FENTON GYRO center caps

I have never seen any Gyro's that didn't have the 5-screw mounts.

Do yours say "Gyro Racing Wheel" and "Fenton" on the back or
could they be Anson, Rocket, E-T, or one of the many other wheels
that mimmicked that style?

Either way, I would go to a place like an old speed shop, tire store
or swap meet etc and do some measurements.