Look at the other side of the wheel. If there is a flat raised band approximately 2" wide near the middle you're dealing with the infamous Firestone RH-5 "widowmaker" wheel. There is a huge amount of information on those wheels on this site and elsewhere on the internet, but to make a short story even shorter, the only really safe thing to do with those wheels is to deflate the tire, disassemble the rim, and destroy it. The locking point is at the center of the rim where the two halves snap together, and they have a nasty habit of separating explosively with no warning. The locking lips are very narrow, and any deterioration from rust or damage from mishandling during tire changes makes them deadly dangerous.

Google "Firestone RH-5 wheel" and you'll find several hours' worth of reading, none of it complimentary.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!