A novel maize variety designated PHRDW and seed, plants and plant parts thereof. Methods for producing a maize plant that comprise crossing maize variety PHRDW with another maize plant. Methods for producing a maize plant containing in its genetic material one or more traits introgressed into PHRDW through backcross conversion and/or transformation, and to the maize seed, plant and plant part produced thereby. Hybrid maize seed, plant or plant part produced by crossing the variety PHRDW or a trait conversion of PHRDW with another maize variety. Inbred maize varieties derived from maize variety PHRDW, methods for producing other inbred maize varieties derived from maize variety PHRDW and the inbred maize varieties and their parts derived by the use of those methods.