Tom, all the tires listed above are PU tires or some kind of rubber tires, they are all fine.
K&D have been the tires from Ranch-Design over the last years. At the very start, RD offered some "Slicks" that have been made out of silicone.
You only see the difference in those tires while sanding - PU has grey/white sanding dust. Silicone are very hard to sand, but make black dust.
Rubber like Jel-Claws are also making black dust.
The way i see that tires are made out of silicone for sure is:
Hold the car up in the rear, push the trigger 50% and let the "burn out making" car go forward 1 inch. If the car leaves a tire mark on my grey track that i can´t swipe away, they are silicones. The sillies leave a slippery residue and it will take 200 laps until PU tired cars get good grip again.
puddle dude