Obtaining Dimensional Accuracy of Prints With Rostock Max v2

I realize that this may not be a reprap style printer but, it is in the delta style and I am having trouble getting the information I need on other forums.
I am having issues with printed dimensions not measuring as expected. My printer is a Rostock Max V2. The firmware is Repetier, that has been pre configured for the printer by the manufacturer. The only modification that has been done to the printer that would influence dimensional accuracy is carbon fiber arms from Trick Laser. Trick Laser claims that they are built on a fixture and the “Delta Diagonal Rod Length is 269mm. My firmware reflects this. I have recently calibrated the bed flatness to within .02mm at the X,Y,Z tower and bed center. According to the Manufacturers instructions.

I have been running some test prints using PLA on an unheated bed using blue painters tape. I have created four single wall cylinders. The first 10mm in diameter then consecutively doubling the diameter to 80mm. I used Cura and the Jaris setting to create a print with a full bottom layer and 1 MM wall about 10mm tall. The extrusion rate was calibrated on the 10mm cylinder to achieve a wall thickness of 1mm within .03mm. All cylinders were printed at this setting. Here is the results of those prints. Each consecutive print measured less than the previous by a greater amount. The greatest difference being roughly 2.5mm. The wall thickness also measures smaller as the overall print diameter increased. Overall part dimensions were taken from the outside diameter of the part. With the exception of the wall thickness.

I have done research regarding increasing the dimensional accuracy of prints. But have not yet put that research to use. From what I have read it involves changing the "#define Delta_Diagonal_Rod" length. When changing the rod length the following formula is used, New rod length = (Expected Measurement / Actual Measurement) x Old Rod Length. One reason for not pursuing this on my own is, I cannot see how this will improve wall thickness accuracy.....
Not being a wizard at math. Will I be able to correct the outer dimensions by the method described, even though the inaccuracies do not appear to be similar throughout the 4 cylinder tests? I am guessing that the inaccuracy changes as some trigonometric function or percent.
Will this change also improve the wall thickness accuracy I am experiencing? If not. Do you have any suggestions as to what will?

I do realize that there is shrink factor involved but, I do not believe it should be as much as I am seeing. I would think that the wall thickness would be consistent, as I am printing a single line width of 1mm.

As always your help is appreciated. Thank you.

I think printing a cylinder is not the best way to calibrate a delta, I'm struggling a bit with this my self.

I have found this: [www.thingiverse.com] and this: [delta-calibration.s3-website-us-west-2.amazonaws.com]

Now both those are for Marlin and I have not yet been successful, but as I understand now I got the instructions somewhat wrong and have not found the time to redo.

Hope it helps.

You mention that the information that you offered pertains to Marlin firmware. Whould you know wether or not this translates to Repetier firmware, this is what my printer uses.

Thank you and good luck to the both of us.