there's always clippings that get on the tires or just blown on the sidewalk or driveway from mowing or trimming.
when making a zero turn the tires grind those blades of grass into the concrete and it either makes a green stain or the clippings get stuck where my blower won't move them.
the clippings not moving with my blower could change this season though as I did purchase a br600 this fall for leaves. so I'm going from a br400 to a br600 so clippings being stubborn may no longer be a problem.
the other reason to avoid turning on hard surfaces is the longevity of your tires.
just caught what orange is saying. it was suppose to be I've never been able to keep grass off the sidewalk/driveway.