Tire Update
I now have had 4 popular tires in my Turbo and following is an updated evaluation for anyone interested:
1. Michelin PS2 (rear lasted about 12k miles)
2. Pirelli Corsa (this is an R compound tire, not normal street tire, lasted about 1 year/10k miles both front and rear)
3. Michelin Pilot Super Sport (lasted about 2 years, from 8/2011 to 2013, 20k miles!)
4. Bridgestone RE 11

What to consider in a tire, for the enthusiasts?
1. Traction Self explanatory. More traction is better, but in general usually means shorter life.
2. Sidewall Stiffness (not talking about the rubber compound, but the *sidewall* construction)
Everyone knows about traction, the stickier the better of course; not frequently discussed is the importance of tire sidewall stiffness. The sidewall of a tire is a critical factor in suspension tuning; yes the tire is part of the suspension system and will affect body roll and weight transfer as much as stiffer springs! The tire therefore involves a trade-off, just like the rest of the suspension, and this trade-off again is about ride vs. handling. Stiffer tire is good for handling, but bad for comfort, and vice versa.
*Street tire tends to has soft sidewall, and therefore is more comfortable, but will also cause the car to lean more in corners.
*R comp tire (Michelin Cup, Pirelli Corsa, Toyo Roxes R888 - made for track, but legal on normal road) has stiff sidewall and will noticeably decreases body lean. The difference is significant and easily noticeable, a night and day change. These tires of course should not be used on wet road and are not as comfortable.


Tire Comparion Michelin PS2 vs. PSS
Comparison is difficult because there was a gap in between my usage of the 2. But to best of my memory, all IMHO:
1. Equal road noise, equal comfort between PS2 and PSS.
2. PSS has better dry traction (objective data, faster time at same track) per Michelin's claim, also per user's opinions, although this is obviously anecdotal and subjective.
3. PSS does seem to last forever - very true to Michelin claim. Remarkable for such a high performance tire to have such long tread wear and I believe best in industry (tirerack has tread wear rating for comparison, where PSS is among highest for hi-perf tire IIRC). I believe tread wear is where PSS is a game changer: everyone makes high performance tire, but to make it last so long and cost so little is where this tire shines.
4. PSS is about 10% heavier than PS2. 2-3 lbs per wheel. Increased unsprung weight means worse steering, handling, braking, accel., etc. Particularly bad at outer part of wheel, as in the tire. How important is 10%? Up to drivers.
5. In US, it's unheard of to have problems with warranty claim from using non N Michelin tire. I could be wrong but I would be shocked if there is such a confirmed case, based on non N tire alone.
6. PS2 is being phased out. If you have a non-fixable flat, finding replacement in future could be difficult.
7. PSS also has claim of special construction between inside and outside part of wheel for wet + dry handling. I believe wet performance is either very similar or might even be better per Michelin claim.

I think that all things considered, PSS is actually the better choice for reasons above. Basic tire construction doesn't change but the compound used in the construction of the tire has changed/improved and PSS has the newer technology (twaron, etc.). The only negative is the increased weight - about 2-3 lbs per weight, a touch disappointing since this is unsprung weight is at outer part of wheel, where it would cause the most harm to handling, steering, etc.

Tire Comparison R Comp (Pirelli Corsa) vs. Street Tires (Michelin PS2 and PSS)
General comments for those new to this: R comp tire is street legal, track oriented tire. They come standard in GT2 and GT3, as opposed to Turbo, which has street tire. R comp tire has 3 important characteristics:
1. The sidewall stiffness of R Comp's is significantly stiffer than street tires. Tirewall stiffness is critical because this is part of the overall suspension system. Tirewall stiffness is an integral part of suspension tuning and matching: stiffer tire means less leaning, less weight transfer.
2. The tire compound itself however is actually softer, wears much faster, and has significantly superior dry traction. The gain in dry traction is easily felt and utterly remarkable. It sticks like crazy glue and like magic. I was skeptical previously how much this gain is for amateur drivers - *NOT* anymore.
MHO: If you are nutty about motorsports, once in your life try R compound tire. This one should be on everyone's bucket list. :-)
3. Very poor wet traction and actually dangerous when it's wet. When it rains, all bets are off with these tires - you must slow down or better yet not driver at all IMHO.
4. When new, the Pirelli Corsa was reasonably quiet and not too stiff, but as the tire aged, it did become extreme noisy on freeway and was quite a bit stiffer.


Tire Comparison Bridgestone RE 11 (EDIT 2019 - replaced by RE 71R) vs. Michelin PS2 and PSS
RE11 is stiffer than PSS, about 1/2 way between PSS and cup tire with respect to stiffness. The stiffness reduces ride comfort a little bit (I think it would be fine for 95% of people with stock suspension and 90% of people with Bilstein :-).) but makes handling and steering so much more precise and fun. Body roll is reducing noticeably compared to PSS. The key is that the reduction in body roll makes the car corners as if it is on rails. This is the best my car has ever felt when it comes to steering and handling, short of the Pirelli Corsa cup tire (which I don't want to use because it is so dangerous on wet roads and so costly). Really, the car corners *beautifully* with these Bridgestone babies.

Road noise is about same between RE 11 and PSS. Traction is close enough that without instrumented, professional-level testing, I doubt I could ever tell a difference. Wear: I don't expect RE11 to last nearly as long as PSS, which IMHO is a game changer with respect to performance tire: 20k miles in my Turbo - unprecedented.

Before you run out and order these tires, please note my bias: I place handling above all so I tend to sacrifice comfort a little more than normal people . I also live in a hilly/mountainous area so body roll has to be minimized for my taste. If you find yourself with same preference, I would recommend them without hesitation. I think of RE 11 as cup tire with less dry traction, but without the wet road danger ;-). Cheaper, sporty, SO MUCH fun!

 

Tire Weights

In motorsports, if there ever could be a reasonable generalization, it would probably be about weight; "weight is the enemy of goodness." The idea of lightness is king is particularly important where the weight is unsprung and rotational force is involved. In other words, better to gain weight at the frame (sprung) than at the wheel (unsprung), and better at the wheel (unsprung, inside) than at the tire (unsprung, outside). Angular momentum is proportional to radius - tire is the worst place for you to gain weight as it is furthest from the center of the wheel.

Note that while we know that unsprung weight is bad, whether anyone could feel say a 10% difference in weight - I leave it up to you to decide. The number in bold are the weights of one front plus one rear tire.

Michelin Cup (R comp): front/rear 20/27 = 47 lbs
Pirelli Corsa (R comp): 21/26 = 47
Continental Extreme Contact DW: 21/28 = 49
Hoosier R6 (Race tire, not for street, 315/30-19 rear): 22/27 = 49
Michelin PS2: 22/28 = 50****
Continental SportContact 3: 22/28 = 50
Pirelli Rosso: 22/29 = 51
Bridgestone RE71R: 24/30=54
Michelin Pilot Super Sport: 25/30 = 55****
Bridgestone RE050A: 24/31 = 55
Hankook Ventus V12: 24/32=56
Toyo Roxes R888 (R Comp): 25/31 = 56
Bridgestone RE11 (EDIT: replaced by RE71 R): 26/32 = 58

(If you think there is not much of a difference. A Turbo with iron brake and RE11 will have close to 60 lbs. more in unsprung weight than one with PCCB and Michelin Cup!)

 

xxxxx

 

An interesting point about our 4WD car is that when you push that Sport button, multiple changes occur. I am sure everyone already knows that the engine and throttle response become more aggressive, less commonly discussed is that the differential also sends less power to the front wheel when you push that Sport button. The car behaves more like a 2WD car when Sport mode is on.

The result is that for me, it has been a great lesson in car's behavior between 4WD and 2WD approximation.
In 4WD (sport button off), the steering is less responsive, the car steering appears to prefer a straighter path, the front end does feel more stable, less twitchy.
In 2WD (sport button on), the steering feels lighter and more responsive to turning. The car wants to turn more (better turn-in response). The front end is subjectively more twitchy and feels "lighter."
I believe there is an explanation for the above behavior. When the front wheels are driven by engine (4WD), slipped angles increase and cause understeer (lazy steering) and poorer turn-in response.
For the above reason, I frequently drives in Sport mode (with PASM normal) because I prefer the feel of 2WD steering. I should note that the car, and the front end, do feel more stable in 4WD mode at high speed.

This observation is with my car as currently set up (you may or may not feel same in your car); most significantly is the slight toe-out and front negative camber that my tuner has set up in my car to improve turn-in response.
I continue to learn and have so much fun with the Turbo - it has a very precise suspension system that allows me to note little changes in car's dynamics. I think that is why I am so in (blind) love with Porsche, despite of the rather high cost of repair and maintenance.

 

Can, just had my car aligned Friday and it has definitely changed the driving dynamics. Went from med setting on the HR sways, to med front and stiff rear. Squeezed out .1 more neg camber our front to a total of -1.1. Rear is set to -1.9. Major change was to the front toe, went with neg (toe out). Definitely can feel the car has less understeer.

Looking to get a bit more negative camber up front after my first DE event. Thanks for the advice.

 

You're very welcome!

Re. front camber, I don't know what else you have installed in your car, but with stock component the most you could get is -1.1 or -1.2, where you already are. If you want more than this, I think you'll need front camber plate like this from Tarett: http://www.tarett.com/items/996-997-...lta-detail.htm
Do keep in mind large negative camber is great for taking high speed corners at the track but adversely affects straightline traction. In other words, straightline braking and acceleration are adversely affected with high negative camber setting. What's good for cornering (neg. camber and toe-out or in settings) is not necessarily good for straightline performance, which really wants no camber, no toe, just a straight set of wheels! For a street car/daily driver, IMHO -1.1 front camber is a good compromise.

Re. front slight toe-out: Glad you like it! This is one of Tom/Lucent's secret recipe in tuning the Turbo and I hope he doesn't mind my sharing it with other enthusiasts ( hi Tom).
Our Turbo, in comparison to GT3/GT2, has very "lazy" steering. This weakness drove me nuts and the slight toe-out alignment is just the perfect solution as it improves turn-in response. The handling is now perfection and I @@@love@@@ it.

 

As far as the front, I'm ok for now as I really enjoy the improvements in turn in, but the track will definitely provide the ultimate feedback. Agree as a street set up it is great, just have to watch that rear now as it wants to come around a bit more (disclaimer, all tests were done on a closed course, thanks PSM) Note I'm still running my pretty/heavy 20's, I'll provide some additional feedback once I get the 19" OZ's w/ MPSS mounted.

Again thanks for the posts and advice.

 

Eurotom & Cannga, adjustable control arms first then camber plates. More than likely the camber plates will be overkill unless your main focus is tracking.

Eurotom, when and where is your first DE?

Cannga, thanks for all the kind words....I'll keep you posted on my never ending journey! Alignment number four is just around the corner....next event is on May 20th.

Best,
VID

 

Thanks VID, will see how things feel after my first session. I'm working on May 19 @ LS.

Question how do you deal with the sound restrictions, wondering if I should be concerned with my tubi street version exhaust.

 

Are you attending a 90, 92, or a 105db event?

If a 92db you should be fine with a Tubi Street system. To be safe you just need to hug the inside of T5 while exiting, short shift, and track left up the hill. You can get back on it just before the bridge while approaching T6.

Regarding your suspension set-up, you'll be fine until your skill sets improve and you start prematurely wearing out the outside edges of your tires versus the insides.

I'll be there on the 20th...105db date!!!!

Have fun and be safe!

VID

 

Thanks for the great comparison! I just installed a set of MPSS tires on 18" wheels (went with 235/40 and 285/35) and tried them out at Thunderhill Raceway. I thought they performed well -- although I had a bit more PSM action either due to the tires or the track. Unfortunately, I couldn't compare since it had been 10+ years since I've been at that track. I'll have more of a direct comparison with MPS2s at my next track day (either Laguna Seca or Sonoma).

 

Beautiful stance on the OP's set up i'm thinking just a plain lowering springs set up when my build is finished either Bilstein or H&R. I'll be basically street driving and occasional road course and drag scene.

 

 

You are very welcome. The PS2 is being phased out anyway so my comparison is almost a mute point, but it's good to know. PSS is very sticky. In case you haven't already tried, once these PSS wear out, for the track you might want to explore some other tires with stiffer sidewall, such as Bridgestone RE-11 (a street tire), or Toyo Roxes R888 (R comp tire - not good for wet road but should be fantastic at the track). The stiffer wall of these tires should improve body lean and therefore handling.
This is the advantage of being a Turbo owner - suspension so precise that one could easily tell difference between tires. Don't think I could do this in my Lexus LOL.

Thanks. I enjoy taking pictures of this baby; post another one above. If you are going to use lowering springs, I would suggest to consider GMG or Techart. Both of these have stiffer spring rates than H&R and therefore will help with the excessive body lean of the stock Turbo and make the car a lot more fun to drive.

 

^^^ up2: Awesome image!