I need help with my dog, I don't know what to do...!?

I have a pit bull, red nose, big dog name Doggie, anyways I have him in the front yard where we park both of our trucks. The problem we have with him is that he pees on the tires of both trucks. He also scratched the penger door on our new truck. My husband wants to buy the electric fence, you know those electrically charged fence wire, to put around the trucks where they park. Do you think this is a good idea? I'm not sure about this. Does anybody else have other suggestions? By the way, I can't put Doggie in the back yard because I have other animals. I like him in the front yard because he's a good watch dog. Thanxs for your comments.