From the Goodyear site:
Should I rotate my tires?
Regular and proper tire rotation promotes more uniform wear for all of the tires on a vehicle. All season tires should be rotated in a "modified X" pattern, meaning only the tires being moved to the drive axle are crossed to the opposite side of the vehicle.
The remaining two tires are moved from the drive axle to the free rolling axle, remaining on the same side of the vehicle.
This method of rotation helps promote a more even and uniform treadwear pattern for all four tires.
The only exception to this would be the use of "directional" tread design tires such as our Aquatred II or some of our Eagle line high performance tires. These tires would remain on the same side of the vehicle and be rotated straight forward and straight back.
If you have a four-wheel drive vehicle, we recommend crossing both pairs of tires to their new axle positions.We recommend tire rotation at least every 6,000 miles. Four-wheel drive vehicles may require rotation even sooner such as every 4,000 miles. Check your vehicle owner's manual for the manufacturer's rotation recommendations. If no rotation period is specified, tires should be rotated every 6,000 to 8,000 miles. The first rotation is the most important. When tires are rotated, inflation pressures must be adjusted to the vehicle manufacturer's recommendations. Uneven tire wear may also be due to misalignment or mechanical problems. Many Goodyear retailers can provide expert diagnosis and repair.