The problem with using treadwear ratings to determine tire
classification for competition is that there is no real industry
standard. Each tire company has their own test methods, so you can
compare different Brand X tires to each other, but you cannot compare
Brand X tires to Brand Y. Unfortunately, treadwear is about the only
factor you can read right off the sidewall, so everyone uses it.
There are a number of other factors that determine how fast a tire
might be for auto-X use - number and type of plys, sidewall stiffness,
tread design, etc.
For the Golden Gate Chapter BMW CCA classification system, I suggested
(based on comments by an Ohio-based former tire engineer) using a
durometer to test the hardness/softness of the rubber of new tires.
Supposedly a member actually bought the durometer, but I haven't seen
it yet. At least that would give us numbers we could compare between
brands, but it does not address that sidewall stiffness factor.
Not an easy issue to resolve.
Scott Miller
>Date: Wed, 28 Dec 2005 23:00:00 -0800
>From: "PAUL TIBBALS" <pault151@comcast.net>
>Subject: Stock vs. R-type DOT tires
>
>OK, in /Sportscar/ Danny Shields (I think it was) tossed out his
comments on
>the concept of using "street" tires based on treadwear rating in the
Stock
>classes. And in the October Pylon one of the columnists went so far
as to
>even chime in about shocks remaining OEM.
>
>For what it's worth, I haven't kept the stock shock absorbers on any
vehicle
>I've owned longer than a year. That is, when it came time to replace
the
>stockers, I didn't even LOOK at the OEM's units, and this was long
before I
>autocrossed with any frequency. So I am not sure that I would want
to go for
>the OEM requirement there, though again it's a leveling influence.
But as far
>as the R tires, I could have lived without them in Stock.
>
>Will the tire manufacturers abuse their power to rate their own
tires, to
>steal some of this market? Have they done this already? How much
will the
>market expand for 140+ rated tires if all the Stock classes went to
them?
>
>Paul
|