One more question: I used to own a Legacy Outback wagon which had some issues with tires (even brand new ones) losing air slowly. Rims were wirebrushed, etc., but it was still an issue. Now that I have my grandfather's car (also a Legacy Outback wagon -- 1997), it is showing the same problem: slow loss of air in three of the tires.

 

Is there a known problem with rims in this model? If so, can anyone recommend the least expensive solution -- i.e., where to find inexpensive replacement wheels?

The valve stems probably need to be replaced.

One trick that does work to check bead seat and valve stems is using a spray bottle of soapy water. Splash on the soapy water and bubbles will start forming where you have any leaks. Little tiny bubbles so look close

 

I've had GREAT luck with "Fix A Flat" spray gunk in a can. Had it hold air in tires that had slow leaks untill the tires finally seperated and were thrashed. Really does seal up tires! Read the directions on the can for best results