I have an aftermarket spoked rim on my fatboy and want to know where to measure it to get the correct width for shopping for new tires? The overall width at the widest point is 4 3/8'' but my guess is its a 4'' or 3.5'' rim.
Thanks

 

inside shoulder to inside shoulder.

Or just do a google search and find the answer on this and thousands of other questions.

http://www.youtube.com/watch?v=B0SLpz3Fs4c

 

Or, if the tire is already mounted, take the measurement from just inside the outer lip on each side. You'll need the tool they use on wheel balancers, or something similar, to take that measurement.

 

Look closely. The width should be stamped on the rim somewhere.