15" seems small for a van. Are you sure the new rims clear the calipers?
Your diameter should be close (confirm that 225/60R15 is a common size - 225 seems wide for a 15") and also confirm the tire will accept the width of your wheel.
I have my doubts, but I'm not sure you're wrong, either.
Edit: Seems I was somewhat correct. 225/60R15 isn't that common for snows - all you get are performance H-rated snows. The TT tire finder suggests 205/65R15 for the 2002 MPV LX, so I guess I have my clearance answer there,