A track-width adjustment system, apparatus and method limit track-width adjustments in a self-propelled product applicator, according to a first speed-based protocol for track-width adjustments initiated by an operator of the applicator, and according to a second speed-based protocol for track-width adjustments initiated by an automatic track-width control arrangement of the applicator. An automatic track-width control arrangement continually monitors and adjusts track-width, as required to maintain a desired track-width at substantially any ground speed while the applicator is in motion. Operator initiated adjustments to track-width are allowed only within a prescribed range of ground speeds.