Spartan Motors Chassis (Spartan Chassis) is recalling certain 2011 SU and 2011 through 2012 model year MM, K2, and K3 recreational vehicle chassis manufactured from January 28, 2011, through June 28, 2011, equipped with air gauges supplied by Ametek. An incorrect value may have been used in the formula for calculating the sweep angle of the dial. This may have resulted in the accuracy of the gauge varying as much as eleven percent from the cutout pressure as opposed to the maximum allowable of +/- seven percent. Consequently, these chassis fail to conform to the requirements of Federal Motor Vehicle Safety Standard No. 121, “Air Brake Systems.”