BKT from India makes a fairly decent looking version of the 13" tire in their sandstar pattern. The lesser ply tires are rated to 40 mph, but they are not DOT rated, so technically not legal for road use in North America.
BKT has a Cdn distributor, and Tirecraft in Winnipeg carries the brand. I placed a call to them a few weeks ago, but never got a call back. I need to pursue this avenue, as the museum is in need of 8 at this time. Add 4 for Niel and 4 for Rob, and the order is starting to become reasonable.
https://www.bkt-tires.com/en/pattern/sand-star