THSCC Forums

No kidding. Once you decided on the platforms (cars) to use, you then have to decide on the locations. Ponder all the different types of concrete and asphalt surfaces for a moment, and then throw that variable into the mix too (thinking here about training Jackie told me about she went to at http://www.ncat.us/).

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Current stable:
2019 BMW M2 Competition slicktop 6MT
2011 BMW M3 sedan slicktop 6MT
2007 BMW 328i wagon (slushbox for now)
1975 CanAm 125MX2

Are you saying that a 200 TWR on a BFG tire is the same as the 200 TWR on a Dunlop tire? I've read that's hardly ever the case.

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Vincent Keene
'06 Ford Mustang GT (track rat)
'15 Dodge Charger R/T (yeah, it's got a HEMI!)
'07 Ford Fusion SE (205,000 miles and counting)
'98 Chevy Z-24 (retired)
'93 Acura Integra (Team SWB 24HOL Car)

The demand for autocross ~200tw tires has encouraged competition among manufacturers to continue improving the product. In addition to class dilution, the vast improvement in street tires was the second most obvious change I noticed in autocross after being out of the sport for 7+ years. In addition to discouraging new attendants, I don't think a spec brand or tire would help foster tire improvement.

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92 Miata 1.9L naturally aspirated. SSM 21

from Tirerack
"Unfortunately, the rating that is of the most interest to consumers is the one that appears to be the least consistent. While the Treadwear Grade was originally intended to be assigned purely scientifically, it has also become a marketing tool used by manufacturers to help position and promote their tires."

and
"UTQG Treadwear Grades are based on actual road use in which the test tire is run in a vehicle convoy along with standardized Course Monitoring Tires. The vehicle repeatedly runs a prescribed 400-mile test loop in West Texas for a total of 7,200 miles. The vehicle can have its alignment set, air pressure checked and tires rotated every 800 miles. The test tire's and the Monitoring Tire's wear are measured during and at the conclusion of the test. The tire manufacturers then assign a Treadwear Grade based on the observed wear rates. The Course Monitoring Tire is assigned a grade and the test tire receives a grade indicating its relative treadwear. A grade of 100 would indicate that the tire tread would last as long as the test tire, 200 would indicate the tread would last twice as long, 300 would indicate three times as long, etc.

The problem with UTQG Treadwear Grades is that they are open to some interpretation on the part of the tire manufacturer because they are assigned after the tire has only experienced a little treadwear as it runs the 7,200 miles. This means that the tire manufacturers need to extrapolate their raw wear data when they are assigning Treadwear Grades, and that their grades can to some extent reflect how conservative or optimistic their marketing department is. Typically, comparing the Treadwear Grades of tire lines within a single brand is somewhat helpful, while attempting to compare the grades between different brands is not as helpful."

So, yes it is a real test with real parameters. But no, you can't directly compare between different brands because of the inherent limitations of only driving 7200 miles, then subjecting it to scientific/marketing extrapolation of the different tire manufacturers.

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Steve Carter
1972 Datsun 240Z-- resto pics at http://picasaweb.google.com/srcartermd
2007 GPW Honda S2000-- STR 86

Or the other way when SCCA changes a number and Toyo sands a 140 off a mold and stamps a 200 back in.

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2006 Civic Si - #24 HS for 2015

2005 GMC Sierra
1991 318is Garage Ornament

OK, I have two brilliant suggestions for street class:

1) Require a minimum manufactured tread depth and ban shaving. Then, define limits on rubber softness at various ambient temperatures. At national events, durometer readings would be required in impound. If the rubber is too soft, DQ. There would need to be allowances for the effects of elevated tire temps after competition runs, but if there was a question the tires could retested once cooled to ambient temperature.

2) The above is too complicated and would likely be subverted by clever tire company chemists/engineers, so just require LRR tires in street class.

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Art McDonald
Premier Amateur #518
2008 Dishman Cup
Pivot Cone Snob

Rodney is a waxer (but in a good way)

It seems like it would be easier for the SCCA to just put out a whitelist of tires. There are only a small number of performance tires that would be contentious.

I did that. Pretty sure I've got worse tire selections than Chad does.

That is exactly what they did. Same tire, same construction, different rating. A driver used R1Rs with a 140 stamped on the side at Dixie this year, was protested and subsequently DSQ'ed.

Quoth the Rack of Tires:
"
NOTE:

At the end of 2014, Toyo changed the Uniform Tire Quality Grade (UTQG) of their Proxes R1R Extreme Performance Summer tire to reflect a 200 Treadwear rating.

UTQG ratings for Treadwear, Traction and Temperature are based on tests conducted by tire manufacturers and reported to the National Highway Traffic Safety Administration (NHTSA). These regulations allow tire manufacturers to under-rate their tires’ capabilities, but prohibit over-rating them. UTQG ratings are required to be printed on their labels and branded on tire sidewalls.

Toyo assigned the 140 Treadwear rating to match the UTQG Treadwear rating required by competition rules when the Proxes R1R was introduced, however subsequent Toyo wear data revealed the tire line earned a 200 Treadwear rating.

With some competition rules now requiring higher UTQG Treadwear ratings, Toyo decided it was time to officially change the Proxes R1R line’s rating to accurately reflect its capabilities.

*In order to help drivers confirm which tire they will receive, we have identified the tires by listing their Treadwear rating on the product Specs tab."

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Steve Carter
1972 Datsun 240Z-- resto pics at http://picasaweb.google.com/srcartermd
2007 GPW Honda S2000-- STR 86