Offset is 50.9. I have since learned that OEM wheels stamp the size and offset into the back of the wheel. Also JK Gladiator Sahara 18" wheel weighs the same. Offset 44.45. Barely clears the brake caliper on the fronts. I can fit a dime between the caliper and the rim spoke.
So I have the stock 18" Summit chrome clad wheels. Since I could not find any info on the wheels, besides 18" x 7.5" and 5 x 127, I took down the spare and weighed and measured it. Wheel and tire weighed 59 lbs (or 27 kg), and the stock spare tire is rated at 32lbs, so the wheel is roughly 27 lbs. Not bad for OEM. Backspacing measure 6.25" was easy and offset was +49mm (assuming my math and measurements are good. Anyone want to confirm?). I hate that they are chrome clad, but if I pretend they aren't, they do look OK and are easy to keep clean.
For tires I'm running General Grabber UHP summer tires. 255/55/R18 Although they won't last as long at the Forteras, the ride is softer and the grip is much better--best of both worlds, right?