I can't quite figure out where you got your Rubbermaster tires, whether it was on eBay or not. I did find some Rubbermaster AG tires at Simple Tire with free shipping and on sale for $77.97 each. If the tire is really any good that seems like a good price. Here's the link.
Ebay Lawngardentire. com It was very weird how i found them . Almost like a certain way you type in tire size it only appears. I’ve been looking for tires for months. Alive never seen them before.