I need to get a set pretty quick and haven't found that much info on comparisons.
What works well?
What's the latest and greatest?
And, is a tread width change recommended from the dry tires?
I think if you can afford Hoosier rains, they're the best. I used full tread RA1's, 255s on 8" wheels, because that's what I had. They were OK, not great.
Hoosier rains are great. The best tire I ever used isn't available, but Dirt Stockers worked as well as their dedicated rains, and were much cheaper.
I was only 3-4 seconds slower in a steady rain on them at Roebling Road than on shaved Victoracers in the dry, the same weekend. They didn't seem to slip anywhere, till it started drying. They went away pretty quickly and corded in just a few laps.
I used full tread Kumho Victoracers years ago. Nothing great, but never fell off a wet track.
I found a 255-50 wet worked better than a 255-45. We used 8X16 rims for everything in A/Sedan. You want a little softer suspension in the rain, and a tad more sidewall give isn't a bad thing.
Rains are something you have, but may not use but once or twice a year. I keep mine in garbage bags to protect from light and ozone.
You want the tires to cut through the water, not ride on time, so yes, I usually go for the narrower tire that will fit the rim.
BTW I hate racing in the rain. No wipers on my car. RainX works fairly well.