OK, so you have those wheels. I have them on the 41 I'm building and it will be duals.
I've read on this site that aftermarket wheels are available in that size. I was reading someone wanted to use trailer wheels of that size because there was a better selection available. Do a search, probably in the Driveline Section and see what you can find. Plenty of info on this site.
Good Luck!

~ Victor
1941 3/4-Ton Pickup (in process). Read about it in the DITY Gallery
1955 Grumman Kurbside "Doughboy" 235/3 on tree w/ OD
1957 3100 - moved on
1959 C4500 Short Bus "Magic Bus" - moved on
1959 G3800 1 Ton Dually "Chief" - moved on
1958 C4400 Viking "Thor" ~ moved on to fellow Bolter