Ever since I inherited my wife's crossover, back in August, I was aware there was a slow leak in the right rear tire. It was losing roughly 1.5 psi weekly, or 5 psi/month.
Today, I found out why:
Why did I have the leak investigated (and fixed), you may ask?
Because this was in the left rear tire:
When I got home, I could hear the hissing as soon as the driver's door was open, and it seemed like a good idea to head downtown to the tire store.
Glad I did.

