Quote:
Originally Posted by swamp2
Next without looking at the book it is hard to say, but to call what they did as testing or scientific (as opposed simply to limited anecdotal evidence) is almost for sure a huge exaggeration. I will not set aside my observations and the identical observation of others herein without much stronger evidence than that.
I am really quite surprised you have not experienced the same effect. More have chimed in that they have (even discounting confounding wet and cold effects).
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I did not call their testing scientific or unscientific, so I did not exaggerate anything. I said, "that is
some reference to some actual data arrived via testing". I even noted that their testing procedure is not documented in the book. I did say I will take their testing and driving/racing observations on street tires over anyone's opinion here. No need to reiterate why.
On the other hand, what makes you qualify their testing as "limited anecdotal evidence"? How do you know that they did not take CoF measurements in a somewhat controlled environment for instance since they are making a specific reference to "CF", a somewhat technical term, as opposed to grip or traction? These guys are not simply drivers, and the book is not simply this is how I drive fast. They run top notch driver training programs and racing series, and have access to resources a driver would not have. And testing a tire is not rocket science.
I don't think we are interpreting what they are saying the same way. My interpretation is that they are
not saying the grip of a street tire will be roughly the same from 5/32" to no tread
as it is consumed and wears out. That would not be a very meaningful test to run as there would be too many other variables. My interpretation is that they took a tire and shaved it to 5/32", tested it, shaved it again to a shallower depth, tested it, and so on. Or, they could have taken several new tires and shaved them to different depths below 5/32" and tested them. Then you can end up with some kind of grip profile vs tread depth without worrying about other effects. That question would be relevant to ask because you need to decide what depth you want to shave your tires to for optimal grip. Since they seem to be running street tires on some of their cars, it makes sense that they want to know the answer. And, they are saying they have not noticed a significant difference in that profile.
There is nothing that anybody has said in this thread that offers any evidence to the contrary since nobody has run such a test here. Gearhead999s has added nothing that disputes such an outcome. He just said that his grip has decreased progressively over the life of the tires. Fine, but again, that's not news.
Quote:
Originally Posted by swamp2
I am not sure what you mean in the your last comment. My point was this: tread wear depth and UV exposure will always be correlated but the level of correlation can vary dramatically. If you drive the hell out of your car with lots of track days and combine that with a less UV intense area vs. then consider opposite of all of those things I suspect you could go from an decided observation of UV hardening effects vs. nearly no effect from it.
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Well, one could try those different conditions, and one would most likely arrive at tires with different traction levels, which is kind of the point, so I don't understand what you mean either. The really informative, but rather unlikely conditions are, you buy a new set of tires and wear them out in a very short period of time--say a week--without any significant UV exposure and compare that to what happens if you tracked them occasionally over a year or something. Apart from UV exposure, there is also the whole business of heat cycling that I haven't gone into as opinions vary greatly on that. And if you wear them out at the track with too much tread on, there is also the issue of overheating and chunking the tires, etc. Again, that doesn't help you pinpoint the effect low tread depth does or does not have on traction, and the reason we are discussing that is the inbalance in handling you reported with your car with different tread depths F/R.