Automotive Smog Check Tips

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Automotive Tire Tips 6 of 13
Published 09-10-2017

                                                                            Tire Tread Wear

Tread Wear - Tread wear grade is a comparison rating based on the wear rate

of a standardized tire, tested under carefully controlled cinditions , which is

assigned a value of 100. A tire rated 200 should have a useful life twice as long

as the standard tires.

Note : The standard tire has a rating for tread wear of 100. This vehicle has

generally been accepted to mean a useful life of 20,000 miles of Normal driving.

Therefore, a tire rated at 200 could be expected to last 40,000 miles.

Tread Wear Rating Number                     Approximate Number of Miles

100                                                                          20,000 miles

150                                                                          30,000 miles

200                                                                          40,000 miles

250                                                                          50,000 miles

300                                                                          60,000 miles

400                                                                          80,000 miles

500                                                                         100,000 miles

The tread wear life of any tire is affected by driving habits ( fast stops, fast cornering

can decrease tread life ), Tire Rotation or lack of Tire Rotations, under inflated, wheel

alignment, road surfaces and climate conditions will play a role in your Tires life.

Traction - Traction performance is rated by the letters AA , A , B and C.

AA is the best.

Note : The traction rating is for Wet Braking distances only ! It does not include

cornering traction or Dry Braking performance. The traction rating is only one of

many factors that affect wet braking traction, including air inflation, tread depth,

vehicle speed and brake performances.

Temperatur Resistance - Temperature resistance is rated by the letters A, B and  C ;

with A being the best rating. Tires generate heat while rotating and flexing during

normal driving conditions. A certain amount of heat buildup is desirable normal

drivung conditions. A certain amount of heat buildup is desirable because tires 

produce their highest coefficient of traction at normal operating temperatures.

Forexample, rare car drivers frequently swerve their cars left and right during 

pace laps, causing increased friction between the tire and the road surfaces,

which warms their tires to operating temperature. However ; if temperatures

rise too much, a tire can start to come apart -the oils and rubber in the tire

starts to become a liquid !



Automotive Principles Technology - James D. Halderman