Rear OEM Bridgestone off my old 2008 after 13,300 miles on it. Yes, the front was toasty, but it made it.

Looks like you have been making left turn only, and alot of left turns 

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The rear 021 is actually an excellent tire, it is the front that needs thrown in the trash right away.

That picture looks like the front 021 that I gave away yesterday with 1,400 miles on it! What a piece of junk! The rear looked fine. But either way, changing to other tires makes a major difference. I have no idea how people get any kind of miles on these tires. My C14 front was toast at 4K. The rear almost worn out also.
 The FJR front was significantly worn and pushing bad at only 1,400 miles. The 021  front is junk! But I will agree that the rear seems OK. But still wears quicker than most tires. I would never use these ties if I didn't have to! And it's beyond me how someone got 13K out of one!

Its not even to the wear bars yet. Thats really good for a 021. I have run several rears and most only got to 6-7k miles.