Tire size

255/50 R 19 103 Y
255: nominal width in mm
50: aspect ratio in %
R: radial tire code
19: rim diameter in inches
103: load rating, not for ZR tires
Y: speed rating, before the R on ZR tires

Speed letter

T = up to 118 mph, 190 km/h
H = up to 131 mph, 210 km/h
V = up to 150 mph, 240 km/h
W = up to 167 mph, 270 km/h
Y = up to 186 mph, 300 km/h

Tire Identification Number

DOT code: DOT xxxx xxx 3510
xxxx: manufacturer code for the tire brand
xxx: tire size and tire design
3510: tire age
Tires with DOT codes meet the guidelines of the U.S. Department of Transportation.

Tire age

DOT … 3510: the tire was manufactured in the 35th week in 2010.

Recommendation

Regardless of wear, replace tires at least every 6 years.

Uniform Tire Quality Grading

Quality grades can be found where applicable on the tire sidewall between tread shoulder and maximum section width.

For example: Treadwear 200; Traction AA; Temperature A

DOT Quality Grades

Treadwear
Traction AA A B C
Temperature A B C

All passenger car tires must conform to Federal Safety Requirements in addition to these grades.

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 150 would wear one and one-half, 1 g, times as well on the government course as a tire graded 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

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

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 Band A represent higher levels of performance on the laboratory test wheel than the minimum required by law.

Temperature grade for this tire

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.

If necessary, have the vehicle towed.

RSC – Run-flat tires

Run-flat tires, are labeled with a circular symbol containing the letters RSC marked on the sidewall.

M+S

Winter and all-season tires with better cold weather performance than summer tires.