Ford 1997 Aerostar Manual page 210

The Temporary Spare Tire
You may have a high pressure temporary spare
tire. This spare tire is smaller than a regular tire
and is designed for emergency use only. Use it
only when you get a flat tire and replace it as
soon as you can. This spare tire is marked with
the words "TEMPORARY USE ONLY" so that
you can easily identify it.
If you use the temporary spare tire
continuously or do not follow these
precautions, the tire could fail, causing
you to lose control of the vehicle, possibly
injuring yourself or others.
The tire size on the E-4WD must be
maintained.
Your vehicle may have a full diameter mini
spare or a full size tire. This full diameter mini
spare is special for the E-4WD and another mini
spare from another vehicle can not be
substituted without the possibility of damage to
your vehicle. All tires should be inflated to the
manufacturer's recommended pressures.
To avoid injury, never run the engine
with one wheel off the ground, such as
when changing a tire.
Extended use of other than matching size spare
tires on a Traction-Lok axle could result in a
permanent reduction in effectiveness. This loss of
effectiveness does not affect normal driving and
should not be noticeable to the driver.
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