Please refrain from telling me to read the manual or do a search of the articles.

Here is the scenario. I have a 2008 CS with 19" Carrera S wheels and I live in Brooklyn with its varied road surface quality. What should my cold tire pressures be front and back?

Right now I have my front tires at 30 psi and my rears at 33 psi when cold, and after they warm up they gain about 3 to 4 pounds depending on the conditions.

Thoughts? Comments?

Comment: You don't want the advice in the manual or the advice of previous experience because?

Maybe there is no thread about running such low tire pressure anyway.

My thought: You're trying to bend a rim and break a steel belt in a pothole so you'll have an excuse to buy new wheels and tires.

If the roads are as badly maintained as they were when I lived there, I'd run 32F - 36R to better protect your wheels from potholes.

PS I don't follow the recommended pressures in the manual so I won't tell you to RTFM.

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Dan

I think the general consensus is to run recommended pressure or 1-2 psi over. With the low pressures you're running, you run the risk of rim and sidewall damage if (when) you run into a pothole at speed. My wife has done that on the Belt Pkwy in the Volvo. She said changing the tire was not fun (at least there was a spare)!

Yeah, run it 2 psi or so higher all around. 19" rims are so easy to damage with our roads unfortunately.

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Pete
2008 Meteor Grey CS, PASM, Chrono, Sport Seats, Sport Shifter, Sport steering wheel, Xenon, Fire Extinguisher, Auto Climate and clear bra!
2007 Blue Slate Infiniti G35s 6-speed

Does running with increased tire pressure also increase the chances of a bubble/blow out? I had a bubble within my first month of having the car hitting a crater doing ~30mph.

I dont know the physics behind a bubble but i suspect because the tire squeezes so close to the rim that the air that was in that space needs somewhere to go so it bubbles the sidewall out? (i know that a 300 dollar tire is cheaper to replace than a 700 dollar rim but im just curious)

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-06 Cayman S Guards Red
Thank you to the old people who put no miles on their porsches and trade them in.

I noticed a similar reading. I have the 19" carrera sport rims and get a reading of 30f/34r when cold. The tires are spot on ( 32f/37r) before I run the car though.

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Success usually comes to those who are too busy to be looking for it.

I'm with Jophus on this one. I thought running higher psi would *increase* the risk of wheel and sidewall damage.

As stiff as the sidewalls are on these modern tires, I'd think they'd have to be about flat before you should be concerned about rim damage.

One of the reasons we're now blessed with TPMS is because people couldn't tell when a tire was flat while travelling straight down the road!

If you like how your car feels with those pressures, then no worries.

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2008 Cayman 2.7
2006 Mercedes-Benz CLS500 (Wife)
2007 Jeep Commander (Son)
2000 GMC Sierra Truck

Not by anyone who cares about handling.

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Dan

A sidewall bubble is the result of a physical defect in the tire in which the sidewall plies separate. It is usually caused by manufacturing defects or impact damage where the sidewall gets pinched between the wheel and the object impacted, e.g., a pothole. Higher pressure will reduce the likelihood/severity of pinching.

Setting pressures is a compromise between many factors to meet one's priorities. Mine is handling above tread wear, fuel economy, noise, comfort and impact protection. What's yours? For that matter, what was Porsche's in setting its recommended pressures?

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Dan

Here's the thing about manufacturer's recommended tire pressures (that are usually on a plaque in the door jamb)... they are supposed to be set to these pressures when stone cold. The manufacturer allows for the fact that ambient temperatures and running the tires on the road will bring the pressures up. These cold pressure figures are not meant to be a target pressure for when the tires are hot from use. If you use them as a target pressure for when the tires are hot, your tires will be quite under-inflated.

That said, these cold pressure recommendations are just that - a recommendation. They are considered a good starting point for when one wants to set their pressures according to their individual priorities such as wear, handling, etc., as Dan has listed above. But, it would be unwise imo, to start out with your tires under-inflated by 4-5#.

brad