Tire rotation is an important part of ensuring your vehicle is performing as well as it ought to, and it isn't terribly difficult. The entire process doesn't take more than an hour, and the tools you need most likely came with your car!
Step 1: Things You Ought to Know
Why should I rotate my car's tires?
Rotating your tires regularly (yearly) ensures that they will wear at a similar rate, ensuring that your car handles like it should. A car with uneven tire wear may handle erratically, especially in poor road conditions, and can make emergency maneuvers unnecessarily dangerous.
Why shouldn't I rotate my car's tires?
In some cases, tire rotation is unnecessary or even inadvisable. If your tires are equally worn front and back, you probably don't need to bother. Also, if your car uses different-sized tires in the front and rear (common in high-end rear-wheel drive vehicles), tire rotation can drastically and negatively impact your car's handling.
Is there a pattern I should follow?
Yes. The pattern in which you rotate your tires is entirely dependent on which wheels are driven on your car. For a front-wheel-drive car, the front tires should move straight back, with the rears moving diagonally across the car. Rear-wheel drive is just the opposite. For 4-wheel and all-wheel drive vehicles, all four tires should move diagonally across the car. This ensures that tire wear is as consistent as possible, even if you tend to turn one direction more than the other.
The car used in the illustrations is front-wheel-drive.