Of course, get a proper patch done from inside the tire (not just a plug inserted from the outside).

 

That is too close to the shoulder in my opinion. They can't get the inside patch to sit down properly there and the shoulder squirm is a problem as well. I've replaced tires with similar damage before.

Here is the link to a Tire Rack photo with unrepairable damage in pretty much the exact same spot: https://www.tirerack.com/tires/tiret...jsp?techid=187.

 

It is close to the edge but about 1" in on the flat area so I'm hoping it can be fixed. It will really suck if I have to replace as the rears have less than 10k miles on them.

That brings ip the next queation. If it does need to be replaced, am I ok with just replacing the one since I have less than 10k miles or would it be both rears? Really hoping it can be patched.

 

TPMS mystery solved. You will get endless debate over whether to fix or replace tire. If it's my car and my life, I'd swap both rears for new. The object is too close to the edge to risk it holding up for long under high load cornering, like you would on an extended curvy road drive or on a track. 10k miles doesn't sound like much, but it's sufficiently different from a new tire's depth such that I wouldn't want the differential circumference causing abnormal wear on the drivetrain or odd handling behavior. If you don't like your current tires and want to switch, let's say from P-Zeros to the latest Michelins, change all four; don't drive around with two P-Zeros up front and something different on the back. It may seem OK at around town speeds, but will likely handle differently when stressed. That might be OK, but more likely the different grip and handling curves for the front/rear difference could make for odd transitions from under to over steer or vice versa, which you may not find out until it bites you. But that's my car, my life. You may be less risk adverse than me. Or have a different view of tires as consumables. Glad you solved your TPMS issue regardless, and found the leak before it stranded you somewhere.

 

As far as the 'fill info', I never pay attention to that. The '-6' OP is referring to is probably the TPMS warning the car throws when a tire is low. I always look at the TPMS window with all 4 pressures shown. On all my cars, it's always 2 psi lower than real where I live. If you pay attention the fill info, you'd overinflate them.

 

Had a 3 psi differential between he front tires coming home last week from a trip. Serviced the tire when I got home. Went out the next afternoon and had a -4 psi warning on the right front. Took it in to the dealer and we couldn't find a nail or anything. Soaped up the rim and found a small leak. Had just put the summers back on and looks like it got chewed up. Replaced it and all good. TPMS good...