Here we go:
-Wet - Pit Shimizu Rain Tires. They are gummy have have S-grooves to channel water from the center.
-Dirty - Nothing, everything works the same
-Extremely cold - CS22's with firm foam inserts (like off road tires) with Paragon Ground Effects. This is what they use in England when its cold and low grip. If its is cold and the track is pretty clean then standard CS inserts are better.
-Extremely hot - If money is no object the Sorex 36R is the best hot tire on earth...but they are only good for one run (5min) so you have to put on a new set every time you run your car. If you don't have an endless budget CS27GL's or CS32GL's with Trinity Tire Tweak are a great combo for the heat and are maybe only 1/10th slower per lap on the first run...and way faster on later runs.
-Lots of oil patches on the floor - This isn't too bad as long as it not puddles of oil. I race on parking lots like this all the time and they seem to have no effect on the car at all unless they are right at the apex of a corner.
-Root Beer surface - My local track (www.speedlinehobbies.com
) runs a mix of 5 gal of water, 5 lbs of sugar spiked with a bottle of Mt. Dew. The tire of choice is the CS27GL
-VHT surface - Any current tire works on VHT. Every top level tire is just as fast as another on VHT. Every tires lasts longer on VHT. Most places run CS27GL's for price and durability.
-Dark Black Asphalt - Makes no difference
-Lighter colored asphalt - Makes no difference