http://www.superford.org/getfile.php?id=48022&toggle=fullsize&filename=tirerp.jpg

Thought this one might be helpful for those too lazy to break out the calculator..
http://www.4wheelparts.com/Tirel_gear_ratio.asp

OOPS.

I have an excel spread sheet I did up a while back that has all the info and can be adjusted for speed range, etc ... if anyone's interested or it could be put up. just gotta find it now.