Well we get plenty of rain here in Scotland and very few people run foam tyres.
Take Off CS22's work suprising well for slicks, infact very well.
Another popular tyre are Pit Schumizu D20's which come ina few forms. You can get them in narrow 21mm and wide 26mm and last year they introduced a 24mm tyre with directional treads. I have the 24mmversion and they work very well, CS22's work almost as well when the track is fully wet but I feel the D20's work better on the greasey not so wet track you can often get after a light shower or as the track dries.