GO:0010420:   polyprenyldihydroxybenzoate methyltransferase activity
Catalysis of the reaction: S-adenosyl-L-methionine + 3-polyprenyl-4,5-dihydroxybenzoate = S-adenosyl-L-homocysteine + 3-polyprenyl-4-hydroxy-5-methoxybenzoate + H+.