When this breaks and you don't want to hunt all over creation for some that will fit, look in the scrap pile for an ole lawn mower back tire..
Cut two 11/2 inch by 5 inch pieces of the tread. Drill out the old ones and drill holes in the new found pieces. Countersink the screw heads and use a washer with self locking nut. Wala,,,
I like it better than it was before it broke.

