Floor protection isn't a single standardized number in most catalogs, but refers generally to how gentle a wheel is on a given floor finish — driven mainly by tread material, hardness (durometer), and whether the wheel is marked non-marking.
Softer, non-marking rubber and polyurethane wheels protect finished floors best; harder wheels and metal wheels roll easier but transmit more impact and are more likely to mark or damage sensitive flooring.
Finished floors — hardwood, polished concrete, vinyl — where scuffing or marking is a real concern, and any environment where floor appearance matters (retail, hospitality, healthcare).
Assuming any rubber or polyurethane wheel is automatically floor-safe. Check specifically for a non-marking designation and appropriate durometer — not every wheel in those material families is gentle on finished floors.
What does "non-marking" mean?
A wheel formulated specifically not to leave scuff marks or black streaks on floor finishes — check the product listing for this designation if floor appearance matters.
Are harder wheels worse for floors?
Generally yes — harder wheels transmit more impact and are more likely to mark or dent softer floor finishes than a softer, cushioned wheel.