1997 Ford Aerostar Owner's 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. RWARNING 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. RWARNING 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. RWARNING 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. 210