Abstract: A pair of substitute adjustable height wheel assemblies 10 10 to replace either the front 101 and/or rear 102 wheel assemblies on a conventional lawn mower 100 wherein each adjustable height wheel assembly 10 includes a contoured mounting plate member 20 having a central portion 21 adapted to be secured at a desired location on the lawn mower housing 103 and including a pair of outwardly projecting leg portions 22 23 having a plurality of vertically spaced aligned apertures 24 dimensioned to selectively receive a securing unit 12 for positioning an adjustment arm unit 13 bearing a castor wheel unit 14 at a desired height relative to the mounting plate member 20 that is selectively positioned on the lawn mower (100).