THSCC Forums

Having switched from 235 Star Specs with 17K on them to 225 Rivals, there are a few distinct differences. Firstly, the turn in on the Rivals seem a bit slower. This may be more noticeable on my car because it's light and the peakiness of the Star Specs may not be as big an issue. Secondly, my very neutral car became pushy. I' m hoping that this was some manifestation of the NCCAR surface. Lastly, it's been years since I have had tires that squealed the way the BFG's did. The Michelins on my wife's mini van being the exception. Overall, I like the tires, I just have to adjust my driving to turning earlier.

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Mike Miller
AutoX VP 2016/2017
Just a C Stock Miata DD
Mazda Speed 3 Family Car
Corvette Z06 Toy

Rev. 2 out in the May Fastrack. I notice the exhaust changes are still there...say goodbye to the turndown?

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Steve Carter
1972 Datsun 240Z-- resto pics at http://picasaweb.google.com/srcartermd
2007 GPW Honda S2000-- STR 86

I personally like this revision. I think in a stock based class having an exhaust follow the stock path is in the spirit of the class. Why I went with a Cat-back ebay special on mine

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2005 Mazda RX8 STX 11

NCR Solo Chair & Cape Fear Chapter Coordinator
http://www.ncrscca.com

I agree...I haven't yet fully configured my exhaust solution, but had planned for a rear exit. It seems philosphically inline with "Street"ability, and won't get you a ticket from the police if you don't want to be under the car pre-event to swap it out.

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Steve Carter
1972 Datsun 240Z-- resto pics at http://picasaweb.google.com/srcartermd
2007 GPW Honda S2000-- STR 86

So I suppose the powerful interests in the SCCA membership overpowered those coming up with the original street class rules, and now they are significantly watered down? Only one sway bar change, i.e. just like now. No camber plates allowed, i.e. just like now. Am I reading the latest FT correctly?

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Current stable:
2019 BMW M2 Competition slicktop 6MT
2011 BMW M3 sedan slicktop 6MT
2007 BMW 328i wagon (slushbox for now)
1975 CanAm 125MX2

Honestly, I think the camber plate removal is a good thing. There are almost *no* camber plates that work with stock springs. WRX/STIs and E36/46 Bimmers are the only ones I know of. So that allowance would give a few select few strut based cars a much greater advantage to the strut cars that only has eccentrics or shims.

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2011/2012 Autox VP
2013/2014.5 President
2013 Top Gun

2015 Fit

22R-EC => 4G63 => D16Y7 + D16Y8 => EJ255 + K24Z2 => K20Z3 + K24Z2 => K24Z2 + M54 => L15B

Personally not a fan of street being granted an allowance to change wheel diameter but Street-R not being granted the same allowance. Sounds like they are intentionally trying to make street R a class that dies quickly. . .

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2012 MX-5 Sport SUV

I need to re-read the new proposed rules for next year. Looks changes might be in the future....

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Rodney

'08 Bullitt mustang, CAM 7
Autox VP '09-'10, President '11-'12, interim President 2nd half of ‘14
proud recipient of the Bowie Grey service award '12
Now just a guy driving a mustang....

Its pretty simple:

All current 2013 rules, except

140 tw tires for 2014, 200tw for 2015 (Except for SS, they get to keep R's if they keep numbers at Nats)
+/- 1" Wheel Diameter
Some class shuffling

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02 Focus SVT
STF 9

Question for the Mustang guys that have run TIRE, etc. on the better 140 TW (soon to be 200) tires, do you get to use full throttle a "decent" amount in autox? The Michelin PSS appears to be almost as good as the best new 200 TW tires, comes in the 235/50 x 18 stock size for my 5.0, and would be a great, but pricey, general use tire suitable for occasional autox.

Thanks,

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Dick Rasmussen

FS 50 2018 Mustang GT

Dick,

I've been using the new BFG Rivals, (tw = 200), and they hook up like crazy coming off elements. I'm super impressed with these tires on the M3. I've continually underestimated the power they will take so far as I've only run 3 autocrosses with the E90 M3 (414hp, 3540 lbs). If your wheels are wide enough, maybe the 275/35-18 or 295/35-18 Rivals would work?

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Current stable:
2019 BMW M2 Competition slicktop 6MT
2011 BMW M3 sedan slicktop 6MT
2007 BMW 328i wagon (slushbox for now)
1975 CanAm 125MX2

Dick,

Although I have only put 100 miles or so on them, I am thoroughly impressed with my BFG Rival's. Chuck's assessment is probably more relevant for you given the size of car, but my sentiments match his. I can say that the grip and feel is on par with my old NT-01's. The Rival's are far more pleasant on the street both in noise and ride quality. I gave them a brief workout on a road that dead ends into a cul-de-sac in an industrial park and in addition to the street miles they still look like new with some of the small flashing lines still in place on the tread. Maybe I am caught up in the hype, but these tires have impressed me all around so far. I can't wait to see how they perform this weekend at NCCAR in the DRY.

Size wise, from what I have read, you may be better off staying with a tread width that is closer to your rim width or even less. In the Miata community, they are faster with a slight stretch, a 225/45/15 on a 9" wheel is faster than the same tire on an 8" wheel. I don't know if that would hold true for your 50 series tire on the Mustang, but it's something to read into.

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92 Miata 1.9L naturally aspirated. SSM 21

Jordan,

I want to learn as much about that aspect of street tires as possible, but there is a serious lack of information/test data out there -- just lots of opinions. Since I could only get 245/40-18 Rivals, I'm using those all around on stock width wheels, 8.5" front, 9.5" rear, and the rears are stretched a nice bit (you can't lay the tire/wheel face down as the wheel hits first, so I have to be careful changing them). The stock M3 front is this size, and the rear is a 265/40-18 (or with the 19" wheels, 245/35F, 265/35R).

I have planned to go to 275/35-18 all around after I wear these out (which is apparently going to take longer than I expected) as I feel like I could definitely use more tire in the rear at times even given how well the 245s are working. Compare that to Rich Wiese in the St Louis region with an E90 M3 F-stock car (consistently PAXing 1st or so) with Hoosiers: 295/30-18 front and 315/30 rears.

I can "feel" the nice taught rear tires in transitions it seems as there is no feeling of sidewall flex at all, just a nice, taught response. That is definitely one nice thing about a bit of stretch, the gain in sidewall spring rate. I guess I'll find out what happens when I make the switch to 275/35 all around...

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Current stable:
2019 BMW M2 Competition slicktop 6MT
2011 BMW M3 sedan slicktop 6MT
2007 BMW 328i wagon (slushbox for now)
1975 CanAm 125MX2

"emilio700" has done most of the legwork on the Miatas for tire/wheel size research. He's the owner of 949racing and a pretty damn good driver to boot. His info is almost always well researched and backed by data. He often posts on 'miataturbo.net', which is a pretty terrible forum, there are about 20 people who know what they're talking about on there and another 100 or so that just follow them around repeating what they've heard with limited understanding. emilio700 and savington are really the only two guys on there I listen to without checking all of their work. Both are respectable shop owners that actually develop products.

The general rule of thumb Emilio came up with is that radial tires are fastest when the carcass and wheel size are the same. His research is focused on track cars though, so things may get wonky in autocross.

That is pretty similar to the conclusion Andy Hollis has came to as well, try to stay less than an inch away tread width to rim width.

On my old red 240sx, it was night and day difference going from an 8" to a 9" wheel with 245's (9.1" tread width). Similar to the "taught" feeling you describe now with your 245's.

YMMV

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02 Focus SVT
STF 9