Part number you looking for is Toro 4-2580. This is the tire only, no rim and if you type this number into a web search they are out there. Be careful as prices range greatly and I’ve seen quality does also. You might also like this manual. https://www.toro.com/getpub/59915
Thanks Rivets, I found the owners manual last night during a search on tires. Haven't gotten to read thru it yet.
I assume the tires can be put in boiling water and stretched on the wheels as with other reel mowers? John