A novel maize variety designated PHRC4 and seed, plants and plant parts thereof. Methods for producing a maize plant that comprise crossing maize variety PHRC4 with another maize plant. Methods for producing a maize plant containing in its genetic material one or more traits introgressed into PHRC4 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 PHRC4 or a locus conversion of PHRC4 with another maize variety.