February Fastrack

ITR Wheel size

JeffYoung said:
It came about this way. Someone with a car (I can't remember make but it is not in ITR) claims that only 16X7s came on the car. So technically he can't run his stock wheel size (I believe only ITR has the allowance for max 17" diamater OR stock, whichever is larger).

That prompted a discussion about wheel size and one of the points made is exactly what Grafton said -- diameter on a wheel is basically cheap gearing.

I'm presonally opposed to the change but willing to listen. Opening up width is where the dollars are in my view. Diameter might have some impact on handling due to sidewall size and strength of various profile tires, but overall, not a lot of change (in my opinion) to performance other than, again, cheap gearing.

I don't see a need, but let's hear what others have to say.
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Jeff,

I believe that is incorrect. In Errors and Omissions of FastTrack of October 2010: "Improved Turing ITR #2477 (David Karably) wheel size. The wheel diameter rules have not changed. ITR is allowed any wheel up to 17inch."

GCR IT rules: D 7 Wheels and Tires, a.1 states in the last sentence, "Cars classified in ITR may utilize any wheel diameter up to 17" or retain their stock diameter wheels if larger."

The wording I see allows any size up to 17", including those smaller than stock.

I could be wrong.

Bill:024:
 
Bill, thanks -- but I think that was my point.

Only an ITR car can run larger than the mandated diameter size wheels if they came stock. For S/A/B, that's 15, and R 17. An R car that came with 18" diameter wheels can run them, but an S car that came with 17" wheels cannot.

There used to be a prohibition on running smaller than stock but I don't think that is there anymore. I'll look -- I think I drafted the first take on it a while back.

billf said:
Jeff,

I believe that is incorrect. In Errors and Omissions of FastTrack of October 2010: "Improved Turing ITR #2477 (David Karably) wheel size. The wheel diameter rules have not changed. ITR is allowed any wheel up to 17inch."

GCR IT rules: D 7 Wheels and Tires, a.1 states in the last sentence, "Cars classified in ITR may utilize any wheel diameter up to 17" or retain their stock diameter wheels if larger."

The wording I see allows any size up to 17", including those smaller than stock.

I could be wrong.

Bill:024:
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benspeed said:
Ahhhh - you guys know I've got a '98 Boxster all tuned up and ready to go - just add cage and go! Always seek to optimize the rules for your car if you can - part of the racing game...

But seriously - I'd take my 968 over the '98 Boxster in ITR - no chance of the Box beating it. The AADD (automotive attention deficit disorder) that I have been diagnosed with will stay in check for this season.

The 2.7 motor in STU - that's a big money motor to run up front with pretty limited R&D done to date. The Boxster will struggle on the big tracks but could be a front runner at the twisties...
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If my boss would get off his a$$ and get the suspension ordered for the Boxster, I could get it done. I have driven the car at Road A on 88k mile stock suspension and street tires. I was very impressed with it. I was doing 100mph down the esses and did 130mph going into 10a. I had to lift early because the car was unstable because of the blown struts. I never got out of 4th gear. This was with 16in rims. I would love to put 15x8.5 on it and run the 275/35/15 Hoosier. I think the Boxster will be a fine ITR car.
 
That is great to hear. I'm a huge fan of the Box and bought one new in 97. I bought the 98 and tested it for ITR but thought it was not there on power for the class - research showed little motor development has been done under IT rules so I decided to look at the 968. So far I'm very pleased with the 968 and look forward to seeing who puts the first Box in ITR.
 
I'm new to IT, but for what its worth, I support allowing alternative wheel diameter options in IT. Having just bought an SSC Protege MP3 which is in process of turning into an ITA car. Who knows how competitive it will be, but the car certainly in theory has potential.

It seems silly to run a 17 inch wheel (only size available for the MP3) on a car where it really isn't necessary. Similar to some of the newer cars in Touring which is where I have most of my experience, the larger wheels are mostly cosmetic, add a significant amount of weight and add expense to tires.
 
JeffYoung said:
Bill, thanks -- but I think that was my point.

Only an ITR car can run larger than the mandated diameter size wheels if they came stock. For S/A/B, that's 15, and R 17. An R car that came with 18" diameter wheels can run them, but an S car that came Iwith 17" wheels cannot.

There used to be a prohibition on running smaller than stock but I don't think that is there anymore. I'll look -- I think I drafted the first take on it a while back.
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As I said in my prior post, the ITA Z3 with the four cylinder motor only came with 16x7 rims. It's probably one of the few in ITA with this allowance.
 
benspeed said:
That is great to hear. I'm a huge fan of the Box and bought one new in 97. I bought the 98 and tested it for ITR but thought it was not there on power for the class - research showed little motor development has been done under IT rules...
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Speedsource ran them in GAC a while back, I bet they have the scoop, though they'll surely prefer the Rx-8.
 
dickita15 said:
Jeff is right I proved it could be done if you accept all the judgments I made during the build. But even so should someone have to spend that kind of effort to get a car to weight? I really do not think it should be necessary in a class that has IT’s philosophy. It really is not something a sane person would do. :blink:
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Exactly. I've got a Mustang that will never make its 2670 minimum weight.

I'm at the point where sanity and insanity begin to blur.

I'm qualifying at only 104-105% (ave.) of the fastest ITR cars.

I'm currently at 2935, should be able to get another 70 pounds out of the car. That's if I desire to spend several thousand dollars replacing the cage with lighter chrome moly, getting an ultra-light seat, replacing the panhard bar with some other rear axle locating device, and scraping/pulling what VERY little is left to remove.

I'm not in this sport to screw around, drink beer and dilly-dally in the paddock. I want to raise hell at the front.

But it sure won't be in my car...

No tears for me, please. I'm the guinea pig in the Great 3.8 Mustang ITR Experiment. :D
 
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On the wheels thing -- sorry Jeff, but you've got some things wrong.

The request that was the genesis of the Fastrack question was to allow smaller wheels than stock on the Protege MP3 (which is not an ITR car). Stock was 17". The easy answer is "no" since as a general practice we are not wild about line-item exceptions ... but it got to a pretty involved conversation about the current rule and its seemingly arcane complexity which probably doesn't accomplish much. If anything was to change, the idea was that simplifying the rule would probably be the best approach. Eventually we got ourselves all twisted around in circles and it was suggested by a CRB member that we ask all of you for input.

The current rules state, basically (the wording is more complex than this in the book):

In ITR: you can use ANY SIZE up to 17". If your car came with larger than 17", you can use that.

In ITS/ITA/ITB/ITC: You cannot use smaller than stock, and stock is the size listed on the spec line. You can use a larger size up to 15" if stock was less than 15". If stock was more than 15", then you are limited to that size.
 
You know on the wheel thing I am not sure why we need to restrict diameter at all. In some categories they are use wheel size to control brakes but that is not a factor for us. As has been said gearing is open anyway, ride height is already limited. I suppose you could argue whenever we add options we add to the testing cost of the full out efforts but I think we are more likely to see some people who can save by using more easily available or cheaper wheels and tires.
 
I'm pretty sure that is exactly what I said -- request came in because a non-ITR car had stock wheels larger than 15".

I do agree the choice is between a blanket change to the rule, or line item exceptions.

We did briefly talk about gearing, and need to discuss that here, because it is one of the consequences of the rule change.

Andy/Jake/Dick -- my point was not t focus on the ITA RX7 specifically, but to use it as an example. Lots of people said it couldn't get to min weight and it did. The ITR MX-5 is close enough to curb weight that we think it possible it can do so in ITR.

Chris, no offense, but I've seen your car and there is a LOT of weight that can come out of that sucker! Talk to Ron. He seemed to think the 3.8 could get close to 2700ish.

JoshS said:
On the wheels thing -- sorry Jeff, but you've got some things wrong.

The request that was the genesis of the Fastrack question was to allow smaller wheels than stock on the Protege MP3 (which is not an ITR car). Stock was 17". The easy answer is "no" since as a general practice we are not wild about line-item exceptions ... but it got to a pretty involved conversation about the current rule and its seemingly arcane complexity which probably doesn't accomplish much. If anything was to change, the idea was that simplifying the rule would probably be the best approach. Eventually we got ourselves all twisted around in circles and it was suggested by a CRB member that we ask all of you for input.

The current rules state, basically (the wording is more complex than this in the book):

In ITR: you can use ANY SIZE up to 17". If your car came with larger than 17", you can use that.

In ITS/ITA/ITB/ITC: You cannot use smaller than stock, and stock is the size listed on the spec line. You can use a larger size up to 15" if stock was less than 15". If stock was more than 15", then you are limited to that size.
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Is there any realistic way to calculate how much of a performance gain their is between using a 6" and 7" wide rim?

Too bad the RX7s aren't in B.
 
Dave we are retilling old ground but the process does not serve the 12a rotary well in B or A. I think the difference between 6’s and 7’s would be more on tight tracks like we run on here. One of the problems with moving the RX to B is that at the B weight about half the cars built would not pass the cage rules. The only way it could have been done is with Dual Classification. I do not have a problem with DP for tweeners but many disagree.

The time top do anything about the RX7 is long since past. We as a club blew it and the invention of IT7 is proof that the system failed the car.

Call it a lesson learned and move on
 
JeffYoung said:
Chris, no offense, but I've seen your car and there is a LOT of weight that can come out of that sucker! Talk to Ron. He seemed to think the 3.8 could get close to 2700ish.
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Well, much of what you saw is now gone. Also, I spent an entire day at a race prep shop creating a laundry list of things to do to reduce weight and the end result wasn't encouraging. Plus, I've had people with some SERIOUS racing and car building cred practically beg me not to throw any more money at the car, and one of them is a trusted friend who doubles as a valued sponsor.

Look, I'm not being negative, just realistic. I still get sporadic email inquiries from individuals interested in building one of these cars. I tell them to think carefully if they want to go the SN-95 Mustang route in ITR. But I also tell them that if they're looking to race a car in IT's fastest class that will be relatively dirt cheap to build and maintain, while putting down respectable, if not fast lap times, then look no further...
 
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dickita15 said:
One of the problems with moving the RX to B is that at the B weight about half the cars built would not pass the cage rules.
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what would the ITB weight be, theoretically? I figure it would be in the 2600-2650 range, which under the current cage rules is still 1.50/0.095" - it used to be that you'd go to 0.120" wall at (I think) 2500#.

I'd bet wheel sizes and the lack of a need to change classes due to IT7 is the best reason to not reclass the RX7, and the disappearance of 12A parts I keep hearing about mean its days are likely numbered anyhow.
 
Chip42 said:
but you can find 15x6 wheels more readily than you can 16x6, and tires are cheaper there too. VW also runs a slightly less common lug pattern so the wheel options are further reduced for THAT car.

point is, allow whatever diameter wheel a competitor wants. what's the harm / clash with the philosophy?
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Whoops. I thought the NB had the same 15x6 minimum stock size as the Golf and Jetta share it's chassis. My mistake.
 
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