In a TireRack tire test, the Michelin Pilot Exalto PE2, Bridgestone Potenza RE750, and Yokohama AVS ES100 were compared with each other. The Michelin performed at or near the best in every test, including those related to traction (braking and g-force cornering). Yet the Michelin only has a UTQG traction rating of A while the Bridgestone and Yokohama both have a superior AA traction rating.

So what meaning does the UTQG traction rating have when shopping and comparing tires?

 

I believe the UTOG traction rating is based on straight line wet coefficient of traction. Short answer is that the UTOG is not terribly useful. Treadwear rating is even less so, as it is not standarized between manufacturers.

For an example of traction ratings, go check out those of some R compound tires, which are massively grippy in the dry compared to the tires you mentioned. For A6, or for DOT Radial Wets, UTOG 40 C A, C being the traction.

Scott
90SM

 

See
http://www.tirerack.com/tires/tirete....jsp?techid=48

Quote:
Traction Grades

UTQG Traction Grades are based on the tire's straight line wet coefficient of traction as the tire skids across the specified test surfaces. The UTQG traction test does not evaluate dry braking, dry cornering, wet cornering, or high speed hydroplaning resistance.

The Traction Grade is determined by installing properly inflated test tires on the instrumented axle of a "skid trailer." The skid trailer is pulled behind a truck at a constant 40 mph over wet asphalt and wet concrete test surfaces. Its brakes are momentarily locked and the axle sensors measure the tire's coefficient of friction (braking g forces) as it slides. Since this test evaluates a sliding tire at a constant 40 mph, it places more emphasis on the tire's tread compound and less emphasis on its tread design.

In 1997, the UTQG Traction Grades were revised to provide a new category of AA for the highest performing tires in addition to the earlier A, B and C grades. Previously the A grade had been the highest available and was awarded to tires that offered wet coefficients of traction above 0.47 g on asphalt and 0.35 g on concrete. Today the grades and their traction coefficients are as follows:

AA asphalt g-force above 0.54, concrete g-force above 0.41
A asphalt g-force above 0.47, concrete g-force above 0.35

-------
Of note

Quote:
When looking at UTQG ratings it is important to realize that the Department of Transportation does not conduct the tests. The grades are assigned by the tire manufacturers based on their test results or those conducted by an independent testing company they have hired. The NHTSA has the right to inspect the tire manufacturer's data and can fine them if inconsistencies are found. While most new tire lines have their grades established when they are introduced, they are allowed a 6-month grace period to allow the tire manufacturer to test actual production tires. Once a grade is assigned it must be branded on the tire's upper sidewall and printed on its label.

-------
So shop and compare carefully. There can be alot of hype with tires.

One thing not mentioned is that tires loose their good qualities with time or age and exposure to the elements. So a tire that is supposed to last a long time might last but with reduced positive qualities. Or a really good performance tire that is old is no longer going to perform in top form.