Bummer ( & not good news for Rick C. )
Here are some foam dimensions from another supplier ! ( found via eBay ) .
( I have no clue if they're really correct / though their marketing blurb would suggest they are, fwiw )
We are a JBL authorized service center and use these parts everyday.
14" Woofer Dimensions:
A - Outside diameter of the surround : 12.125"
B - Roll ends : 11.75"
C - Roll starts / O.D. of the cone : 11"
D - Inside diameter of the surround : 10.5"
15" Passive Radiator Dimensions:
A - Outside diameter of the surround : 14.75"
B - Roll ends : 13.5"
C - Roll starts / O.D. of the cone : 12.75"
D - Inside diameter of the surround : 12"
One thought ( because I can't quite see from the pictures ) ; have you already removed the black plastic trim ring ( snugged up against the metal frame / hiding the edge of the existing surround ) ?
It occupies a bit of space / maybe enough to suggest a bad fit ( if it's still in place ) .
regards <> Earl