In our engineering design course, we were tasked with designing a suspension system for a robot butler to allow it to traverse outdoor terrains. In creating a testable prototype, it became clear that cheaply available caster wheels would not have the pliability required for such terrains, and so I designed functional wheels as a replacement. They ended up performing flawlessly, with the flexible tires providing much better traction than generic casters. In this folder I have included the replacement caster wheels along with the larger drive wheels. The tires were modelled with a 0.15mm clearance, providing a sufficiently snug fit.
Amazon Basics PETG & TPU
The wheels were printed in gray PETG, the tires in black TPU, both with 20% infill. I found that this infill percentage resulted in a tire with a satisfying level of flexibility. I used a standard 2 x 0.8mm walls for both parts and experienced no issues with it, but the wheels would likely benefit from upping the wall count to 4 or 5.