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PostPosted: Sun Oct 01, 2017 9:02 pm 
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After reading the rules closely while preparing my car for ST4 it looks like it needs a clarification for the wing and end plate rules for ST4.

It states the wing height above roof line but does not state if that includes the end plates in the measurements.

The end plate rule just simply states 12" as a measurement. I confirmed with Greg that it is 12" in any direction. The verbiage just needs to reflect a length and width measurement.

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PostPosted: Mon Oct 09, 2017 2:52 pm 
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Hi Greg,

At the ST4 drivers meeting you were talking about new tire rules for next year. There were two aims: 1) level performance between heavy and lighter cars, and 2) incentivize people to use different brands of tire. One of the suggested changes was to have people take points for running "The Tire Who Shall No Be Named", because it performs better than other tire brands of a similar size.

I don't think we need to do this at all. I would probably be on different tires than Hoosier, if it were not for this simple fact:

https://www.facebook.com/photo.php?fbid ... =3&theater

On the left of this picture, a stack of Hankook 245/17. In the middle are my 245/17 Hoosiers, and to the right are Tom Tangs 275 Hankooks. Some takeaways 1)no, Tom does NOT have a tire advantage over me because he runs 275 . They are, fact the same size. 2) I don't care how many points you give me, its hard to give up 4" tire. Look at how small those 245 hankooks are.

The ST/TT rules always use the manufacturers stated Tire Width number when classifying a tire. We should change this to MEASURED TREAD WIDTH when assigning points. Hoosier is only the chosen tire because it grossly under-reports on its tire width, meaning we simply have a larger tire when we run it(not because of some innate superiority in the brand). You also cannot count on the stamp on the side of the tire to be accurate within the same brand! The Hoosier 245/15 is MUCH wider than the 245/17, for example. So if you penalize all hoosiers, you might be penalizing larger sizes for no reason, because their number may be closer to the true number. You just don't know unless you measure them.

The rules as written cannot properly address these discrepancies. And if you write a rule specific to a certain brand, you will have to rewrite it every time a new tire enters the scene. To future-proof any rule, classification of tire should be done by measured TREAD width only, not stated TIRE width, and it should be universally applied to every brand.

After that, let the economics sorts out people tire choices.

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PostPosted: Mon Oct 09, 2017 6:24 pm 
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Joined: Sat Feb 11, 2012 10:22 pm
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Location: redwood city, california
this sounds way too tricky, we need a spec tire.
good quality,not too expensive, and with all sizes for the different car weights!
why wait for another year of arguing, do it now! for the sake of close racing!

clock wrote:
Hi Greg,

At the ST4 drivers meeting you were talking about new tire rules for next year. There were two aims: 1) level performance between heavy and lighter cars, and 2) incentivize people to use different brands of tire. One of the suggested changes was to have people take points for running "The Tire Who Shall No Be Named", because it performs better than other tire brands of a similar size.

I don't think we need to do this at all. I would probably be on different tires than Hoosier, if it were not for this simple fact:

https://www.facebook.com/photo.php?fbid ... =3&theater

On the left of this picture, a stack of Hankook 245/17. In the middle are my 245/17 Hoosiers, and to the right are Tom Tangs 275 Hankooks. Some takeaways 1)no, Tom does NOT have a tire advantage over me because he runs 275 . They are, fact the same size. 2) I don't care how many points you give me, its hard to give up 4" tire. Look at how small those 245 hankooks are.

The ST/TT rules always use the manufacturers stated Tire Width number when classifying a tire. We should change this to MEASURED TREAD WIDTH when assigning points. Hoosier is only the chosen tire because it grossly under-reports on its tire width, meaning we simply have a larger tire when we run it(not because of some innate superiority in the brand). You also cannot count on the stamp on the side of the tire to be accurate within the same brand! The Hoosier 245/15 is MUCH wider than the 245/17, for example. So if you penalize all hoosiers, you might be penalizing larger sizes for no reason, because their number may be closer to the true number. You just don't know unless you measure them.

The rules as written cannot properly address these discrepancies. And if you write a rule specific to a certain brand, you will have to rewrite it every time a new tire enters the scene. To future-proof any rule, classification of tire should be done by measured TREAD width only, not stated TIRE width, and it should be universally applied to every brand.

After that, let the economics sorts out people tire choices.


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PostPosted: Mon Oct 09, 2017 9:37 pm 
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Its not tricky. All the tires publish their true measurements. Or you measure them with tape. We compile these sheets for the 4 or 5 brands being used, and set the limits exactly as they have been set now.

I am not advocating against a spec tire per se, but it would need to be the right spec tire. Spec tires often ruin a series when not every potential competitor can find a fitment. It also reduces the overall contingency payout available for a class, further reducing interest. A spec tire is not a cure-all.

My point here is that if the choice is to keep tire brand open, we should class them by the actual size. Hoosier's tread width advantage is eliminated, and we get to retain the better economic aspects of open tire.

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PostPosted: Tue Oct 10, 2017 7:00 am 
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sorry i meant it was tricky despite coming up with a pretty good system like the one you are proposing; avoiding at the end ,having a preferred brand and model of choice, so why not just choose one now!


clock wrote:
Its not tricky. All the tires publish their true measurements. Or you measure them with tape. We compile these sheets for the 4 or 5 brands being used, and set the limits exactly as they have been set now.

I am not advocating against a spec tire per se, but it would need to be the right spec tire. Spec tires often ruin a series when not every potential competitor can find a fitment. It also reduces the overall contingency payout available for a class, further reducing interest. A spec tire is not a cure-all.

My point here is that if the choice is to keep tire brand open, we should class them by the actual size. Hoosier's tread width advantage is eliminated, and we get to retain the better economic aspects of open tire.


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PostPosted: Tue Oct 10, 2017 7:14 am 
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Why not just remove the tire width mod factors all together and allow people to run the appropriate size tire for the weight of their car. This will eliminate any manufactures side wall claim discrepancies and avoids the need to measure all the tires and avoids the next issue of wheel size. From my experience once you have “enough tire” going bigger doesn’t really help much anyway. I’ve tested this with 265’s, 275’s, and 315’s on a 3200lbs comp weight in ST3. 275’s were the sweet spot. One caveat for this to work is that the mod factors for weight need to be addressed. In a pw/wt class heavier with more power is going to be faster in most cases because low hp cars can’t push through the air as well as higher hp cars. Currently the combination of Tire and Weight mod factors account for this and if we remove the tire width mod factors then the weight table alone will need to account for this and needs to be changed.

This first table is based on the current rules with example cars at different weights and tire size. The resulting combined mod factor provides a benefit to lighter weight cars compared to heavier cars which is what it should do. We could argue for days on how much the adjustments should be and if they should be different for each class but they are in the correct direction of giving a benefit to lighter weight lower horsepower cars.

Comp Weight......Tire Size on Car........Tire size mod Factor.....Weight Mod Factor.....Resulting Combined Mod Factor
2500lbs..............245 or smaller..........+0.7 ..........................-0.2........................+0.5
3200lbs..............275.........................+0.3 ...........................0.0........................+0.3
3450lbs..............285 or bigger.............0.0...........................+0.2.......................+0.2



This table is the proposed mod factors for weight if the tire size mod factor is removed. It’s at least a place to start from to have a discussion.

Comp Weight
Less Than........Weight mod Factor
2200lbs...........+0.7
2400lbs...........+0.6
2600lbs...........+0.5
2800lbs...........+0.4
3200lbs...........+0.3
3400lbs...........+0.2
3600lbs...........+0.1

Thanks


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PostPosted: Tue Oct 10, 2017 7:51 am 
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Any update on the HP calculations? Moving to six data points, or sticking with four? Or something else?


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PostPosted: Tue Oct 10, 2017 7:58 am 
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zigspeed10 wrote:
Why not just remove the tire width mod factors all together and allow people to run the appropriate size tire for the weight of their car.


"Allow" sounds like a very passive way to make people go buy 8-12 new wheels and tire sizes, which would be pretty painful to the wallet. Identifying an "appropriate" tire size for a given weight would be very subjective. I used to race a 3200 lb car that could have never even fit a 275 size tire on it.


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PostPosted: Tue Oct 10, 2017 8:06 am 
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944buzz wrote:
There is also the option to do Rewards weight.

You simply add weight (25 lbs) to the winners car. The max Rewards ballast is capped at (250 lbs.).


The CCR allows 250 lbs of max ballast, what if your car already has 250 lbs? 500 lbs of bolt in ballast?


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PostPosted: Tue Oct 10, 2017 8:38 am 
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I think the faster bigger car with more power theory has already been proven not to be correct in st4. unless that vette was heavy with lots of power, but maybe is torque that makes the difference.

also you jump from 2800 to 3200 lbs why is that?



zigspeed10 wrote:
Why not just remove the tire width mod factors all together and allow people to run the appropriate size tire for the weight of their car. This will eliminate any manufactures side wall claim discrepancies and avoids the need to measure all the tires and avoids the next issue of wheel size. From my experience once you have “enough tire” going bigger doesn’t really help much anyway. I’ve tested this with 265’s, 275’s, and 315’s on a 3200lbs comp weight in ST3. 275’s were the sweet spot. One caveat for this to work is that the mod factors for weight need to be addressed. In a pw/wt class heavier with more power is going to be faster in most cases because low hp cars can’t push through the air as well as higher hp cars. Currently the combination of Tire and Weight mod factors account for this and if we remove the tire width mod factors then the weight table alone will need to account for this and needs to be changed.

This first table is based on the current rules with example cars at different weights and tire size. The resulting combined mod factor provides a benefit to lighter weight cars compared to heavier cars which is what it should do. We could argue for days on how much the adjustments should be and if they should be different for each class but they are in the correct direction of giving a benefit to lighter weight lower horsepower cars.

Comp Weight......Tire Size on Car........Tire size mod Factor.....Weight Mod Factor.....Resulting Combined Mod Factor
2500lbs..............245 or smaller..........+0.7 ..........................-0.2........................+0.5
3200lbs..............275.........................+0.3 ...........................0.0........................+0.3
3450lbs..............285 or bigger.............0.0...........................+0.2.......................+0.2



This table is the proposed mod factors for weight if the tire size mod factor is removed. It’s at least a place to start from to have a discussion.

Comp Weight
Less Than........Weight mod Factor
2200lbs...........+0.7
2400lbs...........+0.6
2600lbs...........+0.5
2800lbs...........+0.4
3200lbs...........+0.3
3400lbs...........+0.2
3600lbs...........+0.1

Thanks


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