Honda 1990 Accord Sedan Owner's Manual page 126

The tires on all Honda cars meet Federal Safety Requirements.
All tires on the ACCORD are also " g r a d e d " according to
Department of Transportation (DOT) standards for tread wear,
traction and temperature.
Tread Wear
The tread wear 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 1 50 would wear one and one half (1-1/2) times as well
on the government course as a tire graded 100.
The relative performance of tires depends upon the actual con-
ditions of their use, however, and may depart significantly
from the norm due to variations in driving habits, service prac-
tices and differences in road characteristics and climate.
Traction
The traction grades, from highest to lowest, are A, B, and C,
and they represent the tire's ability to stop on wet pavement
as measured under controlled conditions on specified govern-
ment test surfaces of asphalt and concrete. A tire marked C
may have poor traction performance.
The traction grades assigned are based on braking
(straight ahead) traction tests and do not include cornering
(turning) traction.
DOT Tire Quality Grades
Three grades
are shown on the
tire sidewall
TIRE
WHEEL RIM
(cont'd)