After much geekery and nerd-dom, and way too much time tweaking, I have come up with Numbers spreadsheet that you can use to plug in your original tire size, transfer case, transmission, and R/P ratios into, in order to compare multiple setups and how it will affect your highway and crawl speeds, and how much your speedometer will be off.
Nooner's Gear Ratio Calculator
Recommend saving it to your computer and then working on it.
The file format is only in Numbers for now (sorry PC users), and I am on vacation, so it will be a little while before I can tweak it for Excel use...the drop down menus may not work for now if you try and open it in excel.
Speaking of drop down: anything in a yellow field may be changed...if you change something that is not in a yellow field, well... good luck with that.
The reason I created this was because although the Ashcroft website has a very good calculator, I found I already needed to have a decent base of knowledge to start using it and I wanted to "dumb it down"... I also wanted to be able to compare multiple setups simulaneously...
As far as drop down menus go, I included what I consider the most popular transmission ratios based on TeriAnn's Expedition Land Rover site
website. I included typical LT230 ratios; stock, some of Dave Ashcroft's optional High TC ratios and some of Bill Davis' GBR LowTC ratios. R/P ratios are a combination of stock, Ashcroft, and GBR. I included Roverdrive as an option as well as Ashcroft Underdrive. As far as tire sizes, there are many many many different options, so I included basic diameters.
If anyone would like to see an option they really have to have, let me know and I'll add it in when I get the chance.
Let me know if you have any questions! I'm sure they will be many.
... And the chance of this working the first time off the bat is probably 15%