What is the actual diameter of the Omniwheel, and what is the actual diameter of the ‘3 inch’ wheels. I downloaded the models, and to me, it looks like the omniwheels are much bigger in diameter than the 3 inch ones. I tried looking for actual diameters, but I have no avail. The Lego website lists both as 3 inch, but I’m guessing that is just approximation/rounding…

I don’t have the parts here, but we discovered that the OMNI’s are slightly bigger than the regular 3" wheels. Maybe 1/8" or even 1/4" larger diameter.

It’s not enough to matter when driving a mixed pair of wheels from the same motor controller, but you can’t put a mixture of three wheels in a row and expect them all to touch the ground.