I appreciate the response to this thread, hope it will have continued response from those who have various opinions. I tend to fluctuate in my thinking and each person's thoughts have weight in making my decision on what tires I will choose.
The Avon tire I have on rear is very stiff, I went from 42 pounds recommended to 36 lbs, the bike rode harsh with 42 and was greatly improved at 36. The Metz on the front I lowered pressure to 36 and it handled much worse in turns and in moving bike around with leg power, I now have the front at 37.5 lbs and it is better. I think I will increase front to maybe 40lbs but think it might make front to harsh over bumps. I will probably have to get Progressive springs on front to get it the way I would like for it to be.
There are pluses and minuses I suppose to any tire choice, and I suppose that the outcome has many factors, such as right air pressure, how the bike is ridden, road conditions, what bike it is on, what day of the week the tire is made, the mood of the person making the tire, etc.
I would probably stay with a motorcycle tire for the rear if it wasn't for the greatly reduced longevity. From my past experience I get at least 5 times the miles on the car tire. I really don't know how long the car tire will last because I have never gotten close to wearing one out. On my VTX 1800 I had 3 motorcycle tires; 1 stock Dunlop, 1 Dunlop Elite 3, and 1 Avon Venom, all lasting from 5 to 6 thousand miles till steel cord was showing. I put a 205/65/16 Michelien Hydroedge car tire on the bike and road it for 20 thousand miles, it looked like it had at least another 20 thousand left on it when I sold the bike.
There were things I liked better about the car tire and some not. I liked of course the longevity but also liked that with the car tire I could go 15% faster in a curve and still feel in control of the bike, the ride was smoother over bumps, and bike had much better traction; these are some of the positives I can think of. The only real negative to the car tire was that on uneven roads at slow speed the bike would rock, which for me was not much of a problem. On my 1800 Goldwing I put a General tire which did not handle nearly as well as the Michelein Hydroedge, it felt mushy even with max air pressure. I had a Michelein Hydroedge on my Stratoliner but the only size offered with the Hydroedge close to the sized I needed was a 215/60/17 which was to big. The tire handled great on good road but bottomed out on rough road, also the larger width made the bike not handle quite as well as the VTX.
I hope to find a car tire that handles on the Rocket as well as the Hydroedge handled on the VTX. Michelein dosn't offer the hydroedge any more but there may still be some sitting in a warehouse somewhere, and there maybe a tire that handles as good or better on the Rocket touring. Any way it will be a while before I get another tire, because the ones on the Rocket are still pretty much like new but the more info I get now will make it easier when the time comes.