At my regionals, my default position will be to require covers over all shooter wheels. It is up to the team to convince me that the danger of caught fingers/hair/clothing is acceptable, and that the wheel won't suffer from sudden and catastrophic failure (for example, the rubber tire on most of these pneumatic wheels could easily stretch and come off at an unexpected angle during a match).
The best route to convince me will be a datasheet from the manufacturer that specifically lists an operating range that includes the speed your running the wheel at. Good luck finding that... even
AndyMark's pneumatic wheel states "The design intent is to be contacting the ground, being driven by a gearbox at a maximum speed of approximately 500 rpm".
Given that statement, running the wheel at 10 times its intended speed, with variable and sudden loading on it from shooting, I
WILL require appropriate safeguards placed around the wheel.