Tires: huge drop in tire psi but no leak found, wheel assembly, nm tx

Question
QUESTION: I'd like your opinion please. I normally keep 36 psi in my tires and after 6 weeks and sub-zero temps I had the pressure electronically checked on all four at Discount Tire. All were at about 34 psi except one was 23psi, couldn't tell by just looking. They put it in water and found no leak so took it completely apart, checked everything and found nothing. They put a new stem on it and said to keep an eye on that tire. But about a week ago, just that one tire (left rear) hit a major pothole really hard. They thought that was unlikely to cause such a big loss of air, but still possible "if all the conditions are right." What do you think? If it wasn't that and no leak was found, how could it lose all that air? (whether it is still losing air remains to be seen).   Thanks

ANSWER: Lee,

Sometimes a tire and wheel assembly will leak slowly enough that it is difficult to determine where the leak is.  To really find the source, some patience would be needed.  Plus, sometimes the leak only occurs at the lower temperature, and seals up at room temperature making it impossible to find when working in a shop.

Hope this helps.

---------- FOLLOW-UP ----------

QUESTION: Thanks, could that deep pothole where just that one tire hit cause it to lose that much air? I ask because the tire was ok before that. And one unrelated question if you don't mind, if tires are 6 years old or more, should they be replaced even if there are very few miles on them?

Answer
Lee,

It's possible to lose some air due to the impact, but the numbers seem a little high for that.

I use this rule of thumb for the age of tires:  If you live in AZ, CA, NV, NM, TX and FL, 6 years is the limit.  If you live in MT, WI, ND, SD, ID, and MN, the limit is 10 years.  Everything in between is .... ah.....uh.... in between.