Street Tire Modifier
 

Back on Sunday I heard some wimpering. After changing out my Falkens I walked over to the registration area. I listened to the conversation. The Vette folks were debating over the Street Tire time modifier. Is this time modifier set at a national level and what could they really do about but complain. Has anyone run our Subarus with race tires and if they for some crazy reason drop the modifier do you think we would be kinda forced to change to race tires ourselves. A Nissan Z runs against myself and Nick with race tires but can usually only match our time much less put us down by seconds. Any thoughts my knowledge full Subaru addicts?

Two words for people who drive Vettes and complain about Street tires: Luke F'in Kunze. ;) To answer your question, our Street Tire modifier is a regional thing- it is set at board meetings. It is based on past data. Dean can best explain how we arrived at .968 I think.

No, the Street Tire modifier is a regional thing. So, if enough people complain they can change it. Heck, PAX is a regional thing too. The numbers are published by "some guy" but are generally accepted as being decent by flawed and a lot of regions use his numbers.

I think you're missing the point ... that is why they complain!

John Evans is doing an analysis of people who have run on both, he indicated to me that the multiplier was just about correct. Don Smith ran both types of rubber on his miata on saturday and did better on race rubber.

I think it depends on the surface more than anything else. At places like Lovelock and Hawthorne where the surface is smooth slicks would be better, compared to somewhere like Stead which turns into a gravel rally by the last run group.

Dean and Sue ran with street tires on the Miata. I'll have to look at some times to see if any of the Miatas with race tires were even close to Dean's times. I'm guessing that the race tires have a high cost but I don't know yet. I think the red BMW in DSP was running race tires and his times are kick ass. My wallet is starting to hurt just thinking about all of this.

Also the street tire modifier we use assumes that on a 60 second course, race tires are about 2 seconds faster than street tires. The data actually indicates that race tires should be about 2.5 seconds faster. So street tires should actually be at a half second per minute disadvantage even with the modifier.

O, multiplier not modifier said the noob (rookie season almost at its end). :oops:

There is actual math and statistics behind the Street Tire modifier, unlike the PAX factors themselves IMHO.

First, .968 = 2 seconds on a 60 seccond course, no mater the class. 60 x .968 = 58.

The two secconds was originally determined by John Evans based on his own imperical testing.

After listening to whining in 2004, to verify it's validity, I took data from the entire '04 National tour and compared times from ST competitiors and their corresponding SP classes.

The bottom line is that the difference is actually closer to 2.5 seconds per 60 second run ST vs. SP.

I presented this to the club for the 2005 sups to support the .968 number, and there was little if any comment/criticism. The whining only rears it's head when someone is getting their arse kicked by a Street Tire car.

You could redo the math on '05 data, but it would be harder as SP now allows boost mods for forced induction engines that ST doesn't, so you wold have to pick your cars/classes much more carefully than I did.

If anyone cares, I could probably dig up the excel spreadsheet I did the calculatiosn with.

Bingo.

I suppose the Subaru's on Street tires beating the crap out of everyone last weekend didn't help matters any.

In my opinion, street tire cars are at a disadvantage at Stead again, I think the surface has improved enough to give the race tire cars a real edge.

One of my first questions was if anyone has run with race tires on there Subaru. I'm guessing no due to not getting an answer yet. Just thinking of what to do to the Wagon for next season and wanted to get some talk going because I was bored after getting up to the empty house. I asked my dogs about my wagon and they did not care as long as they got in more seat time. :lol:

I think I said this in another thread at some point, but one possible reality is that it is easier to be fast on Street Tires as they are much more forgiving of mistakes, and provide significantly more feedback than an R compound.

But there is nothing preventing anyone from running on Street Tires if they think they are "faster". So to all the whinners.... Shut up and drive....

Yes, Allon did this year, and last at Hawthorne. he drove poorly this year, but last year won PAX in an A Stock STI on race rubber.

http://www.renoscca.com/results/2005...ent_06_pax.htm

And only got beat by a Kart on day 1 because they cheat! :)


http://www.renoscca.com/results/2005...ent_05_pax.htm

I seem to remember the street tire factor being discussed when I first started in 2001. A driver named Chris Dellimagine used to drive an RS (I think) on Falkens, and he did fairly well in pax. The argument at that time, was that the Falkens as street tires were better than what was used as street tires before. The before street tires were what was used to determine the street tire disadvantage multiplier. The argument was that the disadvantage should be made harder, because the street tire compounds were getting better.

Having driven on street and race tires this year, albeit differently set up cars, I do agree that the grip for either is affected depending on where we run.

My take on this is that there are 2 sides to a story. Most of everyone on here would argue in defense of the existing street tire pax. But, it would do some of you good to hear the other side too. And not just in overhearing pieces of a conversation, but in having dialog with those who are complaining.

Also keep in mind, my knowledge of the street tire factor debate back in 2001/2002 is 3rd-hand. If someone wanted to know even more, talk to John Evans directly.

I thought Allon was in a corvette this year?

Fixed it for you! :lol:

Dean is a better driver than many other miata drivers, he can make alot of different cars go fast, no matter if they are on street tires or race tires. Not sure that is worth making a comparison on.

Re: cost of race vs. street tires - it depends on how competitive you want to get. Although they are bigger tires, the Yokohama Advan Neovas we are using for the national events are more $$$'s than the Kumho V710 race rubber.

Unless you want to get super-competitive, or run national events, street tires are probably the way to stay, for Reno Region scca solo events.

Part of me wants to try race rubber, just to see what the difference is.

But yeah, street tires are so much cheaper :p And I think while I'm still learning, its not worth the extra few seconds.

You are correct. I remember it vividly, as my life flashed before my eyes (well, not really, but kinda).

That's my take on it too. A "good" driver will probably PAX higher on street tires than on race tires, while an outstanding National championship-contending driver would probably be better on race tires.

And a Kevin McCormick will be outstanding on street tires. Oh - I guess that's because he competes in a street tire class. lol.

That's right, Allon went from a fast car to a slow one... I remember now. :)

As Street tires get better, so do R compounds. The whinning in earlier years and availability of national tour ST data is what caused me to do the math, and prove them wrong at least statistically speaking.

If Lucas was driving Bob's car all weekend, Subarus wouldn't have had a chance at overall PAX IMHO. :)

And look at the T drivers they are complaining about. young, fast reflexes who spend many hours on the track as well and often drive the car in the exact same setup daily. I don't think some of the whinners drive their car other than at Autocross, and drive trucks the rest of the time. 5-6 minutes every 3-4 weeks can't compare with the seat time some of the T folks log per month...

When the Sac guys show up, they are the real reality check. When a T driver beats a well prepared/driven race tire car, then I will question the T multiplier.

That is true, rounds 7 + 8 this year those guys showed up and gave us all a good old fashioned ass kicking. And they all ran on slicks.

Master should run on race tires....No they cost to much. Master should change his intake....No the stock one works fine. Master should buy a STI....shut up Smeagol your not real.

:lol:

I went with "race" tires, just because they where the exact same price as a set of all seasons, so I figured what the hell. At the level I'm at right now, I think I'm still too much of a noob to use them to there full potential. Thinking about it I would much rather learn on a set of street tires, and when I reached the absolute limit of the car and tires then I would upgrade to a set of race tires. I don't think you can appreciate a mod like that until you've reached the cars limit on street tires.

and if you drive your car to the max on the streets like me and my MINI friends then you are way ahead..!

Two cases in point here, at Hawthorne I got my ass kicked by an STi on V710's. I couldn't come close to matching his times.

Poiunt number two, Pat Riley's S2000. For the whole season he has ran on race tires. I can usually come within 1.5 second of his time. Which gives me the win due to the T modifier. Then on Sunday at Squaw Valley, Pat ran on his street tires. Pat was in average of tow seconds behind me. So, based on this unscientific analysis. I would say that race tires do give you an advantage. In Pat's case, it would seem to give him a 3.5 second faster car.

Agh! I see these kinds of comparisons, and it makes me break out into PMS! At least you qualified it by saying it was an unscientific analysis.

Pat has a RWD and you have an AWD. For Squaw we were at elevation, I think the turbo cars 'suffered' a bit less than non-aspirated. Course layout sometimes affects lap times. Condition of tires, condition of the driver (:lol: ), suspension setup, etc etc etc, affect lap times.

Unless you have quite a bit more data I'd have to take the comment '... give him a 3.5 second faster car" with a grain of salt. No offense.

There is a lot of conditional statements in my post. I am glad you saw them. I am just pointing out, from my point of view, it would appear to be advantagous to run on race tires. Of cource, I can't afford them anyway.

The problem with this direct comparison is that typically, people who normally run on race tires get slower when they switch to street tires, because they tend to overdrive, or underdrive trying to fidn the much lower limits of the street tires. You don't think Pat's V710s give him 3.5 seconds do you?

Again, the statistics from nationally competitive cars/drivers say it is actually about 2.5 seconds per 60 second run. It might well be more or less in an average driver, or averagly(is that a word?) prepared car.

That is another huge contributor to confusion in our region. Very few of the cars are extremly well prepared, and fewer still to the limits of the rules and to make it worse, many of those arent nationally competitive in the class they are running in anyway...

So is a 85% prepared SM Subaru that isn't necessarily even a competitive car in that class nationally on street tires faster than a 64% prepared BP Corvette, or 81% prepared EM Rotafire, or a 92% prepared ASP Corvette on race tires with different drivers using a handicapping system that is largely or partially based on one man's beliefs/opinions and and a somewhat statistically accurate street tire multiplier?

When somebody can plug that into their graphing calculator and get a meaningful answer, come get me. Otherwise, shut up and drive. If you want to realy see if you are faster than someone, pick a car and both drive it, then do the same with the other car. Then at least for those two vehicles on those days, you will have an answer... Or not.