Speaker ground?

Finally got the plastic kick panels made by 66Dvert and 6" kenwood speakers in my 66 Barracuda and the radio is not very loud and lots of static. Should the speakers be grounded?

I ran two strand speaker wire to each speaker and spliced the speaker wires together connected to the speaker connection on the original AM radio. The speaker wires from the radio, one is a black wire and the other is (dark green?), hard to tell color in the lighting conditions. Does the original sound system rely on a ground at the speakers?