Long time lurker. First time poster here. Apologies if I'm beating a dead horse, but either my search fu is weak, or my questions haven't been answered yet.

So, after being absent from Autocross for a while, I plan to campaign my 350Z next season at one or more of the local clubs. However, it looks like there's been a few changes to the rule book since I last campaigned the Z back in 2008 or 2009 - most notably the stock class appears to have been replaced by the Street Category with some new regulations. And since my car is bone stock, that's likely the category I want to race in next year.

1st question: I notice that we are now allowed to go up or down 1" in diameter, but I don't see anything about whether we need to keep stock widths. Do I need to maintain the stock width if I were to go up to 18" or am I allowed to increase or decrease width as I see fit (so long as I'm +/- .25" offset of course)?

2nd question: Regarding the +/- 1" diameter change does that mean that I'll only be able to go +/- from the 17" diameter that was stock for my Base model? Or would I be able to go up to 19" or 20" since (I think) the larger wheels were offered as a factory option for the Base model?

3rd question: I don't remember the minimum treadwear rating rule. Since that rules out R-compounds, are there any "cheater" tires left for this class? Or will it be better balanced since most people will now be running RE11/Star Spec/Rival tires now?

Lastly: I read through the rule book, but I'm wondering if there are any "gotchas" that I should watch out for next year that somebody who hasn't raced in a while may need to watch out for?

Apologies if I'm beating a dead horse here. I've been looking for a little while now to try to answer my questions (including the big wheel/tire thread - a lot of great info but not many people stating what class they are running in) but still have ended up with some unanswered questions.

Thanks again to everybody for the help.

 

1) Stock wheel width.

2) The reference point for "stock" wheels is whatever the manufacture specifies for the version of the vehicle you have. As before, you can do an option package conversion, but it has to be complete. (Not just the wheels)

3) At the moment, I know of no "cheater" street tires. There was a specific-size Toyo that fit that description last year, but it is no longer legal due to the move to 200 tread-wear.

Only other difference between now and race-tired stock classes I can think of would be the ability to choose which sway bar you replace. Front or back is your choice...but it's either or. (not both)

 

Umm....Toyo rebranded the R1R to 200tw to skirt the tw change for this year. True Story.

 

A lot of tire manufacturers have "magically" discovered that their 140 and 180 treadwear tires actually are 200 treadwear now.

 

Thanks for the clarification help guys.

I've been out of the game long enough that I have no expectations of competing nationally (is the 350Z even competitive in C Street?), but a wise auto crosser once told me to pick a class and stay with it. And that's likely CS next year.

I do like that they loosened up a bit on minor things like headlight replacements. After experiencing the LED headlights of my '15 STI, I'm thinking about doing some experimenting on my lights this winter.

So, are we sure that the track wheels weren't offered as a factory option for the base Z's? I'd love to use those track model wheels I have sitting in my basement.

 

I think the open diff is your biggest problem from a parts standpoint.

 

With the removal of R compounds from street class, I might be inclined to agree now. Previously, however, I knew of at least 2 guys at local clubs running R compounds. In both cars, the tires seemed to overpower the crappy stock LSD anyway.

But, if I were to move up to a class that allowed an aftermarket LSD, I'd probably buy some R compounds first anyway.

 

They were underdriving if they were not killing the inside tires...regardless of set-up/tires.