Real Nice Goodyear Tire porcelain Sign Protect our good Name Gas Oil

I am not sure of the age of this sign. Found it in an Antique Mall. I have looked on-line and in books and could not find one like it. The porcelain application would lead me to say 1940's. It is a thick metal sign with thick layers of porcelain that show strong definition between the layers. On the back there is a light dusting of white porcelain on the black porcelain with finger prints? The size is 20" x 7" and it is one sided. It has a chain with a grummet at each hole. One of them is loose. One small chip on the upper left hand corner. No repairs or touch ups. Nice looking Goodyear sign. Starting my auction at 9.99 with no reserve. I give a three day return policy on the price of the sign. Please email me if you have any questions.