Believe it or not, rotating tires is an important part of car maintenance. Even modern vehicles with all-wheel drive bias most of the power delivered from the engine to one set of wheels most of the time, with the secondary wheels only receiving a large portion of the torque when needed. As such, the primary drive tires will inevitably wear more than the tires that free-spin or receive little torque most of the time. So, to get the longest life out of all tires, the tires should be rotated every 12,000 miles or so. For most modern cars, rotating the tires at every oil change is ideal.