Spec Twin?

[Twinz]

Originally Posted by Locust

You don't already do that?

I just tried to stay under half a tank all season.

[C4RBON]

Expanding on my previous post...

For compliance purposes the specification tire will have a weight published in the tire section of the Official Specification. The tire and wheel assembly can be weighed “all inclusive” to determine compliance

The problem of using a spec tire weight for verifying wheel weight, is that it essentially changes the allowable wheel weight. See the example:

"Spec" tire weight measured at minimum usable tread depth: 21 lbs
New, unused, tire weight: 23 lbs
Spec wheel weight: 17 lbs

So if we weigh the wheel/tire combo to verify compliance, the minimum weight is 21 (tire) + 17 (wheel) = 38 lbs.

So with new tires (23 lbs), to hit that 38 lb target, you can use 15 lb wheels.

"So what" you may ask?
- It means you can have multiple sets of different wheels to use with tires of varying tread depth. This would be an advantage in the wet, where you presumably want nearly-new tires with deeper grooves.
- It means competitors are going to be monitoring tire/wheel weight between events, and possibly even between runs.
- It means competitors might need to drive over OPR to pick up weight after a run.
- It means a wheel/tire that was legal on run 1 might not be legal on run 3.
- It means TireRack can give us a spec tire weight when the tire still has usable life left, meaning the tires are junk if you have 17.0 lb wheels.

I don't want any of those things (and the associated protests) in SSC. I think the method proposed to verify wheel weight has unintended consequences, and should be changed. I realize the competitive advantage of my above scenarios would be small. However, in a spec class even small advantages are advantages. We have the opportunity to write clear, unambiguous rules that prevent these kinds of cost-adding maneuvers and petty protests to the competition.

I propose the following:

- Manufacturing tolerances and wear affect the weight of the spec tire. The spec tire shall always be allowed for competition regardless of weight, provided it meets safety requirements.
- Competitors may be required to remove one wheel/tire assembly after competition for weighing. TireRack will provide a minimum expected tire weight so that the weight of a wheel may be estimated using subtraction. The wheel weight estimate will be available to all competitors so they may lodge a protest.
- Upon protest of wheels on the basis of weight, tires will be dismounted and the wheels individually weighed (including valve stems and caps, wheel weights, center caps, and TPMS sensors). The weight of any wheel used in competition can not be less than 17.0 lbs.

[Twinz]

"- Upon protest of wheels on the basis of weight, tires will be dismounted and the wheels individually weighed (including valve stems and caps, wheel weights, center caps, and TPMS sensors). The weight of any wheel used in competition can not be less than 17.0 lbs."

I wouldn't have an issue with that.^

[Locust]

Originally Posted by Twinz

I just tried to stay under half a tank all season.

I run with the gas light on.

[Shneegle]

Originally Posted by C4RBON

Expanding on my previous post...

The problem of using a spec tire weight for verifying wheel weight, is that it essentially changes the allowable wheel weight. See the example:

"Spec" tire weight measured at minimum usable tread depth: 21 lbs
New, unused, tire weight: 23 lbs
Spec wheel weight: 17 lbs

So if we weigh the wheel/tire combo to verify compliance, the minimum weight is 21 (tire) + 17 (wheel) = 38 lbs.

So with new tires (23 lbs), to hit that 38 lb target, you can use 15 lb wheels.

Originally Posted by Twinz

"- Upon protest of wheels on the basis of weight, tires will be dismounted and the wheels individually weighed (including valve stems and caps, wheel weights, center caps, and TPMS sensors). The weight of any wheel used in competition can not be less than 17.0 lbs."

With how popular this class is looking I doubt you would need to go that far for the protest. All one would need to do is look up the wheel weight to know if its a legal option. So the weighing as a whole doesn't really matter if you can find manufacturer specs for a wheel. It would be easy to spot someone running different wheels than everyone else and if anyone knows that they are under the set limit then it would be an easy protest.

[C4RBON]

Originally Posted by Shneegle

With how popular this class is looking I doubt you would need to go that far for the protest. All one would need to do is look up the wheel weight to know if its a legal option. So the weighing as a whole doesn't really matter if you can find manufacturer specs for a wheel. It would be easy to spot someone running different wheels than everyone else and if anyone knows that they are under the set limit then it would be an easy protest.

I think in 90% of cases you are correct. However, the for the following situations, weighing the wheel is the only way to determine compliance:
- A "known legal" wheel being modified to be lighter, such as machining the backside of the spokes, machining between the bolt holes, removing paint, or simply removing the center caps.
- A "known illegal" wheel being modified to ADD weight. Someone could machine solid steel center caps for RPF1s, and have a perfectly legal 17lb wheel with lower rotational inertia.
- An "unknown" wheel. Someone could have custom 3 piece wheels made, that may or may not be legal.

I think the method of checking wheel weight compliance is inadequate, and opens doors that aught to remain shut.

[cueball89]

Has anyone weighed a tpms sensor? I bought a set of the Advanti DST Storm S1 wheels back in the spring for daily driving, It would be fantastic if I didn't have to buy another set of wheels.

[Ribface]

Hmmm given the class philosophy I think I'd rather wheel choice be limited to an approved wheel list.

Will remove most weight issues/concerns/protests and make things easier to police.

Or at minimum rule should be that wheel weight has to be a minmum of 17lbs without balast.

[ApexEight]

Don't think this has been already posted: https://dk1xgl0d43mu1.cloudfront.net...pdf?1506722313

[Twinz]

Originally Posted by ApexEight

Don't think this has been already posted: https://dk1xgl0d43mu1.cloudfront.net...pdf?1506722313

This is the second time this has been posted. I am curious where this link comes from?

Most of this PDF clarifies things not specified in the original release on the SCCA's official website and basically just "fills in some blanks".

However, the offset specifications for the wheels actually contradicts both the SCCA's official website and Tire Rack's wheel options for the SSC spec coupe vehicle. People are already buying parts to prep, so this is kind of important to straighten out.....soon.

[bholliday]

Originally Posted by Twinz

This is the second time this has been posted. I am curious where this link comes from?

Most of this PDF clarifies things not specified in the original release on the SCCA's official website and basically just "fills in some blanks".

However, the offset specifications for the wheels actually contradicts both the SCCA's official website and Tire Rack's wheel options for the SSC spec coupe vehicle. People are already buying parts to prep, so this is kind of important to straighten out.....soon.

The class rules are now on the SCCA website. The offset has also been updated on the site.

Sent from my SM-T310 using Tapatalk

[bslate3]

They should just go with Hoosiers! That would be a ton of fun!

[Twinz]

Any rumors on when the tire will be named? Now that they have changed the offset, Tire Track will probably be where I get my wheels from but I would prefer to order the wheels with tires already mounted.

[Jshreiner]

No mention of using the stock crash bolts with the spc bolts so that's not an option now. why the restriction to oem endlinks?