When you buy a new predator you may think you only need to install your tune and can leave everything else stock. I did. But not so. After riding around for a while I was wondering whey my speedometer seemed to be off. Well here is what happens. The Predator is used on both the Harley and Lightning and the Lightning comes with 18" rims (295/45/18). The revs per mile are thus set from the factory at 703. Now on our trucks with the stock setup you need to be at 678 revs per mile. What this means is when your speedometer is reading 60mph you are really traveling at 62.7mph.
Just go into axle ratio then revs per mile and make the adjustment.
the two most common sizes for our trucks are
275/45/20 - stock size - use 678 revs per mile
295/45/20 - common upgrade ( I have these ) use 662 revs per mile.
Thought this might help some like me that was not aware that stock setting means stock Lightning not Harley Davidson.