First Gen door speaker question?

I replaced the front door speakers today in my 02 Tacoma. I had to cut the factory speaker wire to wire them up. Now my question. There was a solid red wire and a red wire with a black strip. Both doors had the same color wires. Which was the positive wire and which was the neg wire? I searched on google and could not find the answer. All it brought up was the color of the wires when putting in the head unit.