• If you never rotated your tires some tires would wear out faster than others.
• Some tire treads on individual tires could wear unevenly with inside or outside wearing out first.
• Uneven tread wear is unavoidable because the weight of a car is not distributed evenly to all four corners.
• Weight of a front engine causes the front tires to carry more weight.
• Front tires take care of the steering duties.
• When brakes are applied the weight of the car shifts forward.
• If alignment is off some tires will drag and wear poorly.
• Worn out struts and suspension can alter the weight distribution.
• Exact rotation pattern depends on your vehicle and the tires: Check your Owner's Manual.

Standard Rotation Pattern

• Move the front tires straight to the rear
• Move rear tires to the front but cross them over
• Right rear tire ends up on left front
  
• The reverse pattern is also common (rear to front, front to rear with a crossover)
• Exact pattern is not as important as long as you are consistent
  
• Makes sure every tire spends time at each corner of your car