Ok, i think i can help. First of all, metzeler is gone as far as rear tires for the Tbird. The stopped making the 880's that came stock and the replacement is not going to be made in 200/50. It may be made in 200/55 tho, not sure. But I along with many Tbirders have been using 55's because there are a lot more choices and 55 works just fine. the only difference is they are about 1/4" tal;ler so you sit a very tiny bit higher. Gearing therefore is slightly taller so accel is a tad less but rpm's are lower at freeways speeds. But ALL of that is barely noticeable if at all.
So the ones I and other have tried are the michelin commander II, the dunlop american elite, avon storm ultra II, avon cobra, bridgestone excedra, and probably one or 2 others i can't recall. The bridgestone and storm ultra II are the only 50 size ones in that list, the rest are 55. The bridgestone is a horrible tire according to severl people. The storm works ok but lasts shorter than any tire i've tried. I'm mainly talking rear.
So heres what i have come to...for the rear i find the michelin and the dunlop both great handlers and the 2 longest lasting rears to date for me. I think the michelin may last a tad longer but i can't decide which handles better, and i can't comment on wet handling because i don't ride in wet. Oddly enough and happily too, those 2 are also the cheapest. I paid around $150 shipped for the dunlop and about the same for the michelin. The rest ran me $220-250 shipped. And they weren't IMO as good in one way or another. I just mounted my 2nd michelin rear. I think i prefer it over the dunlop, but either is great and i'm really not sure. Unless you don't care about mileage i'd stay away from avon rears. they all get low marks for mileage.
So thats rears. Front tire wise it's no contest. The avon cobra according not just to me but everyone who's used them are the best. Not only do the handle so much better then the metzeler it's a bit shocking, my last one went 13k and the reason i changed it was i wore the sides down from riding a lot of twisties....the center tread had no less than 1/2 it's life left !!! Thier rears go about 1/2 as long as other rears but those cobra fronts are amazing. Don't even look further than the cobra front, and it DOES come in the stock size. It falls into turns so easy compared to others it's incredible. Also don't worry about mixing brands. We all do it and it's perfectly fine. The old rule about that is nothing more than a wives tale or applicable only to tires made many years ago. Just make sure the front and rear are the same type, IE: both radial or both bias ply.
So if you want my opinion i'd say michelin commander II rear in 200/55/17 and avon cobra front in the stock size. handling will be superb and lifespan maximized. By the way, how you get 12k from the rear is beyond me. Most of us get 6-7k. The front is a different story, but not many get more than 7k from a rear. My avon storm only got just over 5k.
