Running an ikon 2.1 in the back. you guys think the slant 6 2.0 or 2.2 will come closer to that size?

I mainly ride fire road and single track in socal.

Weight geared up is 245 lbs, tire will be mounted on a FS bike.

What do you guys recommend 2.0 or 2.2.

In the front I run 2.0-2.2.