If 3.55 gears work with a ten speed, try 3.08 with an 18 speed and leave it in 17th gear unless your empty or cruising at 80mph. Tall 22.5's are the same height as LP 24.5's. I suck at posting links but these are the websites I use to spec a truck. www.cummins spec.com/site/gearing. Also SAE Holland for the fifth wheel will let you compare weights and heights. Remember that an 18 speed is .73 to 1 in 18th, .86 to 1 in 17th. If you use the eaton website it will tell you that they don't make a transmission with .86 to 1 so you will have to type that in manually. You will find that the forementioned tire sizes and the 3.08 will compare to 3.55 1/2 gear down.
If I were specing a dirt truck, I would go with 3.25 gears as it matches with 3.70's If you like 3.55 go with 3.08 If you never need " granny" or "crawl" gears, some guys are going with 2.64's and running in 16th gear.

I have a 72 Aerocab flattop I can stand up I'm 6' tall. I would never get the tall aerodyne unless I were pulling a van or reefer. If you get the aerocab with the couch that makes into a bed, you can't get a back window and you lose alot of underbunk storage.

I have a 72 Aerocab flattop I can stand up I'm 6' tall. I would never get the tall aerodyne unless I were pulling a van or reefer. If you get the aerocab with the couch that makes into a bed, you can't get a back window and you lose alot of underbunk storage.