I have a CRX Si and will be setting up my car for AutoCross. I will be getting Rota Wheels which weigh in about 12 Lbs. but I'm not sure what size yet. Just got H&R Race Springs which will lower me about 2.25 inches. Anybody got any ideas...? thanks.

 

Be prepared to get blasted with, "you should learn to drive before doing anything to your car responses".

Let me qualify/disqualify myself first. I'm pretty much a novice/intermediate autocrosser. Even though I've been deemed "instructor" at some local venues, I still feel I have lots and lots to learn.

With that out of the way. What have you done to the car so far? The reason I ask is that if your car is close to stock, then leave it that way until you're ready to dump a fairly large chunk of change to be competitive in your class. If you do not have an engine swap or a turbo, you'll most likely be placed in CSP ("C" Street Prepared). To be competitive in this class your car will, over time, become closer to a trailer queen. This is all based on SCCA rules. However NASA and some other clubs may have more progressive rules.

I'm assuming because you're asking about the "best" size that being competitive is important to you. Since us two seater guys aren't eligible for STS, then CSP is the next class from stock.

If you decide to go into CSP, and all you have are springs and wheels, be prepared to lose on a regular basis. If you can handle that, then I'll tell you that most guys in CSP are running 13x8s or 13x9s. Rota Wheels I think if I can remember correctly are 15x6.5, which is a perfect wheel size for STS and STX, but not the choice for CSP. The smaller diameter wheel size basically changes the gear ratio of the car.

This is my second full season of autocrossing, I purchased a set of 14x7s thinking I'd eventually get into IT racing and didn't really care that much about being super competitive. I also had them mount a set of 195/55/14 Victroracers full tread and heat cycled. Most would probably give different advice about this, but I figured, full tread, more tire life, and I also do track days.

As of right now, my benchmark for CSP in my region is a guy who places mid-pack nationally. I'm on average about 1.5 seconds behind him on a 30 to 40 second course.

Springs definitely help, but the Konis made the springs really come to life!

I'm not sure if this is exactly what you wanted to hear, but I guess I just went stream-of-conscience on ya.

Good luck and remember the driver is most important modification, and ride with an instructor whenever you can.

Now to be as direct as possible to your original question... Best tire size? There are a couple of factors, back spacing and size of the rim will also affect this. After doing a bit of research for my rim size 14x7, I've found that I can go up to 205s without having to worry about shaving the inside of the fender well. However this is "book" knowledge and not first-hand.

Good luck and have fun, afterall that's what it's all about. Feel free to email me with any specific questions.

Damn I hate when I sign twice.


Modified by emwavey at 1:09 AM 7/10/2003

 

If you buy the rotas, youre STARTING in CSP...and it doesn't matter which tires you get, since your 15s or whatever size will be too big to be near the front of the pack...

 

Well, the main reason is I want to eventually get into it and wanna avoid having to buy another set of tires... Not sure if I understood correctly though, will smaller tire size put me in a more competitive category...? I'm actually thinking of going with the 15's now. What do you think..? All I'll have aftermarket is springs,shocks and those tires. And where can I get the rules...? Thanks for the help so far, I really apreciate it.

 

Pseudo's point was (assuming you auto-x with the SCCA or someone who bases their ruleset similarly) that changing the wheels to a non-stock diameter automatically excludes you from Stock class.

You will most likely be in Street Prepared, where everyone competitive is using 13x8 to 13x9's. Technically, you can go up or down in size, since its free. But everyone is trying to shorten their gearing for acceleration (given the relative few amount of power mods allowed), so they typically go down in diameter.

Given some of your engine machining mods (if you have a stock motor) you may or may not have exceeded the allowable SP limits. In that case or if you have a swaped motor (B-series, ZC, anything non-US) you will be StreetMod2.

This link is also in the sticky at the top of this forum:
http://www.moutons.org/sccasolo/

 

Dont waste money on Rotas. If on a tight budget, and assuming you have some decent seat time behind you already, get some cheap 13x8s like Diamonds with 215 or 235-45-13 Kumhos. And definetely look into getting some Konis for those H&Rs.

Also, you should consider running the car as is with whatever tires are on there or getting some 205-55-14 Kumhos, Toyos whatever. Even some cheap used ones will do the job in the beginning....Ask people in your club, as there is allways someone that has some used r-tires lying around.

 

https://honda-tech.com/zerothread?id=556102

tony is selling his 13x8's for a steal, if they aren't already sold.

nate

 

Are you setting up a USDM SI, or the JDM SiR that's in your sig?

If you're trying to race the SiR, you're pretty much screwed from the start. B16a with shaved / ported head is gonna put you in a class with all of the gutted trailer queens and you're not gonna have a chance.

If you're setting up a US Si, don't put the H&Rs on it yet!! also, don't do ANYTHING to the engine yet until you check the rulebook. Get some good shocks, (Koni adj are best, KYB or Tolico adj are ok) get your rotas in a factory size or just use the rotas for street and get some factory steelies for racing. get the tires as wide and short as you can. the width for better traction, the height to lower the gear ratio and give you quicker acceleration. then enter in G stock where you can be competitive.

Don't worry about planning ahead for a tire size that you'll be needing for a higher class later, you'll have these tires worn out and need new ones by the time you're at that point anyway.