Mr. Sharp
I don't know if it will directly compare due to the weight difference of
our cars, but, you can notice (and measure) a difference when about 50% of
the wear indicators are gone. I don't use the tires when 75% of the wear
indicators are gone. With two drivers and a little bit of practice time, I
should use two or three sets of tires a year. Stated another way, 5 events
with two drivers just about uses up the tires in my humble opinion. It
would be interesting to see the data you or someone else might have over
the life of the tires on the same track. We use a spreadsheet to calculate
the average g's.
-Woods
At 07:59 PM 5/7/00 EDT, you wrote:
>In a message dated 5/7/00 12:11:29 AM Eastern Daylight Time,
>woods@mae.uta.edu writes:
>
>> I would like to share with you another number that we have found by
>> plotting the average g's (average of the g-vector from the start to the
>> finish of an autocross). The correlation is quite good and shows that an
>> increase in 0.1 g's average results in 3.0 seconds on a 60-second course.
>> This 0.1 g's can come from driver ability or from the tires. Further,
>> tires drop by 0.1 to 0.2 g's as they wear from new to about 25% of the wear
>> indicators left (I'm referring to racing slicks on a Formula SAE car).
>
>Those are some interesting numbers. So at that point you are 3.0 or more
>seconds slower on a 60-second course compared to new tires? How many
>runs does it take to wear the slicks you're using down that much?
>
>I've always felt that R-compound DOT tires lose a certain amount of grip
>toward
>the very end of their life, but always thought it was mainly due to heat
>cycling.
>And I never felt that the drop-off in time was anything near that amount,
>although
>I've never tried to quantify it myself.
>
>GH
>
>
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