Originally Posted by dendrophobe
Interesting idea. Since they're not made for turning in the same manner as a motorcycle, do you have any issues while leaning the bike over? Either in traction or from the sudden change from that wide flat area?
It is really not any different than a m/c tire that has been worn flat in the center from lots of highway miles.
Some of the high-falutin' hardcore corner carvers claim that they don't like the transition over the corner of the tire, but you get the same effect on a set of worn bike tires.
Here is a video of a dude on a Supercharged Triumph Rocket 3 running a 245/45R18 car tire on the back of his bike running with some other sport bikes on a nice set of roads in Western Wisconsin.
(I apologize for the music...)
I personally did about 6,500 miles of solo riding on my R1200RT with my car tire setup and never had any concerns. Those miles included a trip through the Black Hills of SD, the dirt/gravel/mud of the back entrance to Badlands NP, and some roads similar to the video in my part of Wisconsin.
I will admit to starting out a bit slowly at first, but soon gained enough confidence that I was leaning the bike pretty well.