This is very interesting to hear. I have just a week ago finished going through a tire swap for the same issue. To make a long story short, I put a set of Metzler880's on my Voyager and the front end was terrible. Shake and wabble that was not only bad, but I would also say unsafe. I put on a set of Mich Comander II's and although it is a 100% better, there is still a slight lets just say issue, the stockers were perfect and I miss the way my bike felt. Makes me think the Voyager was built around the tire.
2012 Vulcan Voyager 1700 ABS - Metallic Graystone / Metallic Spark Black
Kawasaki Rear Speakers, ipod adapter and bag liners
Commander II Front and Rear Tires
Power Commander V w/Ign
K&N Replacent Filter
Cobra Scalloped Tip Slip-ons
Kuryakyn "Longhorn Offset Highway Pegs"
Kuryakyn ISO Grips w/RACNRAYs Throttle Mod
Kuryakyn 1/2 rail mount flag
Chrome Pasenger Board Bottoms
Chrome Rear Brake Reservoir Cover
Yamaha Trunk Rack