I want to replace my existing painted wood risers with slate or some durable tile. Is this possible and if so, how do I remove them to replace them or should I tile right over the existing riser?
If the nosing or overhang on the treads extends out enough from the riser, I would just sand the gloss off the existing risers and use them for backing to hold the tile on. There's no minimum overhang required in a staircase, but the overhang should at least cover the thickness of the tile. A nosing looks better, in my opinion, if it overhangs the riser. Conventionally the nosing is 1". In your case, if it still overhangs by 1/2" or so, go for it.