Ford Mercury Villager 1997 Owner's Manual page 307

Failure to follow these precautions may adversely affect
the handling of the vehicle and make it easier to lose control
and roll over.
Tires that are larger or smaller than your vehicle's original tires
may affect the accuracy of your speedometer and odometer.
Wheel and Tire Matching
See an authorized tire dealer for proper servicing procedures.
Wheels and tires must be properly removed, matched and
remounted to maintain the best possible ride.
Information About Tire Quality Grades
New vehicles are fitted with tires that have their Tire Quality
Grade (described below) molded into the tire's sidewall. These Tire
Quality Grades are determined by standards that the United
States Department of Transportation has set.
Tire Quality Grades apply to new pneumatic tires for use on this
vehicle. They do not apply to deep tread, winter-type snow
tires, space-saver or temporary use spare tires, tires with nominal
rim diameters of 10 to 12 inches (254-305 mm) or limited
production tires as defined in Title 49 Code of Federal Regulations
Part 575.104(c)(2).
U.S. Department of Transportation — Tire quality grades: The
U.S. Department of Transportation requires Ford to give you the
following information about tire grades exactly as the
government has written it.
Treadwear
The treadwear grade is a comparative rating based on the wear
rate of the tire when tested under controlled conditions on a
specified government test course. For example, a tire graded
Maintenance and Care
WARNING
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