Summary

These are wheels for radio control airplanes. I modeled them after 35" Alaskan Bushwheels. I've included models for 50 mm (2"), 44 mm (1.75"), and 15 mm (1") with 1.5 mm and 3 mm axle sizes. Print them in two halves, clean the axle holes out with a hobby knife or pin vise, and glue them together.

The picture is a Hobbyzone Sport Cub S 2 with 1 mm piano wire landing gear and the 50 mm wheels.