Wheel diameter rule change Poll

[Geo]

Originally posted by Banzai240:
Shorter sidewall means less flex which means more stable contact patch.

Which has more to do with feel than actual performance.

Originally posted by Banzai240:
So, even though your 13" combo may have a larger tread width compared to your original example, less of that tread is staying in contact with the pavement because your sidewalls aren't stable enough to keep it there...

<snip>

Originally posted by Banzai240:
Larger diameter wheel + shorter sidewall + larger contact patch means more stable sidewalls + less flex means more contact patch remains in contact which translates to better handling which gives higher exit speeds which yields faster straightaway speeds which negates the need for lower gearing which equates to me kicking your ass!

I'm not so sure you have that right teach. My understanding is that the contact patch size will remain the same. The shape will vary some. The feel will certainly change, but tests show that it's very arguable that there is any performance benefit.

It's kind of like swaybars. They do not make a car corner faster. They transfer load quicker (and allow you to alter f/r characteristics, but that's another story), but they do not increase grip. They change feel. Anyway, like a car w/o swaybars takes a while to take a set, so do tires will taller sidewalls. Assuming the suspension is set up correctly, and the sidewalls are not so tall that the car is actually cornering on the sidewalls, the cornering speed should be pretty much the same. It will just feel different as the car takes a set. That is my understanding of the issue.

[/B][/QUOTE]



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George Roffe
Houston, TX
84 944 ITS car under construction
92 ITS Sentra SE-R occasionally borrowed
http://www.nissport.com

 

[Greg Amy]

All sarcasm aside, Darin, I really, really, really don't care about this issue on a personal level, as I have the wheels and tires I need (yes, Geo, I know: "now"). Even if I didn't, I'd want to buy the best I could and that would be Panasports, and I'm gonna pay through the nose for them regardless of the diameter.

However, I see some distinctly inconsistently-applied ideals here, and that troubles me:

- Sam is told that his 14" wheels won't be obsoleted, yet I'm told 15" wheels are a distinct performance advantage ("...equates to me kicking your ass...);
- I'm told that less than 5% of us has the talent to notice the difference in performance between 14" and 15" wheels yet at the same time I'm told I have to spend all that money to get the nth degree of performance before I can prove my car is uncompetitive and must be re-classified (or PCA'd);
- I'm told I should accept a scale of economy over a performance advantage ("perceived or otherwise") any day yet I'm told that unless I spend the money I can't bitch about my ass being kicked;
- I'm told allowing 15" wheels will reduce the cost of the class, yet it's OK to make all the 14" wheels people currnently use obsolete. But wait, it's not a performance advantage, no wait yes it is, no wait it's not, yes it is, no it's not...

AAAAAAAAAHHHHHHHHHHHHHHHHHHHHH!!!!!!!!!!!!!!

What in the hell am I supposed to believe here? What in the hell do YOU believe?

(These are completely rhetorical questions...)

 

[Geo]

Originally posted by grega:
However, I see some distinctly inconsistently-applied ideals here, and that troubles me:

- Sam is told that his 14" wheels won't be obsoleted, yet I'm told 15" wheels are a distinct performance advantage ("...equates to me kicking your ass...);

There are still those who think they are a performance advantage. Controlled tests are pretty inconclusive. So much so that I don't think there is a performance difference. They will feel different, and that could affect an individual driver's performance while not affecting another's.

Originally posted by grega:
- I'm told that less than 5% of us has the talent to notice the difference in performance between 14" and 15" wheels

I know you're not attributing that to me Greg, but I'd like to go on record anyway and say "I didn't say that." In fact, I think they will actually feel different while not actually changing the overall performance.

Originally posted by grega:
- I'm told allowing 15" wheels will reduce the cost of the class, yet it's OK to make all the 14" wheels people currnently use obsolete.

Again, this is related to a perceived performance advantage that controlled tests do not bear out.

Originally posted by grega:
But wait, it's not a performance advantage, no wait yes it is, no wait it's not, yes it is, no it's not...

AAAAAAAAAHHHHHHHHHHHHHHHHHHHHH!!!!!!!!!!!!!!

What in the hell am I supposed to believe here? What in the hell do YOU believe?

All good points Greg. I think you already know what you believe, but you are rightfully making the point that this issue may be getting confusing for some folks.

The controlled tests I refer to are ones done by Grassroots Motorsports and European Car. I don't know the months off-hand but the EC article was a year or so ago and the GRM article was about 3-5 years ago.

For my part....

1) I don't believe there actually is a performance advantage

2) Wheel availability is already very much a serious issue

3) If Panasport decides to stop making 14x7 wheels we're screwed. Then we have to make a decision in a big damned hurry and that is not the way to go about it. We should do this in a controlled fashion and anticipate the loss of availability through Panasport.

4) Again, this does not affect me personally. I can already use 15" wheels and even 16" if I like on my car (I'll be sticking with 15" since I think there is no performance advantage and 15" wheels are significantly cheaper for me).


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George Roffe
Houston, TX
84 944 ITS car under construction
92 ITS Sentra SE-R occasionally borrowed
http://www.nissport.com

 

[ryotko]

The GRM article is available online here http://www.grassrootsmotorsports.com/plustest.html

The results do pretty much favor the larger dia. wheel/tire combos. Something like 2 seconds between 14" -> 17" over an autocross.
...But the tires used were different, 14" were all-season and 15" - 17" were performance tires. So that needs to be taken into account. And you're not talking about autocross here. And one of the testers commented about the 17's "looking the best". And the test was conducted by Tire Rack employees...
So there may have been some incentive to recommend the larger wheels. Come to think of it, the "test" may not have answered many questions at all.
Personally I like 14's but then again my budget doesn't allow the very best of much.
-Bob

 

[lateapex911]

On the sidewall issue, keep in mind that lower profile tires can have better transient response.....but don't allways. It's not apples to apples in every case here folks....

...the old Yoko A001R was a 70 series tire that I did a lot of back to bak testing with, in the same car on the same track on the dsame day with different drivers, and the 60 series version came up short every run for everybody. Consistantly half a second a lap.

Of course, the drivers of F1 cars never stop complaining about the poor transient response of their cars! (sarcasm off)

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Jake Gulick
CarriageHouse Motorsports
ITA 57 RX-7
New England Region
[email protected]

 

[Bill Miller]

I really had to laugh at how quickly Darin gave up his position on the performance advantage of a 15" tire (especially after he thought he did such a good job of proving it) when he realized that he might have just shot himself in the foot. That was priceless Darin, thank you!

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MARRS #25 ITB Rabbit GTI (sold) | MARRS #25 HProd Rabbit
SCCA 279608

 

[Geo]

Originally posted by ryotko:
The results do pretty much favor the larger dia. wheel/tire combos. Something like 2 seconds between 14" -> 17" over an autocross.

The European Car article yielded different results. This was same car, same wheels (except diameter) and same tire. Oh, and on a road course as well.

When you think about it, on an autocross course, you would expect a bit more improvement since so much of autocross is dependent upon transient resonse.


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George Roffe
Houston, TX
84 944 ITS car under construction
92 ITS Sentra SE-R occasionally borrowed
http://www.nissport.com

[This message has been edited by Geo (edited October 09, 2003).]

 

[Banzai240]

Originally posted by Bill Miller:
I really had to laugh at how quickly Darin gave up his position on the performance advantage of a 15" tire (especially after he thought he did such a good job of proving it) when he realized that he might have just shot himself in the foot. That was priceless Darin, thank you!

Again Bill... WTF???

I didn't conceed, or give up anything... WHAT position??? I told my side, and let Greg have his... It's called a "Discussion"... You ought to try it sometime... I wasn't telling Greg how he ought to think, or what he should believe...

What do I have to gain by getting into a pissing match with him? What have YOU gained by trying to get in one with ME?? Do you just like the fight??

Greg wants to know what I believe??? Simple. I believe given the same car, Mine would go faster than Geo's! He can run his 14" wheels and no sway-bars, and I'll run 15" wheels and any sway-bar I choose... all else being equal!

(Sorry George... just couldn't resist...) See... George and I can disagree and still remain peers... It's really OK to do that Bill...

I believe that if 15" wheels were allowed, some would switch, and some wouldn't, but there really wouldn't be that much of a difference in the overall performance of the classes, so the 14" wheels would NOT be obsolete, though, all else being equal (which is RARELY is...) might be at a slight disadvantage... I believe that if you were hell bent on getting to the top, as with EVERYTHING else on your car, you'd likely have to opt for the best tire/wheel combo you had available... I believe...

The reason I let Greg have his is because I've had enough of dragging this shit out for page after page, telling the same story over and over, all for naught... I said what I had to say, and let Greg/George/YOU have yours...

Besides... the more I say, the more you try to find something wrong with it, so I try to be a little selective these days (may be what Greg chooses to call "guyshy"...)

By the way... those Grassroots tests... Did anyone bother to check to see if they adjusted the suspension accordingly to work with the larger diameter tire/wheel combo and the greater "transient response"???

Also, a more stable sidewall means the contact patch is more stable... Basically, the shorter sidewalls won't ROLL OVER onto the sidewalls as easily...

Give up my position....??? PAAALLLLEASSSE...

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Darin E. Jordan
SCCA #273080, OR/NW Regions
Auburn, WA
ITS '97 240SX

[This message has been edited by Banzai240 (edited October 09, 2003).]

 

[Jake]

This is just getting silly with the personal attacks. There is “debate” and “discussions” and then there is “let’s get so and so”. We can debate all day weather larger or smaller diameter wheels are a competitive advantage, but here’s the deal:

Making a large portion of IT depend on ONE manufacturer for wheels is ridiculous.

BTW – I am one of the ones who need 14x7’s. If we opened up wheel diameter what would I do? Probably nothing, I’m too damn cheap. What could I do?

Buy lightweight 15x7 or 15x6.5 wheels that are readily available from many manufacturers for about $100/each. (a purely economic decision) Or buy 13x7 wheels so I can change my gearing because it’s cheaper than changing the final drive ratio in my transaxle. (again – no more of an advantage to what was allowed already – just saves money)

It’s clear that some people thing that going up in diameter is an advantage – some think going down is an advantage – most think it doesn’t matter - and some even think that sidewall height doesn’t matter (I’m looking forward for those 70 series tires on the track!)

But this is an economic thing - not a performance thing. Will it obsolete people’s wheels? No way. It just makes it cheaper for people who need to buy some.

Jake Fisher ITA #28
www.racerjake.com

 

[Jake]

(sorry - double post)

[This message has been edited by Jake (edited October 10, 2003).]

 

[SamITC85]

Jake no flame here, just discussion. You say that it won't make anyones wheels obsolete, but I think it will. Take the Glen for instance. If I am in my ITC rabbit on the back straight I am at as fast as the car can go for a large portion of the staright with 13" wheels. Now my competitor in a similiar car with 15" wheels will be able to go at a faster speed for very close to the same amount of time which means I am at a disadvantage. Now to keep up I need to buy new 15" wheels and tires and I will probably not use any of my 16 13" wheels again. You can replace The Glen with NHIS, Lime Rock and especially Pocono. SO this rule will make my wheels obsolete if I want to be competitive.

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Sam Rolfe
TBR Motorsports
#85 ITC VW Rabbit
#85 GP Scirocco on the way
#11 GP Scirocco on the way

 

[oanglade]

Originally posted by SamITC85:
Jake no flame here, just discussion. You say that it won't make anyones wheels obsolete, but I think it will. Take the Glen for instance. If I am in my ITC rabbit on the back straight I am at as fast as the car can go for a large portion of the staright with 13" wheels. Now my competitor in a similiar car with 15" wheels will be able to go at a faster speed for very close to the same amount of time which means I am at a disadvantage.

How come? I mean, how will that car with the 15" wheels be able to go at a faster speed for very close to the same amount of time?

 

[Banzai240]

Originally posted by SamITC85:
Now my competitor in a similiar car with 15" wheels will be able to go at a faster speed for very close to the same amount of time which means I am at a disadvantage...

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Darin E. Jordan
SCCA #273080, OR/NW Regions
Auburn, WA
ITS '97 240SX

 

[Jake]

Sam - thanks for not flaming - and no flame taken. But like others pointed out - why should 15" wheels make you any faster down the back straight at the glen?

 

[Bill Miller]

Jake,

I think what Sam is talking about is that the car w/ 15's will have 'longer legs', in much the same way you would if you went to a numerically lower final drive ratio.

Which, by the way, is what I've done in the past. I've had multiple gearboxes w/ different final drives for different tracks. It's easy enough to change on a VW (under 2 hours, R&R by myself), and the trannys are pretty cheap (until you start putting Quaifes in them!). In the case of a VW 020 box (works for all the ITC and ITB cars), there are really only two ratios to choose from, unless you want to spend lots of money (well, some may not think $500 is a lot of money, but I do).

I still contend that if you make 15's openly available to all the IT cars, it will hurt the guys who already have 13's and 14's as the tire mfg's will focus on where the larger market is, and I think you'll be left w/ pretty much the same situation you have w/ wheels now, limited options usually for a premium price.

Darin,

Didn't you make a comment to me a couple of weeks ago about a goat?

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MARRS #25 ITB Rabbit GTI (sold) | MARRS #25 HProd Rabbit
SCCA 279608

 

[oanglade]

"I still contend that if you make 15's openly available to all the IT cars, it will hurt the guys who already have 13's and 14's as the tire mfg's will focus on where the larger market is, and I think you'll be left w/ pretty much the same situation you have w/ wheels now, limited options usually for a premium price."

I think this is going to happen anyway as there are less and less 13 or 14 inch wheels available in the market.

 

[Bill Miller]

Originally posted by oanglade:
"I still contend that if you make 15's openly available to all the IT cars, it will hurt the guys who already have 13's and 14's as the tire mfg's will focus on where the larger market is, and I think you'll be left w/ pretty much the same situation you have w/ wheels now, limited options usually for a premium price."

I think this is going to happen anyway as there are less and less 13 or 14 inch wheels available in the market.

So that's a justification to accelerate the process?



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MARRS #25 ITB Rabbit GTI (sold) | MARRS #25 HProd Rabbit
SCCA 279608

 

[Geo]

Originally posted by SamITC85:
Jake no flame here, just discussion. You say that it won't make anyones wheels obsolete, but I think it will. Take the Glen for instance. If I am in my ITC rabbit on the back straight I am at as fast as the car can go for a large portion of the staright with 13" wheels. Now my competitor in a similiar car with 15" wheels will be able to go at a faster speed for very close to the same amount of time which means I am at a disadvantage. Now to keep up I need to buy new 15" wheels and tires and I will probably not use any of my 16 13" wheels again.

Or, you can just buy larger diameter tires. Hell, you can do that now. There is no spec tire size for each car.

Sorry Sam, this does not hold water.


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George Roffe
Houston, TX
84 944 ITS car under construction
92 ITS Sentra SE-R occasionally borrowed
http://www.nissport.com

 

[Knestis]

This whole conversation comes about because of market forces - there isn't enough demand across the enthusiast market to support the production of 14" wheels anymore. I'm afraid that I don't agree with Bill M. that taking ITC and ITB cars off of 13 and 14 inch wheels is going to speed up the process: SCCA IT racers are NEVER going to be a large percentage of the wheel-buying public. If they were, these wheels wouldn't be disappearing off of the shelves.

As far as a performance advantage might go, the point about open tire diameters is a good one. We already have lots of options.

However, the idea that a larger diameter package is somehow going to translate into a faster lap time for a low-powered IT car is wishful thinking, intended to support an agenda - "I don't want bigger wheels to be allowed" - rather than grounded in fact. I absolutely do NOT believe that a larger OD package is going to have this effect. I've made the mistake of going to a 205-60 Hoosier bias-ply on a pokey car and discovering that it was faster on 185-60 Goodyears.

Kirk

EDIT - this is a GREAT example of the kind of thing that paralyzes club racing rules decision making. "I will be at a disadvantage (or perceive that I am) and I'm willing to argue my position six ways from Sunday to rationalize my self-serving position," regardless of the logic of any given decision to the overall, long-term health of the class. Just say, "I don't like it because it what's important to me is more important than a healthy, viable class."

[This message has been edited by Knestis (edited October 10, 2003).]

 

[Bill Miller]

Kirk,

I think you misunderstood my position. My comments were about tires, not about wheels. I agree that racers have little impact on the aftermarket wheel market. I believe that if the wheel diameter rule is opened up to allow those on 13" and 14" wheels to go to 15" wheels, some percentage of those races will make the move due to a perceived advantage. This will reduce the market for 13" and 14" race tires. It is my belief that this will lead to the tire mfg's reducing their offerings in 13" and 14" tires (if not eliminating them).

In that way, I see it as going the way of 13" and 14" wheels. As more options became available (and car mfg's began offer 15" and greater wheels), the market for 13" and subsequently 14" wheels was reduced. This lead to the wheel mfg's reducing or eliminating their offerings in 13" and 14" sizes.

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MARRS #25 ITB Rabbit GTI (sold) | MARRS #25 HProd Rabbit
SCCA 279608