I just put a Dunlop D-404 140/90-15 on the rear and a D404 130/90-16 on the front.
Results:
This raises the GZ nearly 3/4 of an inch in height for better ground clearance. You will have to put an extension foot on the kick stand by 0.7 inch. This extension worked out well for me as I was having to place a 6"x6" pad on the soft sandy ground we have in Florida to prevent the stand from sinking into the ground. The foot extinsion I made from an aluminium extrusion (piece of a telescope dovetail bar) that I bolted through the kickstand foot front and back - 4"x1.5"x0.7"
The large front tire looks impressive, but required a 3/4 inch raise in the fender. I will have to GPS the speedometer to check on the difference in registered speed, but the standard tire diameter made the speedo read higher than the actual speed so we will see how this works out after a GPS run.
The larger rear tire is a tight fit. It has a larger diameter so it works out to about 1.033 extra gear ratio as compared to the 15 tooth to 16 tooth ratio of 1.067 or about the same as going from a 15 tooth to a 15-1/2 tooth gear (not possible as a 1/2 tooth sprocket) This has a very nice feel for gear spacing and I am not looking for 6th gear anymore.
The seat height is 3/4" higher; The bike feels and looks bigger. The overall ride is about the same, but it is slightly "taller". If your inseam is over 30 inches it makes the bike feel full size instead of 90% scale.
More after I ride the GZ "Fatboy" around for a month. --Dan--
