I am running OSS. I want to run 140ish treadwear, the best I can run without dropping to OS. I am planning to run separate track wheels/tires. I'd prefer 17s just to keep the cost of rubber down.

I'm currently at 235 front and 295 rears. I went high on rear pressures, and was pushing 50 pounds hot, with fronts at 34 hot. It helped, but not enough. Gotta get smaller tires on the front, and I would like better rubber too.

Can anyone confirm the 2003 996 C2 max wheel width without rubbing issues? I'm running 235 now, so I'm pretty sure that's ok, but can I got 17x9 and 245??

I got a Porsche spec alignment last week, and it helped quite a bit. I think the alignment was really off before that. I don't want to go too aggressive on my alignment, as this is my daily driver. I'll probably take my car to a better place for alignment next time, but for now I'll live with the factory spec.

I did fine this weekend on the ax, I took second in my class, in my very first ax. I'm happy with that, though I KNOW of at least three places I screwed up. A bit more experience and that guy that beat me is toast. He only nudged me by 64.95 vs. 64.56, and the next closest was up around 66. Drop a wee bit of understeer, get a bit more experience, and I should do fine.

Your points were quite useful, and in line with my thinking. The hard part for me is knowing what is going to actually fit, and then finding it. 17 inch wheels for my widths are proving hard to find...

 

Ted-
You are probably correct in this instance, where the spacers used would likely be of nominal width, but there is a provision in PCA Zone 8 rules that provides for a 2-point penalty for track increases of greater than 2".


Irksome (your real name is Tom, no?)-

I'm not sure if they would work for you, but I have a set of 8 and 9.5 x 17" late-offset HRE track wheels for sale right now. See my ad here. I have some 245 and 275 V710s mounted on them currently, and even if you are not interested in buying them, you are welcome to come over and test fit them on your car to see what offset might be right according to what size tire and rim you might end up using in the future. Email me if you are interested.

TT

 

Hey, Tom!

Yeah, my name is Tom, I always forget to sign it here. I should make a sig, I guess.

Help clear my ignorance. I saw the rule about the 2" track increase, and did not know what that meant. What is that, and how is it measured?

I saw your ad, and while very nice wheels, they are far more than I had hoped to spend. Seems like a fair price, I'm just trying to get wheels that aren't so nice at a cheaper price. =)

I spent an hour up at Wheel Enhancement yesterday, as I happened to be up in Burbank on business. Had a GREAT conversation with Dave there. Based on what my car is wearing right now, and the spacers/studs already on the car, I think I'm looking to get some Carrera III wheels (18" wheels from the 997). If I can find some curb rash used Carrera IIIs, or possibly trade my current 19" wheels for some nice clean Carrera IIIs, I can put some good tires on them and get my rear tires to 285, allowing me to get tires a little bit stickier (140 treadwear, so still allowed in OS/S).

It's kind of amusing how much energy I'm putting into planning my autocrossing considering I've only run one...

Irksome, aka Tom

 

That's great you enjoyed it so much. It's a great sport in many ways. And the good people you do it with are a big part of what makes it fun. It's fairly low impact on cost and time, and imposes minimal wear on the car other than the tires. It is a tire sport, so getting the wheels and tires right is a big deal. Tweed's setup sounds good, as do the Carrera III wheels. A 235/285 combo of Yokohama Advan Neova AD-07's on the Carrera IIIs would be sweet for OSS. That's the best street tire - I wish it was available for the 19" size, but it would probably be super expensive, since 18" Advans are voracious on the Benjamins.

Well, worrying about fine points like optimal wheel width and all that jazz is not what you should think about as a beginner. Treadwear is just a manufacturer number, so 140 isn't necessarily stickier than 180 (e.g., Bridgestone RE01R at 140 v. Yokohama AD-07 at 180). But Hoosier A6 at *0* is definitely smokin' fast. There is so much time to be made in your driving, so just come out, get seat time, and have fun. Let Tom Tweed drive your car and see what it can really do.

- Ted
"Super Chicken" yellow 997S

 

It is very straightforward. The track measurement, front and rear, is published by the factory for every model Porsche. It is the measurement from center-to-center of the rims on each end of the car. If you increase this measurement by more than 2" from the stock spec (either by adding spacers or by utilizing wider rims and/or different offsets), you are penalized 2 points. This would be applicable, for instance, when an early car is converted to a wide-body RS/RSR look and utilizes spacers, or wheels more than 2" wider, to increase the track and fill out the wheel wells.
No problem. As I said, if you're even just wondering what offset and wheel width will fit under your fenders, you can use mine for test fitting. If you're working with Wheel Enhancement, I'm sure they have a handle on what works for your car without rubbing, though. The one thing you might want to consider is the weight of some of the cast wheels over forged racing wheels. It can make a big difference, as the weight is "unsprung", and rotational inertia of spinning up a heavy set of wheels robs power.

This is not unusual, and it is natural to want to go faster. Ted is right, though, the first thing to fix on the car is the "loose nut behind the wheel." There is more time to be made at first by learning how to drive the course better than there is in making mods to your car. Look at Ted's times last week on the same course. He was 4 seconds faster than you. OK, he is in the next higher class and has a faster car, but even taking that into account, he was 2.5 seconds faster on indexed time (the BRI). That's an eternity in an autox, where classes are won by hundredths of a second. Close that gap some first, with seat time and improved driving skills, then go after your setup.

The next most important thing to do would be a competition alignment, as Ted said. I'm not sure that you want to even think about changing the balance on your car with tire sizes before you get it aligned for competition. The factory settings are less than ideal, and you may find that the handling balance changes so much with the competition settings that you are barking up the wrong tree with tire sizes, spending money on the cart before the horse, so to speak. For the moment, you might want to try to learn how to "drive around" your push, either by slowing your corner entry and concentrating on the exit, or by perfecting your trailbraking technique to put more weight on the front tires during turn-in (riskier and harder).

Good luck and have fun,
TT

 

Great, that makes sense. I am not going to come even close to that limit. My car standard wheels were 8" in front, 10" in back. My goal is go get back to those widths. I do have spacers on the front, but they are small (I think they are 10mm?), and should not push me more than 0.5" by that definition, and the rear is running without spacing, so even at 11" wheels, I'm only +1" there. Thanks for the definition!

This has been brought up by a number of folks I've spoken to. The replica Carrera III wheels are 2-4 lbs heavier than the OEM ones, so I'm really hoping to find some of the OEM ones. I don't think I'm good enough to really see a difference between the OEM Carrera IIIs and real race wheels, but when I get that good I'll consider making the investment.


For sure!!! I'm well aware how much my skill affects it, and I am aware of a few things I could have done much better last weekend. That being said, I can't do much to get seat time between autocrosses, but I CAN do something about the equipment. Those fatboys I have on the rear right now are too damned big. =)

There is absolutely no doubt I have a tendency to enter corners too fast. My single run under 65 seconds was the run that felt the best entering the straight with the 2-cone slalom and the curves following it, which set me up for my best final straight of the day. I will definitely be working on that, and hopefully move on to my next worst problem...

Thanks for the advice, all, we'll see how well I'm internalizing it all at the end of the month.

 

There are things that you can practice on the street in your normal, everyday driving, though, like heel-and-toe shifting and braking, matching revs on downshifts, etc. Even though you aren't going to be anywhere close to the limits of grip (hopefully) you can also be cognisant of "the line" thru corners and on ramps, early and late apexes, your driving position, etc. You could also go karting at the indoor facilities and learn some things about car control, or reduce the time between autocrosses by seeking out other venues than PCA-SDR. SCCA has a very active Solo program here in SD, and OCR runs a lot of events just an hour up the coast.

All I am saying is you may be premature in that judgement. A lot of rear grip is a GOOD thing to have on a 911, as the rear weight bias can make them very tail-happy. The factory has gone to great lengths to build understeer into the stock cars over the years for the sake of safety. The slow speed nature of autox exacerbates this tendency. Dialing out some of the understeer by altering the factory alignment settings might improve this greatly, without spending big money on new wheels and tires. By changing your driving technique, you could take advantage of your high rear grip by trailbraking, which can be very tricky in a car that is set up to oversteer, and by applying power harder and earlier on exits, which might cause a smaller rear tire to break loose. When (and if) you take your car out on a big track, you may find that at higher speeds, the understeer is reduced considerably, because the front wheels are not required to turn at such high angles in faster corners. You may be very happy to have a bit of a push going into Turn 8 at Willow at 120mph, instead of thinking "if I lift, I am going to spin."

As counterintuitive as it may sound, sometimes you have to "slow down to go fast."

I think you are at a stage still where "you don't know what you don't know", as obvious as that may sound, and I hope you will temper your enthusiasm for making changes to the car until you get a little more experience, and can make effective decisions about costly mods based on the driver you have become, not the driver you are today.

Best wishes,
TT