How would you make a volumetric wheel collider?

This is a pretty advanced subject, since what you ‘re trying to achieve is a dynamic 3D collider. I’m pretty new to coding physics myself, but I recommend trying to make a 2D physics engine yourself(in Unity or if you want in a standalone programming language), or at least get a good understanding of how they work.

If you’ve come that far, you can experiment with 3D collisions and in your case probably cylinder-box collisions, or any unity collider. I hope this helps, and good luck.