-
I'd have thought they would be more likely to trap debris.
They do, but less likely to pierced the tyres, hence why I found them useful.
I usually have to use a knife to remove the small debris stuck inside a slick tyres (very common), whether tyres with groove, the debris simply got lodged in that can be removed with a brush.
I have a rules at work, if I removed more than 10 debris from a road tyres, I'll tell the customer that he's better off with a new one.
Either way, "rain channels" is bollocks.
That I'll agree on.
They do serve a purpose on less than ideas road, gravel etc. and actually reduced the risk of puncture as the channel mean any object get caught will not get embedded further into the tyres.