One thing about that, is are those number most useful within a given tire brand line up?
Or is it helpful across brands. Somehow i thought they were most useful for within a given product line as compared to each other?
Here's the deal.
The UTQG ratings have to be based on tests. The treadwear rating is based on a test conducted on the highways around San Angelo, TX. The tire has to be compared to a control tire (The SRTT - Standard Reference Test Tire - a formerly Uniroyal design, that uses certified materials so the test results are consistent over time)
The test is expensive to run, so to reduce costs most tire manufacturers contract with a local company to conduct the test - along with many other companies - against a single set of controls. This company then reports the results and each tire manufacturer interprets the results. Some are conservative - like Michelin who think that the UTQG implies a warranty - and some are aggressive - like Cooper who think they need to report the highest value they can to be competitive.
Then there is the issue of how marketing wants to use the results. For example, if a company wants to have a Good/Better/Best set up, they might want the UTQG rating to be 500/600/800. But manufacturing says that if they produce the Good and Better using the same tread compound, they can save a ton of money, the company might downgrade the Good to meet their marketing position.
So the UTQG ratings are
NOT the direct result from a test, but the UTQG ratings
CAN be compared
WITHIN a given company and
BETWEEN companies, keeping in mind that your own results could be better than the rating suggests. (I know this may be difficult to keep straight!)
Also, most tire wear occurs during cornering - driving straight ahead is practically free!! Driving in the city wears tires quickly while driving in the country wears tires slowly, so there will be a HUGE! difference from the same make/model tire just because of where you drive.
That makes this whole thing messy and difficult to understand. Sorry, but that is just the way it is.