In my opinion, the main reason for using spikes on any floor is to stop the speaker cabinet moving back when a dynamic driver moves forward, and vice versa. It is Isaac Newton's law of action and reaction. For this reason, IsoAcoustics makes isolation devices specifically for speakers. These are more rigid in the fore-and-aft direction than sideways, when compared with the pucks they make for other components. I mention this as a design philosophy, not a specific recommendation.
With big speakers like yours, any solid metal disk under a spike will be very effectively clamped by gravity! Another of Newton's Laws ....