That doesn't sound right....
On the drivers side door pillar is the VIN and Model Code. Using the lookups for those is your best assurance that you are not wasting your time. Also, AWD vans have the 18" wheel/tire package with the higher grade multi-spoke alloy wheels, and there will NOT be a spare tire under the 2nd row passengers side seat. Do you have a sideview photo so that we can see the wheels?