Figuring out maximum safe RPMs of CD without risk?

EcoDisc (0.7mm thick) was a failure due to many breakages, yet no bad idea.

The race of 56×CD-ROM drives (eg. AOpen) and even 52× mostly is dead.
Many CD drives limit speed to ×48 or ×40 for CDs.

But a DVD is much more robust, because 24× drives reach incredible speeds that match 75× of a CD by rotation count (all values in CAV. 75×CLV at inner edge would cause the outer edge to break the mach speed).