I don't recall anyone going up one inch in size. They usually jump up to 21". But most of them remove the fender altogether. Depending on the tire size you might have to modify the fender bracket to increase clearance, just like when you put a 120/90 on a stock wheel.
I see you have a Speedmaster. Are you switching to spokes? If not, where are you getting a 19" wheel made? If spokes, are you going single disc or are you going to look for the ever elusive Thunderbird Sport wheel?
