2007 Street Tire modifier

[Dean]

I just sent the following to the RenoSCCA Mailing list for those of you not on it...

2 years ago, I did the math between ST and the corresponding SP
classes and found that the actual difference was over 2.5 Seconds per
minute.

There is much speculation that the difference has diminished.

Attached you will find a spreadsheet comparing the ST and SP classes
again. I have included the fastest car in each class, and similar or
identical cars in the trophies at the 2006 Solo Nationals.

I only included normally aspirated cars as forced induction cars in SP
are permitted additional boost. Please note that the difference
classes include AWD, low HP and high HP RWD cars.

As you will see, the difference has not decreased, and may well have increased.

For STS-DSP it is just shy of 2&3/4 seconds per 60 seconds.
For STU-BSP it is actually over 3 seconds per 60 seconds.

For STS2-CSP, it is off the charts. You may say that is because of the
model years for the Miatas. While I agree, I also included the CS
Miata numbers and with our current 2 seconds per 60 second .968
modifier, the STS2 Miatas just barely beat the CS Miatas.

Feel free to go over the numbers yourself, but I think they are pretty
convincing that our current modifier remains very conservative
compared to to the data.

If our intent is to allow ST and R tire cars to compete fairly in the
same class, we may well want to increase the ST modifier to 2.5
seconds per 60 seconds. The data certainly supports that in my
opinion.

[dknv]

I'm going to have to sit down for a bit of time to study the data so that I can better understand what you are talking about. However, I did want to caution that inferring the data is correct based on 2006 Nationals results, is going to result in a flawed evidence base. The new site, compounded by some numbers of drivers changing their tire choice at the last minute due to the surface characteristics, and several other factors I don't have the energy right now to record, may or may not have skewed the data. (Even the participants who WERE there can't agree that there is one, or two, or how many factors there were affecting results. The one thing most can agree on, is that results were unexpected, unpredictable, disparate.)

[Dean]

Data is data. At least we have some. Is it perfect, no... Is it better than nothing, probably. If nothing else, it reinforces the data from 2 years ago from the crappy concrete surface.

There has been one major change in R compounds since then, and one in ST really, so a wash makes sense to me.

I am not strongly advocating going to 2.5 seconds, but it should give the grumblers something to think about.

Get most of SECCS to show up for a club meeting and you could probably get it passed though .

And on weather conditions, etc. I just sent the following to the list as well...
__________________________________________________ _____________

Some people have asked if weather could have played a role or skewed
these numbers.

Yes, it could have, but for the most part it says the gap is even
bigger. For the Miatas and BMWs, the R compounds ran when cold, and
Street Tires when it was warmer, and they were still behind by those
margins.

There was no measurable precipitation for any run group according to
the weather source I have.

Fortunately, all the pairs ran on the same days. Times are at
approximately the second half of their run group based on 2 hour run
groups starting at 8:00 am each day.

BSP: Tues. East Heat 1= 56 degrees@9:00, Wed. West Heat 1 = 61 degrees@9:00
STU: Tues. West Heat 2= 69 degrees @11:00, Wed. East Heat 2 = 66 degrees @11:00
13 & 5 degrees warmer for ST, and still slower by over 3 seconds per 60.

CSP: Thur. West Heat 1= 49 degrees@9:00, Fri. East Heat 1 = 55 degrees@9:00
STS-2: Thur. East Heat 3= 57 degrees @1:00, Fri. West Heat 3 = 66 degrees @1:00
8 & 11 degrees warmer for ST, and still slower by well over 5 seconds per 60.

In DSP vs. STS the weather does slightly favor Race Tires.
DSP: Thur. East Heat 2= 66 degrees@11:00, Fri. West Heat 2 = 59 degrees@11:00
STS: Thur. East Heat 4= 69 degrees @3:00, Fri. West Heat 4 = 70 degrees @3:00
3 & 11 degrees warmer for R, but ST still slower by well over 2.5
seconds per 60.

If you would like to look at humidity and other weather factors, feel
free to check to this site for historical weather data for Topeka.

http://www.wunderground.com/history/...q_statename=NA