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PROPOSED RULE 2015: Limit maximum tire width


JSG1901

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Proposed change

Input a max tire size rule into each GTS class.

 

GTS1 - 235

GTS2 - 255

GTS3 - 275

GTS4 - 305

GTS5 - 315?

GTSU - Unlimited

 

Reason

The main purpose of developing a tire size restriction per class would be to maintain competitiveness across newer and older platforms as some older cars may allow to not be possible to add larger tires and increase overall grip without significant capital investment and R+D to modify the body.

 

An example of this would be an e92 BMW that de-tunes to run 230 HP in GTS2 but utilizes a 295 wide Hoosier A compound. Even though the strait line speed of the car would be reasonable compared to other cars in the class, the 295 tires allow for much more cornering grip and longer stint longevity/durability.

 

This creates a situation where a car that was initially intended for a higher class (GTS4-5) could come into the lower classes and be significantly more competitive.

 

Proposed wording

GTS mandates the following maximum tire size per class. Tire size will be indicated by the printed number on the sidewall of the tire.

 

GTS1 - 235

GTS2 - 255

GTS3 - 275

GTS4 - 305

GTS5 - 315?

GTSU - Unlimited

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I dont agree with this one. i think it will affect the smaller calsses (gts1/gts2) more than others. guys running 944's and 968's run much bigger tires already.

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Cars like the 911's also run big staggers, so the rears will be an issue.

 

Even stock sizes in some years in some of the classes (gts3 or 4) would be larger than what is proposed here.

 

Thanks

 

Ed

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Disagree.

 

Not all GTS3 cars will be able to run 275's under factory metalwork anyway - if we want to make this "fair" then we'd need to mandate 245's or 255's.

 

This is GTS. If you want to be competitive, you need to own a swazall. Sorry.

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Disagree.

 

Not all GTS3 cars will be able to run 275's under factory metalwork anyway - if we want to make this "fair" then we'd need to mandate 245's or 255's.

 

This is GTS. If you want to be competitive, you need to own a swazall. Sorry.

 

^this!

 

plus we all know the tire manufactures lie about the actual size of the tire. Ie the hoosier 255/35/18 is the same width as the 275/30/18 I believe that the time trial rule call this tire out specifically.

 

also this would increase cost for those competitors that now need to buy new rims or rim parts to become compliant.

 

in short......NO

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for the record at the last championships (Road Atlanta) I got my ass kicked by a bunch of guys on 245-255's when I was on 295's.

 

Against!

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I think this one is more for the lightning group. Or GTS1 and 2. on a newer 911 this just wouldnt work with the rules. I think having a v8 m3 de-tuning 200 horspower and coming into gts2 with tires that are 4 sizes bigger then everyone else is a problem. If all things are equal (HP/Weight) except someone running 3-4 tire sizes larger then everyone else tires out there is a unfair advantage. An e30 will never be competetive with a car that can fit those tires. In the end the hole point of running the slower class gts1 or gts2 is to keep cost down. The Gts 3,4,5 classes seem to have pretty close tire sizing and flaring isnt a big $ iteam for them. Maybe we should vote this into the lightning group or gts1 and 2 group. I vote yes for GTS 1 and 2.

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Cars like the 911's also run big staggers, so the rears will be an issue.

 

Even stock sizes in some years in some of the classes (gts3 or 4) would be larger than what is proposed here.

 

Thanks

 

Ed

 

I think this is the point of what this rule would be trying to contain.

I agree with it. These cars stock as Ed alluded to already have a width advantage

I like the idea, and I think its mainly focused on the issues with detuning as are most of the

the other proposed rule changes..

 

Benzito

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I think this one is more for the lightning group. Or GTS1 and 2. on a newer 911 this just wouldnt work with the rules. I think having a v8 m3 de-tuning 200 horspower and coming into gts2 with tires that are 4 sizes bigger then everyone else is a problem. If all things are equal (HP/Weight) except someone running 3-4 tire sizes larger then everyone else tires out there is a unfair advantage. An e30 will never be competetive with a car that can fit those tires. In the end the hole point of running the slower class gts1 or gts2 is to keep cost down. The Gts 3,4,5 classes seem to have pretty close tire sizing and flaring isnt a big $ iteam for them. Maybe we should vote this into the lightning group or gts1 and 2 group. I vote yes for GTS 1 and 2.

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CARVAL Motorsports

Against the spirit. Put GTS1/2 on those sized tires and bring in weighty car, you introduce other problems for the competitor. No here.

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CARVAL Motorsports

Against the spirit. Put GTS1/2 on those sized tires and bring in weighty car, you introduce other problems for the competitor. No here.

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jackhaberman

Against. Part of the spirit of open rule set is figuring out what combo works best. Wider wheels / tires also means more weight of the worst kind. Design and tune until you figure out the best combo for your chassis and hp.

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Against. Tire size has a peak beyond which is diminishing return. If you gots too much tire, you can't get enough heat in it and no advantage gained. If you can't get enough tire on your car, cut the body, or lose some weight and horsepower.

 

I have an old 911 widebody and I could put 12 inch wide wheels on it with 315 tires. I only have ~225 hp and 2500 lbs and wouldn't get enough heat in that tire to make it worthwhile for me. Plus it's increased unsprung weight, more rolling resistance, and more aero resistance at very high speed tracks. Bigger ain't always better.

 

BTW the 911 does not have an unfair advantage in this regard. IMO the larger rear tire is allowing the 911 to keep pace with the other makes due to its considerable rear weight bias, which one could argue is a disadvantage in certain instances.

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I vote no. If you mean to fit tires under stock bodywork, these limits don't really allow for that. It also will unfairly penalize heavier chassis.

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