Who says we must mask off the wheels?
[:-^]
Definitely one of those “reality vs. aesthetic” photos. It’s a good shot of the final step in a factory for painting and any overspray on the wheels would quickly wear away due to sand/dirt, flexing of the rubber, etc. Have to admit you did give me a bit of a laugh by creating this mental picture of Hans walking around with a giant circle template. [:D]
I couldn’t see the picture, but I’m reminded of waht a friend who was a C-5 loadmaster saw during the buildup to Desert Shield/Storm. The guys who repainted vehicles from NATO 3 color to desert tan would not even mask windows. They just gave the drivers a scraper for the overspray.
Same way I paint mine 
except with an airbrush.