street class wheel size rule interpretation question

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SafetyThird
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street class wheel size rule interpretation question

Postby SafetyThird » Sat May 06, 2017 8:32 am

I've seen the statement that the wheel width must be the same size as standard. I have also seen references to wheel width that could be purchased from the manufacture for that model as an option. I'm trying to determine if it is acceptable to have a wheel width that is available to the make of the car, but not the exact package. Here's my situation. 19 inch tires cost much more than 18 inch tires. I've acquired a set of 18 by 8.5 wheels. Yet my vehicle came OEM with 19x8.5 fronts, and 19x9 rear. However other variations of G37 did include 18x8.5 wheels, just not the G37S.

If it is acceptable to the rules for street class for me to use these wheels of different (smaller) width, then I'll likely put some 200 TW on them...

If its not acceptable to the rules for street class, then I'll likely have to face the fact that I'll have to shell out real money to buy wheels of appropriate width . . .

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Re: street class wheel size rule interpretation question

Postby glenthompson » Sat May 06, 2017 10:34 am

If you want to adopt one feature of an optional package, you have to adopt all of the package. That means that if the desired wheel size was in a package that included different shocks the. You would have to change the shocks.
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Re: street class wheel size rule interpretation question

Postby BFisch06 » Sat May 06, 2017 6:31 pm

From the 2017 SCCA National Solo Rules (Page 62)
13.4 WHEELS
Any type wheel may be used provided it complies with the following:
A. It is the same width as standard and as installed it does not have an offset more than ±7.00 mm (±0.275”) from a standard wheel for the car. The resultant change in track dimensions is allowed.
B. Wheel (rim) diameter may be increased or decreased 1" from the standard part.


So do you have a full set of 18x8.5? Moving from a 19" wheel to a 18" wheel with the same width seems to be allowed.
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Re: street class wheel size rule interpretation question

Postby hklvette » Sat May 06, 2017 6:48 pm

If the G37S was not available with 8.5" wide wheels all around in any configuration, then you may not use them. What differences were/ are there between the S and non-S aside from the wheels?
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Re: street class wheel size rule interpretation question

Postby diggles240 » Sat May 06, 2017 8:14 pm

It looks like the 8.5" width wheel is for for the rear only.

Sedan OEM wheel specs

G37 Sport and G37x Sport
Front: 18"x7.5". Cast aluminum-alloy. Bolt pattern 5x114.3 Offset +45

Rear: 18"x8.5". Cast aluminum-alloy. Bolt pattern 5x114.3 Offset +50
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Re: street class wheel size rule interpretation question

Postby SafetyThird » Sun May 07, 2017 7:33 am

That answers my question (meaning, I can't use the 18 inchers I bought and stay in F street).

--- here are the original G37S measurements

OEM 19" 10 spoke G37 Sport wheels & tires

Front:
Wheels: 19"x8.5". Cast aluminum. Made for Nissan/Infiniti by Enkei. Weight: 26.5 lbs. Bolt pattern 114.3 x 5 Offset +43
Tires: Bridgestone Potenza RE050A 225/45/19 92W. UTQG 140AA, weight 27 lbs., tread depth 10/32"

Rear:
Wheels: 19"x9". Cast aluminum. Made for Nissan/Infiniti byEnkei. Weight: 27.5 lbs. Bolt pattern 114.3 x 5. Offset +45
Tires: Bridgestone Potenza RE050A 245/40/19 94W. UTQG 140AA, weight 30 lbs., tread depth 10/32"

--I've been running Michelin PSS (300 TW) as they cost less than the Potenza

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Re: street class wheel size rule interpretation question

Postby Julius-X » Fri May 19, 2017 2:22 pm

If both trim levels fall within the same class, then wouldn't any OEM wheel for the car be acceptable? Plus, Street class already has an allowance of moving ±1" in diameter. (This would conceivably allow 17-20" diameter since the car came with 18" and 19"

There is no special classing for the G37S vs the G37, so the only problem with this is that it moves from a staggered setup to a square one. However since some trims already used the 8.5" wheel in the rear the only problem to me would be that the wheel stays within the offset requirement.
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Re: street class wheel size rule interpretation question

Postby tehmaxfactr » Tue May 23, 2017 9:41 am

Julius-X wrote:If both trim levels fall within the same class, then wouldn't any OEM wheel for the car be acceptable? Plus, Street class already has an allowance of moving ±1" in diameter. (This would conceivably allow 17-20" diameter since the car came with 18" and 19"

There is no special classing for the G37S vs the G37, so the only problem with this is that it moves from a staggered setup to a square one. However since some trims already used the 8.5" wheel in the rear the only problem to me would be that the wheel stays within the offset requirement.


No, in street class it has to be full package options, no mixing and matching parts between trim levels. could you imagine what the rule book would look like if they had to list every trim package separate?
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Re: street class wheel size rule interpretation question

Postby sjfehr » Tue May 23, 2017 5:19 pm

Yeah, you can't mix & match pieces from different option packages in Street. If you want one thing from an optional package, you need to retrofit the entire package.

There is a new allowance for wheels in Street that lets you change the diameter +1" or -1", but it has to stay the same width and offset must be within 7mm of a standard (factory installed or port installed) option available for your car and trim package. If your vehicle came with 19x8.5 fronts, and 19x9 rear, you could legally run 18x8.5 front and 18x9 rear, provided the offsets were within 7mm. (That's what I'm doing with my Boxster this year; I had an inexpensive set of Forgestars made in 18" but matching 19" width & offset.)


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