Full car with 4 passengers? A rare occasion but that would still be only an extra 100 lbs. in a 996: two kids @ 40lbs each and a 20 lb suitcase in the frunk! Not enough to change tire pressures for.

 

Thanks for taking the time to respond everyone!

 

With 2 people onboard the pressure should be 34/36.

 

I'd also tend to stick with factory specs ... but I did wonder why on other cars they recommend higher pressure when running 100MPH+ (Mercedes for example) - so does that mean Porsche only specs for high speed - and does not have a low speed spec (for better ride) ? At a AutoX I went to , many owners ran their tires at a slightly lower spec for better grip (but this is also low speed). If you go too low you run the danger of cracking the rim - like the picture above. I dropped my rears to 42, and have been running like that for a while - with no apparent problems (I run 265/35-18 on the rear - which is the a/s spec) - but I think Thundertub gives the best advice here ....

 

36/44 is WITH A FULL LOAD, 4 PEOPLE and luggage. Read the manual.

 

Unbelievable!

I should have never posted in this thread:

 

17" & 18" Tire OD dia is the same, 1" larger rim = lower sidewall = less protection for the rim.

 

ouch, Daredevil - just discover it?

 

I would not change the recommended tire pressure because of a harsh ride (you may need to change tires at your next opportunity instead). We get to 80mph without even realizing it...

 

I run 36/44 in my 19's. Ride is, lets say.....stimuating with lot's of feedback from the road surface.

 

I run much lower then recommended. I can't deal with the bumps on our roads, just way to bumpy. If I plan on driving long distance on the highway, I'll boost it up a bit...

 

Yep!

 

36 front, 44 rear. No issues here.

 

That's happened to each of my rears from pot holes however I really suspect shops that install the tires weaken the rims over time.

 

Yes, this. Anyone who frequently autocrosses can tell you that Porsche's spec alignment & tire pressure suck for performance. They're very clearly intended to produce safe, boring, predictable understeer to keep trophy wives out of ditches. Rear tire pressure/alignment is, in my experience, pretty close to optimal- Porsche's compromise here is to favor excellent grip at the expense of tire wear to prevent the rear end losing grip before the front. Front tires at OEM spec, however, are very undertuned. Rather easy to increase air pressure and test on the skidpad until optimal. You don't even need a real skidpad, just find a parking lot and drive in circles; keep adding more pressure 2psi at a time until you find the sweet spot. Wider than OEM tires helps, too, as does as much negative front camber as you can get (it still won't be enough without camber plates or adjustable lower control arms). And yes, I did stay at a Holiday Inn Express once. Several times, in fact!

Honestly, I'm always amazed at people complaining about firm ride or tire noise. You do realize you're driving a Porsche, not a Cadillac, right? Of course, if you drive like a trophy wife (if you're complaining about ride comfort, you do, admit it!!), then you probably want to stick with Porsche's recommended pressures.