Used tractor tires from John Deere, Ford, Kubota, Foton, and countless others. There is no reason to spend good money paying retail, when you can used tractor tires at a 10th of the price.
These used tractor tires are still in great working condition. You'll find literally thousands of listings on used tractor tires. It doesn't what kind of tractor you you will find what you're looking for!