Stradale Tires: Chunking Problems? Pressures?

Robin, my 44 yr old brother in law also is a hard core bicyclist, mountain and off road variety. I once found him reading an article on "how to fall." He has more equipment than I could have ever imagined, exactly as you describe. Do you suppose chess players spend their spare hours searching for carbon fiber boads, etc?

 

Brian,
I have Pirelli P-Zero corsa's (245-18 f, 295-18 r) on my '99 Modena and have tracked it pretty hard a few times. I experienced the same problem on my front-left (mostly right hand turns) due to too high pressures. 35psi cold is too high. I had better success starting at 29psi (on a cool day) and building to 39psi hot. The chunking has not repeated in two different track days, albeit not at the same track. After a hot session check pressures and bleed down to 39 psi hot all around. Check again after the next session etc... I found my left rear tended to build more on a track with a lot of right turns.

Best of luck with the Stradale!

John B

 

can you post pictures of your tire - I have not run into problems so far - Pacific Raceway - rain in the morning / sunny but cool in the afternoon - see picture after half of session - tire pressure or track surface would make sense to me as reason

 

5k miles - several track days - front right done - I think I need a second wheel/tire set - found the following (tire pressure recommendations):
...........................
Pirelli P Zero Corsa
The P Zero Corsa has replaced the P Zero C as the dual-purpose road and track tire in Pirelli's lineup since its launch this spring and is available in 13 different 17- and 18-in. sizes. It benefits from many of the construction and compounding technologies developed for the P Zero Rosso, which was introduced in 2000. Unlike that tire, however, the P Zero Corsa eliminates the compromises that must be made for comfort and low noise levels in a street tire in favor of maximum grip and the handling performance competition drivers require.

Pirelli states that the P Zero Rosso's construction technologies lead to all-around improvement in "on-limit" characteristics in both wet and dry conditions versus the P Zero C. The P Zero Corsa's tread is both asymmetric and directional. The long, directional grooves in the center of the tire maintain safety and performance under wet conditions but end before the outside shoulder for maximum cornering performance and durability. The P Zero Corsa's compound is designed to maintain its durability and grip characteristics at higher operating temperatures than either the P Zero System or P Zero Rosso.

Relative to the P Zero Rosso, Pirelli states that the Corsa excels by about 10% in braking, 20% in grip, 5% in wet handling and roughly 15% in "hard handling," a term used to describe a tire's behavior at the limit on dry pavement. The P Zero Corsa can be safely driven to and from the track, given sufficient remaining tread depth, but is not recommended for daily street use because of its roughly 15% less hydroplaning resistance and dramatically reduced tread life compared to the P Zero Rosso.

The P Zero Corsa System was developed for use as original equipment on the Ferrari Challenge Stradale version of the F360 Modena, bringing the benefits of the P Zero System concept to the Corsa. The water-ejecting Direzionale is sized 225/35-19, for the front, and the traction-delivering Asimmetrico is sized 285/35-19. The P Zero Corsa System matches the P Zero Corsa in braking, grip and wet handling with just the slightest reduction in "hard handling." However, it matches the O.E.-friendly P Zero Rosso in hydroplaning resistance and nearly matches it in noise characteristics, while just slightly beating the regular P Zero Corsa in comfort.

Pirelli states that the P Zero Corsa is designed to offer its full performance characteristics at the starting tread depth, so most users should have no reason to shave it. Pirelli doesn't recommend high running pressures for the P Zero Corsa, instead stating that it should typically be run near 2 bar, or about 29 psi. Pirelli suggests setting initial pressures about 6 psi below the intended running pressure, going on the track for three to four laps to get the tires to operating pressure, then pit and immediately adjust pressures to the desired level. Of course, testing will be required to determine the ideal operating pressure for any given vehicle and/or driver.

 

I've experimented with different hot tire pressures for the Corsa's (albeit in a GT3 rather than 360) and agree with Pirelli's recommendations to run lower pressures. I found the Corsa's to get a bit slippery above 36 psi hot (I target 32/36 psi hot with r-compounds in the GT3).

I've been running MPS Cups on the 360 and have found good grip with 32F/30R hot pressures. I typically get a +8 psi gain so the starting cold pressures are very low.

 

CS best track car I can think of but the P Zero Corsa’s stink – I did use the tire pressure recommendations I posted before – don’t

I had the hope that I could get another track day out of the tires but it turned into some kind of struggle – I did spin three times... - I have not analyzed the data logger results yet but I am sure the tires are the reason - see picture

I have bought new P Zero Corsa’s because I was unable to find another tire – the only one was - I believe - a Goodyear track tire that would not work for the car’s weight – did anybody have more luck especially in the EU?

 

I'll be running on a set of shaved Corsas at the Glen next Mon and Tues, and will let you know how it turns out. I found the same info about pressures - notice that it says that "most" users won't need to shave the tires. I wonder what that means ... I know that less experienced track day drivers won't brake/turn as aggressively, and that is much easier on the equipment.

My plan, depending a bit on conditions, is in the first session to get the brakes hot and not worry about the tires, then in the second session to try to get the tires good and hot, then let the car sit for a while. Perhaps too cautious, we'll see.

 

You are at the limit is the tire just starts to slide - that’s when the heavy wear occurs - I always say I am taking it easy - not going to happen with the CS

I have calmed down about the tires from yesterday – I assume that I drive them outside of the range they have been designed for – it is simply annoying if the margin of error is zero – the tires still pull nice g’s for the state they have been in – what we need is a real track tire for the CS

 

Brian, Thomas,

I am tracking my CS in about two weeks. Any definitive numbers on tire pressures? There have been a lot numbers bandied about on this thread and was wondering what your latest suggestions are for cool and/or hot days. Also, ASR should be disabled to save the rear brakes, correct?

thanks

Paul

 

Don’t have a good recommendation since I struggled with the tires all the time – although my lap times have been great I felt that the tire behaved inconsistent – I ended up with a reduced pressure of -3PSI (cold/cold) at the end – most of the chunking occurred in the low pressure range; once I went higher the tire stabilized

 

it is a fun car isn't it - by 32psi do you mean all around or front?

I would guess the delta is more like 6-8psi if the tires are hot – however my guess is that the tire actually requires > 32 psi – I wonder if the chunking has to do with age/#of heat cycles – I did not have problems before the last track day, but I also was not pushing that hard

I have a shaved tire set on order and hope to run it next week – I did talk to Pirelli and F and it looks like the P Zero Corsa is the only choice – factory considers my tires and tire wear “normal” – seems to be that folks use one tire set per race/track day – I ordered a second wheel set from F since running shaved tires in Seattle seems risky

 

>The 32psi is measured "pretty hot", not "cold"……
yes I overlooked that – pressure increases 6-7 psi from cold

>get the oil temp back to vertical...
do you see temperatures over 230F ? - I have never gone above but I have not seen outside temp. > 85F - I run 10X-60 now for ease of mind although it makes warm-up a pain; very higher oil pressure until 175F

not sure if driving around slowly has a big/positive impact? - I do a cool down lap + run it for a few minutes to distribute temperature evenly before shutting down

 

Posted tire temps and pressures from my Watkins Glen track day here:

http://ferrarichat.com/forum/showthread.php?t=21314

I'll post pics of my tires etc tomorrow when I'm home. Started with shaved tires, it looks as though I've got another day or two left on them.

I saw temps slightly over 230. I also cool down a fair amount - did slow parade laps of the paddock after each session.

Think we need to find some slicks or near slicks.