FYI: (A long read, sorry, just trying to cover all issues).
I bought a '05 Triumph Rocket III a little over two years ago and was appalled at the cost of keeping tires on the bike, (changed every 5-6K at a cost of $300+). This began a web search of everyone who had an
R3 and had gone to the "dark side". When I saw the CTOW, (car tire on Wing), video and saw it didn't ride upon the actual sidewall, I was convincined to try it. NOTE: the
R3 and rider weighs about 1000 pounds. I have not tried a car tire on any other of my bikes, nor will I. The lighter bikes may or may not have enough weight to force the car tire to flex and the tread stay on the ground.
It seems that two tires stand out for this application. 1) the F1 Eagle by Goodyear and 2) the Hydro-edge by Michelin. Due to availability, I ordered the Michelin in 235/60R16. This tire is a little over 1 inch larger in diameter and about the same width as the original bike tire. The speedometer was 8% fast witht the bike tire. With the larger car tire, it is less than 2% off. My RPM's are about 450 rpm's less at highway speeds.
Problem: the independant bike shop wouldn't mount the car tire citing liabiliy reasons -- that's ok -- it's his call and his shop. A used tire shop where I take my farm equipment mounted it for $10. (the standard rate for mounting any tire). He had no way of balancing the tire, so I just took off all previous weights. After trying it out, the imbalance speed was WAAAY about 100mph, so the tire is still unbalanced. Please note: It is smooth as silk up to triple digits.
Now to the point of this post... How does it handle?
Contrary to what seems logical, the slower you go, the worse it handles. The engineer in me has come up with a probable reason for this. Remember the bike tire is, for all practical purposes, a ROUND tire. If you run over slightly uneven terrain, the bumps and ruts simply push the bike straight up. The car tire, however, is almost eight inches across. Thus, when you run over irregularities, the bike is still pushed upward, but if the bump is "off center", it also pushes the bike to one side. With an eight inch wide tire, that is almost vilolent in action and thus the re-action has to be very firm. It would be like trying to lift the bike up with a jack mounted 2 to 4 inches off center.
When cornering, the tire flexes and stays on the ground until you are leaning over to the extreames. The tire then flexes in the middle of the tread and still stays firm with NO "squirming" or slippage that can be felt. The Vice President of our chapter has rode behind me in town, on Interstates, and sharp curves and hills. He reported that even under extreme leans, there was more tread on the ground that with the bike tire.
Now about countersteering. You HAVE to countersteer every curve, bump, and irregularity to keep it in control at all times. Thus, riders who "lean" their bikes to turn, absolutely cannot handle a wide car tire.
Our Road Captain is quite aggressive and rides a 1400cc Kaw Crotch Rocket. Let me state we were NOT racing. Coming down to Mena, Ark. from Willimena mountain, he got on it and we reached speeds of just over 100mph and took curves roughly 2X faster than the caution speed signs said. I felt that there was at least 10-15% more speed in curves the bike would have handled. Again, we wern't racing just expelling the myth you can't corner with a car tire.
In Conclusion: There are pluses and minuses to everythning. You have read most of the minus side, here's the plus side. 1) Longer tire life. This tire now has about 4K on it and I would now be saving up for another bike tire. The Michelin shows little or no wear. 2) Tho I rarely use the rear brake, I have learned to rely on its greater stopping power. 3) Behind large trucks on the Interstate, the bike tire was "mushy" feeling, but with the car tire, it's much more stable. 4) Likewise,when the bike is loaded with a trailer and passenger and misc. stuff, it is much more stable. 5) And lastly, I get a kick out of people who have never tried a car tire telling how it can't possibly work. It's sorta like when I trusted Jesus as my savior, I got all kinds of feedback telling me I was going crazy and that there was nothing to "religion". But I've tried the car tire as I've tried Christianity and it works!
Metzler rear tires
I too had above average miles on the rear skin; 8100 at time of replacement. I will admit though that I was fretting that last ride. Some road construction had rock debris scattered in a few areas. I was on borrowed may-pop any-time
And are feeling mid-life mental-pause after the first change. 
2Hozhoni 
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