Street Touring classes + TIR class?

Zach Hill · **Posted:** Wed May 19, 2010 1:46 pm

The registration page appears to allow Street Touring classes to be selected as PAX adjustment for entries into TIR class. Is this allowed, since the ST classes are, by nature, street-tire-only classes? We even had a driver run TIRSTR at the last event.

I'm hesitant to even bring this up, but I noticed a discrepancy with the new STR class. The PAX multiplier appears to be 0.842, while a B Stock PAX is 0.847. Does this mean that an S2000 gets a better PAX adjustment for running in the more-modified STR class than its stock class? Doesn't quite seem right to me, although if those are the rules, I'll be happy to play by them :lol:

Stephen Westerfield · **Posted:** Wed May 19, 2010 1:55 pm

Zach Hill wrote:

The registration page appears to allow Street Touring classes to be selected as PAX adjustment for entries into TIR class. Is this allowed, since the ST classes are, by nature, street-tire-only classes? We even had a driver run TIRSTR at the last event.

I'm hesitant to even bring this up, but I noticed a discrepancy with the new STR class. The PAX multiplier appears to be 0.842, while a B Stock PAX is 0.847. Does this mean that an S2000 gets a better PAX adjustment for running in the more-modified STR class than its stock class? Doesn't quite seem right to me, although if those are the rules, I'll be happy to play by them :lol:

You are correct Zach. Don't forget PAX numbers are determined assuming fully prepared cars. Fully prepared in stock class means R-comps (and that is why we have a TIR class). In regards to running an ST car in TIR class, that shouldn't happen.

http://www.scca-chicago.com/solo/indexes/rtp2010.html

Dustin Fredrickson · **Posted:** Wed May 19, 2010 1:59 pm

Zach Hill wrote:

We even had a driver run TIRSTR at the last event.

Woops, that shouldn't have happened. TIR is a class only for classes that would otherwise allow R-comp tires only. No ST* cars allowed.

JamesShort · **Posted:** Wed May 19, 2010 1:59 pm

I asked about this because I saw a TIR-STU car in the results in early 09

.

No you can't do TIR-ST*

And a BS S2000 on unlimited width r comps will devour a fully prepped STR S2000 on 255mm street tires.

Think of it this way, let's say there was a class called STR+ that allowed all the suspension and intake/exhaust goodies of regular STR and had no limit on tire width AND allowed Rcomps.....the PAX would be higher than both STR and BS. This hypothetical class would be for all intents and purposes BSP (though there are a few more fun things BSP allows).

So ST* class PAX effectively like taking the stock car and given it suspension, intake, exhaust (etc) mod freedom.....so the PAX would head upward.....then you steal the r comp allowance and tire width allowance and then the PAX plummets to below what the stock class PAX was in the first place....race rubber means a lot

.

With that said, the ST* classes already have r comps taken out of their pax, so going against TIR-*S cars (stock cars) whose pax is the same as what they'd be in true open, the ST* cars have the advantage since their pax already has taken into effect 140+ UTQG rubber.

Stephen Westerfield · **Posted:** Wed May 19, 2010 1:59 pm

You replied before I got my edit in. See above. We shouldn't allow that, but I know my wife (the registrar that was working Saturday) didn't know that.

Zach Hill · **Posted:** Wed May 19, 2010 2:00 pm

Ahh, I had forgotten about race rubber in stock classes. Thanks for the info!

JamesShort wrote:

With that said, the ST* classes already have r comps taken out of their pax, so going against TIR-*S cars (stock cars) whose pax is the same as what they'd be in true open, the ST* cars have the advantage since their pax already has taken into effect 140+ UTQG rubber.

Interesting. After I got to thinking about this, I realized the same thing. I guess this is why TIR isn't an SCCA-approved official class.

Makes my better-than-usual PAX results this past weekend less impressive considering it was my first weekend in a Street Touring class

michaelsmiller · **Posted:** Wed May 19, 2010 11:13 pm

I'm hesitant to even bring this up, but I noticed a discrepancy with the new STR class. The PAX multiplier appears to be 0.842, while a B Stock PAX is 0.847. Does this mean that an S2000 gets a better PAX adjustment for running in the more-modified STR class than its stock class? Doesn't quite seem right to me, although if those are the rules, I'll be happy to play by them :lol:

[/quote]

You are correct Zach. Don't forget PAX numbers are determined assuming fully prepared cars. Fully prepared in stock class means R-comps (and that is why we have a TIR class). In regards to running an ST car in TIR class, that shouldn't happen.

That doesn’t explain why 99 and newer Miata’s pax goes from 0.84 to 0.842 going from R compounds to street tires used in STR. I can’t quite imagine shoe horning 255’s on Dustin’s or my car. Does that mean that the SCCA likes S2K’s but not Miatas? Why do Miatas always get screwed?

JamesShort · **Posted:** Wed May 19, 2010 11:24 pm

michaelsmiller wrote:

That doesn’t explain why 99 and newer Miata’s pax goes from 0.84 to 0.842 going from R compounds to street tires used in STR. I can’t quite imagine shoe horning 255’s on Dustin’s or my car. Does that mean that the SCCA likes S2K’s but not Miatas? Why do Miatas always get screwed?

Just a guess....the wide rcomps on an s2000 in BS help drastically in pure straight ling acceleration and braking compared to an s2000 on street tires given they are heavy (and have a lot of power). The NB/NC possibly don't benefit as immensely on rcomps compared to street tires (relative to the aforementioned s2000)

Think of ST* classes as two parts going from stock to ST*:

1. subtract PAX for the loss of the rcomps and width limitations (s2000s loose A LOT on this loss, whereas the miata does not)

2. add PAX for the addition of suspension/intake/exhaust goodies (the drop in the s2000 PAX due to rcomps is not quite eclipsed by the addition of this factor wheras the miata benefits more from these mods than they loose due to rcomps and therefore this addition eclipses the loss of the previous 'part' of the equation and the STR pax is higher than the CS pax)

Just a hypothesis.

And only NBs with LSD go to STR...non LSD NBs can compete in STS FYI.

Dustin Fredrickson · **Posted:** Thu May 20, 2010 12:27 am

michaelsmiller wrote:

Why do Miatas always get screwed?

One might say that that Miata drivers are used to taking it .... uh, nevermind.

Donnie Barnes · **Posted:** Thu May 20, 2010 8:14 am

The reason 255 is the max width in STR is because that's the biggest size an S2000 comes with. Therefore someone showing up to an event in a brand new S2000 that they've already put coilovers on have a class to race in. Plus it just seems dumb to make the width SMALLER than OE.

So unless you think the S2000 shouldn't be in STR at all, well, it really does make sense. And if you don't think the Miata can compete with an S2000 in STR, well, that's a different argument entirely.

As for "why does the Miata always get screwed", I'd like to point out historically that SCCA autocross classing has had SEVERAL classes at any given time where the Miata is the car to have. ES, CSP, and DP right now, and you could make an argument that they're still competitive in CS depending on the course. *shrug*

--Donnie

Ryan Holton · **Posted:** Thu May 20, 2010 1:38 pm

michaelsmiller wrote:

That doesn’t explain why 99 and newer Miata’s pax goes from 0.84 to 0.842 going from R compounds to street tires used in STR. I can’t quite imagine shoe horning 255’s on Dustin’s or my car. Does that mean that the SCCA likes S2K’s but not Miatas? Why do Miatas always get screwed?

I find it kinda tough to say Miata's get screwed. You have to remember, this is a first year class and I'm sure the first year PAX number was a best guess. It looks to me that, for the Miata, the person who puts the PAX #'s together thinks a STR prepped Miata vs a CS Miata are almost a toss up. That .002 translates to .12 seconds over a 60 second course.

Also, FWIW, 255 are an easy peasy fit on a NC, the CSP guys run the 285's all the time. The NB runs into the problem of no 15" WIDE "hot" street tires. Most 255/245's are 17" and would probably suck for the NB

JasonWatts · **Posted:** Thu May 20, 2010 2:45 pm

Ryan Holton wrote:

michaelsmiller wrote:

That doesn’t explain why 99 and newer Miata’s pax goes from 0.84 to 0.842 going from R compounds to street tires used in STR. I can’t quite imagine shoe horning 255’s on Dustin’s or my car. Does that mean that the SCCA likes S2K’s but not Miatas? Why do Miatas always get screwed?

I find it kinda tough to say Miata's get screwed. You have to remember, this is a first year class and I'm sure the first year PAX number was a best guess. It looks to me that, for the Miata, the person who puts the PAX #'s together thinks a STR prepped Miata vs a CS Miata are almost a toss up. That .002 translates to .12 seconds over a 60 second course.

Also, FWIW, 255 are an easy peasy fit on a NC, the CSP guys run the 285's all the time. The NB runs into the problem of no 15" WIDE "hot" street tires. Most 255/245's are 17" and would probably suck for the NB

I have been looking around in my spare "im bored time". There are two rim choicese that I am aware of that will give me, and dustin a wheel wide enough to squeese a 255 on.

However, as Ryan said, there dont really seem to be any street tires in the 255 range that fit a 15 in rim. (if only there was a way to "shrink" a tire a few inches. I have been told to wait for the hankook as they will be releasing a 255 something 15 soon... then again, soon was said several years ago. Maybe the STR class will give them the motive to push out a 255 and then other makers will hop on the band wagon.

Keith Vail · **Posted:** Thu May 20, 2010 4:18 pm

But Jason you have the perfect NB to put 17's on because you have the 6 speed transmission so it will make your 2nd gear much more usable. I also know you can squeeze 17x9's and a 245 under your 10AE with rolled fenders. :twisted:

JasonWatts wrote:

I have been looking around in my spare "im bored time". There are two rim choicese that I am aware of that will give me, and dustin a wheel wide enough to squeese a 255 on.

However, as Ryan said, there dont really seem to be any street tires in the 255 range that fit a 15 in rim. (if only there was a way to "shrink" a tire a few inches. I have been told to wait for the hankook as they will be releasing a 255 something 15 soon... then again, soon was said several years ago. Maybe the STR class will give them the motive to push out a 255 and then other makers will hop on the band wagon.

JasonWatts · **Posted:** Thu May 20, 2010 4:21 pm

Keith Vail wrote:

But Jason you have the perfect NB to put 17's on because you have the 6 speed transmission so it will make your 2nd gear much more usable. I also know you can squeeze 17x9's and a 245 under your 10AE with rolled fenders. :twisted:

JasonWatts wrote:

I have been looking around in my spare "im bored time". There are two rim choicese that I am aware of that will give me, and dustin a wheel wide enough to squeese a 255 on.

However, as Ryan said, there dont really seem to be any street tires in the 255 range that fit a 15 in rim. (if only there was a way to "shrink" a tire a few inches. I have been told to wait for the hankook as they will be releasing a 255 something 15 soon... then again, soon was said several years ago. Maybe the STR class will give them the motive to push out a 255 and then other makers will hop on the band wagon.

and be looking at an acceleration rate of 1 mile per year? :lol:

I am at least a year away from any purchase to go in any direction. I have wondered if going to a larger rim will hurt me bad enough to not justify the wider tires.

Keith Vail · **Posted:** Thu May 20, 2010 4:30 pm

I believe it would put you in at about the same speed at the top of 2nd gear that the 5 speed cars see on the 15's so you wouldn't be losing anything to a 5 speed car than and you would have more tire to the road. I already did all the math on just about every car in STR. A 10AE on 245/40/17's would have about the best weight per inch of tire compared to every other car in the class.

JasonWatts wrote:

and be looking at an acceleration rate of 1 mile per year? :lol:

I am at least a year away from any purchase to go in any direction. I have wondered if going to a larger rim will hurt me bad enough to not justify the wider tires.

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