I have the speaker wires for my rear speakers running on each side of my car. So for the left side speaker, the speaker wire is run down the left side of the car, and the right side speaker has its wire running down the right side of the car. I know when you run RCA's down the same side as the power wire, you'll get interference. Is it the same game with speaker wires?

 

You could be safe and just run the power wire down the middle on either side of the driveshaft hump. I personally have never noticed any noise from the factory wiring with the power wire running down the side.

I think the issue is that whey you have RCAs running next to a power line the level of sound on the RCA is so low that it can pickup noise from the power wire. I don't think that is an issue with the speaker cable because it is already has an amplified signal with a lot of power going to the speakers....but then again I could be wrong.

To be safe you could run your speaker cable up the windshield pillars over the headliner and down to the speakers if you are that worried about it

 

There is a possibilty that you might pick up noise, but this usually happens with cheaper equipment or poor insulated wires.

If you are planning to do RCA's also, get the twisted kind. helps block radiated noise!