Why do dogs prefer to pee on parked-car tires?

It might not even be a real preference. ^^' Dogs can and will pee over anything that smells like the urine of another dog, so as to cover it with their own scent. It's not that one thing is more enjoyable to pee on than something else.

Because when they try to pee on the moving ones they get all tangled up and fall.

moving cars move way too fast for the dogs .