There are several very valid reasons for rotating your tires. Tires tend to wear unevenly. Your front tires will have to do different work than your back tires. They will wear differently because they are used to steer the vehicle. This will create extra wear and tear on the outside edges. Your back tires on the other hand simply follow on in a straight line. Your tires might also wear differently depending on how the weight is distributed across your vehicle. Most vehicles have the engine in the front so there is more weight over the front tires than the rear. If you have a front-wheel-drive vehicle the need for more frequent tire rotation can be even higher because of the additional weight of the transaxle.

Uneven wear means you may end up replacing your tires sooner than need be. Depending on how uneven the wearing it could mean losing out on possibly thousands of miles of extra usage.