With absolutely no evidence, my first thought on the postcard was that the Wagon Wheel had (1) a western-style band and (2) a signature mixed drink (the "flaming forest") that the bartender is making. One of those high-proof drinks that you light the alcohol on fire?

Unless the place had a very unusual mural depicting a forest fire ... but that's quite an unusual subject, IMO.

But still, Harold's Club had their huge "Roaring Camp" mural out front, so who knows?!