slick tyres in the rain?

[Gravity Aided]

Not in the US necessarily, although, if they think of it, manhole covers are coated in tar. Gutter located sewer covers, not so much. It seems to me the compound in tires is much more important than tread, as a bicycle is pretty light, and probably does not make as much use of tread pattern as , say, a heavier vehicle like a car or motor-cycle would.

 

[biggs682]

They usually use tarmac to cover pot holes round here.

you are lucky then

 

[Gravity Aided]

Spotty at best, some covered, some not. And there are still some sewer grates with the lateral slots that catch bike tires. My father broke his tailbone and the back axle of his 3-speed that way. I did not point out his need for "situational awareness" as he was observing about that himself at the time.