[obermd]

Thanks @snowwy66 for the advice. The valve stem got changed with the new TPMS sensor. I'll have to check the date on these tires. I'm pretty sure they are about 3 years old. I was kind of wondering if maybe the tire didn't vulcanize correctly since its just a cheap Uniroyal tire.

I bought this car off my cousin and I had to rebuild the engine and a few other things so I don't know much about its history. This will just have to get added to the list, lol. Apparently Subarus right around 100k need a lot of work.

One of the OEM tires on my 2012 ECO MT did this - lost about 5 PSI per week. I finally got tired of it and replaced all four tires.

 

[obermd]

Take a close look at the tire in question. My bad tire had an excessive number of surface cracks, which indicates the rubber was deteriorating.