Not sure if you have replaced your Metzlers yet, but a very good radial tire is the Continental Conti Motion series. The 170/60-17 rear worked well for me, and the 120/70-17 front. I got about 11,000 miles on the rear before I replaced it, and I did the front too, as it had some wear, like scalloping, but not bad. I could have got another 4,000 miles out of it, I am sure. Both tires were shipped to my door for under $160.
I replaced the rear with a 150/70-17 because I needed one, and the 170 that we mounted at my friend's shop wasn't any good, had a bad bead from him mounting it on another bike, and removing it. But, I like the 150/70-17, it rides very nice on the Mean Streak rim. I wish Continental made the tire in a 160/70-17, but they only offer it in the 160/60-17 size, which I felt would be too low a profile tire for my taste.
Try them, you might be pleasantly surprised!
Charlie