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    Correct tyre pressures?

    I have TPMS which has proven to be a really useful option to have.

    I usually prefer a partial load which, for cold tyres, is 2.3 bar (front) and 2.7 bar (rear) according to the owner's manual (for 19 inch summer tyres).

    Recently, the weather has been especially cold in London at night (sometimes the minimum temperature overnight falls to as low as 3 degrees Celsius).

    As such, I sometimes get a reading first thing in the morning of 2.1 bar (front) and 2.5 bar (rear) even though my tyre pressures were adjusted just a couple of days ago by my local dealer (albeit once the tyres were already warmed up by my journey to the dealership).

    As soon as my tyres have warmed up to normal operating temperature, they are at 2.3 bar (front) and 2.7 bar (rear) again. (But these are supposed to be the levels when the tyres are cold). The fact that they were set when the tyres were already warm is what appears to be causing this.

    How do other rennteamers here ensure that their COLD tyre pressures are correct according to the owner's manual? Do you simply overinflate by 0.2 bar when the tyres are already warm so that they are at the correct pressures when the tyres are cold??

    Re: Correct tyre pressures?

    I'd suggest that you over-inflate your tires during winter. Look at the pressure guide (sticker) that appears when you open your door, and inflate the tires to the second level (mine says 37 and 43). Ride becomes a little harsher, but handling improves and wire tear decreases.

    Re: Correct tyre pressures?

    Remember TPMS is notorious for being off a few pounds!
    I have trouble getting fronts or rears to match in pairs.

    Re: Correct tyre pressures?

    Quote:
    Oxonian said:
    Look at the pressure guide (sticker) that appears when you open your door, and inflate the tires to the second level (mine says 37 and 43).



    Wonder why your '06 C2S door sticker says 37/43 and mine says 37/44? US vs. ROW model?

    Re: Correct tyre pressures?

    And mine say's 33F and 39R for 19". these are for Pirelli's. The door sticker numbers are not for the MAXIMUM pressure but for normal day-to-day pressure: it's easy to misread. I check the pressures when the tyres are cold and adjust to suit the outside temperature.

    Re: Correct tyre pressures?

    Mine is 33/39. I think you can get max tire life at 33/39

    Re: Correct tyre pressures?

    Strange actually - the manual says 33/39 and the door sticker says 34/40. Not much difference really. I tend to go for 34/40 and always check them when car has been stationary for at least 3 hours.

    Re: Correct tyre pressures?

    Mine sticker said 33/39.

    Re: Correct tyre pressures?

    Quote:
    uzj100 said:
    Quote:
    Oxonian said:
    Look at the pressure guide (sticker) that appears when you open your door, and inflate the tires to the second level (mine says 37 and 43).



    Wonder why your '06 C2S door sticker says 37/43 and mine says 37/44? US vs. ROW model?



    My '06 C2S inside door sticker also says 37/44 for a fully loaded vehicle (equipped with 305/30 19s on it--same size a the C4S which might explain the discrepancy of 43 versus 44 pounds mentioned above). There is also a discrepancy with what it says in the manual--it says 36/44. The sticker does not list a pressure for a "partially loaded" vehicle. The manual states 33/39. A yellow sticker that is next to the white sticker inside the door states that the tire pressure can be maintained at the partially loaded value as long as the weight of people and luggage does not exceed 160kg/352lbs. This is the approximate weight of me and my wife so I have been keeping them inflated to the fully loaded value (37/44). I guess that they are slightly overinflated when I am by myself but I believe that it is better for them to be a little overinflated than to be underinflated (when I have a passenger with me).

    Re: Correct tyre pressures?

    Quote:
    uzj100 said:
    Quote:
    Oxonian said:
    Look at the pressure guide (sticker) that appears when you open your door, and inflate the tires to the second level (mine says 37 and 43).



    Wonder why your '06 C2S door sticker says 37/43 and mine says 37/44? US vs. ROW model?



    you're correct...its 44, not 43....

    i prefer fully-loaded pressure during winter....i'll deflate in summer

    Re: Correct tyre pressures?

    You should inflate your tyres when the outside temparute is around 18 or 20 degres. That would give you the most accurate base.....but hard to do in winter, unless you are in a garage.
    Then , after a cold night it is normal to have a drop in the pressure, same as a rise when tyres heat up.

    I do not worry too much anymore and trying to have them set perfectly..... specially when ' only' driving on public roads in winter.

    Re: Correct tyre pressures?

    33/39 is written on my sticker.
    When the car first came, The pressures were 35/44 which was too stiff; on the second day I made the pressures 33/39 which softens the ride. In summer I'll make rears 37 at COLD.

    Re: Correct tyre pressures?

    How do other rennteamers here ensure that their COLD tyre pressures are correct according to the owner's manual? Do you simply overinflate by 0.2 bar when the tyres are already warm so that they are at the correct pressures when the tyres are cold??



    I have an option that may not be available to you. First I use a very accurate tire pressure guage to check the tires when cold. If extra air is required I have a air compressor in my garage to inflate the tire(s) as necessary. I generally check my tires every week or whenever there is a large change in ambient temperatures.

    You may have to overinflate your tires prior to putting the car away for the night then checking them in the morning before setting out. If you have the "no spare tire" option you probably have a compressor in the boot which you could use to inflate your tires if required.

    Frankly, the TPMS IMHO is only useful in telling you that a tire is leaking air as you're driving, and is neither a reliable nor an accurate way of measuring tire pressures.

    Some simple principles

    I may be way off but this is what I do. If I'm wrong please correct me!

    "Cold" pressures are typically standardized at 70F.

    Work on 1lb pressure for every 10F change in temperature.

    So if the garage temp is 70F and the outdoor temperature is 60F then you need to add 1lb pressure to each tire to compensate.

    So at 40F you would need to add 3lbs of pressure to each tire to compensate.

    Simple!

    Re: Some simple principles

    Just came back on vacation and need to put air in.
    Am I reading something wrong here?
    My door sticker says 41/44 psi

    It is so much higher than what you guys are reading.
    I have a '06 with 19 inch tires

    Fully loaded

    Quote:
    kw sofadv said:
    Just came back on vacation and need to put air in.
    Am I reading something wrong here?
    My door sticker says 41/44 psi

    It is so much higher than what you guys are reading.
    I have a '06 with 19 inch tires



    I'm pretty sure you will find when you read the small print that this is for the car fully loaded. Check in the instruction book for the correct partially loaded pressures, and if still in doubt call the dealer service department.

    Re: Fully loaded

    On my P2's pilot sports, I do 44 in the back and the 37 in the front...ready to race me anyone!!!!!!!!!!

    Re: Fully loaded

    my dealer always give the tires,
    2,5 front
    3,0 rear

    2,3 and 2,7 is more comfort.

    Re: Correct tyre pressures?

    I have TPMS, and based upon experience in using the TPMS, here's how I set my tire pressures. I have followed Fritz's advice about "trusting German technology" on the TPMS and usually don't set my pressure according to the electronic gauge that I still use. I use the TPMS system to set the pressure.

    You program what season you are in and what tire size and load size you are running in the computer.

    I check the TPMS before running the car to see whether or not I am at the specified tire pressures for all the tires (you need to insert your key and turn it to the right to activate the computer). If all my readings are "zero," I basically have the right amount of air in the tires.

    After running for a while, the pressures, as you state, get up to the recommended levels. These readings of the TPMS while the car is running are quite accurate, and I notice that in the handling of the car.

    As an aside, if some tires run at a pressure above the other similar tire (front versus front and rear versus rear), upon returning from a drive I do a little "fine tuning" and let a small amount out of the one that runs a bit high (usually 0.1 or 0.2 lbs, as measured with an electronic gauge).

    The next time I run I check the TPMS to see if all the tires are inflated properly. If I get the "zero" reading from the TPMS I know I have basically not altered the air level to any significant extent as far as the initial computer reading is concerned, but I have changed the pressure enough so that all front and all rear tires are usually at the same pressure reading that is given while I am driving.

    Hope I haven't confused anyone, but I think that while this is a more time consuming procedure, I am able to take full advantage of the TPMS. Maybe I have taken a leap of faith, but while driving the car handles better.

    Jim

    Re: Correct tyre pressures?

    This subject is still a little puzzling for me.
    Our cars are all made in the same plant, and they don't make that many comparing to other manufacturers.
    So why is that we have stickers on the door that say different things?

    On top of that, mine says 41/44.
    Le Chef said that's for fully loaded.
    May be that's true, but my manual said 33/39 with 2 persons, 36/44 fully loaded.
    So why the differences between the sticker and manual?
    Can't Porsche come up with one standard?

    In my mind, this is an important issue since this is a high performance car with
    no spare tire and 19" wheels. Tire pressure should be accurate.
    Someone, please enlightens me.

     
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