Rubber tire broke, new costs 30ish€. Had an old spool of flex material so poof!, half an hour late, I was printing. Print settings for old flexpla included in project file. Tire is for Ø170mm , 35mm wide rim, tight fit. PS: Welcome r/3dprinting and r/functionalprint ! EDIT 2021: When printing in NINJAFLEX, add some shrinkage in your slicer! (Needed to much CA glue to keep them on. Good schrinkage and a dot of CA glue is desired.