Tire wear

When the tread is worn down to 1/16th of an inch (2 mm), tires must be replaced to help prevent your vehicle from skidding and hydroplaning. Built-in treadwear indicators, or “wear bars”, which look like narrow strips of smooth rubber across the tread will appear on the tire when the tread is worn down to 1/16th of an inch (2 mm).
When the tire tread wears down to the same height as these “wear bars”, the tire is worn out and must be replaced.

See also:
Traction AA A B C
The traction grades, from highest to lowest are AA, A, B, and C. The
grades represent the tire’s ability to stop on wet pavement as measured
under controlled conditions on specified government tes ...
Motorcraft part numbers
Refer to scheduled maintenance information for the appropriate
intervals for changing the spark plugs.
Note: Replace the spark plugs with ones that meet Ford material and
design specificati ...
Traction AA A B C
The traction grades, from highest to lowest are AA, A, B, and C. The
grades represent the tire’s ability to stop on wet pavement as measured
under controlled conditions on specified government tes ...
