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Discussion Starter · #121 ·
The redrilled 17x9 +45 RPF1s from FM Wheels fit over my Wilwood brakes, but clearing the Fortune Auto 510 struts requires a 5mm wheel spacer. Longer wheel studs are required because the redrilling (or the size) makes them thicker than the factory 17x8 +48 RPF1s from Tirerack that were commonly used by GS autoxers, so there's not enough thread engagement with the wheel spacer.

This is essentially the same problem I have with the Titan 7 rims and the 5mm wheel spacers, so longer wheel studs are making a lot of sense for the front. Pressed for time & money to some extent, so putting off this change for a bit.
 

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Discussion Starter · #122 ·
391777


At this ride height (about 3/4" drop), -3 deg front camber and -2.1 deg rear camber, here is the fender clearance for the 18x9 +38 Titan rims with Bridgestone RE71R 265/35-18 tires. These tires have a 10.7" section width, so likely the Falken RT660 265/35-18 tires will not fit my current setup since their section width is 10.9". The Yokohama A059 in that size has a section width of only 10.6".

As you can see below, after driving home on the RE71R tires, the rear tires gained a fender rub due to the worst highway bumps. I'll see about rolling the fender lip and/or raising the suspension a bit.

391778
391779
 

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Discussion Starter · #123 ·
Quality time testing tires today!

265/35-18 on 9" wide rims vs 255/40-17 on 17"rims. Both sets are RE71R.
Weather: 53F to 63F
5 runs with the 265s, 5 runs with the 255s, and then back to the 265s for 3 runs to confirm results after the weather stabilized.

Conclusions: the 255s are best choice below 60F if you only have 3 runs to get a victory. 60-70F, the 265s are better, but only if you are comfortable with the rear being un-nerving, having a twitchiness. Above 70F, the 265s are clearly best.

I really do like Pepper's balance with the 255s, but the 265s win on ultimate grip. I think the weird twitchy feeling with the 265s when the rear tires are cool is the inside rear wheel lifting... the outside wheel just isn't warm enough to grip correctly.
 

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My first autox on sunday! The weather is supposed to be 65 in the morning, going up to 90 in the afternoon. Is there anything I should be concerned/aware of regarding this temp change? I wasn't worried about not having an IC, before i saw the high temp. No humidity at least.
 

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Discussion Starter · #125 ·

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Discussion Starter · #127 ·

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Discussion Starter · #130 ·
Took these before I left for Lincoln, NE. Looks like there’s more room in front than I thought, but I’ll still need to measure before mounting 255/40-17 tires.

Front strut clearance, 17x9 +45 RPF1
392131


Rear shock clearance, 17x9 +45
392132
 

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Looks like the fronts will be close. My +40 offset wheels with the 255/35's had similar clearance when I was running FA's lower locking collar (the one with the allen screw) because the overall diameter was almost, if not exactly the same as the spring perch. Hopefully the tires clear without issue, or with a very small spacer. The rears look like they have plenty of clearance.
 

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Discussion Starter · #133 · (Edited)
Notes from Lincoln Tour 1 & 2

  1. The driver and the driver's mental state makes the most difference. Perhaps the most dramatic expression of this was in G Street, where Brad McCann had one of the best comebacks of the weekend on Monday.
  2. When I don't trust cold rear tires, I underperform. I'm also not utilizing the full grip in longer turns even when I do trust the rear tires because I'm putting too much value on clean driving lines.
  3. Whatever the power claim for 2.5 liter WRX's in STH, the FoST is not lacking any accleration by comparison. I hit the rev limiter in second gear at the same places as both WRXes (I could watch the first quarter of Tim Miller's runs and all of Julie Heaton's runs)... that's 58 mph for Miller at this event, 58-62 mph for the Heatons (because I forgot to check their tire size), and 62 mph for myself. Miller's WRX is at 3100 lbs, same as Pepper.
  4. Plenty of rain tire choices at the top: Michelin Pilot Sport 4S, Continental Extreme Contact Sport, or Yokohama A052. Note that only one of those is also a good tire for the dry. Falken RT660 are a step down from these. Lots of experiments with other tires & combinations, none of which rose above the noise.
  5. Kumho Ecsta V730 was the surprise tire. Apparently it does not suffer cold rear tire syndrome and handles both cold and hot events. Two problems with it for STH FoST cars is that the largest size is 255/40-17 and it is an awful tire for the wet, so for us it's best placed as the cold & dry tire or the budget dry tire.
  6. Yokohama A052 is the favored Street Touring tire. First runs are nearly as fast as later runs, so works extremely well in cold conditions and also works well in the wet. Lots of sizes available. A proper STH FoST has the negative camber and rim width for them to wear well... it's mostly a matter of getting used to their lazy feel and, I think, dialing in a loose setup.
  7. A potential dry setup to consider that a friend is successfully employing on his HS FiST is Falken 660T on the front with Yokohama A052 on the rear.

Directions & Experiments for Myself
  • Apart from a probable cold dry weather setup with the 255/40-17 Kumhos, 265 tire width is the still the best bet.
  • When the current set of Michelins wear out, I'm probably going to jump the next set up to 265 width from my current 245 width. Crossing my fingers that fuel economy won't suffer much, but it is too important to have the extra contact patch available when wet conditions begin drying to not go wide. Curiously, Michelin does make them in 265/40-17 in addition to the usual 265/35-18.
  • Once I verify the 17" tire clearance (today?!? tomorrow?), I'll put RE-71R tires on the front and A052s on the back. I have both tires, so it's only mounting & balancing costs to test out my friend's setup. Aiming to test the mixed setup on the Friday before Father's Day.
  • Frankenbrake to improve the brake bias.
  • [EDIT - forgot to include this one] Rolling rear fenders to eliminate mild rub when using 265/35-18 on +38 rims.
 

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Discussion Starter · #134 ·
So the 9" rim's outer edges are 10" apart. All the 255-width tires have a section width of 10.2" (most of them) to 10.4" (Falken RT660). Which means they fall 0.1" to 0.2" outside the rim and it looks like there is easily 0.25" to the strut, particularly as the strut angles away from the wheel.

Tire mounting will proceed next week!


Took these before I left for Lincoln, NE. Looks like there’s more room in front than I thought, but I’ll still need to measure before mounting 255/40-17 tires.

Front strut clearance, 17x9 +45 RPF1 View attachment 392131
 

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Discussion Starter · #135 ·
Tire mounting will proceed next week!
Nope, no tire mounting nor tire experiments. Very careful measurement revealed that the Wilwood caliper doesn't quite clear the rim. Yes, you can bolt it on, but then there's interference when you try to spin the wheel. Even if the caliper wasn't in the way, the clearance of the bottom collar on the strut is also questionable. I can't get around the need for a 5mm spacer with these 17x9 RPF1s and that also requires longer wheel studs for these rims. Not a big deal, just an unfortunate delay.

Testing plan for the Friday before Father's Day will now switch to building up the table of ambient temperatures vs. rear tire pressure and then sampling rear shock adjustments.
 

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Discussion Starter · #136 ·
  • Rolling rear fenders to eliminate mild rub when using 265/35-18 on +38 rims.
Crap. There isn't anything to roll under there as it's already flat. Will just have to stay away from big bounces or raise the rear a touch or use something like +40 rims in the rear with 265s.
 

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Discussion Starter · #137 ·
The soft rear swaybar will rotate well when rear tire pressure is 36 psi and fronts are 35ish psi. RE71R, 265/35-18. Air temperature 70-80F.

It was a bit too warm for a proper cold rear tire test. Not going to happen this weekend with climbing temps!
 

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The soft rear swaybar will rotate well when rear tire pressure is 36 psi and fronts are 35ish psi. RE71R, 265/35-18. Air temperature 70-80F.

It was a bit too warm for a proper cold rear tire test. Not going to happen this weekend with climbing temps!
Yeah, I am trying to find a good cornering setup and I swear the rear acts so funny when it's cold. Once they're warmed up it's Sticky McGee and settles super fast. Just kicking myself for not getting the Fortune 510's... I new I wasn't gonna be happy with the 'alternative' set I got (since I wanted gravel-spec's but they were so out of spec it would have done more harm than good to use them, for anything).

You've done some killer runs man! I haven't been on long enough to catch up with everything, but those 'auto-X/road course' runs you're doing look super fun!!
 
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Discussion Starter · #139 · (Edited)
After 41 runs over 3-days & 4 courses, I'm feeling pretty good about the setup, that I'm taking Pepper in the right direction. People say Pepper looks planted, very planted. Tire wear is light compared to GS trim, so light I didn't bother rotating tires this weekend. Not needing to spray water on the RE-71R tires very much unless the runs are absurdly close together, even in 80 degree weather; might spray on last runs when dual driver at a national event.

Pressure in the rear for first run is 31-34 psi depending on air temp and then bumping to 36 psi and not bleeding for subsequent runs. Front pressure is bled to 35 psi until pressure rises are 0.5 psi per run and then I'll set it to 35.5-36 psi. Just wish I could test first run at 60F or below; hoping when I do, it won't be during a big event, LOL!

Will probably add a touch of front toe-out before the Packwood Championship Tour now that I'm trusting what the rear will do. Not that turn-in is slow, but I found I would get behind in steering if I wasn't paying full attention, so a little sauce to make up for my own shortcomings.

After the Tour, I'll likely try some spring adjustments (front & rear) in conjunction with swapping to the Strano rear swaybar on soft.
 

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Discussion Starter · #140 · (Edited)
Interesting what I'm seeing happen in the STH GTI camp with tires...

One guy, Eric Sienkiewicz, is intent on having an 18" / 17" stagger setup with Yokohamas, so he's got:
265 / 235 width​
fronts are 18x9 +45 with 3mm spacer​
rears are 17x8 +45​
Most are running 255 Falkens in either 17" or 18" because, like the ST, they're running into clearance problems with the section width of 265 Falkens. Todd Kunze has a slightly higher ride height to fit the 265 Falkens on his car.
 
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