with what you are doing i would have thought 100" ish would be good. In trials you want to be short and have a good turning circle but i know you guys just winch yourselves overand for timed specials i think the longer wheelbase will add more stabilitywhat do they run in states for events with speed
From an old JP Magazine suggests that a good start for wheel choice is by wheel base of vehicle, and has a chart as follows;Wheelbase (inches)_________Tyre (inches)80-90____________________32-3390-95____________________33-3595-100___________________35-36100-105__________________36-37105-110__________________40-42120-plus__________________42-44 plus