2006 Dodge Caravan how long should the brakes last

I don't know of any unusual brake issues that are a big problem, causing premature wear. The materials used to make the brake pads, the way they are used and yhe weight and type of driving all play a role in premature brake wear. Maybe this time, they will last. In september of 2005 your van was sold or rather made. 3 years and 18,000 miles is very little driving on highways, so short stop and go type driving over three years will do it. Maybe you will get more time on these pads. I hope so. It is a good van. It is expensive but normal(on the low side) wear sometimes.