What compound full spikes from the old days

[samd]

Now im going back a bit now to racing at haltemprice sports centre in hull about 13/14 years ago. I remember the tyres to use were schumacher full spikes, cut down then ragged around the car park for a bit first but i seem to remember they were some sort of special compound, not the usual blue/green/yellow - anyone know what im talking about or is my memory mush?