(– by LugNutz #5331 –)
Hi Karen, welcome to the forum.
What type and brand of "airdowns" did you buy? There are a few different styles out there. The Stuan tire deflators simply screw onto your valve stem and start airing down when you pull the pin, they'll shut off when they reach a pre-set pressure… 12PSI from the factory if I recall correctly. There are a couple of Chinese versions out there too by companies like Smittybuilt and Titan that may not come factory preset. I've got a couple sets of these and while they work great, I find they can easily lose their calibration if improperly unscrewed from the stem when your finished. Is this the type you have? If so they are fairly easy to recalibrate to your chosen PSI.
As for the airing up, I know a few people who have bought or built "spider inflators", a 5 hose assembly with distribution manifold. You simply hook the input hose up to your compressor, and clip the four output hoses to the wheels and it inflates all four tires equally at once. They can be a little pricey but can certainly be worth it.