There was a big Olds 88 there with those exact rims. Somebody here also has a 81 Bville with those rims.
I don't doubt you, except for the "exact rim" part. That style was used on a lot of Pontiacs from that era. I've seen Firebird/TransAm (5x124), Sunbird (also 5x100), Grand Prix (5x???), with that same style rim. Just saying that the rims off the Fiero will not fit the Bonneville.