The abs works off the wheel bearing in the left side of the front wheel(sitting on the bike) and the abs pick up which functions as the left side front wheel axle spacer only which talks to the computer. The wheel size does not affect the abs.
If the wheel diameter is changed does it cause problems with the ABS?
For instance if a Road Glide Ultra with ABS and a 17" front wheel is changed to an 18" front wheel....
If it does matter, is there a setting in the ECM or ABS that can be changed to correct for the wheel diameter change?
in your example, if you are talking stock 18'' vs stock 17'', then is almost no difference in overall height between the 2 because of the different profile of the tires. so even if it did make a difference, in this case it wouldn't make a difference
in the stock harley sizes, there is no discernable difference between the 16'', 17'', 18'' or 19''. just fyi
I understand the concept of reality, but find it too confining for a way of life.