Softest spike tyres

[woodey]

I have returned to indoor racing after a couple of years off. We race on a polished wooden floor and 99% of people use schumacher fullspikes yellow. They are ok but only start working when really well worn in. People have tried schumach mini spikes with varying levels of success but i am looking to try something different. Having come from 1/8th rallycross the soft compounds are a lot softer than the equivalent 10th.

Does anyone have any suggestion as a softer spike tyre to the Schumacher range? and what type of insert would you think goes best if any?