Greetings Retro,
Summit Racing has these: Coker Vintage Truck and Military Tires 71016 $274 Coker Tubes 86255 $39
You might contact Coker Tire directly: https://www.cokertire.com/
Les Schwab will work on Split Rim tires, or at least they did at one time.
I only changed a couple of split rims back in the day. After they are changed, they must be inflated inside a cage!
Welcome to the forum.
Eagle5
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2019 Minnie Winnie 22M on an E-450 frame