There are. That said, IMO, they aren't "good" options. I don't want to bog down the discussion here but the issue for me is that with the 1-series you have (rear) wheels that are 9.5" wide and designed for use with a 12" wide tire. While you can by R1s in the same 26x12x12 size as the R3s, they're sort or a "high flotation R1". They're great for tractor pulling in a groomed arena but in field use you usually want a narrower R1 tire so that it cuts through mud and gets to solid ground underneath instead of floating on top of the mud.Are there aftermarket R1 tire options?
There may be after market wheels better suited for a narrower tire that will fit the 1-series machines. I'm not sure. To be honest, it isn't something that comes up a lot on here. Most 1-series discussions tend to be more focused on lawns and/or snow removal where you're talking about actual field work as your primary use.