The Michelin rep. told me to start with 36 rear, less in the front.

 

Seriously??

 

I'm running 36 all around on my Pirellis, would do the same if I got the Michelins.

 

What is the purpose of 36 all around?

Doesn't that give you even more understeer??

 

curiously it didn't give me as much understeer as running 32/38. Yet to go out on the track with the 36/36 pressure but on the street it felt better..

 

Any tire will gain 1 psi for every 10 degree increase in temp. over ambient. So, if you get into your car on a 70 degree morning and run your tires to 150 degrees, they will increase about 8psi. Same reverse if cold. If you are running stock sizes, run at Porsche recommended PSI.

 

Well said, they all have their comprimises. Check out our test results.

http://www.tirerack.com/tires/tests/mi_ps2_nextGen.jsp

I have driven all of these tires, and with the exception of the Cups these have the best road/track grip I have ever been on.

 

Damon,

Will tirerack's insurance policy cover both tires on same axle in case one tire goes?

 

No. Our road hazard is priced per tire. If you blow one out, the coverage is for that tire only. We always recommend replacing tires in pairs, too unless they are within the first 2/32nd.

 

Damon..since many of us have done (or are going to do) a plus one up to 19's...what do you recommend we run for tire pressure? The vast majority of us go with 315/25-19 rear and 235/35/-19 front. Also, since my cold tire pressure is typically done at around 85 degrees and I have no idea how hot the roads actually get, is there any adjustment that should be taken into consideration? TIA for your insight.

 

If you start with the porsche recc pressire of 44 rear you'll be over 50 hot, even in normal freeway driving. That seems wrong. On the record the tire manufacturers and retailers have to stick with Porsche's reccomendations. Off the record they'll tell you different. There is a fear of lawsuits, and they don't want to contradict their big customer (Porsche).

 

Why would Porsche say to run 44 in the rear if they know it's going over 50 psi when hot and that was too high? Apparentely they don't think it's a problem??

 

Porsche knows they will go over 50 psi hot, it's OK. Let's back up here so I can clarify..........

Tire manufacturers know that tires will usually gain 6-10 psi from cold pressure as they warm, and build that into the tires. Also, the car manufacturers know the tires will gain pressure, too. The max inflation pressure is listed as the COLD pressure. One thing to remember is the tire construction allows for the difference in inflation. One thing to **NOT** do is to lower a tire's cold pressure so it will "build" to the sidewall's max inflation pressure as it warms. The tire at cold pressure will be underinflated, damaging the sidewall because of too much deflection. You CANNOT underinflate a tire this skinny without damaging the sidewalls.

 

[QUOTE]Originally posted by damon@tirerack
[B]Porsche knows they will go over 50 psi hot, it's OK. Let's back up here so I can clarify..........

One thing to **NOT** do is to lower a tire's cold pressure so it will "build" to the sidewall's max inflation pressure as it warms. The tire at cold pressure will be underinflated, damaging the sidewall because of too much deflection.


Now You have it.

Thanks Damon

 

Damon
I've been taught to have a 'target pressure' for the tires you are using For me, with MPCs in stock size, it is 36F/32R. When I track the car, I start with that pressure and after each 20 minute run, I reduce pressures to 'target pressure' and go out again. After two and three runs I find that the need to reduce pressures less.
Is this a proper way to set pressures?