I have been using Specialized Fatboys for the last few months and am really happy with them. If they have been discontinued, you may still be able to find some stock around (I got mine mid-year). Another advantage of these slicks over other ones is the weight - they are listed at 325g for the 1.25", compared with over 500g for some others (eg IRC Metro). I have not used them in the wet, so I can't comment on handling on wet roads.
Regarding the effects of tread - have a look at this article by Jobst Brandt (author of "The Bicycle Wheel"😉:
sheldonbrown.comslicks.htmlOpen ↗
Some quotes from this article:
"machines that measure traction show that smooth tires corner better on both wet and dry pavement"
"Tread patterns have no effect on surfaces in which they leave no impression. That is to say, if the road is harder than the tire, a tread pattern does not improve traction. That smooth tires have better dry traction is probably accepted by most bicyclists, but wet pavement still appears to raise doubts even though motorcycles have shown that tread patterns do not improve wet traction."
"Besides having better wet and dry traction, smooth tread also has lower rolling resistance"
artemidorus said:I've used IRC Metros for years. Are you aware that cheaper and more expensive variants exist? They look identical, apart from the recommended pressure ranges. The better sort go to 100psi, the cheaper sort only go to 50 or 60psi, I can't remember which. I can confirm that the high pressure sort are not slippery and do not crack after 4 years, more like 6 or 7. They last for ever and rarely puncture.
Having said that, they are quite heavy and the rolling resistance is much greater than my road bike tyres. I've been intending to go to a lower profile tyre when they wear out, but they're taking a long time to do it.
The 2 versions of IRC Metro are regular and "Duro" which have kevlar somewhere and are more expensive. I had the Duro's for years and really liked them, though they were a [censored] to get onto the rim (maybe the kevlar reduced how much they could stretch).