My first thought was front tire. That is the only time at any speed mine wobbled up to 96,000 miles. Then they weren't bad but changed when up graded the suspension to Race Tech with Gold Valve.
However, since you have a new tire and balanced, hopefully correctly, then I would agree with the steering head bearings unless the they need a little tightening. New ones would be the best way I would go then you are sure.
As stated above there are other factors in the rear that can cause it and the shock bushings are cheap to try first.
as used on Race Tech site
rode to 49
States+DC & 11
on my '07 Black Cherry VTX1300R
w/aux tank, Race Tech Gold F&R
,Mean City Cycle, Motolights, Glen's Light Bar w Rivco H-4 aux headlights w/SS Utra bulbs,Radiantz LEDs,Baron tach,Marlin therm&clock, PowerLet,Break-A-Way,K&N, IBA: 2xSS2000,12xSS1000,4xBB1500,2TX1000,NPT 29/76; Lake Superior Circle Tour