I've not seen a tire bulge like this before-- seems kind of small, but starting to think I may want to replace it -- curious other opinions as the tires are relatively new. Thanks in advance

 

Looks like it hit a pothole hard & the inner liner spit to cause the bulge. I would replace it.

 

Yes, that tire should be replaced. It will continue to separate and could catastrophically fail under high speed or load conditions and could develop a leak too. Will probably cause a vibration as the damage progresses from driving too.

 

Thanks very much to you both!! I dont recall hitting any potholes (but being in Chicago-- the streets are littered w them in some places), and the rim is w/out even a scratch-- but that is what I was thinking-- my first 911 (997.2)-- was driving w my two 7 year old boys in back seat (about the only size of person that fits back there-- lol) and felt a little rumble as the car hit about 75mph-- got off highway and after checking the tires, found that little bump. The fronts have about 7mm left on them, and 8mm passnger rear-- but driver rear is maybe 5 or 6mm. Would you say replacing all 4 is best course? Thanks again for the advice!!

 

Also-- if replacing all 4 (on a 2012 C2 Black Edition), can I go w 305/30/19 on the rear ? Currently 295/30/19. Thanks.

 

Your photo actually shows a mark on the rim right at that same point, even if it's not a dekt and didn't damage the finish. Most likely some kind of pothole.

Yes you can go to the 305 width on the rear.