Tires degrade over time depending on many factors such as weather, storage conditions, and conditions of use (load, speed, inflation pressure, etc.) the tires experience throughout their lives. In general, Ford Motor Company recommends tires should be replaced after six years regardless of tread wear. You should replace your spare tire when you replace the road tires or after six years due to aging even if it has not been used. Your local Ford Dealership has the right tires for your vehicle and is the best place for any other service your vehicle needs, including tire rotation, wheel alignment, and more.