>Good info Jim. I had thought, though, that the reference tire you
>mentioned was provided by the government? Or at least specified by the
>governent to be the industrie's base-line. Hence, the 100 treadwear
rating
>for all companies to start from.
There are government *standards* for the traction, temperature, and load
range ratings. The treadwear rating is a guideline *only* and there is a
testing procedure and a *suggested* tire configuration for the reference
tire.
The reason it's a *suggestion* and not a *standard* is because each tire
maker has proprietary rubber compounds and construction techniques and the
chemical composition of the rubber changes during the molding, curing, and
vulcanizing process (so an analysis of what's in the tire after it's made
isn't what went into it). So it's nearly impossible to standardize this
stuff. Ask twenty tire companies what their version of the suggestion
reference tire is and you'll get twenty different answers -- primarily due
to the compounding, carcass/belt materials, and curing/vulcanizing
techniques unique to each company.
And again, the problem with a standard for treadwear is that it has zero
correlation to real-world usage. There are too many variables that affect
tire wear - loading, inflation pressure, balance, maintenance/rotation,
alignment, even the road surface itself -- to easily and economically
account for all of them in an all-inclusive standard.
So treadwear is merely a voluntary guideline. And as such is a shaky,
unstable foundation on which to build a rules package.
Jim Crider
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