Load rating was made to indicate how much weight or load the grates can withstand without being damaged or becoming warped.
1-160 PSI Residential,pedestrian, and bike trafic
61-175 PSI Residential and Light commercial, Sidewalks curbs, driveways and parking lots
175-325 PSI Residential, Commercial and Municipal Sidewalks curbs, Parking Lots
326-525 PSI Commercial, Municipal Highways, Roadways, Warehouses, Causeways
525-650+ PSI Industrial areas, Frok-lifts, Ports, Docks