Four leaking tires?

Philadelphia, WHYY, Sunday 2009-03-29: The last call of the show was from a young woman who parks her car in a warm garage but drives it during the day it cold weather. She claims every morning all four tires are a bit low and she adds a few pounds at a station down the street from her house. It passes belief that all four tires could be leaking, and at about the same rate, but what other explanation is there?

Is it possible that all four tires were mounted incorrectly?

There have been a lot of bad valve stems lately. I have replaced 2 recently for leaking. When she bought tires the shop may have had a bad batch.

If we assume that she has the facts straight, I was assuming that this had to be the case. My own assumption was that whomever mounted them was probably either inexperienced, lazy, or in a big hurry and didn’t bother to worry about checking and cleaning the inner rim surfaces - thus allowing all 4 to leak slowly due to improper rim seal. Consider that w/ the previous tires all 4 rims were subject to similar conditions and would have similar levels of defect/grime/etc. The same could be true of the valve stems (defective batch?) but if it is really all 4 I think poor sealing is most likely.

Having to air four tires everyday is a issue I would get resolved without waiting to ask a radio show for help. Myself I cannot detect a few pounds low by eye.

Oldschool is correct. If the pressure is down so low you can see a difference…then it probably down 10lbs or more. The sensors on my 4runner kick on LONG before I can visually detect them being low.