A833 Speedo Gear Drive Question

@AJ/FormS , wow, thats a lot of information, thank you for that :)
I actually didnt guess when I came to the height of my tires,(but I did round off so that I could use the chart) I took one off and stood it against the garage wall and using a square, marked the height against the wall and measured from the ground up, same way you would measure the height of one of your kids with their back against the wall :) That method gave an actual measurement of 25 5/16. I just measured the circumference of the tire like you suggested, and got 80" as the circ. Doing the math gives a height of 25.5", so given that Im not using exact laboratory scientific methods for measuring, Id say thats pretty close :) .
I dont know how much more accurate I could be with the gear ratio, I measured the circumference and using masking tape, marked it out in one in increments with a half way point which would give me a 3.55 ratio should it stop there. Twice it gave me a slightly more than 3.55, but slightly less 3.73.
My next step, is when it stops raining to do an actual speed test against a GPS and see where Im standing like @Dan Brewer suggested.
Thanks again for all the info.