I'm thinking fiction. What IS different is the plastic center caps . . . they look identical but you can't tighten the steel wheel version down on the aluminum wheels because the little plastic lug-nut simulators won't reach. If you use the Aluminum wheel caps on steel wheels they rattle because the similators bottom out before the cap is really tight. This could explain why somebody thinks the lugnuts are different. What's really different is the thickness of the wheel flanges.
Aluminum wheels have a lug nut with threads on the outside (male) to accept the ugly plastic fake nuts that hold the center cover on. I've been looking for a chrome center cap that mounts from behind the wheel so I could replace nuts with chrome ones. Haven't found one with a small enough diameter yet.
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