I don't know enough about the tire thing to say whether or not they work in the ocean for anything. However, as Ace said, there are other uses they can be put to rather than dumping them so I'd prefer that we go that route for now.

Papa, your comment with regards to cans and bottles is valid, they do provide habitat for all sorts of critters and will, ultimately, be broken down but I'd hate for people to begin using that as an excuse to dump them in the ocean. Aesthetically, they are an eyesore for a long time so I'd rather they be recycled by us than waiting for mother nature to do her thing.

When it comes to planetary recycling, ultimately, everything gets broken down and recycled, even the plastics, but it will take thousands of years and the potential for doing harm along the way is enormous.

As for train stations vs SUVs, I understand that you have to look at the whole picture with regards to any impact on the environment, but that seems a strange comparison. Difficult to drive the train station to the grocery store (or dive site) and also difficult to fit 1000 people in an SUV while they wait for the 8:15 to Downtown.