* The owner's manual: This is the best source. It will specify the correct lug pattern for your van.
* The driver's side doorjamb sticker: This sticker often contains information about the vehicle's specifications, including tire size and sometimes lug pattern.
* The existing wheel: Count the number of lug nuts and measure the distance between them (center to center) to determine the bolt circle diameter (BCD). This is often expressed as something like 5x135mm (five lug nuts on a 135mm diameter circle). However, this is only reliable if the wheels are original. Aftermarket wheels could have a different pattern.
Without checking one of these sources, it's impossible to give you a definitive answer.