In response to petitions for rulemaking from the American Trucking Associations (ATA) and the Natural Gas Vehicles for America (NGVAmerica), NHTSA is proposing to amend the visual inspection labeling requirement in Federal Motor Vehicle Safety Standard (FMVSS) No. 304, "Compressed natural gas fuel container integrity," to state that CNG fuel containers used on heavy vehicles should be inspected at least once every 12 months. NHTSA is proposing this change because CNG heavy vehicles are typically used in high-mileage commercial fleet operations and following the current mileage-based inspection interval on the label means conducting multiple visual inspections per year. NHTSA has tentatively concluded multiple visual inspections per year based solely on mileage would not improve vehicle safety for these high-mileage CNG heavy vehicles, and could potentially reduce safety. Because the current periodic visual inspection interval is intended for light vehicles and is consistent with the operation of these vehicles, no change is proposed to the periodic visual inspection interval for CNG fuel containers on light vehicles.