[QUOTE="jamesearl]I wonder if the same amount of contact patch is on the road for both.I guess I figured the bigger the wheel,the less contact?[/QUOTE]
It would seem so but not necessarily. I could go into a long and boring dissertation on why but it would be more productive for you to Google "Motorcycle Tire Contact Patch"; it's more complicated that at first glance. Think about it; leaning into a corner, the tire is contacting the road surface at a lean angle where the width of the tire really doesn't come into play; the tire is in the "chcken strip" area of the tire.
Most of us, I think, that ride a bit on the aggressive side, use trail braking as a cornering technique. Applying front brake as one enters a turn shifts weight forward "loading" the front tire which increases the contact patch in mitigates against slide out. Riders that do not use the front brake to trail brake and/or the back break, lighten the front end which can contribute to slide out. There are so many variables that are in play, like tire compound, tire pressure, road surface, sidewall stiffness and tire temperature which make the contact patch issue anything but straight forward as wide tire vs narrow tire.
When I know I am going to be running the Three Sisters in the Texas hill country where there are many changes in elevation and many, many, corners marked from 30, 20 and 10mph, I run 4-6 pounds less pressure in the front 90/90-21 tire on the Deuce.