Newer Tires constantly losing pressure causing Pressure reading on dash to drive us crazy. What is causing the tires on both of my BMW's to do this?

Tires lose air pressure for the following reasons: 1) Air temperatures fluctuate more than 30 or 40 degrees in a day. With air temperatures going from - say - 20 degrees to 55 degrees in a given day, when cold, the air pressure goes way down and when warmer it can go up several pounds. This can cause a light to illuminate. 2) A puncture can be present in one tire, not usually more than one, but possibly. 3) The tire valve stem can be leaking. 4) the tire where it mates to the wheel can have a poor fit or corrosion build up causing a really slow leak. That's really about it. There's nothing wild and crazy, just normal areas to check. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops