2010 Rule Change for Street Stock – Stock tire sizes only?

[UKAYMAN]

I was reading the highlights of the rules changes for 2010, and see that street stock classes K through R “do not take any points for modifications”, as per the “note” stated for the street stock points, classifications columns.

I understand that you will be able to run your car as it came from the factory with no point penalties for additional factory options, and that you’re not allowed to add any performance enhancements as previously, with the exception of adding aftermarket wheels. Previously a common way to use your 2 point allocation in S/S was to increase the tire width. For example, I am running in MS/S and my maximum stock tire size allowable is 270mm. If I was to increase between 270 and 285 I would have taken 2 points. If I wanted go beyond 285 it would be 4 points, which you couldn’t do in S/S because you don’t have that many points to play with.

So somehow, I’m managing to interpret the rules in two ways, and was just wondering how someone else interprets it with regards to tire sizes. I see it that as a) you cannot exceed a maximum of 270mm width in MS/S because you have no points to play with to increase the size, or b) because you don’t take points in this class, you can run whatever width you want. Tire size increase was one of the few and popular modifications you could do in street stock.

I’m about to replace my set of tires and I currently have 275mm width in the rear. If it doesn’t matter in the rules and I can still stay in S/S, then I’ll be going for the same setup again, otherwise I’ll find a 265mm setup.

Interested to hear your thoughts on this.

Cheers,

[KeithV]

You know exactly what the rules mean UKAYMAN .... You're just stirring things up as usual!!

You don't honestly think any tire size is allowed do you?

[UKAYMAN]

Haha.. According to Porsche the Cayman does like to "Stir Things Up" so you can't blame the driver!!!

And yes I wouldn't have posted anything if I didn't think it could go both ways. It does have some impacts you know because I can think of a number of others falling into this category if the increased size isn't allowed. Now they atent going to want to change tires if theirs are still in good shape.

Good to know what you think. Does your car still start BTW?

[mrondeau]

It looks like you're going to have go back to 265's or move up to MS class. I'm sure you'll still do very well. I suggest BF Goodrich All Terrain tires for the other car AX in case it rains

[UKAYMAN]

It looks like you're going to have go back to 265's or move up to MS class. I'm sure you'll still do very well. I suggest BF Goodrich All Terrain tires for the other car AX in case it rains

265's it is then. I thought about the all terrains for the Stadium, but then from the posted pictures I saw, you guys did a great job repairing the broken up surface, so no need to consider that option. Nitto NT-05s will be better suited to the new conditions.

[tb911]

You don't honestly think any tire size is allowed do you?

Amazingly, Keith, you are correct , not just any size is allowed.

See the actual proposal that was approved here: http://zone8.pca.org/rules/2009/FinalRuleProposals2009.pdf

(Sorry, I don't have the new rules doc up yet, just the highlights, so I have to refer you to the proposal.)

Yes, it is true there on "no points" for K-R S/S classes any more, meaning any factory original car may run there, with or without options.
It is also true that you are allowed to use aftermarket or factory optional wheels. No limits are placed on these, so you may use wheels that are bigger than standard.

Because the wheel size may grow, that means that the allowable tire size needs to be able to grow as well, and therefore it does.
However, you must keep in mind that there is a safety rule that states the tire must be covered by the fender. So that limits the size of the wheel/tire combination.
There is also a new addition to the Street Stock limitations: You may not enlarge the fenders.

So, yes, you may run with increased tires sizes, as long as they fit inside the factory fenders.

[mrondeau]

I stand corrected. It seems that increasing tire sizes that would be penalized in Stock through Modified classes should be addressed in Street Stock, but that's just my take on it.

[Carl Vanders]

Good to get the clarification. Thanks Tom.

I stand corrected. It seems that increasing tire sizes that would be penalized in Stock through Modified classes should be addressed in Street Stock, but that's just my take on it.

I tend to agree that it seems like it would make sense to follow the Stock rules. And just allow going up one size taking 2pts. But I think the issue is some cars come from the factory with larger tires than the chart stock.


Well Hassan, you know have many tire choice's. to stir things up . On the extreme side, I think a 285 on a 9 inch rear wheel should fit upfront under the fender. You could actually run a 305 in the rear on a 10-10.5 in the rear- Lots of room in the back. The 305/315 is a tall tire and will affect your acceleration. (I think someone in LA had a 315 on their cayman.) Its best to stay below 25.5 dia. It would not be my first choice for autox. My first choice tire would be the Kumho XS its 25" dia. On a 17x9 in front with a 255 and a 17x10- with a 295. XS tires are awesome and are also cost effective. The next best gearing would be Yok's on a 18 wheel 245/285 its the smallest diameter tire combo at 24.8, but quite pricey @ 315.00 per rear tire!. Careful on the 275 choice's as most are very tall and the 265's would actually be faster.

[tb911]

It seems that increasing tire sizes that would be penalized in Stock through Modified classes should be addressed in Street Stock, but that's just my take on it.

I can see your point of view, but keep in mind with the new K-R S/S, nothing that is assigned points in the higher classes is addressed here (unless it is explicitly prohibited). So this is consistent.

The goal is to help the neophyte. Someone who just rolled their car off the show room floor and who hasn't a clue. Should they be bumped into some class for reasons they don't understand that they have no hope doing very well in against the souped-up cars? This is why any factory original car is now allowed here, regardless of options. After market wheels are allowed because often people buy them just because they look cool, without any regard to performance and certainly not with a thought to rules for an activity they haven't even tried yet. So again, the thinking is, allow it, don't bump them up to Stock for reasons they don't understand.

Some of the same reasoning went into allowing 6 points in A-J S/S a couple years ago. How many factory original 30 year old cars are there? Some yes, but what percentage? Again, the goal is to not force the average person to know and understand the rules until they want to leave S/S and move up.

Can the experienced driver take advantage of the rules? Of course, but can you ever stop that?

[UKAYMAN]

Thanks for clearing up the rules Tom, as I feel at ease that I can still continue to run my current set up next year until they wear out. The rules won't change again now for 2010 will they? Or can we expect some last minute rulings?

Good to get the clarification. Thanks Tom.

I tend to agree that it seems like it would make sense to follow the Stock rules. And just allow going up one size taking 2pts. But I think the issue is some cars come from the factory with larger tires than the chart stock.


Well Hassan, you know have many tire choice's. to stir things up . On the extreme side, I think a 285 on a 9 inch rear wheel should fit upfront under the fender. You could actually run a 305 in the rear on a 10-10.5 in the rear- Lots of room in the back. The 305/315 is a tall tire and will affect your acceleration. (I think someone in LA had a 315 on their cayman.) Its best to stay below 25.5 dia. It would not be my first choice for autox. My first choice tire would be the Kumho XS its 25" dia. On a 17x9 in front with a 255 and a 17x10- with a 295. XS tires are awesome and are also cost effective. The next best gearing would be Yok's on a 18 wheel 245/285 its the smallest diameter tire combo at 24.8, but quite pricey @ 315.00 per rear tire!. Careful on the 275 choice's as most are very tall and the 265's would actually be faster.

Carl, it does bring into play some interesting scenerios but my combo of 245/35/18 up front, and 275/35/18 in the rear with the Kumho Ecsta XS that I currently have is really great. I can strongly recommend this set-up to anyone running 18s, and a bunch of us Cayman drivers have them. I got mine in January and they have lasted very well, including being used as daily driver tires over the latter part of the year, they're still producing good times. I think they may still have a few events left in them. Price wasn't bad either, but now i'm a married man with mortgage payments I have to be cost concious with what tire i'll be running next year. Nitto have a new 200 tread wear street tire, the NT-05, so given the current sizes available i'll go with 235/40/18 up front, and 265-275/35/18 in the rear depending on availability. They're $150 cheaper per set, than the Kumhos were, but anyways my times will tell whether or not they end up being the right choice.

Now I just have to get my brake fluid bled/changed or something after boiling my brakes last weekend.

[tb911]

The rules won't change again now for 2010 will they? Or can we expect some last minute rulings?

Nope, all done for 2010. No more changes.