The spare tire on a 2006 Dodge Caravan is typically located
under the vehicle, in a compartment underneath the rear cargo area. You'll likely need to remove a panel or access cover to reach it. However, some 2006 Caravans might have had the spare tire located in different places depending on the trim level and options package.
To be certain, check your owner's manual. It will show you exactly where the spare tire is located for your specific model.