Buy a Dunlop winter run flat 175/60/16 car tire (CT) this will lower it about 1". Go here and read as much as you can, then make up your own mind. http://forums.delphiforums.com/DarkSiding/start P.S. this tire wil last 3 times a motorcycle tire (m/t).
I know some older model (the bike not the rider!!) riders that lowered their 100's and 1100's. They sacrificed a lot of cornering clearance and ride quality to do it. Also renders the centerstand difficult to operate. The seat and boots thing is better IMO