OK, got the measurements I wanted, and hopefully the measurements y'all wanted too!
I have been running stock Hummer H2 rims with BFGoodrich All-Terrain T/A KO2 tires in 315/70R17 (~35" x 12.5"). With the H2 rims, there is only minimal trimming of the lower plastic bumper and some "massaging" of the cab seams to fit. My hope here was these WCFab PYO rims would match the stock H2 rims for width and backspacing.
So not to bury the lede:
the WCFab PY0 rims are identical to the factory Hummer H2 rims in terms of diameter, width, and backspacing!! This is exactly what I was hoping for, though WCFab would not confirm it. But I can confirm!
I compared the new WCFab PYO, the Hummer H2, and the stock PY0 rims:

Those polished + chromed GM PY0 rims somewhat steal the thunder of the polished aluminum WCFab PYO. However, I think the stock finish looks good, and plan to run them as-is, at least for a while.
Not that anyone but me is likely to care, but all 3 rims appear to work with the stock GM 15114379 TPMS sensor (and therefore probably any TPMS sensor). I've been running that sensor in the H2 rims for 10 years now, and plan to put new ones in the WCFab PYO when I get the new tires in.
The WCFab PYO are labeled "SAE J2530 RATED 3200 LBS" which is a bit below the rating of the new BFGoodrich KO3 tire (load index 128 = 3968 lbs).
It does beat the load rating of my old KO2 (load index 121 = 3197 lbs), so at least I won't be losing capacity with the new setup, though I don't really gain any either.
| Wheel | Weight (lb) | Diameter (in) | Width (in) | Backspacing (in) |
| Stock GM PY0 | 17.1 | 16 | 6.5 | 4.9375 (4 15/16) |
| WCFab PYO | 23.1 | 17 | 8.5 | 5.59375 (5 19/32) |
| Hummer H2 | 33.2 | 17 | 8.5 | 5.59375 (5 19/32) |
So the WCFab PYO is 10.1 lbs lighter than the Hummer H2 rims! I am impressed. And lucky, because the new BFG KO3 is fat AF, more than eating up the weight savings from the rim swap. Dangit BFGoodrich!
| Tire / Combo | Weight (lb) |
| BFGoodrich KO2 (10 years old, 56k miles, 3/32" tread left) | 58.5 |
| BFGoodrich KO3 (per their website) | 69.5 (+11.0 lb, +19%) |
| BFG KO2 on Hummer H2 | 91.7 |
| BFG KO3 on WCFab PYO | 92.6 (+0.9 lb, +1%) |
If you want to see the full set of photos of my measurements, they are here:
https://immich.reaperlegion.net/s/WCFab-PYO-comparison
That's just the measurements, I'll get some glamor shots once I get the new tires in and mount them on my truck.