Originally Posted by cannga

Jason, yes, pretty sure. We're talking about cup tires, which use very low pressure. For example if you now deflate your front tire to 26-27 cold (pressure used in cup tire, for final reading of 32 hot), the alarm will go on regardless of how you reset.

Originally Posted by TT Surgeon

^ very true, 'hot' at the track is completely different than any street situation. When I come off after a run, the rubber is literally melting at places. In fact, I'll come into pit row after about 6 hard laps to check tire pressure and temps across the tread with a pyrometer. That's the only way to set track pressures. I find my car turns the fastest laps at 33-35 hot on a long track, 31 on a short technical track. For pure street use, ps2s are probably a better bet. if you never really heat them up on the track, you'll never see the benefit of cups imo. On the street, I seldom run my cups below 35-37, corsas could be a different story, as I've only had one set on my car and didn't care for them at all.

Originally Posted by TT Surgeon

Will do, those #s are based off my pyrometer readings, usually the most even temps across the tread are at those pressures. However, what you say makes sense on a 19 rim. Agree, one will never see the real benefit of cups in a street only application. I run cups pretty much year round, of course snows are up now. Does it make the most $$ sense, prolly not, but I gots da scratch!

Originally Posted by cannga

Happy new year to you Can and no worries as always. Love a good discussion even if i have strayed you all someway off the beaten track with your OP.

Cant say ive had the time to do so outside of 6speed. One gets only so much time for forums but i will endeavor to do so at one point. I did join up as a member at renntech or rennlist (forgot which) some while back but just never got the time to take it further. Ive found 6peed to be better formated and the easier to use site so thats where i put whatever time i get for any forum viewing and chat. There is undoubtedly some valuable information over there, as there is here also, but i still cant overlook where the most valuable source is often found, that being each tire manufacturers technical advice service. No matter which way you look at it these guys should know what works best after all they work with manufacturers such as P to get the right tire combo working, and to get the business for proving their own tire case.

And on the 18's i totally agree they seem to be the choice over 19's for the die hard guys.

Agree road environment and terrain of operation is usually key as is suspension set. On road environment i would say if you are doing 80% general street and 20% aggressive sporty driving in canyons or likewise then the PS2 is a better and more practical choice. I have even seen some guys with GT3's remove their R cups and use PS2 in this situation just for added comfort and convenience of being able to drive safely in the wet. If on the other hand you are just using your car for the weekend thrash then i would agree the R cups are the better selection.....regardless of suspension set up etc. Re suspension stiffness and the better tire selection: I would agree that the r cups are better suited to stiff suspension hence P selecting them as standard equipment on their GT cars. My comment made in my post where i stated i fail to see the point using r cups on street was generalized and made in reference to 997tt stock suspension cars such as mine and, using the car predominantly as a DD in regular driving conditions, so i will edit my post on that to be more specific to clear up that point. However that said i maintain the 997tt sport setting is far from soft and not a great deal different from Bilstein's pasm normal mode so there are similarities there. Th SC sport being slightly firmer than the Billy normal. The main difference i found between the Bil pasm in normal mode and the oem susp in sport mode was that the Billys gave a more "overly taught and jiggy ride" on the rebound which wasnt all too comfortable during general street use/non sporty driving etc. After owning cars with both set ups i find the oem suspension in SC mode setting can easily advantage whatever benefits an R cup tire can offer in sporty driving conditions (for most drivers) so on the track or similar conditions you can certainly drive much faster through corners with R cups than say PS2's....no question on that. I agree there is always going to be an advantage of sorts using a tailored coil over set up for track use....no question....but lets face it many of us like the flexibility of retaining the use of our cars as a DD's without getting our fillings shaken out of our mouths. Now if i was using my car predominantly at the track then i would (probably) go the set up you now have. Would still consider the TPC set up in favor tho....no offense .

Tracks generally have a mixture, usually many more tight corners than long sweepers so the tires certainly come up to temperature after a couple of warm up laps. In fact some of the corners are full horseshoe double apex so the tires sure get one heck of a work out. With no cops and a more controlled high speed driving environment with no trees or posts to crash into (or oncoming traffic) i believe a track will certainly give any canyon a good go for its money in terms of which works the tires harder through the corners. A track will any day of the week imho. You tend to push way harder than what you would ever contemplate on a country back road or canyon.

Driving skills will determine any limits there and again in oem sports mode the car stiffens right up and still maintains a nice compliance so R cups are of a huge advantage in the right conditions using oem suspension.

Im assuming you are talking about Walter Rorhl? Anyway, no argument from me on that. He of all people would more than know his stuff when it comes to P cars.
Agree. Stock Ps2's vs Cup r's are worlds apart....as are slicks again. But Stock suspension in sport mode is hardly soft. Maybe not as stiff and taught as a bilstein coil over set up but still stiff enough for most drivers to more than take advantage of a set of R cups in sporty driving conditions. Remember that very few of us possess the skills of Walter Rorhl or professional race drivers that are able to micro anylize and utilise the benefits of a race suspension set up.....making the various comments to explain the differences etc.

No worries and agree with you Can. But re the wet conditions on R cups, they are a waste of time imo and should be avoided in fast driving conditions. When at the track when its wet you are always better using stock PS2's.....swap back to R cups when it dries etc.

Originally Posted by cannga

Re. pressure for track use, what you say could well be true, but again, I would bring that discussion to rennlist's GT3 forum. A lot of trustworthy experience there!
For street use, I am quite confident of my observation & could only report what works best for me (YMMV, depends on car, setup, etc.): I *try* not to let the tires go over 32/36 hot, for street, and when the driving gets serious, would stop occasionally to bleed off as needed. Above this 32/36, I don't feel that traction is optimal. I cannot find the chart now but I believe this is as recommended by manufacturer, and of course confirmed by the people whose advice I seek.

Originally Posted by speed21

I have even seen some guys with GT3's remove their R cups and use PS2 in this situation just for added comfort and convenience of being able to drive safely in the wet.

Originally Posted by cannga

This is actually much related to my discussion of matching tire to suspension. For the same reason that you don't want to put stiff wall tire into a soft suspension, you don't necessarily want to put soft tire on a GT3. While this could be done (and I don't mean to be critical - I'm sure said GT3 owners are aware, just discussing here because it's relevant), even after acknowledging that it's an "planned" compromise, it's still a bad idea. The higher cornering speed of a GT3 will cause tire wall deformity, so for the short time the tires will be more useful in the rain, the owners are willing to sacrifice the very function of the GT3? (Use a different car is a much better idea.)


Its probably not the best idea if your driving flat out but the guy i specifically spoke to said he used slicks on the track and just wanted his car to be more user friendly in all conditions during DD use. Im sure if he pushed the car to the limit during street use there would be a trade off but lets face it how often would that ever happen.

BTW, when I iron out the details/possible misunderstanding, we agree on a lot of points, just expressing it differently. One example: Yes all my reference to soft Turbo suspension is in the normal setting, and I understand immediately and agree when you mention that the Firm is a good match for the stiff tire. That said, there is a reason that I had assumed the Normal setting is the only one worth using in the Turbo:


For general traffic use while not pushing too hard near the limit normal is usually used...correct. But its nice to have the comfort during those majority moments and the degree of limit you normally operate the car the normal mode setting and stock suspension is fine.

The Firm suspension of PASM gen 1 in the Turbo has drawn criticism from a number of (good) reviewers, tuners, and users from its very beginning.


Yes but the majority of those comments come from very experienced drivers driving the car at the upper limits, usually on a track environment too. For most drivers, pushing a car to test its limits is a minority situation and one which may never even happen for many drivers who simply don't possess that level of skill to even go near those limits. Sometimes having less surety in the hands of the less experienced is a good thing. I've heard it said once you raise the handling limits of a car beyond the capability of the driver you create a situation where the first off/crash will be the last....as the speed will be that much higher again. I think there will always be pluses and minuses in every performance upgrade. Not saying they shouldn't be done....but saying when they are done one does them with full understanding of any shortfalls or misgivings and, within ones own limitations as well.

It achieves stiffness the wrong way: because of the inherently soft spring rate, stiffness was achieved by jacking damping rate to very high level. (Stiffness is much better done by stiffer spring and then matched damping, not just jacking up the damping.) The result is a very harsh and very jittery firmness. The ride is almost bone-jarring, besides the nervousness, to the point that I think the Firm setting is unusable unless for perfect glass smooth surface -- not the intention of a Turbo.


True but in may ways the same could be said for the damptronic coil over firm setting as well. These Firm settings are always best kept for those perfect smooth roads.

Gen 2 PASM's change was acknowledged in reviews and interviews at the time of gen 2 Turbo release, and is much improved over gen 1. If you have a chance, test driver a gen 2 and you'll see what I mean. PASM Firm in gen. 2 Turbo is also firm, but much more compliant, a significant improvement over gen 1.


Can I covered this point in the other thread where i said if i had not been for GTR, P would not have paid so much attention only to then spruce off about it.
Needless to say P never makes any successor worse. As i also said, just wait for 991tt and i will be hearing how bad .2tt is too. Then we will all be crying in our soup.....modded suspension or not .

BTW, I know you might not agree with what I write now about stock Turbo suspension and PASM gen 1 (at best a work in progress, at worst a design flaw), but given your mod oriented history of track usage/Bilstein and your knowledge of suspension tuning and what it does, I will wager a (friendly) bet that by this time next year, the stock suspension or spring will be gone from your car.

Originally Posted by cannga

Paul, another example of us talking apple and orange, even though we might be saying the same thing: When you wrote 38, you meant pressure on the rear tire, didn't you? When I wrote 32, I was talking about the front tire! 32 front/36 rear.

No. The Michelin guy set it 38 front and rear. I asked why the same front and rear and he said pressures are kept the same front to back. Mind you when i was running 31's and 32's they were always kept the same front and rear as well. I always thought that was odd but everyone was doing it so i had no reason to challenge guys that were more experienced than me. He did say that the front at 38 was good as thats where the load really happens more coming hard under late brakes in high speed corner entry.


And yes, no argument that track usage is a world apart. Just think of the fried PCCB's at the track: "Never" happens on street driving.


Yes. I can just see it all now. Rohrl says to P during a full PCCB changeout....come on guys...whats another set of replacement PCCB's amongst friends . I think thats why the steels will be better for me....and many others. The PCCB's may be better but boy do they cost, and then maintain .

The forum I mentioned was www.rennlist.com , not the other renn -- the GT3 section only (Turbo is at best so so). That GT3 section is the only Porsche forum that I don't post, but lurk often. And yes serious and trustworthy track knowledge -- for example your point of running 38 cup tire would generate a ton of agreements, or counterpoints, there I am sure. (And so will my post on matching tire to suspension, etc.)


Yes well again i go back to the manufacturer knowing what should be best. Opinions are a bit like backsides.....everyone has one. Not saying they should be dismissed or ridiculed but logically there should be no arguing with the maker who has done the real yards in track and street testing on the car using that specific product. I generally prefer to put my money on a given. Mind you i had a lot of expert opinion/users bleeding my tires off to 31 prior too.


Yes it was Walter Rohrl I was talking about. Despite of the rumors - ha ha - most of what I write does not come out of thin air; but mere repetitions of extensive web research - grin. He mentioned tire/spring matching when he was talking either about the 997.2 Turbo suspension and/or about the street GT3 that they were going to race at the 'ring last year. As soon as they decided to use stiffer tire - cup to slick I believe? - in the car, they changed the spring specifically for the tire.