Would these cake trays improve aerodynamics? (Wheel covers)

[mapky]

I found plastic cake trays that are the right size for my wheels, but the center part protrudes about 1 cm outside of the wheel.

Do you think that these would improve the aerodynamics or make it worse?

[Xist]

I would recommend sanding down that circle. Good luck!

[MetroMPG]

I wouldn't be able to guess. That hard edge on the tray is a problem. Then again the open spoke pattern of the uncovered wheel is pretty bad to begin with.

Too close to call.

Experiment!

[mapky]

Thanks for the comments. I think I'll try to find something with better shape. I only bought one to see how it would fit. I don't have fuel gauge yet, but maybe I could do roll down testing when I get something ready.

Any tips for fastening these or something similar?

[freebeard]

Drill it for your bolt pattern, take off the wheel and sandwich it between the wheel and brake. It will never fall off, and it might even help.