Damage
Periodically inspect the tire treads and sidewalls for damage (such as bulges in the tread or sidewalls, cracks in the tread groove and separation in the tread or sidewall). If damage is observed or suspected have the tire inspected by a tire professional. Tires can be damaged during off-road use, so inspection after off-road use is also recommended.
WARNING: Age
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, tires should be replaced after six years regardless of tread wear. However, heat caused by hot climates or frequent high loading conditions can accelerate the aging process and may require tires to be replaced more frequently.
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.
See also:
Vehicle storage
If you plan on storing your vehicle for an extended period of time
(30 days or more), refer to the following maintenance recommendations
to ensure your vehicle stays in good operating condition.
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SENSE AND STYLE
Family Friendly (Not Really, Fair, Great, Excellent): Fair
Fun-Factor (None, Some, Good Times, Groove-On): None ...
Snow tires and chains
WARNING: Snow tires must be the same size, load index, speed
rating as those originally provided by Ford. Use of any tire or
wheel not recommended by Ford can affect the safety and
performance o ...