Proposed PCA PCR AX tire changes
 

Posted this over at Pelican as well.

The PCR committee is proposing restricting production class cars to 180 tread ware tires. While I understand the idea (production cars drive to the track), I have real problems with the rating because my search of available 180 tread wear tires for 15 inch rims reveals ONE tire in the 225/205 combo (the BFG Rival), and ONE in 225/195, the Hankook Ventus. If it's opened up to 140, it brings Toyo and Pirrelli into play, so there would be a whopping total of 4 available.

In the proposal, which can be found on the PCA website under ebrake news (search for 2015 PCR proposed changes), the committee states there are numerous options for those of us with older cars that have smaller rims.

Not sure who's input the committee took on that, and I've asked Mike and Leeds for the rationale behind the proposal and a source for the tires they say are available. I sure hope it's not due to SCCA street class changes. Inconsequential. If your car is a production class PCA car, your not street SCCA street class anymore.

Here's the kicker: some new Pcars are delivered with race rubber. They are proposing allowing them to continue to use those tires in production class. If you don't use the HUGE Parade classing rules then you might be competing against a car in your local class that can wear 140 tires...and you can't. While I think equitable (everybody gets a trophy) is silly, I think fair (everyone has a chance at a trophy) is not.

If you'd like to see 140 treadware open to all Production class cars, both for fairness and availability of tires, then please open up the file from the PCA website and contact POC as listed in the proposal. Or, just send a message to the general PCA inbox, and be sure to ask it be forwarded to the PCR
committee chairman. It's got to be done by the 10th.
Thanks
Scott MacKie
Peachstate PCA AX minion.

I don't mind, I've been using 200TW under SCCA rules this year, so I'm used to it. I use those same sizes on the MINI this year, can you go up to a 16" rim, there's a goodly selection of similar size tires in 16". I've been using ZII in 16", though I was considering trying RS3V2 in 15", they do seem to work well.

There's a good list of all the usual suspect tires and their sizes: http://webpages.charter.net/mitchlew...tire-sizes.pdf

16 inch rims are not optimal for autocross. Changes the gearing completely. 15 inch rims were the stock rims for a gillion Porsches manufactured between 1974 and 1989.

The proposed change impacts those that will run in large, medium, and small regions as there are some cars in the production classes (newer) that will be allowed to use 140 TW tires. FOUL.

You link proves my point: There is 1 tire that comes in 205/225 by 15, the Rival. The Toyo is a 140 treadware and therefore is out. There is so little difference in 140 to 180, why not let those of us that don't give a crap about the SCCA have a wider choice of tires for our older cars? Unless the overall sentifiment is 'to bad, you have an older car, good luck."

Toyo's coming out with a 200 treadwear version of the R1R this year -- they showed it at SEMA.

I have also spoken to both of them and the conversation I thought was left at 140 treadwear as the deciding line between "R" compound and street tires. The object of the rule change was to eliminate "R" tires from production so as to get more people involved without having to bring "R" tires.

Additionally you will note that there is no "showroom stock" class nor has there been for any car over 20 years old.

Also brought into the conversation is that manufacturers themselves will admit that there is not across the board common tread wear rating from manufacturer to manufacturer as each sets their own by whatever standard they want.

Again, with older cars and the limited tire offerings 140 instead of 180 brings more street performance tires into the mix.

That's factually incorrect.

Contrary to the oft-stated misconception, treadwear ratings aren't set "by whatever standard they want". The treadwear tests are conducted using an NHTSA-defined process at an NHTSA facility. The treadwear rating is relative to a control tire (aka "Course Monitoring Tire") provided by the NHTSA.

As in any other domain, the manufacturer can claim a treadwear rating worse than what they tested (as Hankook did with the R-S3), but not better.

The wording of the rule proposal, as it relates to 140 TW tires in Production is as follows:

In addition, we will allow those Showroom Stock classed automobiles delivered with less than 180 tread wear tires, to compete in the automobile’s respective class in the Production Category, with those tires (N-spec tires as specified by Porsche for that model and year), provided they have not made any other alteration(s) to the automobile. This keeps these automobiles from having to jump two categories (Showroom Stock to Improved) because of how their automobile was delivered from the Porsche factory.

http://www.multibriefs.com/briefs/pc...nges111814.pdf

That does not say ANY 140 tire can run in Production, it says a SS car on factory delivered N-Spec tires can run in Production with no other changes allowed. Factory N-Spec 140's have never been the tires to have in AX.

BTW, TTOD for Showroom Stock at last year's Parade was on 200 TW RE-11's.

What is unsaid in the rule as written but implied (and confirmed when I asked Mike about it) is that the reason for the 140 SS to Production allowance is that SS is also going to 180 TW.

I was confused by the rule change as it don't say anything about Showroom Stock.

I'm considering Showroom Stock for next year, I could use a Michelin Pilot Sport Cup 2 which is now 180TW.

As was I. I kept re-reading thinking I missed something that would require the SS 140 to Production allowance.

Brian, it's not the number, it's the dirth
 

of decent tires in the preferred 15 inch wheel sizes (225/205 I would guess) for the gazillion cars produced between 1974 and 1986 that have 15 inch rims as stock. Sure I've got a set of 16's for street and the odd track day, but the difference in gearing is noticeable.

It is good news if Toyo is going to make the R1R in a 15 inch combo in 200 TW. Now if Dunlop, Kumho, and Hankook would get on board...we'd be in business.

Sure wish PCA would establish a PAX system for the PCR's. A PAX champion at Parade and in the regions might encourage more participation. Worked pretty good down here in Peachstate.

Cheers

The control tire used by NHTSA is offered by the manufacturer. So there is one control tire for Yokohama, and a different control tire for Dunlop, and for Michelin, etc. Each year the manufacturers produce an arbitrarily sticky tire to use for the control tire, so they can publish specs for generic tires that say they have a TW of (roughly) 2 bajillion .

In my experience 200 TW will be fine. Tire companies have already started to reclassify their autox rubber as 200 TW to sell to SCCA folk -- there's not a big enough market to make these tires without appealing to SCCA -- so the tires will come as we head towards spring.

Dunlop already offers the Z2 Star Spec in 15" at 200 TW. I fully expect Yokohama to move the Neova AD08R to 200 TW next year.


Although I was not officially in SS at Parade this year, the only change I made to my car was to use Euro GT3 seats. I was second to Monte Pack in P12 (if I remember the class correctly) on Yokohama Neova Advan AD08R which were 140 at the time, but the exact same tires have since been reclassified as 180. I'm pretty sure I was the fastest car on "street" tires at Parade this past year, and those same tires will be legal under the new rules. Monte was running on Hoosier tires. I ran AD08Rs because I drove to Parade from Seattle. I think the new rules are entirely appropriate for Production (streetable cars with some basic modifications).

Hopefully Dunlop will offer the Direzza ZII Star Spec in 295 (already offered in Japan) and I will move to those.

That's also factually incorrect. :p

From here.

That doesn't say who makes the control tires. The information I got is from Greg Fordahl, chief engineer for the 2013 Daytona 24 winning Audi R8, and the Alex Job 911 that ran at Le Mans. He said exactly what I described during a PCA tech session two years ago. It also explains how the Neova AD08R was reclassified from 140 to 180 this year.

I know Greg and have tremendous respect for him, but as you pointed out, he's a race engineer, not a passenger car tire test engineer.

When the new ASTM F2493 standard for 16" test tires was released, the sole manufacturer was BFGoodrich. This appears to still be the case, as the test tire order form on the ASTM's website lists only one option for either of the two test tire sizes: Michelin. (Michelin is BFGoodrich's parent company and in some cases handles the latter's account ordering, as demonstrated by this earlier version of the same ASTM test tire order form.

Before this generation of reference tire, previous generations were produced by Uniroyal, and before that, Goodyear.

I'm not aware of the AD08R ever being rated at 140; its predecessor was rated at 180, and I don't recall any discussion of the R having a different rating.

Even if its rating did change, there are other, more plausible explanations. The tire could have originally tested to a higher number, but been classified to a lower number for marketing purposes (this was apparently the case with the Hankkok R-S3 initially being rated at 140 then changing to 200). Alternately, the manufacturer could have reformulated the tire's rubber compound (this was apparently the case with the Toyo R1R changing from 140 to 200 this year). Neither of these explanations requires a tire manufacturer to subvert a government and standards organization-specified standardized test process.

I stand corrected. I never meant to imply subversion, just explain the process as it was explained to me.

Ok. Maybe I do know of one case of subversion where exactly one size of a certain autocross tire was manufactured with a special compound but that's just a fun anecdote and I don't mean that tire TW ratings are a joke.

Still: I am a big fan of the TW changes even though the tire I want is not yet available in the size I need. I do expect the tire to become available soon, and I believe the proposal will enable people with daily driver Porsches to have a fair chance at Parade even if they don't live within a few hours of the hosting venue.