MFD gear ratios and tires re: Oliver 1855

I have an Oliver 1855 with MFD. I want to work out the correct calculations for the % lead/ lag.

Here are the numbers for mine

When one side of the tractor is raised with the mfd engaged:
The driveshaft turns close to 29.50 times for 2 turns of the rear tire and
20 turns for 2 turns of the front tire (by the way the tag was wrong).
I could be off slightly if slack between gear teeth can make a difference.

When the rear tire is turned once, the front tire turns 1.4706 times (once around plus 8 of 17 tire lugs).
Or inversely 0.68 measured the other way.

Currently the front tires are BKT 14.9x25 with manufacturer RCI of 152.1
The rears are Goodyear 18.4x38 with a listed RCI of 207.
These are the tire sizes suggested in the operators manual for this tractor.
Unfortunately there were different ratios used and the manual does not specify which ratio their recommendations are for.

There seem to be different opinions on how to calculate the lead. By what I read the desired lead is 2 to 6%. To me it seems higher here.
I have posted before but never really got a complete answer. Some good replies on this would be so helpful. It would also be nice to hear more comments from guys familiar with these tractors as well.

The easiest way I know of is to check the tag on the 4wd unit for the gear ratio. You should be able to find the proper charts in a shop manual, or contact someone like Ag Parts First, or Maibachs and they can get you the chart which will tell you what size front and rear tires are compatible with that gear ratio. It does not surprise me that you may not have the proper ratios/tire sizes. You certainly wouldn't be the only one. At that particular point in time White/Oliver was in complete chaos and it seems the problem of the wrong front ends being fitted on 4wd drives was a common one.

Are you figuring your differential is turning faster with one wheel up ??

No, with one wheel up you just have to rotate the tire twice to get the right count on the driveshaft.