I live within a 30 minute drive to dozens of trails and the national forest where I do most of my offroading. here is the chart I used:

http://www.therangerstation.com/tech_library/gearandtirechart.html

It said that it was based on 65 mph in 4th gear at 1:1 ratio. I have a fifth gear that should bring the rpms down to 26-2800 on hwy at 65 which is good by me. Let me know if I am missing something.