Reply to "speedometer ratio?"

this seems like it would be a simple gear ratio calculation, however I could not find all the information needed.

the math I could play with would be determine the tire diameters and revolutions per mile
The original rear tires were 215/70 at 26.9 dia or 255/60 at 27.0 dia
Your tires are 335/35 at 26.2 dia. So the revs per mile will increase by 27/26.2 = 1.03

Now I wanted to reverse to the cable revolutions and here is where I had to make a lot of assumtions.
lets call the original tire diameter 27", this would give 746 tire revolutions per mile.
with a 4.22:1 axle gives 3147 r/m
RBT list two different speedo worm/gear ratios,2.0:1 and 2.4:1
choosing the 2.4:1 worm gear gives 1311 r/m
then using the angle between the two angle head ratios of 1.1:1 and 1:1,
choosing the 1.1:1 angle head gives 1192 r/m as the original cable turns for a speedo labeled 1200.
Using the 26.9" diameter for the original tire it comes to 1197 r/m
(using the 2:1 worm and the 1:1 angle, it comes to 1597 r/m)

for your tires and the same assumptions, that would be 1228 r/m.

Now, I have no ideal if this is correct, but is just me playing around with the calculator. I would appreaciate if those that can fill in the assumptions would either show me my errors or confirm