Lincoln Navigator (1999) — понимание оценок износа и сцепления шин для безопасности [173/216]

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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 grade 150 would wear one

and one-half (1 1/2) times as well on the government course as a tire

grade 100. The relative performance of tires depends upon the actual

conditions of their use, however, and may depart significantly from the

norm due to variations in driving habits, service practices, and

differences in road characteristics and climate.

Traction AA A B C

The traction grades, from highest to lowest are AA, A, B, and C. Those

grades represent the tire’s ability to stop on wet pavement as measured

under controlled conditions on specified government test surfaces of

asphalt and concrete. A tire marked C may have poor traction

performance.

The traction grade assigned to this tire is based on

straight-ahead braking traction tests, and does not include

acceleration, cornering, hydroplaning or peak traction characteristics.

Temperature A B C

The temperature grades are A (the highest), B, and C, representing the

tire’s resistance to the generation of heat and its ability to dissipate heat

when tested under controlled conditions on a specified indoor laboratory

test wheel. Sustained high temperature can cause the material of the tire

to degenerate and reduce tire life, and excessive temperature can lead to

sudden tire failure. The grade C corresponds to a level of performance

which all passenger car tires must meet under the Federal Motor Vehicle

Safety Standard No. 109. Grades B and A represent higher levels of

performance on the laboratory test wheel than the minimum required by

law.

The temperature grade for this tire is established for a tire that

is properly inflated and not overloaded. Excessive speed,

underinflation, or excessive loading, either separately or in

combination, can cause heat buildup and possible tire failure.

Maintenance and care

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