Front wheel drive settings should really be set to OFF for rear drive chairs, but many manufacturers leave it set to on regardless as it makes swapping power modules between chairs easier in the feild or possiblm because they dont really get what it does.
Its purpose is to reduce the amount of steer responce you get from the joystick as speed iincreases (actually at full forward stick) on UNSTABLE front drive wheelchairs to attempt to stop them from fishtailing or swapping ends at speed. In reality it doesent do much other than make steering feel mushy and inadequate at full speed. Or reduce steer responce as you accelerate and make it hard to predict where you end up pointing.
So if it was me I would set it to about 80 on front drive chairs, (and is one reason I dont like them) anywhere from 30 to 60 on mid drive chairs, and zero or off on rear drive chairs. But you will proably find them all set the same on all permobils regardless.
The REAL way to set it it to test it. Now you know what it does. But unless you set all the 4 minimum and maximum turn acceleration, and deceleration settings to 100 first, you will never be able to tell. As these delay everything and make the chair basically uncontrollable and dangerous. And you CANT choose these 100 settings on many chairs unless you first use the OEM programmer to remove the OEM/ABS walls that are set up to stop you from setting these correctly...
We are being protected from ourselves again.
As for knowing the stock settings, I really dont see any point, because they are usually already incorrect and generally the same ones used regardless of chairs/motors.