Rotating tires is important (and always has been). The idea here is to rotate the respective wheels and tires on a given axle so that tire wear is even. The result is almost always balanced traction and handling over a period of time. Most tire warranties demand the tires be rotated on a specific mileage schedule. And many tire manufacturers recommend rotation at between three and five thousand miles.
Balancing Tire Wear.
As noted above, tire rotation works by evening out tire wear. Making each tire function in as many of the vehicle's wheel positions as possible makes this possible. Naturally, this can't make up for tire wear caused by tired or malfunctioning mechanical components or improper inflation. When considering the mechanics of a motor vehicle, keep in mind that the front end often has a more difficult task than the rear. For example, in a front-wheel drive car, the tires are tasked with steering, stopping, moving up and down and, of course, pulling the vehicle forward.
If the car in question is a high-performance rear-wheel-drive example, you'll likely find that the rear tires take more abuse than the front. Four-by-four vehicles and all-wheel-drive models bring their own tire wear peculiarities to the party. The bottom line here is, no matter what the car or truck, the wheel position can cause different rates of wear along with different types of wear on a tire.
There's more to consider: As a tire wears, the tread depth is reduced. If all four tires wear out at more or less the same time, you can replace four tires at once. This is actually advantageous when compared to replacing tires in pairs, simply because you'll always have equal fresh rubber on all four corners. Additionally, you have to consider that the manufacturers are constantly releasing new and improved tire configurations. The result is that your old tires could become obsolete by the time they're worn. If replacing only two at once, there's a good chance you'll end up with mixed tire technology that could negatively affect how your vehicle drives.
So far so good, but tire rotation isn't anything like it was a few decades ago. Way back when, most cars had identical wheels and tires on all four corners, and the spare was also a full-size job that matched the road wheels. That's a difficult combination to find today, with space saver spares, spare tires mounted on dedicated steel wheels (with the rest of the rolling stock on aluminum wheels), different wheel offsets and sizes front and rear, mixed tire sizes and so on. Because of this, the rotation process differs. Here's a look at a number of different rotation options (and there are plenty of them):
Four Same-Size Tires, Non-Directional.
If the tires are non-directional and the tires and wheels are all the same size, there are three different four-tire rotation patterns most commonly used:
Front-Wheel Drive: Rotate the tires in a forward cross pattern. This means that the left front goes to the left rear. The right front goes to the right rear. The left rear goes to the right front and the right rear goes to the left front.
Rear-Wheel Drive or AWD/Four-Wheel Drive: Left rear goes to right front. Right rear goes to the left front. The right front goes to left rear. Left front goes to the right rear.
(Alternate) Rear-Wheel Drive or AWD/Four-Wheel Drive: The left rear goes to left front. The right rear goes to the right front. The left front goes to the right rear. The right front goes to left rear.
What if the vehicle in question has different sized directional wheels and tires or is equipped with wheels with different offsets (wheel backspace) front and rear? In this case, the tires will definitely require dismounting, remounting and rebalancing in order to rotate the tires. Other typical rotation patterns are as follows:
Same-Size Directional Wheels and Tires.
The left front goes to left rear. The left rear goes to left front. The right front goes to the right rear. The right rear goes to the right front.
Different Size Directional Tires With Different Size Wheels.
Tires must be dismounted and remounted on the appropriate wheel/direction of rotation.
Non-directional Wheels and Tires With Different Sizes Front and Rear.
The left front goes to the right front. The right front goes to the left front. The left rear goes to the right rear. And the right rear goes to left rear.
Yesteryear, a 5-tire rotation was possible, simply because the spare was full size. That's seldom the case today. Even many light trucks are equipped with spare wheels that do not match the drive wheel combination. If, however the spare matches the drive wheels and tires, and all tires are the same size and are not directional then you can perform a five-tire/wheel rotation:
Front-Wheel Drive: The left front goes to the left rear. The left rear goes to the right front. The right rear goes to the left front. The spare goes to the right rear. The right front goes to the spare.
Rear-Wheel Drive or Four-Wheel Drive: The left rear goes to the left front. The left front goes to the spare. The spare goes to the right rear. The right rear goes to the right front. The right front goes to the left rear.
The idea here is to distribute the wear over five tires throughout their life. This is particularly important on many all-wheel-drive vehicles in that all tires, including the spare are, in theory, worn identically.