205/50/15 R7 on a 15x9 does not fit the 226mm template.

edit

Dude...

Yes. The 205 R7 must be run on an 8 to fit within the 226 template. The ST5 thread has some measurements of various tires and wheel widths in it.

2019 rules are now official, no longer provisional.
The calculator is live. https://form.jotform.com/drivenasa/s...ification-form

A few more cars have been added in by Appendix.
Appendix C—Additional ST6 Eligible Vehicle Models The following vehicles are approved to compete in ST6 despite either an OEM HP or engine displacement greater than the listed maximum in Section 4. For the vehicles with engine displacement greater than 2449cc, no modifications to increase displacement are permitted. A 10cc variance from the factory displacement listing shall be permitted, but any vehicle inspected with greater than 10cc over the listed displacement below, shall be disqualified. Engines from these vehicles may only be used as a swap donor to ST6 eligible vehicles of the same model of a different year.
BMW E30 325 (’87-’91) (2494cc)
Ford Focus SVT (’02-’04) (2.0L, 170hp)
Nissan Sentra SE-R (’02-’06) (2489cc)
Nissan Sentra SE-R Spec V (’02-’06)(2489cc)
Porsche 924 S (’87-’88) (2479cc, 8 valve)
Porsche 944 (’83-’88) (2479cc, 8 valve)
Porsche 944 (’89) (2688cc)
Subaru Impreza RS (’98-’01) (2457cc) (AWD)
Subaru Impreza 2.5i (’08-’11)(2457cc) (AWD)

Break points and notable items:

Weight Factors.
<2250 is -.5
2250-2449 is -.4
2450-2549 is -.3
2550-2649 is -.2

Section width/wheel size.
2400lbs opens up the 257mm template. This allows a 205 or 225 Hoosier on 9" wheel, and pretty much every 80-200tw tire in existence.

Raw ratio(easier "raceability" with more raw power and a better ratio)
2250/120 is 18:1 after Aarms and BTM aero. 18.75 raw.
2400/128 is 18:1 after Aarms and BTM aero. 18.75 raw. 9" wheel
2450/131 is 18.1:1 after Aarms and BTM aero. 18.70 raw.
2455/132 is 18:1 after Aarms and BTM aero. 18.60 raw. (Sweet spot IMO. Easy for a healthy stock NB motor with bolt ons.)
2555/138 is 18:1 after Aarms and BTM aero. 18.51 raw.

2555 would be tough to hit without serious forethought and zero weight removal. Ballast rule prohibits simply bolting in 400lbs of steel plate, so you'd have to do things like use full OEM doors, glass windshields, full dash, carry an airbag, OEM hardtop top, etc. Which kills the Cg and polar moment.

You don't make your seat mount out of 1" steel?

Or eat more cheeseburgers.

For sale; my full interior, A/C, power windows, daily driver that took 3rd at champs and can make 2550lbs with ease, especially after you add a cage :p

Weeeeelp I didn't do any ST/TT5 prep OR acquire truck/trialer/SM, so looks like I'm just gonna run TT6 for first event. Just going to run what I already have. Should end up somewhere around...

2450/130avg (don't have txt file yet)
-.7 a-arm
-.3 weight
-.2 ELBJ
+.4 BTM aero

= 18.05

Running over 2400lbs can keep SM7s on 9's. Throwing the RB/SuperMiata sways back on along with steering rack spacers and either gonna drop front rate to 800 (400r) or bring rear back up to 500 (1000f). 400 rear rides a whoooole lot better on the street so kinda leaning towards 800/400 and if it's terribad udersteer on track I can always swap springs around. On 93 not a whole lot different than my TTE* setup, just add 20lbs and get sways back. On TTE* e85 tune I'd be closer to 133avg and full power 135avg, so more weight, but I don't feel like going through the hassle of getting e85 anyways.

If you're putting 1.125"/14mm sways back on and have 1000, 800, 500, 400 springs to choose from, I'd go 800/500.

Thought the consensus, even with sways, was to add a bit more spring up front for hoosiers? Aren't you guys shooting for 900/500 with a the 1.6? I ran 800/500 out of the box, definitely works just fine so could definitely start there. Other than stock sways I really like how 1000/400 feels b/c it basically never tries to step out unless over doing it, super stable.

You're adding a ton of front roll stiffness if you go RB front bar and 1000. My car is that way, and is tight even with a 4" splitter and the wing trimmed out with no gurney.

The SPM S2 I raced last had a standard BGK with 800/500 and 1.125"/14mm bars. It was stellar. Better balance than my 1000/500 car.

By all means play around and test. Run what you like.

No splitter = 800/500

Splitter = 1000/550

Splitter + wide hoosiers = 1100/600

The general recommendations are all good and well, but if 800/500 is best for no aero / 205 hoosier why is Miller spec'd for an extra 100lbs up front with a lighter motor? I also have A/C, so even an extra bit of weight in the wrong places up front. I had no real intention of running 1000lbs with the RB sway, I really don't want to as it blows on the street with that combo and would be overly stiff on our more bumpy tracks for sure, just an inquisitive question.

Rear springs are silly easy to change, so I think I'll just try 800f and both 500/400 rear to satisfy my curiosity and exercise in futility.

You're comparing a race car built to win nationals to your street car ride quality requirements. Even with a B6, It's still a heavy in b. That brings a significant roll and pitch moment. Beyond that Sonny and I simply both prefer the feel of the stiffer front springs.

In any case spring rate recommendations are not written in stone. Every driver has their own preference.

Sure, but that's a pretty lax requirement considering I've been running 1000f and 500-400r for a year or so along with 4.78's. The compromises thusfar are more so in OEM hardtop/glass, full interior (minus passenger seat whici is ESR ballast), A/C, etc which leaves a lot of weight in the wrong places. I was running anywhere from 2480 (full tank) to 2436 (nearly dry) at champs, so my NA is a bit of a porker too :) I ended up about 1.5 seconds off Bubbles with an optimal showing another .7 on the table (shame), so I expect the TT6 rules to play even more in my favor. Stil has street car compromise with no cage and weight in the wrong places, but better than going against a full tilt PTE car, that's for sure.

The driver preference is what I was looking for, really. I thought maybe that was the case, but didn't know if there was some more technical reason. Thanks! Always appreciate the insight from you and team.

I didn't suggest a compromise, you did. You were concerned with ride quality. "Blows on the street". Indicating you like the way it handled but did not like the ride quality on the street therefore you made a compromise. Personal preference. We have met drivers who feel that 450/300 is too stiff and others who like 1000/500 on their daily.

In any case, Miller will be a new case study for us as we have never built anything quite like it. Our 2013 Runoffs NB6 was something like 2150lbs/146whp, 3" splitter and APR GTC-200 (spec). S2's, lighter w more power and a BP.

Got a hold of my dyno txt file and also got the calculator to work. My 93e10 136whp tune comes out to 129avg, so I'll merely be adding 10lbs to my TTE* setup, while getting sway bars back, and send it.

2440 / 129 - .7 - .4 (weight) - .2 (ELBJ) + .4 = 18.01

Fair enough.

Swap to offset LCA bushings instead of ELBJs and you could lose 28lbs,
2412 / 129 -.7 - .4 +.4 = 18.00
Or, lose 9lbs and gain 1whp.
2431 / 130 -.7 - .4 +.4 = 18.00

You're at 129 avg with 136 max? Man I need to put my files into an actual calculator, maybe I have less avg whp than I thought!