I designed these wheels to be rims and tires separate so when the tire wears out, you just print new tires instead of wasting filament printing a whole new wheel. The tire is meant to slide on tightly onto the rim but to be safe, a few little dabs of super glue on the lip of the rim should keep it in place. don't go crazy on the glue otherwise it will be next to impossible to remove the worn out tire from the rim.