General Motors LLC (GM) is recalling certain 2018 Chevrolet Express and GMC Savana vehicles with certain combinations of front-tire and gross-vehicle-weight option codes. The Tire Pressure Monitoring System (TPMS) may be incorrectly calibrated, causing the TPMS warning lamp to illuminate when tire pressure reaches 37 PSI, not 41 PSI. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard (FMVSS) number 138, “Tire Pressure Monitoring Systems.”