoming lane, pointed the correct way to be in that lane, accelerating back the other direction, meeting the trooper at the crest of the hill, sometimes, in the mountains of TN. Never was comfortable trying it any faster... . .. on a two lane road.

What do you think the hubs Tabs do? Keep your wheel from coming off if the studs break? It would make no difference in stopping if your wheels are hub centric or stud centric. The studs carry the weight of the car either way.

Feel free to put your life on the studs, do away with the stabilizing effect and security of the center hub on your vehicles. Please refrain from suggesting this to anyone.

And is it only tabs on the rear end and not a machined surface? Guess you are suggesting grind the front hubs all the way around and out to the end of the machined surface too?
Think I would get my advice somewhere else.
Sometimes when one is wrong, the maturity shows in admitting it, not crying "Mommy, tell them my way is the only, best way!".
Please let us not forget this is about safety, and sensible, not a pissing contest.
You are already up on a ladder.

And maching a wheel is safe? Thats funny. Go ahead and enjoy your hairline cracks and enjoy your wheel breaking.

Higher on the ladder to piss higher on the wall, still? Shallow comeback, rim i.d.'s were machined, NEW.