GreatWhiteNorth said:
I tried the P-tire once on my NSX -didn't like them. Actually the rears delaminated big time after only 4-5 heat cycles. I admit I overcooked them but still that never happened to me with the RA1s. Mind you, they were the older DOT R-compound. Perhaps the newer model is more rugged to abuse.
Derrik Hanson (who I assume Rui will aknowledge has god-like wisdom about these matters) and I had the conversation about EXACTLY what we're talking about here vis a vis a guy who approached me at a Porsche Club event and told me I had to lose my Pirellis and get Toyos FAST.
Derrik explained to me a week later that the story that he (and most of us) don't understand is the relationship between spring rates and tire sidewalls. The Pirellis are built on a street legal carcas and therefore have softer sidewalls, which is good if your spings are softer but bad if they are a lot harder than the sidewalls.
The idea is the tire is supposed to compress first to its "optimal" compression before the springs take over in a linear manner and continue to compress.
If this is all linear then the result is a very confidence inspiring ride becasue your brain doesn't have to try to process the random nature of the non-linear compression and resulting rebounding of over-hard springs actually bouncing the wheel on the pavement or the body compressing before the spring does all its work.
Now, if you have hard (perhaps too hard?) springs, then you need a tire with a harder sidewall so the compression stays linear, if you have softer springs then you need a softer sidewall.
What I started was amature-hour mechanic bullshit advice to Dave where I suggested a tire based on my experience with a totally different car with totally different spring rates, balancing, etc.
Obviously my car was set up by a MASTER (Fiorano built, maintained, and modified many leading Cup cars) but he spec'ed the Pirrellis based on his set-up math formulas.
I spec'ed Dave's Perrellis based on the fact my car runs them well.
Anyone talking about any tire should also provide their spring rates, shock brand and model as well as wheel and tire size - otherwise we're probably just proving our ignorance when it comes to deep knowledge of this technical stuff.
It would be interesting to build a chart and compare. I know my (P) car's spring rates are 150-200 lbs softer than what many guys who built their own (P) cars by feel chose.
When my buddy who built his car based on the Porsche factory specs (as recited by a guy who worked at Porsche in Germany) he used a set-up that is almost identical to mine - you'd think that Porsche's resources (including computer modeling based on all the construction data) would beat a guy in his garage talking to his pals - but these garage guys swear by their setups and run really hard tires to make sure they don't wear out.
My friend won his CASC Division last year with softer springs!
