Motorcycle Repair: vibration, wt oil, metzler tires

Question
I have a 2007 streetglide that I had a new custom built 103 motor put in along with chrome front fork legs 15wt fork oil and floating rotors. The motor is strong and powerful and I'm at about 75 % break in. My problem is that when I ride the cars in front are bouncing up and down as well as the scenery. I had progressive rate strings in and took them out and now am back to stock springs with 15 wt oil. My back tire is bald which might contribute to the problem. I tour and am at my wits end about what can be wrong. I'm planning a trip in august across country and do not care to look at the country vibrating up and down. I'm planning on getting two new Metzler tires this coming weekend. The cars going up and down tend to happen after 55 mph. At low speeds the bikes feels fine. A friend who has the same model and year only stock rode mine and told me the engine is fine but at high speeds he sees the scenery bouncing up and down also.

Answer
First thing you need to do is check your tires. Since that back one is bad, go ahead and replace it. Check the front for wear. run your hand over it, it should feel smooth. If not then its worn too and needs replaced. See if that doenst solve your problem
Good luck and happy riding
Mike