Edge DAD

I have a 2010 Edge SEL with 18" chrome rims. Mileage approx 22k. This winte,r if we experienced a very cold temperature with in few days of higher ambient temperatures or vise versa the rims leaked loosing about 10 psi.. Sometimes it is 2 on one side or one on the dl side. I happens over a few days or so. It seams like I have to fill the tires every other week. Vehicle is garaged..