Well my caliper only goes to 5" so it's pretty useless for this. But see below for the rim measurements. Crude measuring tape shows 10" diameter.
I tried the heat gun again, this time hotter. At one point I banged it enough to barely hang on. But it popped off with a slight touch.
I also noticed that the front right isn't as smooth as the others, indicating that @Theron had trouble getting that one as well.
I unpacked the second one (my spare) just to see if it's a bad stamp. They look and measure the same. I tried delicately to press that one on and it's the same exact size.
I can't see any markings on the wheel to tell me what kind they are. Maybe you can tell?
I think I'm done for good. Anything more is just testing my sanity.... unless there's something new to try.