If you do not get the car aligned when you get new tires, you wear out a single tire quickly. This means you have to replace FOUR tires. In fact, the tire company we use will not replace one tire on a Subaru. They will only replace all four so that they do not have to replace a transmission. So if you get a nail in one, you have to purchase FOUR! This is extremely expensive, and we've spent hundreds of dollars paying for warranties (which are marginal insurance at best). We replaced all four tires from one damaged many times.