120/70/21 with stock fender but you have to drill out the back hole with 3/8" bit, to raise it and tip the back of the fender up. I did the 21/18 combo with wheels & tires at the same time. Jus6t couldn't see riding around with the wheels looking different even itf you can't see much of the rear. I know what's back there !!!
If I don't get the new Agitator wheels from HD, then I am going to look at getting a 21" fat spoke up front and leaving the rear the stock spoke. Not sure if I want to go the full 21 up front. Heard handling is a little different.