The temperature in New England has dropped about 25 degrees F between September and October.... so I attribute some of the pressure drop in my fronts to this...but another P-car owner told me he needs to fill his 19" tires quite frequently. Is this true? How often is "frequently" for the other daily drivers out there?

Also, what PSI do folks put in their fronts in the the Fall Months in cold weather states? (997 C2S w/ 19")

-M

 

There are explanations at Tire Rack about the rise or drop in tire pressures relative to ambient temperature. I believe that once a tire is properly inflated it is not going to lose any more air at cold temperatures than at higher ones; obviously if you fill it with hot air (like my post?) it will drop some when it cools down. Lastly, and most important, certain Porsche tires should not be used when the temperature is going to be below 40F, so check this out.

 

If you have to refill a tire more than once a month there might be a small leak. I've heard that 10 deg F equates to 1 psi. Regardless, once the pressure drops and is stable, you should only have to fill them once to have the proper pressure at that temperature (and then perhaps every 3 months to account for any normal leaking/deflating).

I'm in Chicago (similar weather to NE), and I'm running 32F and 38R right now. I'm thinking of dropping the pressure in the rear to 36 though to soften the ride (I hate these P Zero Rossos - they ride way too stiff and they don't grip all that well in any conditions).

 

Just curious why do you run at 32/38 when stock numbers are 37/44?

 

It rides a bit smoother and doesn't noticeably affect handling.

 

Leakage of about 1 lb per month is normal - more for older tires which become porous. For each 10 degrees, pressure change is just over 1/2lb - same for each 1000ft altitude change.

Tire should be checked at least monthly - early in the day before driving.

Good article: http://www.tirerack.com/tires/tirete....jsp?techid=73

 

Because he hates the P Zeros and wants to wear them out faster.
http://www.aa1car.com/library/tirepres.htm

 

Damn straight. I'm probably going to end up swapping them out for PS2's prematurely.

 

These are one of the ones that should not be used for Winter driving;

From Tire Rack : "
Specific design techniques, raw materials and manufacturing methods have been incorporated to produce Pirelli's most comfortable Max Performance tires. Like all summer tires, PZero Rosso tires are not intended to be driven in near-freezing temperatures, through snow or on ice.

 

I have no intention of driving on these tires once temps drop below 40. I'm trying to buy a set of 18" OEM Porsche 5-spoke wheels to fit my winter tires. Does anyone have any suggestions on where I can find them, new or used, at a reasonable price? thanks

 

19" is all about looks, if ride comfort is needed then perhaps it makes more sense to go back on 18" rims.

I saw carera classics take-off on local craiglslist couple of times, sometimes they are on ebay but there you get big chance to get cheap chinese replicas instead of original ones.

I have my 18" rims on a shelf with almost new PA2 on em already.

 

Lower pressures are discussed in the manual for less than full load and do provide a more comfortable ride without significantly impacting tire wear. If you get pressures down in the teens or twentys yes, and that is the kind of low pressure these articles reflect - many people never check their pressures. Lower pressures are also used on the track for better grip - but I won't argue tire life is not impacted on the track. Tires have a short life on the track but there is a lot more at play there then just tire pressure - extreme acceleration & braking, and sliding around the corners come to mind.

 

I have P Zeros, and while I am not a tire expert, I don't agree that they "don't grip all that well" - at least in my experience with them.

 

Tire rack in their own tests showed the Pirellis outscored the PS2's on the dry track test.

Dave

 

I bought a set of knock-off 5-spoke wheels from WheelEnhancements within a week of buying my car (they also had the Michelin Pilot Alpin winter tires so I bought the package). I since bought another set of factory 5-spoke CIII wheels from a post on another board. I used that set on the track so they are scuffed at the lug openings from putting them on and off the car, but otherwise in fine condition. I've just decided to go to 19 in wheels for track use and purchased a set (again a set of factory wheels, used). I will decide in a week or two whether to sell my factory 18 wheels.

Other sources besides the boards are Porsche Panorama (club rag), and eBay.