When a race is called a rain race, the competitor most of the time has a choice in using slicks or rain tires depending on their own forecast of their race. In areas that have lots of rain I could see a ruling for a spec rain tire just like a spec racing slick. But here I agree, no need to muddy the water when it hardly ever happens anyway.
I also don’t see the need to say that grooved slicks aren’t allowed, as the racer can all ready choose to run a regular slick tire in a rain race if they feel that the track will be drying during their race.
If we are allowing any rain tire as the norm for the rules, and assuming I am right with a racer can choose to run slicks or treads, give me one reason a groved slick would be bad to allow?
How good do the Mycrons and Digitrons hold up in the rain?