I have an old trailer with split rims on, and it was hard to find tires for it. I got what I felt was the best tire I could, which was the Deestones. I bought them from Simple Tire.
I bought the tubes from Pete's Tire Barn back east, they had Firestone tubes which I was told are better than the common Carlisle.
That said, it's really hard to get people to work on split-rims, I had to damn near bribe a guy...
Most of the big places in California won't work on them for small guys, so you need to go out towards the agriculture areas where split-rims are common. Coker Tire carries a lot of wheels and knows replacement sizes, why not give them a call?
https://www.cokertire.com/
