The default radius is 73mm so this is a big wheel. You can change the radius in the settings by editing,

• hub_diameter
• spoke_radius
• and rim_thickness.

I will probably update the .scad file so you can set the radius with one parameter.

By default the tire has a slightly smaller inner radius than the rim so I recommend printing the tire with TPU or another flexible fillament. The tire and rim are friction fitted together. I printed it with no infill and I think 3 parimeters which made the tire fairly squishy.

I printed the hub in PLA.