I've reduced the stable to my old track bike and a 2008 Karate Monkey with 3 sets of 29"/700C/622 wheels - one single speed- and two Rohloff-based with 19 and 24 mm wide Andra rims. (Right, an old mechanic, I still find wheel building relaxing, though the Rigida/Ryde Andra rims still have seams that defy perfect true... Another reason for disk brakes.)
The rim manufacturer will tell you the range of recommened tire sizes, but as you might know, a general rule is 1.5 to 2 times the rim width. So, depending on payload, I go anywhere from 622(700c)- 28 mm to 2.5 inches - the max width for my bike.
I'm currently planning a big trip which will see me on the 24 mm wide rims using some smooth puncture-resistant Continental Top Contact II, 622-37 tires as I ride pavement and smooth gravel a few weeks, at which point I'll slip on some Conti 2.25 inch Mountain Kings as the trip goes off-road in the mountains for a few more weeks. (I figure the improved efficiency of less rolling resistance justifies the extra weight of a couple of folded tires in the bottom of the frame bag.) I've used both these tires for their intended purposes for thousands of miles, so I know they work for me and my riding styles.
So, take a look at your payload, quality of the roads, desired tire pressures, how bulletproof you want your wheels, and then cruise the tire manufacturers' websites, and have fun. If you find you're wasting too much riding time thinking about this crap, then go with what you got. A good bike mechanic can give you advice and help you avoid problems.
If your Fargo came with i23 or i25 WTB rims that are 23 mm or 25 mm wide, You might decide to simply get a relatively high pressure smooth rolling, 622-37 mm tire for the road. Even the WTB i30 rim foumd on some of Fargos, will let you use a nice 47 mm road tire.
Try not to overthink this, and don't spend money on wheelsets if you can spend that money on travel with what you have.
Did I say, have fun?
