Acclaim wheels on an A-body?

Well I am not going to say no way since Chrysler has done odd things over the years but considering every other fastener on a Caravan is metric I can't see why they would not be metric on the wheels. Also the early Caravans had 5 on 100mm, it was not un common to see people mounting Dyatona Alumium wheels on them.

FWIW, my 97 Avenger had 5 on 115mm wheels.

Nope , the 97 Avenger is 114.3 just like my 96 Avenger. The thing is if get your tape measure out it looks like it is 115, but actually is 4.5 or 114.3. (a lot of Honda's and Mitsu uses this same bolt pattern as well)
But you are right the old Caravans were 5 on 100, like the cars.
The 115 bolt pattern came in when the 300 and Magnum and Charger came out. They got it from the Daimler side of the house.

1997 Dodge Avenger
Diameter: <ALL>
Bolt Pattern: 5/114.3

From www.1010tires.com