Miata Mailing List: April 1996, Message #183
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   From: naruz@skidmore.EDU (Nedim A Aruz)
Subject: Tire Ratings...
   Date: Tue, 2 Apr 1996 18:52:14 -0500


>You wrote on Tue, 02 Apr 1996 14:46:48 -0500
>
>Ok,
>
>I've heard you talking about treadwear ratings of 200 and 500, and it would 
>seem that the lower treadwear coincides with stickier tires (well, duh.)
>
>But here in New Zealand, I've never heard of these ratings, are they 
>specified by the US DOT?
>
>I just checked my tires, (Falken FK-06G) and they have treadwear of 280, 
>which I guess makes them fairly short-lived and fairly sticky, but on the 
>same panel it also says Traction A, and Temperature A. I also checked 
>several other tires in the work car-park, most tires did not have any of 
>this stuff. (My tires are made in Japan, for an international market, most 
>of the company cars have NZ or Australian tires)
>
>Can somebody explain these ratings?
>
>Yours, curiously..
>
>Fletch.  '90 red.
> 
>     Fletch,
  
      As far as the traction, temperature and treadwear of tires go, each
are required to have a coresponding numerical value on the sidewall of the
tire.These requirements are set by the U.S. Department of
Transportation.The ratings are also known as UTQG ratings(Uniform Tire
Quality Grade)The problem is that they are only uniform within each company.
This is due to the fact that each company independantly test their tires and
then report their findings back to the government. Thus comparsions between
two diffrent company's ( ie.Yokohama and Dunlop) would be next to useless.
Also you are correct in assuming that the lower the treadwear # the stickier
the tire, but by no means are your Falkens rating of 280 low. My Yokohama
AVS i's are 160. But who knows what that means in relation to your Falkens. 

      Traction: This refers to the ablity of a tire to stop in a straight
line on wet pavement. Ratings range from A to C  with A being the highest.
Note: This does not have anything to do with cornering traction. 
1
      Temperature Resistance: This is a test that rates the ability of a
tire to resist heat generated by constant running at high speed. It too is
rated from A to C with A being the highest. Note: C is the minimum value
alloted by Federal Motor  Vehicle Safety Standards.

      Treadwear: The tredwear test is done at a set government specified
facillity. A tire that has a wear rating of 150 will wear 1.5 times longer
than a tire that has a rating of 100, and so on. Note: The actual treadwear
of the tires depends on your driving style; You can make a 150 tire wear as
long as a 300 tire if your favorite day to drive is sunday. Yet in a miata I
doubt this is possiable. 


                                    Nedim