Mine is personal experience. I currently have 20x10x10 and 22x11x8 haulers. The 22's hook way better, climb better and have much less rolling resistance (when I pull in the clutch with the 22's, I coast).

The 20's slide alot easier.

 

Proven fact.

 

look at all the drag bike whether be 2 or 4 stroke and that will prove the 8 inch rim is the way to go!