[autoavia]

Silicon tyres put a film of silicon onto the track and will ruin the grip for urethane and rubber tyres so if you buy silicons for this car you are going o need to buy them for any others that you run on the same track. If your track tends to get dirty you will also find that silicons will pick up all the dirt from the track very quickly and then lose grip. 
In the 60's if you turned up, at a commercial raceway in the UK with silicon tyres you wouldn't be allowed to run the car unless you changed them for something else. They allowed silicon tyres at the annual vintage meeting in Bordeaux a couple of years and have loads of complaints from racers who found that if they ran on a lane immediately after someone who was running silicons there was no grip. They now only allow them in the "thingies" class and run that at the end of the meeting.