Snrub

iTrader: (1)

I recently bought some new Fuzion ZRi tires to replace my worn out Yokohama ES100s. I was washing the car and I noticed that the UTQG for Traction Grade was "A" instead of "AA" like on my old Yokos. "UTQG Traction Grades are based on the tire's straight line wet coefficient of traction as the tire skids across the specified test surfaces." (http://www.tirerack.com/tires/tirete....jsp?techid=48)

Part of my decision for purchasing the Fuzions was based on the Tire Rack's testing. For instance their test found that in 50-0 wet braking that the ES100s stopped in 103.8' compared to 95.8'. http://www.tirerack.com/tires/tests/fuzion_zri_c.jsp If this is the case, do the UTQG tests have any value? I realize that traction and braking are not necessarly the same thing, but one would think they'd be pretty similar. I also realize that differing amounts of wetness would effect the tests, but there seems to be enough of a difference that it doesn't seem like the ES100s would ever be similar to the ZRi's wet performance. (not to mention a substantial tread pattern difference) Thoughts?

DamonB

UTQG ratings have very limited value. Since the test only measures a locked tire's ability to stop in the wet all you're really measuring is the softness of the rubber.

"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."

This test will not take into account tread pattern because if the tire is skidding it is not turning and thus is not pumping water from under itself via the tread pattern. It also doesn't mean squat about dry grip because the tire is not tested in the dry. Is this rating useful? Somewhat. It will denote some very basic "flavors" of grip, but there are still enormous traction difference between tires that carry the same rating.

connor@tirerack

The first thing you should understand about the UTQG (Unified Tire Quality Grading) is that you cannot use it to compare between manufacturers or different classifications of tires. Every manufacturer has there own tire testing methods and scoring system to come up with the ratings that you see on a tire. However, there is no DOT governing laws or standards that tells these manufactures how to test the tires to give them some form of comparable equality. As an example we used to have two tire that both had a 320 tread wear. however one of them wore around 12-15,000 miles and the other would run around 35-40,000 miles. There is really no way to tell what the Individual codes of the UTQG rating mean to you as a consumer.

As long as you are comparing two tires in the same class and same manufacturer of tire (example: Michelin pilot sport vs. Michelin pilot sport PS2) then you could get a fairly accurate comparison. But this is the only time you could use this information as a reference point. This is also why we never use the UTQG code as a comparison tool when customers ask what we recommend.

Snrub

iTrader: (1)

That's very odd. I would have thought that "The NHTSA has the right to inspect the tire manufacturer's data and can fine them if inconsistencies are found" (from the above link), would ensure that they were reasonably accurate. That wouldn't appear to be the case. I didn't realize that the test was conducted with the tires locked up. That's of little value in a world where every new car sold has ABS.