[ihc] RPM, Gearing formula needed

[ROCKY LEAR <rockylear@xxxxxxxxxxxxx>]

I am trying to figure out my gearing questions. Maybe someone here can help. I know that there used to be a formula for calculating oversized tires that used to be in some of the 4x4 mags but darn if I can find it now. I want a truck that will run 80 mph without too much winding. Here is what I have:

Two gearing options I have are 4:88 and 6:17

44" tall tires, actual measurement may be closer to 45"

An OD out of a 71 t-all...what is that model number any way? T34?

Is there any way to determine what my RPM will be at 80 mph in OD?

I am simply guessing from past experience that the tires alone will put the 4.88's in the equivalent of a 3.50-3.70 range. 

Is ther any way to figure out this?

A free 6 pack of your choice to anyone who can give me definite answers!

Rocky