There are way too many videos out there showing bikes with car tires shredding the curves to question the traction aspect.
When you corner an owner though, they will admit that it took getting used to, and how road imperfections will cause the tire to track which will pull the bike.
They also wear the tire out a lot faster than a car would.
I saw a 1400 at the Moonshine Lunch run with a wide rear car tire mounted. Look strange to me.