I've had this issue too... fortunately, only one tire and only the winter months. Have to add air to that tire once a week.

Dealer has looked at it twice... replaced valve stem once and cleaned up the bead area of the wheel and tire the second time around. A bit better now but still problematic in the cold weather.

 

I bought my used SS three weeks ago. The guy I bought it from said he had experienced an on-again off-again leak in one tire. What's weird is that none of the tires had lost any air in the three weeks and 4,000 miles that I have had it. I had the tires rotated a week ago--no problems since. Then yesterday I asked the dealer to re-match the tire pressure sensors to the DIC while they were installing the Stage I kit. This morning the RF was down to 11 pounds. Pumped it up to 32 and now it is back to 26. I realize it may be a nail that I just picked up, and will check for this if it ever stops raining here in Tampa. However, since the previous owner had this problem I am wondering if anything they could have done when it was in the shop yesterday (other than picking up a nail or screw) could have made the previous problem with the same wheel reappear?

 

I had the same problem with my 2008 SS. Tire shop found a bar code sticker causing the leak ,

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