I don't think that you would find a dealer that would be willing to risk the liabtily assosciated with putting a car tire on a bike. Car tires are too flat across and don't have the wrap around sidewall for the cornering traction.
kemo
I've heard this before and don't buy it. Being flat across is not bad for a touring bike..better grip. I've thought about this sidewall issue..I would think the stress put on a CT by the vehicle during turns and curves would be more than a 900 lb motorcycle could apply.
I do believe for those who ride aggressively they might notice some handling differences. Most of us that ride touring bikes are beyond that stage in life. I know my brother has a CT on his Nomad..we rode the dragon last year, he had no issues. Would like to try it on my scoot.
A bike tire can easily see 20 degrees of - or + Camber. (my factory bike has a lean limit of better than 30 degrees) You never will even come close to that with a cage. Apply 20 degrees of camber to a CT and I bet you will force the outer edge of the tire to lift. I really think that would a bad move & I would not do it.
But like Smitty says "Your Ride, you decide"