I used long the Conti GP4Season 28mm in the non-snowy months. Now since a half year with the Panaracer Gravelking 28mm (slick version, not the SK = small knobs) and like them! Had since April only one flat, which was my own fault (snakebite, not enough air and heavier bag and too fast through a construction site with a metal board over the bike lane). My new bike will have the same but 38mm.