How much air should you have in your tires on your 05 caravan?

That would depend on what size tires you have installed on your vehicle, are your tires the factory OEM size tires? ...Do you use your mini van to carry heavy loads? ...Do you use it as a taxi? ...Do you frequently make long trips? Are your driving in winter weather conditions, i.e: snow and or ice?...Without knowing the answers to these questions it is almost impossible to answer your original question... Also remember that Underinflated tires can wear out and or burst just as fast or as easily as Overinflated tires can, proper tire inflation helps tires last longer and helps fuel economy, also a good wheel alignment can make a huge difference to your rideability, fuel economy and tire-lifespan ....ALL tires have a "Max Tire Pressure" number on the sidewall, if your Max Pressure number is say 44psi than take 10 to 12 psi off of that number and go with 32 to 34 PSI, although SOME vehicles DO recommend different tire pressure on front and rear tire, i.e. front tire pressure 34, rear tire pressure 32... Higher inflation will also give your vehicle a stiffer or harder ride, while lower pressure would give your vehicle a softer more spongy rid.